Mercedes-Benz Forum banner

Questions Regarding Timing Chain, Tensioner, and Valve Covers

8K views 61 replies 9 participants last post by  mclare 
#1 · (Edited)
So my engine's timing chain is now rattling occasionally at start up (it's done this twice in the last 2 months, usually after sitting for more than 2 days). I'm a bit tired of these noises at start up, so I'm planning on pulling the valve covers again, inspecting the chains, tensioner, guide rails, and cam oilers. However, before I do this, I had several questions.

  1. Do you always need to replace the valve cover gaskets after pulling the valve covers, or can I reuse the old gaskets? The last time my valve covers were removed was a year ago (gaskets were replaced at this time).
  2. How do I inspect the chain tensioner? Is it simply a matter of pushing on the tensioner to see if there's any resistance, or is there more to it?
  3. Is there any place to get a new OEM tensioner (not the Febi) for less than $250? Right now, the cheapest tensioner I found was $400. I'd be happy with a used one that works as well.
Here's a pic of one of the cam oilers. That stuff you see on it wipes off pretty easily.
 
See less See more
1
#2 ·
DO NOT START CAR ANY MORE WITHOUT REPLACEING TENSIONER CHAIN AND RAILS.
$400.00 is cheap compared to $5000.00 to replace the bent valves when the chain jumps.( its not a matter of if the chains jumps its when the chain jumps)
Over the years i have done so many of these with bent valves it is crazy:eek
Dont take the chance GET R DONE
 
#3 ·
Yeah, I could not agree more! If you do the tensioner and not the fails, the increased tension will for sure crack the rails, jump a cog and bend the valves. This happened to me and that's what led to my rebuild. You can read about it in my "Trek up north" thread. The motor lasted exactly 3 weeks after I put the new tensioner in.

And don't go cheap! Also, a guy in Australia makes beefier rails to last a lot longer!
 
#5 · (Edited)
So my engine's timing chain is now rattling occasionally at start up (it's done this twice in the last 2 months, usually after sitting for more than 2 days). I'm a bit tired of these noises at start up, so I'm planning on pulling the valve covers again, inspecting the chains, tensioner, guide rails, and cam oilers. However, before I do this, I had several questions.

  1. Do you always need to replace the valve cover gaskets after pulling the valve covers, or can I reuse the old gaskets? The last time my valve covers were removed was a year ago (gaskets were replaced at this time).
  2. How do I inspect the chain tensioner? Is it simply a matter of pushing on the tensioner to see if there's any resistance, or is there more to it?
  3. Is there any place to get a new OEM tensioner (not the Febi) for less than $250? Right now, the cheapest tensioner I found was $400. I'd be happy with a used one that works as well.
Here is MY personal opinion, as if this would have been MY car:
1) If the valve cover gaskets are old, yes replace. If it was just replaced, you can reuse. In your case I am estimating existing gaskets are okay to be reused.
2) If it rattles at start up you don't need to test it. You already know is not able to retain its internal oil pressure. Is time to change it.
2) NO. The least you can get is just shy of $400.

Avoid revving the engine after startup, it may jump the timing. Basically you are running on borrowed time with big consequences (as already explained). If the oiler plastic holders have not been done, I would do those too. Since I am already in that area, I would do the valve oil seals too. Parts less than $50, but well worth replacing with new ones. The labor is more intense, it requires a special spring compressor too.

EDIT: upon taking the covers off, you may find that the guides have to be changed too. A timing check may show if your timing chain has stretched and needs replacement. I do not know how many miles is your car nor when these have been done last time, but just keep it in mind.
 
#6 · (Edited)
My car has 321,000 miles on it.

If I recall correctly, the chain was done at about 305,000 miles.

Anyway, here are pictures with the valve covers off.

Driver side rails


Cam Oilers (Passenger)


Passenger side rails


The cam oilers definitely need to be replaced, but I'm not sure about the condition of the rails. There are no broken pieces, and oddly enough I don't see any markings where the timing chain was slapping (driver side). Considering how long this has been going on, I was expecting some visible damage.

Something interesting I found was that the driver side cam oiler pipe has some play to it (I can shake it back and forth). The passenger side isn't like this.
 
#7 ·
From what I've read the rails/guides should be an off white color, chocolate brown is old and brittle. What is the brown goo all over the inside, you mentioned it can be wiped off ? Possible coolant seepage going on there ??
 
#11 · (Edited)
Before I purchased the car, I think either the dealer or the previous owner ran the car with low, old oil for an extended period of time (considering that's what was in the car when I purchased it). It smells like oil and it wipes off pretty easily.

During my time of ownership, the fluids have always stayed separate, as they should be.
Those guides are kaput! Yes, WCB is right, they should be milky white, not Hershey brown!

Rebuilding the front of the engine won't colt you 5K, maybe 1800.00 to 2,300.00 at most. And if you are handy and brave, I can walk you through it doing it yourself.

I've done it and while hard, not impossible if you are somewhat mechanically inclined.

PM me if interested and I can send you some light reading to do.

