M119 timing chain rail replacement question

[gsxr]

UPDATE - see post #3 below for the answers:

Hey guys,

I was working on getting my spare 500E motor ready when I noticed the top of one chain rail was snapped off - see attached photo. It's the upper, inside rail, the one which is the same on left + right sides, part number 119-052-11-16. My question is, what is required to replace these rails? I can't find the procedure anywhere in the W124 CD-ROM, nor the WIS. I assume it's one of those things that MB thinks is so simple they don't have to explain it, but for someone like me who has never done this, I could use a little guidance.

Do I just need to remove the camshaft gears / adjusters, pull the chain out of the way, remove the pins, and the rail pops out? I really do NOT want to pull the timing cover on this engine if I can avoid it. From what I can tell, there is only one rail that requires timing cover removal, and I'm going to hope that one is ok; and just replace the others. I searched both 500 forums and PeachParts, seems that most people either just replace the top rails (above the camshafts), or pay the mechanic to do everything. A couple folks pulled the timing cover and changed all of them but that's not in my plans for this motor right now - that's a separate project for next year.

If anyone has tips about how to R&R those inside/upper rails, and also the long curved rail on the passenger side, I'd greatly appreciate any assistance... thanks!

 

[ivanned]

Hi Dave,
I am about to replace the timing chain and rails on my e500 152K miles. From what I understand it is a pretty big job. Unfortunately I have a very limited time to get it done and once I start I will probably be able to work on it for 3 days tops. Therefore I want to make sure I have exactly the right tools to get everything done.

I am planning on replacing all rails including the bottom one which I know is a PITA, the tensioner and the chain of course

Is there anything else to that repair that I need to know that is specific such as how to make sure that chain has the right tension? Do I have to adjust the timing after I am done? Any other wear items that are not in the chain kit?

I know I am asking too many questions but any information would help. So far I have not been able to locate a write up with pics. I just found bits and pieces regarding tools, diagrams and some procedures.

My goal is once I am done to post a nice step by step fool proof write up that can be followed by anyone so I would appreciate anyone's help actually.

Thanks!

Ivan

 

[gsxr]

Ooops! I forgot to update this thread. I completed the job shortly after the original post. Detailed photos are at this link. Anyway:

I would not replace the lower two rails (inside the timing cover) unless they are damaged. Pulling the timing cover is a miserable job, unless you are also pulling the cylinder heads to change the head gaskets - then it's much easier. Be warned that if you mess with the 2 lower rails (including the long/curved "banana" rail), you're opening up a serious Pandora's box by attempting to R&R the timing cover with the cylinder heads in place. Additional tools will be required, including a flywheel lock tool, and a torque wrench capable of 400Nm to re-install the front hub. These are not needed if you don't remove the timing cover.

The guide rails inside the cylinder head require removal of either the camshafts, or at least removal of the cam sprockets... which is a minor challenge due to the complicated nature of the cam adjusters. There is a special tool for assembly of the cam adjusters, and at ~$75 or so it's worth buying. You'll need a chain rail pin puller tool, about $30 on eBay. If you replace the chain, you'll need the special tool to crimp the master link for the new chain; some places will rent this tool (it's very expensive to purchase).

The tensioner is automatic, no need to worry about the "correct" tension. You will need to set the camshafts in position when installing the chain+sprockets, this is outlined in the FSM (factory service manual)... have crank at 45°, pin all 4 cams, install chain & tensioner. Straightforward, but not particularly simple. You can measure chain stretch, if the stretch is not excessive, you don't even need to replace the chain. Edit: Scroll down to post #30 below for more info on acceptable chain stretch.

Rolling in a new chain is a challenge in itself and requires two people, and constant checking to ensure the chain does not skip a tooth as you roll it in (mine skipped 1 tooth about 4 different times, requiring adjustments mid-roll-in, not fun). There is not a step-by-step replacement writeup anywhere that I am aware of. Next time I do this job I'll try to get photos of each step. Edit: As discussed later in this thread, it is likely that the chain will NOT need replacement. However, you MUST replace all the chain rails first, THEN measure chain stretch with brand new rails. Broken rails can cause what appears to be excessive chain stretch.

