HOW-TO: Replacing M119 Coolant Thermostat (500E, E500, 400E, E420)

[gerryvz]

For some months now, I've noticed what I've come to believe is a "lazy" thermostat .. meaning that the car takes a while for the coolant temp needle to get to the 80C mark. In cold (40-60F ambient...remember, I live in Texas!) weather, it can take 6-7 miles, which is too long.

Seeing as in 11+ years of ownership, I've never replaced the thermostat, I felt it was time to do this.

My E500 is a fairly early 1994 model year production car, with production date of Oct. 18, 1993. The EPC indicates that the correct thermostat for the car is the part number 116 200 03 15, which is also shared with my 560SEC. I had a spare Behr thermostat with this part number in my parts stock.

Tools needed:

• 8mm socket (1/4" drive)
• 10mm socket (1/4" drive), wobbly & short extension optional
• stubby flat-blade screwdriver
• long flat-blade screwdriver
• Brake cleaner
• Six-quart drain pan
• Shop towels and absorbent rags
• MB coolant (if needed)

Parts needed:

• Thermostat kit, MB part number 116 200 03 15 (most cars, all USA-spec 036's)
• 90° coolant hose 119-203-02-82 (optional, but prudent to replace)

The first thing to do with this job, is to clean the area thoroughly by giving it a nice shot of brake cleaner. Here's an overview of the area, as cleaned and just before the job is started.



After you've cleaned the area, you want to remove the plastic under-cladding panel. Remove the 6-8 eight-millimeter bolts that hold the panel to the bottom of the engine compartment. Set the cladding panel aside; you may want to clean it up later.

Then, you want to drain the coolant from the radiator. To do this, look up and behind the front bumper until you find the pet-cock. This should be a little knurled plastic wheel with a slot for a screwdriver in it. Using your stubby flat-blade screwdriver, and getting your drain pan ready, loosen the pet-cock a few turns, and the coolant will start to flow out the drain tube. Loosen it a bit more with your fingers, but don't remove it totally from the bottom of the radiator.

Here are a few photos of the pet-cock wheel, loosening it, and the coolant draining. You should expect around a gallon of coolant to drain into your pain. Be sure to check the condition of the coolant -- it should generally be a light golden color (sort of like pee) but should be clear and free of any cloudiness.



Let the coolant drain into the pan for a couple of minutes. Then, the next step is to remove the short hose that attaches to the thermostat housing. This is a straight ring clamp, so you can use your long, flat-blade screwdriver to loosen its clamp. Slide the loosened clamp down onto the hose body.

Side note: Look at the condition of the serpentine belt in the first photo directly above. You should ALWAYS examine your belt visually for cracks, and replace it if you see any cracks or fraying. Note that this serpentine belt had last been replaced in January, 2013, so it is exactly two years old. Texas heat is not very forgiving of rubber parts.


After loosening the clamp, CAREFULLY stick the end of your screwdriver, or a hooked tool, in between the end of the hose and the housing, to break the hose free from the housing. This will help you remove it from the housing in a minute.

If you are feeling REALLY ambitious, also loosen the bottom clamp that attaches the other end of the hose to the alternator support. This will make it MUCH easier to remove the thermostat housing from the side of the water pump. Otherwise, you can just bend the hose out of the way, but you should be VERY careful not to rip the hose, and if it looks old/beat up or otherwise not in good condition, REPLACE THE HOSE ASAP.

In my case, I didn't like the look of the hose - it was slightly bulged - so I opted to replace it. See below for the condition of my hose after I removed the top clamp.



After working the hose free from the thermostat housing, you can begin to remove the thermostat housing itself. It is held to the side of the water pump by three 10mm bolts, with washers. Two of the three bolts are extremely easy to access; the third one, down and behind the hose, is much more difficult. This third bolt is best accessed with the hose out of the way, and using either a wobbly extension with your 10mm socket, or with a "deep" 10mm socket. It is very difficult to see this third bolt, so you have to do this partially by "feel." Take good care not to strip this third bolt head !!



Here are all three bolts, removed. You can see the wobbly and socket apparatus I used to access the third (difficult) bolt. The engine oil dipstick, which is partially in the path of accessing this third bolt, can also be loosened from the cylinder head (it's a single, small Allen bolt to do this) and that can make a bit more room for a "straight on" purchase on the head of this third thermostat housing bolt.



