Re: M104 / W124 Top-End Rebuild
I don't mean to pester you, but have you got that minute yet?
I don't mean to pester you, but have you got that minute yet?
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HOW-TO: M104 / W124 Top-End Rebuild [Cylinder Head / Gasket]
- Thread starter gerryvz
- Start date
Re: M104 / W124 Top-End Rebuild
I don't have the gas receipts, but the E320 wagon has had a low of 21.4 MPG and a high of 24.1 MPG, according to my online records.
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I don't have the gas receipts, but the E320 wagon has had a low of 21.4 MPG and a high of 24.1 MPG, according to my online records.
Sent from my iPad using Tapatalk HD
Re: M104 / W124 Top-End Rebuild
Is that from the trip to Texas or is that in general usage?
On the trip you were driving, correct? And in general usage the wife is doing most of the driving, correct?
Can we assume she is a more mellow driver?
Does your car have the 2.65 gears or the 2.87 gears?
Sorry for all the questions, I'm just really interested in what life is like with a HFM M104.
Is that from the trip to Texas or is that in general usage?
On the trip you were driving, correct? And in general usage the wife is doing most of the driving, correct?
Can we assume she is a more mellow driver?
Does your car have the 2.65 gears or the 2.87 gears?
Sorry for all the questions, I'm just really interested in what life is like with a HFM M104.
Re: M104 / W124 Top-End Rebuild
That particular mileage us with my wife driving. The car has the stock gearing.
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That particular mileage us with my wife driving. The car has the stock gearing.
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Re: M104 / W124 Top-End Rebuild
All the M104 wagons (124.092) in USA have 2.65 gears. The 2.87 gearset [used in all 124 chassis] is 185mm and this smaller diff was never used behind an M104. The corresponding ratio in the 210mm size is 2.82 (not 2.87).
Re: M104 / W124 Top-End Rebuild
The early (1994-1995) C36's have 2.87 gear sets. All I had to do was swap diff covers to bolt-it up to the .090 rear subframe. The C36 has the highest power of a factory M104, and I'm 99.99% sure the gearset is 210mm just like when MB installed a CIS M104 in the W124 coupe.
Because I do so much highway driving, I changed to a 2.65 non-ASR from a late E320. I also scored a 3.06 210mm diff both in ASR and non-ASR from a CIS M104 W124 coupe.
These all have 210mm gears with the rear-cover that fits the 1988 wagon's rear-subframe.
neil
The early (1994-1995) C36's have 2.87 gear sets. All I had to do was swap diff covers to bolt-it up to the .090 rear subframe. The C36 has the highest power of a factory M104, and I'm 99.99% sure the gearset is 210mm just like when MB installed a CIS M104 in the W124 coupe.
Because I do so much highway driving, I changed to a 2.65 non-ASR from a late E320. I also scored a 3.06 210mm diff both in ASR and non-ASR from a CIS M104 W124 coupe.
These all have 210mm gears with the rear-cover that fits the 1988 wagon's rear-subframe.
neil
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Re: M104 / W124 Top-End Rebuild
Neil, the C36 through 1996 model year had 2.87 ratio, however I believe it is neither a 185mm diff nor a 210mm diff. MB introduced a new diff size in the mid-90's in between the previous ones, the new size is 198mm. I'm 99% certain the C36 used this 198mm diff. It is definitely not a 210mm.
Neil, the C36 through 1996 model year had 2.87 ratio, however I believe it is neither a 185mm diff nor a 210mm diff. MB introduced a new diff size in the mid-90's in between the previous ones, the new size is 198mm. I'm 99% certain the C36 used this 198mm diff. It is definitely not a 210mm.
Re: M104 / W124 Top-End Rebuild
Yeah, the 198mm is sort of an oddball. It was mostly used on the 203 and 208 chassis, and a couple of low-powered 210/211 (210.025 diesel, 210.055 E320, 211.004 CDI, 211.006 CDI).