Don't even think about doing this job without following the factory service manual, available online here, see Group 05 for info on the chain & rails. Also - use the factory-specified anaerobic sealant (click here) on the upper head covers, and the timing cover to block (if you do end up removing it). DO NOT use RTV or any other sealant. Yes, the factory sealant is ~$30/tube, but do you really want to do the job over again if it leaks? Edit: Factory anaerobic sealant is NLA from Mercedes dealerships by early 2024, but aftermarket Loctite or equivalent anaerobic sealant is suitable for this application. I'm not sure when Mercedes stopped supplying this sealant.


BTW - welcome to the forum!

 

[gsxr]

FYI. For rolling in a new timing chain, I used the factory method (shown here) using the blue wedges... but this method is awful. I'd highly recommend buying this aftermarket tool (link below), as it should eliminate the chain skipping teeth. Unfortunately I did not know about this tool until after I did my timing chain. SG Motorsports is operated by an MB dealer tech in Seattle, btw. Real nice guy. He also sells the chain rail pin puller tool:

http://cgi.ebay.com/ebaymotors/350497872119

 

[ivanned]

Dave, this is awesome information. I'll share all I can when I get the job done. Basically what you are saying is to replace only the top rails. I read another post saying you can replace the vertical guides inside the cover without actually removing it. Is this advisable? I just don't want to ruin the engine since it has exactly 150K miles on it. I will be pulling the lower oil pan so I guess I will see if there are any pieces of rail down there.

Thanks again!!

 

[gsxr]

There are multiple rails... the ones up between the cam sprockets, then three straight rails inside the heads, and finally two down inside the timing cover (one long/curved, the other short/straight). You cannot replace the 2 guides inside the timing cover without removing it, I'm not sure who posted that, but it's not possible. Those lower 2 rails behind the timing cover rarely need replacement, but you should definitely replace all the others, even if they look ok.

 

[500ESpain]

So the ones that can't be replaced without removing the timing case are the ones marked in red? I'll be replacing the timing chain, tensioner and rails soon and I want to have full peace of mind but I don't want to waste time and money replacing those lower rails if there's no need to. The broken ones you can see in the picture are the upper ones, right?

Thanks!

 

[gsxr]

So the ones that can't be replaced without removing the timing case are the ones marked in red?

Correct.

The broken ones you can see in the picture are the upper ones, right?

Yes - the broken ones in the photo are #8 and #14 in the diagram.

 

[ivanned]

I guess I was wrong, no super humans here the guy was saying he leaves the heads on and uses roof flashing to preserve the head gaskets.

With the proper tools how long does it take to do the top 4 guides and rails along with the chain and a tensioner? Could it be done in a day?

 

[gsxr]

I guess I was wrong, no super humans here the guy was saying he leaves the heads on and uses roof flashing to preserve the head gaskets.

I read that post too. He's leaving the heads on, but still removing the timing cover. This method risks having leaks at both the oil pan and heads where the timing cover mates.

With the proper tools how long does it take to do the top 4 guides and rails along with the chain and a tensioner? Could it be done in a day?

For a professional mechanic who has done this before, maybe 1 long (12+ hour) day. Maybe. Even then, I doubt it.

As DIY, plan on a full weekend, if not two weekends; assuming you have all the special tools required. Note there are more than 4 guides - top 2-piece guides between the sprocket, then the 2 guides in the "V" above the middle idler sprocket, and finally the one below the left/driver side exhaust cam. All those should be replaced. When that's all done, the chain is another 1-2 hours by itself. Half the work is removing everything off the front of the motor. It's not fun removing the p/s bracket or fan support bearing. You'll also spend a lot of time properly cleaning the front head covers & cam soelnoids so the anaerobic sealant will work.

This is why the job often costs $3-$4k at a shop...

 

[J-Sauce]

Dave, what needs to come off to replace the chain? The P/S bracket and fan bearing support? Or are you referring to what it takes to replace the lower rails? If you are referring to the chain job, I thought it was just a matter of rolling the new one in once you get the valve covers off and the old chain de-linked.

 

[gsxr]

To replace the CHAIN ONLY, you need to pull the valve covers, and remove the fan clutch. That's all done up top.

To replace the rails inside the head (the ones held in place with the pins), you need to pull the p/s bracket, fan support, etc mostly to access the pins for R&R. And remove the front head covers, and remove all four cam sprocket, disassemble the cam adjusters. It's a real blast.

 

[gerryvz]

This is why the job often costs $3-$4k at a shop...