After the three bolts are removed, you can generally break the thermostat housing away from the water pump housing by wiggling it back and forth with your hand. First photo below shows it starting to come free; the second one shows it broken free and ready for removal from the vehicle.




Here are a few views of the thermostat and housing, as removed from the water pump housing.



CONTINUED IN NEXT POST ...

 

[gsxr]

Gerry, if you do not drain the block, removing the t-stat usually is followed by a pint or two of coolant dumping out from the t-stat housing. Draining the block (at least one side, if not both) will avoid the spillage. I'd add that to the steps, or note that spillage will happen if it isn't done.

BTW - all USA-spec E500E's will use the early t-stat. The break point is at .974 engine numbers 10204/10205 and the last 036 imported to USA was below engine # 9999. Only late-build, Euro-spec E500's would use the late t-stat.

For the hose clamps, a flex-handle hex driver is awesome. Hazet makes them, and AST has a set (click here). I would have sworn there were cheaper Asian alternatives but I can't seem to locate any at the moment. I have a set and they are fabulous for all the coolant hose clamps, and also the MAF clamps.

EDIT: New links for flexible drivers.

Amazon.com: CTA Tools 1051 Flex Nut Driver Set (4 Pc.): Automotive

Amazon.com: CTA Tools 1051 Flex Nut Driver Set (4 Pc.): Automotive

www.amazon.com

Amazon.com: CTA Tools 1057 Flex Nut Driver - 7mm: Automotive

Amazon.com: CTA Tools 1057 Flex Nut Driver - 7mm: Automotive

www.amazon.com

Great writeup & pics as always!

 

[gerryvz]

At this point, I had a bit of a scare. The thermostat and housing came out as a single piece, and for about 30 minutes I thought I actually had the later "integrated" thermostat+housing as used on the later M119 engines. I had given a fair bit of effort to separate the thermostat from the housing, with no progress.

I started to post my situation to the HOW-TO, and Clark Vader intercepted my post, and quickly did some "on the fly" research, and informed me that he felt strongly that my housing & thermostat were indeed the early-series units (he did a comparison check of my photos with the later ones).

Clark directed me to go out to my shop and try harder/more forcefully to separate the two parts, as he said the O-ring can cause them to stick together. After clamping the housing in the vice, and wrapping the thermostat bottom with a rag, I was able with considerable force to separate them.

Clark was correct, and for this I am grateful. I was almost ready to hit "SEND" to order one of the later thermostats, and Mr. Vader shrewdly and quickly provided some very nice assistance. Thank You, Clark !! :clarkz3:

Here is a view of the separated thermostat and housing, as I removed them from the vise.



I pulled out my Behr replacement thermostat, and put the new one (on the left) next to the one I'd just removed. Indeed, the one I removed was for all intents and purposes, identical to the new one.



To prepare the new thermostat for installation, I placed the new O-ring that came with it onto the thermostat rim. Then I re-installed the thermostat into the housing.



I pulled off the short hose to make plenty of room to get a good bite on the three bolts that hold the thermostat housing to the water pump housing. There was a little gray goo inside the end of the hose, and at the rim of the lower hose connection, so I cleaned that residue up from both parts.



When re-installing the thermostat, an important thing is to make sure the little round hole at the inside of it, is located at the top of the thermostat. So, you should rotate the thermostat inside the housing, before mounting it, to make sure this little hole, and the protrusion on the outside of the thermostat, is in the upper-most position when the thermostat housing is bolted to the water pump housing.



Here I am, fitting the thermostat housing to the water pump housing.



And to double-check the position of the hole/protrusion, I removed the housing one last time to make sure the hole was in the correct position. Then I fitted the housing back onto the water pump housing, and started threading the three bolts....then tightened them down to their specified 10 Nm of torque.



Then I fitted the short hose to both flanges, and tightened the clamps. This is what everything looks like, all buttoned up.



The next step is to close your radiator's pet-cock (knurled drain wheel at the bottom passenger corner of the radiator). Important that you do this !!!