The W210 E420 uses the same 210mm diff as the 500E (and can accept a Quaife or WaveTrac), however the housing does not have provision for ASR sensors. Around 1995, MB moved the ASR wheel speed sensors to the wheel carrier, not the diff.
Yeah, the 198mm is sort of an oddball. It was mostly used on the 203 and 208 chassis, and a couple of low-powered 210/211 (210.025 diesel, 210.055 E320, 211.004 CDI, 211.006 CDI).
The W210 E420 uses the same 210mm diff as the 500E (and can accept a Quaife or WaveTrac), however the housing does not have provision for ASR sensors. Around 1995, MB moved the ASR wheel speed sensors to the wheel carrier, not the diff.
Re: M104 / W124 Top-End Rebuild
1996 model year on the ABS sensor move to wheels Dave.
The W210 E420 uses the same 210mm diff as the 500E (and can accept a Quaife or WaveTrac), however the housing does not have provision for ASR sensors. Around 1995, MB moved the ASR wheel speed sensors to the wheel carrier, not the diff.
1996 model year on the ABS sensor move to wheels Dave.
Re: M104 / W124 Top-End Rebuild
The W140's which shared the same diff housing changed as of chassis #A212245. I can't pin this to an exact date, but it appears this may have been mid/late 1995 (USA) model year production. It's possible that some late 1995 (USA) model year 140's had the sensor move to the wheel. However, I'm not certain...
The W124 never had the sensor move to the wheels - the sensors were always on the diff, even on very late Euro-only production cars, according to the EPC.
The W140's which shared the same diff housing changed as of chassis #A212245. I can't pin this to an exact date, but it appears this may have been mid/late 1995 (USA) model year production. It's possible that some late 1995 (USA) model year 140's had the sensor move to the wheel. However, I'm not certain...
Re: M104 / W124 Top-End Rebuild
Correct, as there wasn't a 1996 W124 in the US, at the 1996 model introduction training in Jacksonville I worked on and was trained on the new w140.
That's where my information is from, w210 as well.
The EPC does not show 1996 Euro W124 as having the wheel sensors either, so it's only the others that have it
Remember, 1996 was the big changes, ME injection on the M119, 722.6 transmission, wheel speed sensors, back up antenna/indicators delete (w140)
W210 introduction.
You keep forgetting I was a dealer technician, and I was there for the changes.
The W124 never had the sensor move to the wheels - the sensors were always on the diff, even on very late Euro-only production cars, according to the EPC.
The W140's which shared the same diff housing changed as of chassis #A212245. I can't pin this to an exact date, but it appears this may have been mid/late 1995 (USA) model year production. It's possible that some late 1995 (USA) model year 140's had the sensor move to the wheel. However, I'm not certain...
Correct, as there wasn't a 1996 W124 in the US, at the 1996 model introduction training in Jacksonville I worked on and was trained on the new w140.
That's where my information is from, w210 as well.
The EPC does not show 1996 Euro W124 as having the wheel sensors either, so it's only the others that have it
Remember, 1996 was the big changes, ME injection on the M119, 722.6 transmission, wheel speed sensors, back up antenna/indicators delete (w140)
W210 introduction.
You keep forgetting I was a dealer technician, and I was there for the changes.
Re: M104 / W124 Top-End Rebuild
Yes, I knew that. I meant to say 2.82 but had 2.87 on the brain because of the C36s that I'm always facinated by.
Speaking of C36s though, I had read that it got a new diff that was destined to be released in the then soon to be released W210 M104s that was actually a 185mm diff but with wider gear teeth (In a cost-cutting move that was typical of Benz's dark years, W210 M104s didn't get the 210mm diff.) Have you heard of this one? The 210mm diff was supposedly too large for the little W202 floorpan.
Any of the rest of you know anything about this stuff?
The 2.87 gearset [used in all 124 chassis] is 185mm and this smaller diff was never used behind an M104. The corresponding ratio in the 210mm size is 2.82 (not 2.87).