Ouch. I'd say the same job is a 4-6 hour job on an M117. Definitely something a mechanic could do in a single day.

 

[gsxr]

Ouch. I'd say the same job is a 4-6 hour job on an M117. Definitely something a mechanic could do in a single day.

Really? New chain *and* all new rails in 4-6 hours on an M117?

 

[gerryvz]

No I was talking rails only. Add 1-2 hours (experienced mechanic) to roll in a chain. A timing chain is only about a third as hard of a job to do on a 117 as it is on a 119, and all you need are a couple of vise-grips or zip ties in the way of "special tools" (and a pin puller for the rail pins, and perhaps a spring compressor). I'd say perhaps $1,200-1,500 job (upper rails + chain).

 

[J-Sauce]

Damn, I haven't gotten that far into it yet, but it looked like I could get to the pins with the P/S bracket in place. At least for the inner rail on the left head. I can't imagine how the fan support would be in the way, but I guess I will find out. I suppose this would be the time to also replace my fan clutch (ACM) and all those pesky leaky power steering hoses (which I've had for some time now, just too lazy to actually R&R).

I am going to attempt to do the job without removing the cam adjusters though Dave. I think it will be easier to remove the entire cams than to buy the tool for the adjusters and the new bolts, AND make sure I get it all together right on the assembly process. At least, for me that might be easier, since I have to remove the cams anyway to fit my new lifters. Maybe the average person would prefer to just disassemble the adjusters....

 

[gsxr]

Justin, the p/s bracket is in the way of the lower rail in the left head, the one below the driver's side exhaust cam sprocket. I can't remember exactly why I had to remove the fan support... it's possible that isn't necessary, but don't worry, you'll find out when you get in there! I recall some stuff being in the way of the right/passenger side rail pins, i.e. the oil dipstick tube... maybe I had to pull the fan support to get the tube out of the way. (??) You'll need to at least remove the right exhaust cam sprocket, but you may be able to leave the cam adjusters intact and pull the cams - never done this, but in theory it should work.

The fan has to come out anyway, so yes, might as well swap that if it's on the list. If you do the P/S hoses, try to get all 3 of them (below reservoir, S-shaped, and straight), but the straight one along the frame rail is a real PITA. If it's totally dry, you may want to skip it for now. Otherwise, take the time to do it right. It's soooo nice to have all the leaks eliminated!

 

[Cadence]

At 118k miles how concerned should I be with replacing the timing chain guides as preventative maintenance?

My M119 is running beautifully and not making noise of any kind but I am OCD about replacing parts before they cause problems!

 

[J-Sauce]

At 118k miles how concerned should I be with replacing the timing chain guides as preventative maintenance?

My M119 is running beautifully and not making noise of any kind but I am OCD about replacing parts before they cause problems!

Your best way to tell would be to drop the lower oil pan during your next oil change and check for plastic debris. If you've got any inexplicable particles down there, they likely came from your guide rails. You should also be able to shine a flashlight up the front of the engine and get a decent idea of their condition. I would think that at 118k, you should be fine for some time before symptoms develop. Mine began ticking around 160kmi. As preventative though, you're probably right on timing-wise. I believe Dave had an engine with bad rails at 85kmi!

 

[Cadence]

I believe Dave had an engine with bad rails at 85kmi!

Yikes, hopefully that was a freak failure! Other than bits of plastic in the oil pan are there any other symptoms of bad/broken guide rails?

Has anyone ever heard of an M119 being lost due to a chain jumping teeth or breaking because of broken guide rails?

 

[Odessit86]

Is that DIY timing chain replacing? If you never done this before!

 

[Dario]

Is that DIY timing chain replacing? If you never done this before!

How many timing chains have you replaced before??

 

[Odessit86]

None

 

[gsxr]

M119 timing chain failures are very, very rare. Now that I've fiddled with several different M119 engines, I'm finding the chains don't typically have any measurable wear, at least if the engine was maintained reasonably well.

You can't get an accurate measure of chain stretch if any of the rails are broken, you first need to replace any bad rails, then see if there is any stretch. If it's only 2°-4° stretched as measured at the passenger exhaust cam, I'd leave it alone.