Then, it was time to pour the drained coolant in the drain pan, back into the radiator. To do this, first of all I transferred all of the drained coolant from the drain pan, into an empty, spare, one-gallon distilled water jug. But, to be safe, I used a funnel in the mouth of the jug, with a fine cotton Griot's Garage buffing towel in the mouth of the funnel, to filter out any particles that had drained along with the coolant into the very clean drain pan. And sure enough, there was a fair bit of particles and small solids that got caught in the cloth as I poured the coolant into the jug. Filtering your coolant is NOT a bad thing to do.....keeps solids and crap out of your precious cooling system !!

Next, to pour the filtered coolant back into the radiator, I removed the clamp on the upper radiator hose where it attached to the top of the water pump (not the radiator side of the hose). Then I inserted a long, skinny funnel into the hose (tilting it up almost vertically), and poured around 4 quarts of coolant into the hose, where it directly drained into the radiator.

Here are a few views of removing the upper radiator hose from the engine. You pour your drained coolant right into the end of this hose.



I had about a quart of coolant left in the jug, and the radiator was full and the hose wouldn't accept any more coolant. So I re-attached it at the engine, and tightened up the clamp.

Then I started the engine to circulate the coolant, and also to check for leaks at the upper radiator hose, thermostat housing and thermostat coolant hose connections, and at the pet-cock.

No leaks, thankfully. I let the engine run for a couple of minutes to circulate the coolant, and then shut it off. Then I opened the coolant expansion tank, and carefully poured the rest of the coolant into the expansion tank. The level had gone down just about exactly the amount of left-over coolant that I had, so it worked out just about perfectly.

WARNING: DO NOT open the expansion tank if the engine is hot or you ran the engine more than a few minutes from cold.

And that was the end of the job. Again, a big thanks to Clark Vader for his real-time detective work for me, while I was out in the shop.

Cheers,
Gerry

 

[vatc5637]

Great writeup & pics as always!

+1!

 

[clarkz71]

Great how to and excellent pictures. It was the pictures
that promted me to contact Gerry and inform him that the
thermostst housing was the early version. Easy to spot
compared to the "flat" late version.

One of the benifits of this write up was that Gerry experienced something
that is very common. The o-ring compresses quite a bit, and over time hardens up
This results in a stuck thermostat that takes conciderable effort to remove from the housing.

Easiest way is remove the o-ring with a pick

The late one piece flat housing/thermostat, look at Gerry's then this.

 

[gerryvz]

Just a point of follow-up on this.

Just before the Super Bowl started, and after buttoning up the belly pan and inspecting everything, I took the car out for a six-mile drive in my area. Ambient temperature: a chilly 65F and threatening to rain.

The coolant temp needle hit the "80C" mark before the two-mile marker, and settled nicely for the duration of the drive to the 82C mark (about a needle's width above the 80C mark. So this confirmed my lazy thermostat. Before, it would have taken 4-5 miles for the needle to get above the 80C mark.

I'll report back again once the ambients get up above the 80F mark, which will be the signal for the south-western Texas springtime. Should be around 4-6 weeks from now.

An inspection of the area after returning from the drive confirmed no coolant leakage in the thermostat area or at the upper radiator hose.

Cheers,
Gerry

 

[Spruce500e]

Any particular reason not to pour fresh antifreeze into the car why reuse old antifreeze?

 

[gerryvz]

For me, it would depend on the age of the antifreeze. Mine was last replaced July 6, 2013, so still has some life left in it.

If the coolant was more than 2 years old, it would be a great time to replace it, in conjunction with draining the block.

I confirmed this morning after driving the car that there are no coolant leaks, nor power steering leaks after tightening up the hose clamps between the power steering reservoir and the tandem pump to remedy the seeping there.

 

[Spruce500e]

Thanks for quick reply. Mine is significantly older than that, sounds like another call to Lionel for parts and another add on the "to do" for the spring refresh. Damn the jobs are piling up

 

[gerryvz]

My recommendation is to go to your local O'Reilly's (or Zoro online) and order about 3 gallons of non-diluted Zerez G-05 coolant, which identical to the MB coolant that came with our cars. Then get some distilled water at the grocery store. Mix the coolant and water in a 50-50 mixture. You'll want to have a bit extra on hand for jobs like this one, where I ended up replacing about a quart of coolant that spilled on the garage floor while messing with the hoses and such.