Yes, I knew that. I meant to say 2.82 but had 2.87 on the brain because of the C36s that I'm always facinated by.
Speaking of C36s though, I had read that it got a new diff that was destined to be released in the then soon to be released W210 M104s that was actually a 185mm diff but with wider gear teeth (In a cost-cutting move that was typical of Benz's dark years, W210 M104s didn't get the 210mm diff.) Have you heard of this one? The 210mm diff was supposedly too large for the little W202 floorpan.
Any of the rest of you know anything about this stuff?
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Getting ready to say "sayonara" to the jetronic mechanical injection in my 300CE, and was wondering if anyone had any experience on the best way to add a trigger for megasquirt to the M104 24v? Do later models have a crank trigger that works well, or do I need to go the custom route..... ??
Hi Gerry!
Just checking in.
Any updates on the transmission rebuild?
I had the transmission rebuilt in my old 1993 300E (3.2) "E320" in 2001 or 2002 by Sun Valley, and it cost $1,500 back then. The problem with the tranny was a very slow and hard shift into reverse.
I drove it about 50,000 miles until I sold it, and it performed like new.
Edit ----- and I just checked my old fuel economy records, and over 5 years of ownership and about 60,000 miles, I averaged almost exactly 21.5 mpg in mixed driving.
In mostly city driving I'd get about 20 mpg, and my best tank was 26.0 mpg in 100% freeway driving going to Las Vegas.
Just checking in.
Any updates on the transmission rebuild?
I had the transmission rebuilt in my old 1993 300E (3.2) "E320" in 2001 or 2002 by Sun Valley, and it cost $1,500 back then. The problem with the tranny was a very slow and hard shift into reverse.
I drove it about 50,000 miles until I sold it, and it performed like new.
Edit ----- and I just checked my old fuel economy records, and over 5 years of ownership and about 60,000 miles, I averaged almost exactly 21.5 mpg in mixed driving.
In mostly city driving I'd get about 20 mpg, and my best tank was 26.0 mpg in 100% freeway driving going to Las Vegas.
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No updates. About 1,000 miles on the rebuild and all is good - no leaks, no issues, no drama. Your MPG is about exactly what our wagon has gotten in mixed driving. I can get up to about 24-25 MPG over a long highway trip if I take it easy on the gas. 20-22 MPG in regular driving is about right on though.
Re: M104 / W124 Top-End Rebuild
Sometimes you see something on the thread and even though it's ancient you just want to comment anyway.
Ron, I like you just for knowing about that damn album !
Rum, Sodomy, and the Lash! Damn that brought back great memories. The record was pretty good too!
Sometimes you see something on the thread and even though it's ancient you just want to comment anyway.
Ron, I like you just for knowing about that damn album !
Rum, Sodomy, and the Lash! Damn that brought back great memories. The record was pretty good too!
Re: M104 / W124 Top-End Rebuild
I met my love by the gasworks wall, dreamed a dream by the old canal, kissed my girl by the factory wall, dirty old town, dirty old town… had that song in my head for decades, my favourite album ever !
I met my love by the gasworks wall, dreamed a dream by the old canal, kissed my girl by the factory wall, dirty old town, dirty old town… had that song in my head for decades, my favourite album ever !
Re: M104 / W124 Top-End Rebuild
On the topic of a leaky oil level sender do y'all posit that a high engine load, like 85mph up a sustained hill, could push enough oil out to blow back to the cat causing a lot of smoke?
On the topic of a leaky oil level sender do y'all posit that a high engine load, like 85mph up a sustained hill, could push enough oil out to blow back to the cat causing a lot of smoke?
The OM60x engines use the same sender, and I had the same leak... as you discovered, if it leaks between the plastic center and the housing, you must replace the entire sender.