What I highly recommend, if you have never done so on your M119: Pull the lower oil pan at oil change time, inspect for any plastic bits which indicate rail breakage. Replace the rubber sump pickup while the pan is off, and replace the oil level sender O-ring too. Whether or not you find any debris in the pan, also pull both valve covers and visually inspect the rails. Try to remove the 'fingered' rails (119-052-09-16) intact; the ones between the sprockets. If they are brittle, they will break during removal, indicating you needed to replace them anyway. If they come off in one piece, bend the lower 2 tangs against the bottom of the rail (4-5mm air gap). If they flex ok, they may be pretty recent. If they snap off, again, they needed replacement. The fun ones are in the "V" of the block... no way to test them, and requires lots of disassembly to replace, as described in post 3 in this thread.

 

[emerydc8]

Is it true that most of the timing chain slips occur when the upper rail breaks, allowing the chain room to slap and rise above the sprocket teeth? In other words, would it be pretty unusal to have it jump a tooth if the upper rails were in good condition?

 

[gsxr]

Is it true that most of the timing chain slips occur when the upper rail breaks, allowing the chain room to slap and rise above the sprocket teeth? In other words, would it be pretty unusal to have it jump a tooth if the upper rails were in good condition?

Jon, I think you are correct. Klink could probably confirm. Thankfully, those upper/center rails are the easiest to replace!

 

[Odessit86]

When they usual breaks ? i mean when you start the engine or it can happen at any time..?

 

[emerydc8]

Thanks, Dave. I always looked at the upper guides as cheap insurance. They are definitely easy enough to replace.

 

[Odessit86]

Just wonder guys! The guy says that chain can break at any moment.. when is jumped is that true..? .. just read the comments under this video..

[video=youtube_share;gGp6SRazPp4]

 

[gsxr]

Just wonder guys! The guy says that chain can break at any moment.. when is jumped is that true..? .. just read the comments under this video..

I don't think I've ever heard of an M119 chain actually breaking. Even jumping time is pretty rare, but possible if the top/center "fingered" guides are broken or missing, as on this car. If your top/center guides are recent, there isn't much to worry about.

Chain stretch is a different subject. To get an accurate measurement, all the guides must be intact, particularly the two in the "V" below the intake sprockets. There is no official spec but IME, anything in the 2°-4° range at the passenger exhaust cam is totally normal. I'd start getting concerned if it measured more than 7°-8° with all new guides. As a reference, my '93 with 190kmi measured about 4-5° stretch with broken guide rails. With new rails installed, the driver cams pinned dead on 45° (zero stretch) and the passenger exhaust cam pinned at 43° (only 2° stretch, almost as new). My '94 with original/worn guide rails and original chain measures 3° at the passenger exhaust cam, at 105kmi - more miles than the car in the video.

All I can figure is the car in the video must have experienced significant abuse (i.e., oil changes not done on time, and/or with poor quality / wrong type of oil) to get SEVENTEEN degrees of stretch with NEW chain guides! That's insane for only 101kmi, assuming the engine is original and odometer accurate. I agree with the comments, with that amount of stretch, the chain should have been replaced. Crazy.

Jono / Klink, you guys ever see one this bad?

 

[emerydc8]

It's puzzling that he couldn't pin the driver's intake and exhaust cams at the same time, but the passenger side cams lined up okay. You would think the same stretch would exist throughout the chain. Maybe it was just stretched more where he had it on the driver's side. 17 degrees is a lot of stretch. It's amazing the engine ran so well. Maybe the tensioner made up for some of the stretch.

 

[Klink]

I don't think I've ever heard of an M119 chain actually breaking. Even jumping time is pretty rare, but possible if the top/center "fingered" guides are broken or missing, as on this car. If your top/center guides are recent, there isn't much to worry about.

Chain stretch is a different subject. To get an accurate measurement, all the guides must be intact, particularly the two in the "V" below the intake sprockets. There is no official spec but IME, anything in the 2°-4° range at the passenger exhaust cam is totally normal. I'd start getting concerned if it measured more than 7°-8° with all new guides. As a reference, my '93 with 190kmi measured about 4-5° stretch with broken guide rails. With new rails installed, the driver cams pinned dead on 45° (zero stretch) and the passenger exhaust cam pinned at 43° (only 2° stretch, almost as new). My '94 with original/worn guide rails and original chain measures 3° at the passenger exhaust cam, at 105kmi - more miles than the car in the video.