Your coolant should be changed every 2-3 years -- three years at the most. Draining just the radiator will net you about 6 quarts, and if you siphon out the expansion tank you can get a couple more. This would be a significant percentage of the coolant, but really to do it right both block drains have to be removed and then the engine drained.

When you do the block drains (the M119 has two of them) please use extreme care with the block drain plugs. On my M104 in my G-wagen, I had an extreme challenge late last year to remove the aluminum block drain plug, and literally had to drill it out of the block. It took me around 11 or 12 hours to extract the plug because a previous "mechanic" had 95% rounded off the plug so that I couldn't get an adequate "bite" on it. See photo below of a new M104 plug next to the one I extracted Obviously this is an M104 not an M119, but the care taken should be the same (plus you have TWO plugs on an M119).

If/when you do drain the coolant, take care to use the factory procedure to refill things and to "burp" the system once you start the car back up. I've had situations where the temp needle shot up from rather cool almost to the boiling point in just a couple of seconds while initially running the car, which is quite alarming !!

Cheers,
Gerry


M104 block drain plug, after surgical extraction from the block.

 

[gsxr]

Bottom Gear Top Tip: For the E500E, it's best to pre-mix the coolant and pour in whatever your desired ratio is (most people use 50/50). As noted in other coolant-flush threads, the factory capacity specs are highly suspect and the best way to avoid any issues is to pre-mix. You can buy G-05 pre-mix at 50/50 ratio but it also costs, coincidentally, about 50% more. Go figure. Make sure you double-check the label, you don't want to dilute already-premixed stuff...

 

[Ron500E]

M104 block drain plug, after surgical extraction from the block.

I just bought one of those new plugs for my Gerry Approved 104 Head Gasket Replacement and the new plug is a work of art.
Use nickel based anti-seize on the threads BTW. Makes it easy the next time around. Also, you might be able to connect a hose so it drains the old fluid into an EPA approved container.

Ron

 

[gerryvz]

If I remember correctly, the later M119 plugs are a bit neater to work with than the earlier ones, in terms of being able to drain with less mess, but I could be wrong on that.

The M104 plugs per above are extremely simple to push a hose onto for draining ... if there's enough to get it loose

 

[gsxr]

The early M119 plugs are flat with no hose connection.

Late M119 plugs are similar to the M104 style shown above. These are designed to connect a hose and eliminate making an unholy mess when draining.

 

[gerryvz]

Dave, do you know the approximate cutover point/date for the early style M119 coolant drain plugs, to the later style?

Cheers,
Gerry

 

[gsxr]

Dave, do you know the approximate cutover point/date for the early style M119 coolant drain plugs, to the later style?

The EPC says the late style drain plug is used as of engine #8072.

However, my 1993 500E with engine # 7619 (March 1993 build) has the late drain plugs. And my 1994 E500 with engine #8050 has the late drains as well. Clearly the EPC break point is wrong. Best I can tell, the change occurred in early 1993 (calendar year) production, which would be mid/late USA model year production. The engine block is machined to accept only one type, you CAN NOT replace early drain plugs with late drain plugs.

Additional details and photos are in this thread:
http://www.500eboard.com/forums/showthread.php?t=5343

 

[gerryvz]

The engine block is machined to accept only one type, you CAN NOT replace early drain plugs with late drain plugs.

Additional details and photos are in this thread:
http://www.500eboard.com/forums/showthread.php?t=5343

Hey! I resemble that thread !! OK, thanks, and you proactively answered my next question about late plugs being able to be retrofitted to an earlier block, which I'd forgotten about the manual saying one couldn't do.

Have you ever had issues with loosening drain plugs on your M119s? My reason for asking was that when I did my M117 top-end rebuild, I had a heck of a time with one of the two drain plugs on that engine; the other one was not much trouble. I decided to leave one plug in place and NOT strip it out, which means I didn't get quite all of the coolant drained, but probably 80-90% of it (which was good enough for me).

Cheers,
Gerry

 

[gsxr]

Have you ever had issues with loosening drain plugs on your M119s? My reason for asking was that when I did my M117 top-end rebuild, I had a heck of a time with one of the two drain plugs on that engine; the other one was not much trouble. I decided to leave one plug in place and NOT strip it out, which means I didn't get quite all of the coolant drained, but probably 80-90% of it (which was good enough for me).