If your pressure sender is original, that is likely the cause. A new one should fix it. It isn't likely to be the lower harness, nor the gauge, but you'll find out soon enough. The aftermarket Hella sender is $10-$20 cheaper via aftermarket sources, compared to parts.com, and is identical to OE.
Congrats on the successful marathon!
Re: M104 / W124 Top-End Rebuild
My G320's 104.996 also has a plastic insulator strip that fits between the wires and the coils, interestingly. The wagon's engine did not have this (or perhaps it had been removed)?Gerry, our '95 wagon had two plastic insulators (104.159.14.40) that insulate the ignition wires from the two front coils. The rear coil does not have an insulator, since it only has ONE set of ignition wires running parallel to the coil. Mine were very fragile, and broke when breathed upon. Current retail is $7.00, parts.com: $5.25
I marked-up your picture with the location of the insulator, and have included a close-up.
Re: M104 / W124 Top-End Rebuild
They are in assembly aid for the assembly line. They retained that secondary wire set into a nice tangle free falls into place" bundle. I think all of those three coil 104's have them. They are frequently AWOL. Last time I checked they were still readily available.
They are in assembly aid for the assembly line. They retained that secondary wire set into a nice tangle free falls into place" bundle. I think all of those three coil 104's have them. They are frequently AWOL. Last time I checked they were still readily available.
You give me so much material Honcho.
I was reminiscing about your head rebuild/R&R with Bob036
He came over to discuss posting on the forum again.
Touché
Excellent Write up Gerry.. Complete coincidence I came across this as just this week I finished the same job on my M104 - 3.4 AMG.
Very similar but of course subtle differences.. Mine has older style intake, but all else is very similar.
My front cover leaked initially, had to strip it all again. Seems like I didnt use the correct sealant.. Used MB sealant and it has been perfect.
Very satisfying job...
Very similar but of course subtle differences.. Mine has older style intake, but all else is very similar.
My front cover leaked initially, had to strip it all again. Seems like I didnt use the correct sealant.. Used MB sealant and it has been perfect.
Very satisfying job...
Re: M104 / W124 Top-End Rebuild
We're your insulators intact ? I'm ordering with my next order from Lionel . . .
neil
We're your insulators intact ? I'm ordering with my next order from Lionel . . .
neilM104 / W124 Top-End Rebuild
This is enormously helpful, thank you! I am planning to dive into replacing the head gasket on my W124 (M104.992) soon. In the attached pic from post #147, the water outlet hole in the front cover seems to be missing an o-ring. Is this correct? If so, is this o-ring included in the Elring head gasket set?
This is enormously helpful, thank you! I am planning to dive into replacing the head gasket on my W124 (M104.992) soon. In the attached pic from post #147, the water outlet hole in the front cover seems to be missing an o-ring. Is this correct? If so, is this o-ring included in the Elring head gasket set?
Attachments
Re: M104 / W124 Top-End Rebuild
Regarding post #160, specifically about re-installing the exhaust manifold, did some of the bolts come out of the head rather than the nut coming off of the bolt? If so, do these bolts need to be replaced and is adding some thread lock to the block portion of the bolt helpful for future manifold removal?
Did you torque all of the nuts? If so, how did you pull it off with some of the underside nuts? Thank you, again!
Regarding post #160, specifically about re-installing the exhaust manifold, did some of the bolts come out of the head rather than the nut coming off of the bolt? If so, do these bolts need to be replaced and is adding some thread lock to the block portion of the bolt helpful for future manifold removal?
Did you torque all of the nuts? If so, how did you pull it off with some of the underside nuts? Thank you, again!
Re: M104 / W124 Top-End Rebuild
Please see below, copied directly from post #147.
And also elsewhere in the HOW-TO:
Evidence of my purchase and utilisation of an MB head gasket kit is below, as found in my parts list.
Please see below, copied directly from post #147.