All I can figure is the car in the video must have experienced significant abuse (i.e., oil changes not done on time, and/or with poor quality / wrong type of oil) to get SEVENTEEN degrees of stretch with NEW chain guides! That's insane for only 101kmi, assuming the engine is original and odometer accurate. I agree with the comments, with that amount of stretch, the chain should have been replaced. Crazy.

Jono / Klink, you guys ever see one this bad?

No. At least not still in one piece.

 

[samiam44]

Ithe sound like 2 degrees + a tooth =17 degrees.
??

 

[samiam44]

I read a peach parts posting maybe 10-15 years ago. A pro in Georgia went inot great detail on how to do the lower guides and oIL pump chain a tensioner too.

It was not easy.

 

[gsxr]

It's puzzling that he couldn't pin the driver's intake and exhaust cams at the same time, but the passenger side cams lined up okay. You would think the same stretch would exist throughout the chain. Maybe it was just stretched more where he had it on the driver's side. 17 degrees is a lot of stretch. It's amazing the engine ran so well. Maybe the tensioner made up for some of the stretch.

Jon, that seems to indicate abnormal stretch between the driver sprockets... this could be either the chain itself, OR it could be worn sprockets. Ideally, when measuring chain stretch via this method, it should be done multiple times so it's over various different points along the chain's length. If stretched evenly, the results should be repeatable.

No. At least not still in one piece.

We may have a new record here! Niiiiice. Thanks for the input, Klink, I suspected this one might be freakishly bad.

Ithe sound like 2 degrees + a tooth =17 degrees. ??

Michael, there are 36 teeth on sprocket, which translates into 10° cam angle / 20° crank angle per tooth. This also assumes the pointer on the water pump is accurate. If a particular cam has jumped 1 tooth on the sprocket, assuming new chain/rails/sprockets, and the other 3 cams pin at spec of 45°... the cam which is 1 tooth off should measure either 25° or 65°, depending if it is advanced or retarded.

 

[Odessit86]

It's puzzling that he couldn't pin the driver's intake and exhaust cams at the same time, but the passenger side cams lined up okay. You would think the same stretch would exist throughout the chain. Maybe it was just stretched more where he had it on the driver's side. 17 degrees is a lot of stretch. It's amazing the engine ran so well. Maybe the tensioner made up for some of the stretch.

It's amazing the engine ran so well. Now does that another proof of M119 durability??? i can imagine when i am gone be 60 years old .. i always is gone remember M119 Hmm

 

[samiam44]

Might verify the timing point then.. I'm having problems with the 17 degrees being real.

How clean are the heads and valve covers? I is there signs of neglect?

 

[emerydc8]

I don't know about the M119, but I just rebuilt a small block Chevrolet and discovered that sometimes the timing pointer gets shifted and has to be re-adjusted to 0 with the #1 piston exactly at TDC. Maybe the pointer is off as some have suggested. 17 degrees sounds like a "yuge" amount.

I hadn't considered worn cam sprockets. Good point, Dave.

 

[gsxr]

Might verify the timing point then.. I'm having problems with the 17 degrees being real.

The engine can run just fine with the cams 17° off. My old 6L had the adjustable cams all hosed up and both exhaust cams were 17-19° retarded, right intake retarded 11°, ran smooth as butter and power output seemed ok.

Now, the driver intake cam has to be REASONABLY close to spec, because that is where the cam position sensor is that measures cam timing and cam advance. If that's way out, the LH or EZL will complain and throw codes, and may cause running issues. But 20° out (1 tooth) generally shouldn't bend any valves or cause other disasters. More than that... I dunno, and hope I don't ever find out!

 

[samiam44]

Thats amazing Dave! ₩

 

[TerryA]

Hey guys,

I was working on getting my spare 500E motor ready when I noticed the top of one chain rail was snapped off - see attached photo. It's the upper, inside rail, the one which is the same on left + right sides, part number 119-052-11-16. My question is, what is required to replace these rails? I can't find the procedure anywhere in the W124 CD-ROM, nor the WIS. I assume it's one of those things that MB thinks is so simple they don't have to explain it, but for someone like me who has never done this, I could use a little guidance.