Other than being very tight and stressing the swivel joint (typically needed) for connecting the hex driver... no, I've never had one seize or otherwise refuse to come out, on any of my M119's. No leak issues either.

 

[Spruce500e]

The early M119 plugs are flat with no hose connection.

Late M119 plugs are similar to the M104 style shown above. These are designed to connect a hose and eliminate making an unholy mess when draining.

If I use the part number in the indexes will that give me the later plug and is it recommended to replace for ease later down the road?

 

[Spruce500e]

Is this part correct? Coolant hose 119 293 02 83 (optional, but prudent to replace)
I cant find it as a fit...I find a fit with 1 digit off as 119 293 02 82 is that the right number?

Also can someone help me with the newer block plug number? If its possible to replace with new ones on an older build car I'd like to for ease the next time I do a drain and refill

EDIT: as to my second question i just came across a note in MB manual that says I can NOT use the newer plug in place of my older plug...is that really true?

 

[emerydc8]

EDIT: as to my second question i just came across a note in MB manual that says I can NOT use the newer plug in place of my older plug...is that really true?

GSXR has confirmed this to be the case.

The engine block is machined to accept only one type, you CAN NOT replace early drain plugs with late drain plugs.

Additional details and photos are in this thread:
http://www.500eboard.com/forums/showthread.php?t=5343

 

[Spruce500e]

Omg I'm so blind I read so many threads on this and didn't even see his note in this one.

I know folks are thorough on here with part numbers but can someone verify the part number I noted above for the hose from tstat?

 

[gsxr]

Is this part correct? Coolant hose 119 293 02 83 (optional, but prudent to replace)
I cant find it as a fit...I find a fit with 1 digit off as 119 293 02 82 is that the right number?

That was a Honcho Typo. Correct number is: 119-203-02-82

I'll edit the original post. Only buy the OE/dealer item for this particular hose. Current MSRP is $18.50 and it's usually a once-per-ownership replacement as long as you don't puncture it during R&R in the future.

 

[Spruce500e]

That was a Honcho Typo. Correct number is: 119-203-02-82

I'll edit the original post. Only buy the OE/dealer item for this particular hose. Current MSRP is $18.50 and it's usually a once-per-ownership replacement as long as you don't puncture it during R&R in the future.

Thank you for clarifying im making the list of parts and mine looks worse than gerry's pic with major bulging

 

[gerryvz]

That was a Honcho Typo. Correct number is: 119-203-02-82

Indeed it was ... sorry.

 

[emerydc8]

When replacing my small 90-degree hose today, I also replaced the large thermostat O-ring, which is part # 015 997 23 48 (I have the old-style T-stat too). I bought the hose and O-ring through the dealer since it was only about $20. Upon removing the old O-ring, I noticed that it is not rounded -- the sides are actually flat. I'm thinking this is either a variation of the round factory O-ring (the one I got from the dealer), or someone installed the wrong part the last time they were in there. Gerry, I noticed your O-ring appears to be round too. Since it isn't leaking (so far), I guess I have the correct O-ring now. Anyone ever see a flat O-ring.

 

[gerryvz]

The o-ring when new is round. It gets smashed into square edges over time in the thermostat housing.

Totally normal to see this.

 

[gsxr]

Jon, I've found the same thing on most of my engines. I believe the O-ring begins life round, and ends life square/flat. Klink can probably confirm.

 

[Klink]

Jon, I've found the same thing on most of my engines. I believe the O-ring begins life round, and ends life square/flat. Klink can probably confirm.

Yep. Those are round profile O-rings upon installation. They tend to keep that square shape upon removal years later.

 

[Spruce500e]

Ok moving down my list of To Do's replaced all cooling hoses, thermostat and expansion tank. I did not remove the block plugs as I didnt want the hassle if a possible drill out.

So Im ready to refill. I bought the premix Zerex and noted the incorrect fill limits per the manual but I have a question and clarification:

1. Clarification = Ive seen suggestion to fill from upper radiator hose which I get but does it matter if you fill into the block vs into the radiator with that hose? Six of 1 half dozen of another?