And also elsewhere in the HOW-TO:
As I remember it, yes, the head gasket kit does include the water pipe o-ring. I also recall that I obtained an MB head gasket set for my M104 top-end refresh, not an Elring-branded kit. Elring did manufacture the head gasket for MB, but the head gasket kit itself that I purchased, was very definitely an MB kit, shipped directly to my home from MBUSA parts warehouses.
Evidence of my purchase and utilisation of an MB head gasket kit is below, as found in my parts list.
Re: M104 / W124 Top-End Rebuild
As I remember it, all of the exhaust manifold bolts (studs) remained embedded in the cylinder head, except one that came out as a unit. I did not replace the studs, although I did replace all of the nuts with new MB copper exhaust nuts, per the factory manual. I did not use thread-locker as I remember, because of the high temperatures involved at the engine block, which would probably "bake off" any thread-locker used.
There is no torque specification provided by the factory manual for either the M104 or the similar M103 engine. It does specify that all of the copper self-locking (ovaled) nuts be replaced when the exhaust manual is re-installed. You want to make sure the nuts are well tightened down. None of the nuts are extraordinarily difficult to reach, and this is rather easily done with a combination of ratchets, extensions and "wobbly" joints found in most tool-boxes.
Thanks for these clarifications and extra pics. Definitely helpful in having the confidence to do it right. Speaking of doing it right, in your opinion, is there a significant quality difference between MB's head gasket and Elring's? Is MB's the same gasket but only with MB's name on it instead of Elring? Thanks again in advance!
Sometimes there are differences between MB-spec parts and OEM parts by the same manufacturer. In the case of Elring and this particular gasket, it's hard to say unless one sourced an Elring gasket and a factory/OE Elring gasket and put them side by side. The MB head gasket for the M104 engine has been redesigned at least four times over the years to help solve leaking problems at the corners....I don't know if this has been also subsumed into the OEM ("aftermarket") Elring head gasket design or not.
That being said, I have complete confidence in Elring products (used them both aftermarket Elring on my M117 V-8 and my M104 MB Elring) and would not hesitate to use them.
I do not have the same level of confidence in Victor Reinz and other aftermarket products, although some people say that Reinz stuff is fine, and I have seen factory MB gaskets that were manufactured by Reinz, so they are an MB OEM. But given the choice of a Reinz or an Elring, I'd take the Elring every day of the week.
Cheers,
Gerry
That being said, I have complete confidence in Elring products (used them both aftermarket Elring on my M117 V-8 and my M104 MB Elring) and would not hesitate to use them.
I do not have the same level of confidence in Victor Reinz and other aftermarket products, although some people say that Reinz stuff is fine, and I have seen factory MB gaskets that were manufactured by Reinz, so they are an MB OEM. But given the choice of a Reinz or an Elring, I'd take the Elring every day of the week.
Cheers,
Gerry
Thanks again, Gerry for the previous info and I have more questions if you are willing.
1) Before you'd responded about Reinz parts, I had ordered a set of Reinz head bolts. Standing them all on their heads in a row, a couple of them did not stand perfectly erect and a couple of others were up to 1/2 mm shorter than the rest, right about 171mm without using calipers. Am I better off returning the set or are these discrepancies too nominal to be a concern?
2) I'm guessing you replace the camshaft bearing cap bolts only because of the craziness in removing them. Is that true? Are those bolts re-usable?
3) I may have missed it somewhere but I don't recall reading the you replaced the head bolt washers. Are those also reusable?
Thanks again!!
1) Before you'd responded about Reinz parts, I had ordered a set of Reinz head bolts. Standing them all on their heads in a row, a couple of them did not stand perfectly erect and a couple of others were up to 1/2 mm shorter than the rest, right about 171mm without using calipers. Am I better off returning the set or are these discrepancies too nominal to be a concern?
2) I'm guessing you replace the camshaft bearing cap bolts only because of the craziness in removing them. Is that true? Are those bolts re-usable?
3) I may have missed it somewhere but I don't recall reading the you replaced the head bolt washers. Are those also reusable?
Thanks again!!