Do I just need to remove the camshaft gears / adjusters, pull the chain out of the way, remove the pins, and the rail pops out? I really do NOT want to pull the timing cover on this engine if I can avoid it. From what I can tell, there is only one rail that requires timing cover removal, and I'm going to hope that one is ok; and just replace the others. I searched both 500 forums and PeachParts, seems that most people either just replace the top rails (above the camshafts), or pay the mechanic to do everything. A couple folks pulled the timing cover and changed all of them but that's not in my plans for this motor right now - that's a separate project for next year.

If anyone has tips about how to R&R those inside/upper rails, and also the long curved rail on the passenger side, I'd greatly appreciate any assistance... thanks!

Dave,
Can you give me the part numbers for Parts 6 & 7 on the attached PDF?

Looking for a little advise here. Will I be able to change the top slide rails 6 & 16 without removing the cam gears or chain?

It looks like the 2 inside slide rails are more than I want to think about attempting. If they look bad when I get in there I will probably give the job to Matt Stockwell @ Leistung Autohaus

Thanks in Advance

 

[Hakie]

6 and 16! consists of:

2x 119 052 0916 (top clips)

And left and right top guide.

1x 119 050 0216 (guide)
1x 119 050 0316 (guide)

This was for my E500, but I believe they are for E500E?

You can easy replace them without removing cam gears/chain.
But beware to not let parts drop. Old plastic is often brittle.

There is also a (easy) procedure to determine chain stretch. I did that too, while I was “in there”. Search “pinning M119”.

https://www.500eboard.co/forums/index.php?threads/hakie.10464/post-150458

 

[TerryA]

6 and 16! consists of:

2x 119 052 0916 (top clips)

And left and right top guide.

1x 119 050 0216 (guide)
1x 119 050 0316 (guide)

This was for my E500, but I believe they are for E500E?

You can easy replace them without removing cam gears/chain.
But beware to not let parts drop. Old plastic is often brittle.

There is also a (easy) procedure to determine chain stretch. I did that too, while I was “in there”. Search “pinning M119”.

https://www.500eboard.co/forums/index.php?threads/hakie.10464/post-150458

Hakie

Once Again you have given me the answer I’ve been looking for. I didn’t want to remove the chain or gears if possible. I will inspect before I order any chain rail parts.

Thanks Again lol

 

[gsxr]

Hakie is correct. 6+16 can be easily changed.

Inner rails 8+14 require removal of the intake cam sprockets / advance mechanism and is a RPITA. However, these are often broken, and should be closely inspected, particularly the bottom portion which can snap off and drop into the timing cavity. Use a flashlight to check for pieces floating around that don't belong.

Chains rarely stretch much unless the engine was not maintained well. If stretch measures over ~4° at the passenger exhaust cam, it's far more likely that one or more chain rails are broken, possibly where you can't easily see them. Normal stretch is 0-2°. There is no factory procedure or spec, but there are old threads discussing this in more detail.

 

[TerryA]

Hakie is correct. 6+16 can be easily changed.

Inner rails 8+14 require removal of the intake cam sprockets / advance mechanism and is a RPITA. However, these are often broken, and should be closely inspected, particularly the bottom portion which can snap off and drop into the timing cavity. Use a flashlight to check for pieces floating around that don't belong.

Chains rarely stretch much unless the engine was not maintained well. If stretch measures over ~4° at the passenger exhaust cam, it's far more likely that one or more chain rails are broken, possibly where you can't easily see them. Normal stretch is 0-2°. There is no factory procedure or spec, but there are old threads discussing this in more detail.

Dave

Thanks for confirming Hakie. Two heads are always better than one.

I will wait until I have the valve covers off and can actually inspect the chain rails before ordering these parts. There was nothing in the oil pan when I changed the O-Rings on the oil level sender a few years ago. Probably within 3K miles.

Thanks Again

 

[JC220]

I checked my replacement used m119.970 motor tonight for chain stretch. Am I correct in thinking that you find the "true" TDC of cylinder one meaning that both valves are closed on cylinder one and turn the crank until the drill bit on the right bank (Adjacent to cylinder 1) slips into the slot – then read the pointer on the crank pulley? See photos below.





It looks like it has 2.5 degrees of stretch in the timing. And one top guide is definitely broken off like post #1. It also appears the pointer reading is BEFORE TDC.... is that normal? Would chain stretch not mean the passenger cam would lag behind TDC? Or should I verify actual TDC with a spark plug out and a screwdriver on the piston?