2. Question = what are the proper refill and "burp" procedures per the manual? I didnt see it maybe I missed it on the wiki or FAQ?

I have this refill, refill of the PS after fixing the leak and replacing both harnesses and hood pad to do this weekend. Good Lord willing shell be back on the road instead of lift shortly.

 

[gerryvz]

I think for a block-drain situation it's a good idea to fill via the top radiator hose both the block (loosen the radiator end) and also the radiator (loosen the water pump end). The radiator itself will take about a full gallon. And then you need to top off the expansion tank.

What I would do is the above, and then leave the cap off the expansion tank and start the engine. Put the heater on "DEFROST" or "high heat" mode with the blower on high. Let it run and warm up, and as the coolant level in the tank goes down as the thermostat opens, keep it filled up to the seam/line. Once it won't take any more at the tank, close the expansion tank cap and drive the car for 10-12 miles (take some coolant with you in the car, with a rag, if you need it) or so and get it good and hot.

Then park the car and the next morning top it off if needed to the correct level. Taking the coolant and a heavy rag (so you don't scald yourself if you need to remove the expansion tank cap) is a good precaution in case there's a leak somewhere or the coolant light comes on while you're on your 10-mile drive.

As far as the block drain plugs are concerned - in my case with the inline-six M104, there's only the one drain plug, and some previous "mechanic" had butchered the plug so that it was 85% stripped when I got the vehicle.

When I drained the block on my M117 when I did the top-end job five years ago, one of the two plugs was also pretty well stripped but I got the other one out and drained that side of the motor. There was no issue with the side of the M117 that I didn't drain, though a bit of coolant (not much) leaked a bit when I removed the cylinder head on that side.

I've never had to drain the block on my E500 and I've replaced the coolant often enough in recent years with radiator replacements and such that the coolant is pretty new and in good shape, as verified when I removed the radiator recently when replacing the fan clutch.

If you do re-use coolant, be sure to strain it before putting it back into the engine. That will at least make sure that any large particles don't go (back) into the engine. I just use a clean white Griot's cotton detailing towel to do this and it works great. I'm sure a fresh shop towel would also be OK for doing this, but I hate the lint that some of them give off.

Cheers,
Gerry

 

[gsxr]

1. Clarification = Ive seen suggestion to fill from upper radiator hose which I get but does it matter if you fill into the block vs into the radiator with that hose? Six of 1 half dozen of another?

Primary goal here is to fill the engine block, which may not otherwise get properly filled. Adding coolant to the plastic reservoir will fill the radiator. Assuming a fully drained block/radiator, you will probably get 5 quarts into the block, and another 4 into the plastic reservoir. After the engine reaches operating temp the level will drop and you will probably have to add another quart, after it cools down (don't open the cap when hot).

2. Question = what are the proper refill and "burp" procedures per the manual? I didnt see it maybe I missed it on the wiki or FAQ?

Assuming the system is filled per the above, and you can feel liquid when squeezing the upper radiator hose, and the plastic tank is filled all the way to the top of the neck (not the tank seam)... drive the car with heater on max temp and keep an eye on the engine temp. The temp should not go higher than normal, and you should feel heat out of the vents. When it gets to 80-90C and the t-stat opens, the level will drop as noted above.

Looks like the forum does not have a specific "HOW-TO" on coolant flush / refill, will need Honcho to do one of his in-famous writeups on that.

 

[Spruce500e]

Thank you both for the prompt replies. I did not do the block drains as I did not want to push my luck every project has turned into more than it should, case in point what was to be simple swap of brake hoses didnt turn out as such.

So I will use the upper hose and will fill through the block and radiator as Gerry notes. I am using brand new anti freeze so no need to filter it.

Sorry for late thanks but thread responses dont alert me with an email only PM's do that, is there a setting I need to enable?

 

[nocfn]

Subscribe to a thread

 

[Spruce500e]

So I followed the instructions to a T and I didn't have any issues it seemed, thanks guys. Drove the car well over 30 miles even had an emissions test where they ran it on a roller for test and it seemed to run cool and lower than 80 and the expansion tank level is right below the seam. Can I consider this job done successfully or do I need to carry an antifreeze jug with me any more?