Okay, Gerry, equipped with all your document knowledge and insights, I'm diving into replacing my head gasket this weekend. Can you shed light on a couple more points:
1) What can I look for or notice on the timing chain tensioner that will indicate it needs to be replaced?
2) Is there a benefit one way or the other in removing the camshafts before removing the head, or saving the effort of turning the crankshaft to 30 degrees BTDC and removing the camshafts after the head is removed?
Thank you, again!
1) What can I look for or notice on the timing chain tensioner that will indicate it needs to be replaced?
2) Is there a benefit one way or the other in removing the camshafts before removing the head, or saving the effort of turning the crankshaft to 30 degrees BTDC and removing the camshafts after the head is removed?
Thank you, again!
Timing chain tensioner change should be according to mileage imho. If you do re-use yours, make sure you completely disassemble it (to reset it) before re-installing. DO NOT install without disassembling it.
In my opinion it should be replaced say at 150-200K miles. They are not cheap but not super expensive either. If you get a new one be sure to get factory MB.
You can remove cams before removing head or after. May be easier while the head is bolted to the block from a leverage perspective. My problem was that the cam tower bolts were super tight so I had the machine shop remove them for a bit more cost. After stripping out two cam tower bolts I gave up & had the experts do it. Next time I would buy a higher quality tool (Hazet or Stahlwille) which would give a better "bite" into the bolt heads.
Hope this helps.
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In my opinion it should be replaced say at 150-200K miles. They are not cheap but not super expensive either. If you get a new one be sure to get factory MB.
You can remove cams before removing head or after. May be easier while the head is bolted to the block from a leverage perspective. My problem was that the cam tower bolts were super tight so I had the machine shop remove them for a bit more cost. After stripping out two cam tower bolts I gave up & had the experts do it. Next time I would buy a higher quality tool (Hazet or Stahlwille) which would give a better "bite" into the bolt heads.
Hope this helps.
Sent from my iPad using Tapatalk HD
Removing the camshafts while the head was still on was extremely helpful. I probably needed 150-200 ft/lbs to break the cam bearing cap bolts loose - had to use a lot of downward pressure on the bit in the breaker bar to keep the bit seated completely in the head. Fortunately, they all broke loose. Thank you!
The square nuts on the manifolds are really fused on hard. Can those be safely used again?
Here's a likely very controversial subject to broach - I spoke with a retired MB tech who has done 100s of head gasket jobs on this vehicle. He claimed the reason for the consistent failure of the gasket was not the gasket design but the small oil journals in the front and rear corners of the block (about 1/4" in diameter next to the bolt holes) that ultimately go nowhere. My head is at the shop so I can't confirm this on the head. By these seemingly useless journals pumping oil by the gasket, the gasket breakdowns and leaks in these areas. According to him, the fix is to plug these oil journals on the block with a number of options. As a dealer employed tech, he was not allowed to make such a modification. Have you heard of this and what are your thoughts on it? Anyone other members aware of this? Thank you!
The square nuts on the manifolds are really fused on hard. Can those be safely used again?
Here's a likely very controversial subject to broach - I spoke with a retired MB tech who has done 100s of head gasket jobs on this vehicle. He claimed the reason for the consistent failure of the gasket was not the gasket design but the small oil journals in the front and rear corners of the block (about 1/4" in diameter next to the bolt holes) that ultimately go nowhere. My head is at the shop so I can't confirm this on the head. By these seemingly useless journals pumping oil by the gasket, the gasket breakdowns and leaks in these areas. According to him, the fix is to plug these oil journals on the block with a number of options. As a dealer employed tech, he was not allowed to make such a modification. Have you heard of this and what are your thoughts on it? Anyone other members aware of this? Thank you!
I am not sure about why there would be "oil passages to nowhere" -- doesn't seem very MB-like to do something like that. Klink would likely know for sure, but I do not recall seeing such on the cylinder head on the M104 that I did. In the sometime future I'll be doing another M104 head gasket job, so will have another chance to check this out. But, I could very easily be wrong on this.