I think I may leave the timing cover alone, pull the camshafts (to avoid having to play with the camshaft sprockets) and fit new upper chain guides. In this instance does the timing chain require splitting? Or can you normally get just enough slack to slip out the cams / sprockets etc and leave the chain in one piece? This is if I was not planning on fitting a new chain at this moment and time. Basically get all the upper chain guides replaced since they get brittle.

ALSO - does anyone have data on a new chain with new upper guides? AKA the chain stretch reading. Does it ever reach zero or what really is "healthy" Earlier in this thread it is stated several times that 2 - 4 degrees is considered not to be a cause for concern and can be left alone. However, If I had an expectation that a fresh chain and new upper guides would bring it back to at or near zero stretch I might consider just doing all now.

 

[gsxr]

Joe, the 45° BTDC reference is arbitrary; something MB designed to set basic position of camshafts (see job 05-2230, link below):
http://w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/119/05-2230.pdf

With new rails/guides and a new chain, all 4 cams should pin at 45° BTDC. Issues with guides or chain will change when each cam pins. Your photo does not show 2.5° off... it shows ~12.5° off! Each line is 5° on the balancer. Remember to turn the crank very, very slowly so you can catch when the pin just barely slides in. Otherwise you can overshoot and get a false reading that is worse than actual.

I'd measure each of the 4 cams separately to see where the pin (driver exhaust cam should show the least "stretch", passenger will show the most). And then measure again after you install new guides/rails. If it's still far off with new parts, the chain may be stretched, but this is not common IME.

I've never done it, but I think if you remove the tensioner and exhaust cam sprocket, you may be able to remove the intake cams with the adjusters/sprockets intact? Worth a try anyway. You don't want to split the chain if you can avoid it.

 

[JC220]

Thanks Dave - I should have looked that up before posting. Oops - been too long since I last did a timing chain. I assumed TDC was needed not the 45 mark.

I forgot also that I actually have a "proper" set of m119 cam locking pins. I should be using those rather than an ill fitting drill bit. Tonight was just an arbitrary look over - I need to study the FSM and re-visit tomorrow night properly.

Remember to turn the crank very, very slowly so you can catch when the pin just barely slides in.

Silly question - is this reffering exclusively to the passenger (In LHD vehicle - my S500 is RHD ) exhaust cam? Is that the camshaft used to determine chain stretch really? And should I also check when the other 3 cams pin goes in for science?

EDIT: checked with the proper cam setting pins. It appears I do have 12.5 stretch! New chain and guides it is.

Will pulling the upper sump pan make pulling the timing cover somewhat easier? (Since the motor is out anyway) and if the timing cover is off I may try removing the upper / inner head chain guides DOWN and out though the timing cover area... might that work or am I speaking too soon / missing an obvious reason why they would not drop down? Thus leave the cams and cam sprokets alone as much as possible.

 

[gsxr]

OOops. I keep forgetting your cars are wrong-hand drive. Less stretch will be measured at the left exhaust cam (#5 cylinder), more is measured at the right (#1 cylinder).

Remember that broken rails can cause the measured stretch to be abnormally high; this is why you replace the rails first, then re-measure stretch. 2-4° is normal with a used chain.

Yes, if the main oil pan is removed, this should make it much easier to R&R the front cover, if needed. Just be careful with the head gaskets. I've never done this so I'm not sure what you'll encounter along the way.

 

[JC220]

A quick update on my used m119 motor with 12.5 degrees chain stretch. This was due to broken upper guide rails. The chain was actually just beginning to kiss the metal slide pin in one location - since the lower sections of both upper middle slide rails were totally MIA!



I have the camshafts out and safely stored. That was the easiest way IMO rather then mess with the cam sprockets. I will be replacing everything in the timing system – photos to come soon. I do hope that removal of the upper sump pan and timing cover will definitely allow the lower chain rail guides to come out, at the moment it looks like the left bank slide rail come up into the cylinder head cavity somewhat.

I am also thinking of changing the valve stem oil seals since I am in this far. I bet at 27 years old they are well overdue!! Since all valves are now closed (with the cams out) I cannot see any issue with me turning the crank to do the valve stem seals. AKA with rope in the cylinders to stop the valves dropping into the cylinders!

Here are also some great videos by Victor – note the subject car had the same issues as this used motor of mine so it is likely more common than we think.