 

[nocfn]

If you did that and your expansion bottle is at the seam, you are done!!

 

[Spruce500e]

If you did that and your expansion bottle is at the seam, you are done!!

Thanks man for prompt reply. Good news finally seeing the end of the revitalization I think

 

[nocfn]

It's rewarding. That is how I am in the c126 but now I decided to remove and replace the back glass for a new one. And yes, one project begets another real fast!!

 

[Spruce500e]

It's rewarding. That is how I am in the c126 but now I decided to remove and replace the back glass for a new one. And yes, one project begets another real fast!!

EXACTLY. Seemed each project spawned at least 1 more. I can say 1 thing without my friends and this board and members providing parts and advice this would have been a much longer and more expensive effort for sure

 

[nocfn]

Indeed!!!

 

[400E_Owner]

I have a 1992 400E--during my t-stat replacement, the t-stat did not come with its housing. From your experience, it seems I will have to use force to extract it from the pump housing!

 

[gerryvz]

Well, I wouldn't use too much force. Perhaps prise it out with the tip of a screwdriver or something. Be careful ... don't force it out !!

 

[FU2]

Nice thread

one question...is the m119 difficult to bleed?is it a must to vacum bleed the system..or will it be okei just filling it up in the expansion reservoir the "normal" way...and it basically bleeds itself?i Guess since the reservoir is the highest point for the air to get out..i reckon there will be no issues?

thanx

 

[gsxr]

The W124/M119 cooling system is difficult to bleed if you try to only fill it from the plastic expansion reservoir.

However, if you fill the block via the upper radiator hose first, then connect the hose to the radiator, and fill the rest from the plastic reservoir... it's not a problem. With an empty system you should get about 4-5 quarts into the block via the upper hose, then another 3-4 quarts into the reservoir, filled to the absolute top. Drive the car until the t-stat opens and the system will "burp". After it cools, you may need to add ~1 quart to top off at the proper level (at the plastic tank seam, with engine cold).

 

[FU2]

thank you .
Ill do it this way then...but i guess its not harder to bleed than on the BMW"s...and especially Smart cars..where you HAVE to use the vacum bleeding method.


But thanx.cause im thinkn about replacing my water pump, and thermostat and some hoses while im at it.

is there a recomended type of thermostat going on?as ive seen to different types?are they interchangeable?

 

[gsxr]

Only use the OE/OEM thermostat. Check if your engine uses the early or late style, they are not interchangeable. Early OEM is Behr, late OEM is Wahler.

More t-stat info is in this thread: http://www.500eboard.com/forums/showthread.php?t=6830

 

[FU2]

i have the early one
so there is no interchangability between the waterpumps either?what i mean..is..would it be an idea" to put a later type waterpump on to make the late type thermostat fit?

 

[gsxr]

You can convert to the late water pump if desired... also need the late t-stat, late top housing pipe, and a different bolt for the top housing. Otherwise, I believe it's a straight swap. I'm planning to do this on my 6L project. Someone else on the forum did the conversion years ago. I'm not certain if there is any significant advantage to the late style water pump, someone claimed the impeller may be 1-2mm larger diameter?

 

[Klink]

You can convert to the late water pump if desired... also need the late t-stat, late top housing pipe, and a different bolt for the top housing. Otherwise, I believe it's a straight swap. I'm planning to do this on my 6L project. Someone else on the forum did the conversion years ago. I'm not certain if there is any significant advantage to the late style water pump, someone claimed the impeller may be 1-2mm larger diameter?

I never saw a reason given for the change. My guess is that it was simply a production rationalization, as all of the newer engines being introduced around that time (M120, M111) were using the integrated housing/plate valve design. IMO, the late version is more physically durable. I've never seen one of those broken, while I have seen a few of the early version broken. Maybe that was the reason...

 

[gsxr]

The early pump uses impeller p/n: A1192010007

The late pump uses impeller p/n: A1202010007

When I have one of each loose, I'll try to measure and see if there is any visible difference. I have a late pump in a box that I can measure, if anyone happens to have an early pump to also measure.

One side note - the late pump has the weep/drip tube located at the front, behind the pulley. If converting to the late pump, you cannot use the catch tank+tube that is used with the early pumps.