It has generally been my experience that MB has not put "useless" features and attributes in its products unless they are the result of some sort of mid-production design change. However even then, it would not be a huge issue to change the casting mold of the aluminum to block said oil passage from the get-go, and it seems logical to me that if there was a problem then MB would have done this.
I do know that MB has revised the head gasket design at least four (and possibly more) times for the M104 engine over the years, because of oil leakage at the rear corner and sometimes oil leakage into one of the coolant passages (although this "oil in the coolant" thing seems to be a bit more prevalent in the M103 engines; external oil leakage seems to be more prevalent on the M104 but that could just be my own informal observation).
The most recent design of the head gasket seems to have (finally) solved most of the gasket shrinkage problem at the FRONT of the gasket at the "Bermuda Triangle" (where the head, block and front timing cover meet) and also the oil leakage problem at the rear of the gasket. It seems that the M104 gaskets tend to go around 90-125K miles before needing replacement, whereas the timing covers go about 50-75K before requiring a removal/re-seal.
As far as the square nuts on the manifolds are concerned, if I remember correctly I think I re-used them, yes, because the square nuts are permanently attached/fused to the manifold. I only replaced what the factory manual said to replace, which was on the exhaust system the copper manifold hex nuts, which are ovalled when new.
It has generally been my experience that MB has not put "useless" features and attributes in its products unless they are the result of some sort of mid-production design change. However even then, it would not be a huge issue to change the casting mold of the aluminum to block said oil passage from the get-go, and it seems logical to me that if there was a problem then MB would have done this.
I do know that MB has revised the head gasket design at least four (and possibly more) times for the M104 engine over the years, because of oil leakage at the rear corner and sometimes oil leakage into one of the coolant passages (although this "oil in the coolant" thing seems to be a bit more prevalent in the M103 engines; external oil leakage seems to be more prevalent on the M104 but that could just be my own informal observation).
The most recent design of the head gasket seems to have (finally) solved most of the gasket shrinkage problem at the FRONT of the gasket at the "Bermuda Triangle" (where the head, block and front timing cover meet) and also the oil leakage problem at the rear of the gasket. It seems that the M104 gaskets tend to go around 90-125K miles before needing replacement, whereas the timing covers go about 50-75K before requiring a removal/re-seal.
As far as the square nuts on the manifolds are concerned, if I remember correctly I think I re-used them, yes, because the square nuts are permanently attached/fused to the manifold. I only replaced what the factory manual said to replace, which was on the exhaust system the copper manifold hex nuts, which are ovalled when new.
Everything Gerry said up above corresponds to my experience.
The square nuts that attach the downpipes to the exhaust manifolds do not need to be replaced unless they are damaged. As long as you got the bolts out intact, they are not damaged.
I have not heard of any such passage oil passage plugging to effect a permanent leak repair. The "passage to nowhere" that I think your contact may be referring to is most definitely a passage to somewhere, it is an oil drain return to the crankcase. There are many other drain return ports, so perhaps that one at the rearmost bottom corner could be blocked off, but I wouldn't do that.
Anybody else heard of this, and/or is practicing it? It seems to me that this would be a perfectly natural repair for the factory to have implemented if it came without any potential downside. The fact that they did not perform and/or make available such a "obvious" permanent repair really makes me leery of it. Of course, it wouldn't be the first simple/obvious repair solution that they did not implement. Still, I'd pass on it, thank you very much...
The square nuts that attach the downpipes to the exhaust manifolds do not need to be replaced unless they are damaged. As long as you got the bolts out intact, they are not damaged.
I have not heard of any such passage oil passage plugging to effect a permanent leak repair. The "passage to nowhere" that I think your contact may be referring to is most definitely a passage to somewhere, it is an oil drain return to the crankcase. There are many other drain return ports, so perhaps that one at the rearmost bottom corner could be blocked off, but I wouldn't do that.
Anybody else heard of this, and/or is practicing it? It seems to me that this would be a perfectly natural repair for the factory to have implemented if it came without any potential downside. The fact that they did not perform and/or make available such a "obvious" permanent repair really makes me leery of it. Of course, it wouldn't be the first simple/obvious repair solution that they did not implement. Still, I'd pass on it, thank you very much...
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Thank you both for your response on this. I have some pics to share that sheds some light on the subject but will have to wait. I have a more urgent matter that I would love some feedback on. I got the head back today and have a concern with torquing the head bolts. While following the service manual procedure, some of the bolts on the 3rd phase of tightening were significantly easier to turn than the others. So, I put the torque wrench on the 1st bolt to be tightened and kept inching up the torque to get the 'click' on the wrench without turning the bolt. I stopped at 102nm, then checked all the others. The 2nd bolt in the procedure did not move, all of the others did and one took at least another full round. To prepare for the new bolts, I tapped out, cleaned out, sucked out and dried out all of the bolt holes.
Should I be concerned with this? Do I need to redo the whole process, re-check them tomorrow, or have another drink and pretend it never happened? Any insight is appreciated.
Should I be concerned with this? Do I need to redo the whole process, re-check them tomorrow, or have another drink and pretend it never happened? Any insight is appreciated.
That does not sound good. Yes I would be concerned. I would consider re-doing the whole process, however what I don't know is if you can re-use the same gasket... if it's already partly compressed, the procedure may not provide accurate torque. Need some input from the pros... Jono? Klink?
Now, to continue with this mystery, I took some pics of the head deck after getting it back from the shop. The tech with whom I spoke was partially correct:
1) The small oil journal in the far most corner of the front passenger side of the block indeed meets a dead end at the head. The gasket accommodates for the hole in the block but no such corresponding passage exists in the head. (See pics)
2) The rear passenger side is a different story. The oil drain on the head is located to the inside of the head bolt hole. The corresponding oil drain on the block is located to the outside of the head bolt hole. Thus, the oil has to travel through a cavity in the head, around the bolt, then down the opposite side to the block drain. (See pics) This seems like a wacky arrangement and a likely cause of the inevitable oil seal failure. The metal compression seals around the bolt hole and this oil passage in the block do not seal 360 degrees around each hole.
With this in mind, the front oil journal to nowhere could potentially be safely sealed up in some fashion for a permanent fix. However, it seems a moot point since no feasible/reasonable fix for the rear corner exist and the head gasket will need to be replaced at some point anyway. I chose not to make any modifications and will reassemble everything according to service manual procedures.
Thank you Gerry and Klink for your consideration and responses!
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I used a factory MB head gasket for my M104 project. I sourced things through parts.com at the time, but would recommend MB Gainesville (just Google "Lionel" on this site to get contact information) for the best pricing.
My reason for doing this is because MB uses the very latest version of the head gasket. I was not confident that the aftermarket versions (even by the same manufacturer Elring) available would incorporate the latest MB revisions to combat oil leakage. The M104 head gasket has been "updated" and modified several times over the years, and I wanted the best/latest/most durable design I could get, so hopefully the current owner of the car will never have to pull the head again (or at least, not before 200+K more miles pass).
For my M117 rebuild I did go with aftermarket (again, Elring) gasket set as this is a proven & straightforward design that checked out to be same as factory.
My reason for doing this is because MB uses the very latest version of the head gasket. I was not confident that the aftermarket versions (even by the same manufacturer Elring) available would incorporate the latest MB revisions to combat oil leakage. The M104 head gasket has been "updated" and modified several times over the years, and I wanted the best/latest/most durable design I could get, so hopefully the current owner of the car will never have to pull the head again (or at least, not before 200+K more miles pass).
For my M117 rebuild I did go with aftermarket (again, Elring) gasket set as this is a proven & straightforward design that checked out to be same as factory.
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