M
Damn, looks like I can't weasel my way out of this one. :smile

When you say "rebuilding the front of the engine", you're talking about a valve job? my mechanic quoted me around 2.4k I think if that ever happened, which at that point, I'd try to do it myself. However, my main issues are that I lack both the tools to do the job and the space to do it (small garage, small inclined driveway). In fact, I even had to get the rear valve cover bolts off with an improvised tool.
As already advised, you should replace the guides. I am speculating (the term is carefully chosen) that your chain may need replacement too. So, it may look like this: timing chain, timing chain guides, timing chain tensioner. The oiler brackets and the valve seals are a want, not a need. I am not familiar with the latest prices, but the parts for the above and the valve spring compressor tool should be @ $800 (all MB except the tool). The labor is another story.

The high mileage of your car makes me wonder if the lower chain guides shouldn't be also replaced. There has been much debate about those two guides if they should be ever changed, so I will not steer the pot anymore (although I do not agree that they last forever). In case is determined that those should be changed too (based on their wear) , then the labor goes up dramatically, and at that point you may want to ask yourself if is all worth it.
The chain was supposedly replaced before I purchased the car according to the dealer (my mechanic also commented on the chain being newer than the other parts a year ago).

So far, this is what I have ready to order:
Timing chain tensioner
Timing chain guides (ah, but which ones and how many?)
2x Cam oiler sets

If the timing chains become necessary to replace, I have a vague idea of how to do them without removing too much from the engine; I saw a video of someone rolling the chain in with just the valve cover gasket off.

Edit: Oh hey, I found the tensioner on parts.com for $325! https://www.parts.com/index.cfm?fus...5040&Title=Mercedes-Benz-All-Models-TENSIONER
 
#8 ·
Those guides are kaput! Yes, WCB is right, they should be milky white, not Hershey brown!

Rebuilding the front of the engine won't colt you 5K, maybe 1800.00 to 2,300.00 at most. And if you are handy and brave, I can walk you through it doing it yourself.

I've done it and while hard, not impossible if you are somewhat mechanically inclined.

PM me if interested and I can send you some light reading to do.

M
 
  • Like
Reactions: wooky_chew_bacca
#9 ·
Just reading this thread makes me want to grab my trusty dental mirror and have another peek at mine, I'll do that tomorrow. According to paperwork from the PO's shop the heads were rebuilt with new chain, guides, etc at 175K miles and it's just now coming up on 225K. Better safe than sorry
 
  • Like
Reactions: liviu165
#10 ·
As already advised, you should replace the guides. I am speculating (the term is carefully chosen) that your chain may need replacement too. So, it may look like this: timing chain, timing chain guides, timing chain tensioner. The oiler brackets and the valve seals are a want, not a need. I am not familiar with the latest prices, but the parts for the above and the valve spring compressor tool should be @ $800 (all MB except the tool). The labor is another story.

The high mileage of your car makes me wonder if the lower chain guides shouldn't be also replaced. There has been much debate about those two guides if they should be ever changed, so I will not steer the pot anymore (although I do not agree that they last forever). In case is determined that those should be changed too (based on their wear) , then the labor goes up dramatically, and at that point you may want to ask yourself if is all worth it.
 
#12 · (Edited)
When the chain is replaced, people also replace the guides. You appear to have old guides, that made me think the chain might be old too. However, the correct alignment of timing marks will show how stretched your chain is and if needs replacement or not. The MB chain choice is IWIS, check if that appears stamped on chain's every link.

Somebody with the 560 engine should advise you on the PNs to order for guides. I think the 420 guides are not the same and if so, I don't want to advise you wrong on PNs.

Consult with Michael Clare (mclare) if that web site is trustworthy. Somebody some time ago had some problems with the parts quality from a web site, I think it might had been him and that could have been the site. Otherwise the price is good, but count also $42 S&H.

You should start consulting the repair manual. It will help you a lot. Before I start a job (any job), I read it so many times, that by the time I start the job I already have it memorized.

EDIT: I can also tell you what rail PNs to order for your car based on your VIN and EPC.
 

Attachments

#21 ·
Good point, I can have my mechanic check the chain when I tow the car over to him.
I got my tensioner here,
Tensioner | Genuine Mercedes-Benz | 116-050-18-11
took about a week to get delivered to my US PO box, the rest of the parts I got from Autohaus who post next day every time I have dealt with them, the improved rails are from MB spares in Canberra Australia.

In your third photo you can actually see the mark where the chain has slapped against the head, scary stuff. :eek
Thanks for the link!

Whoa, I just noticed those marks as well! Odd though, the chain slap noise always came from the driver side, but those marks are on the passenger side. On the other hand, I could still hear the chain a bit even after it stopped slapping, so perhaps it was dragging against the passenger side head a bit.
Parts.com lists a low purchase price then gouges you with high shipping and handling. Parts.com total price is $366.76 while MBOEMparts.com offers a total price of $353.37.
Jeez! A total price of $353.37 isn't too bad. I'm planning on ordering the parts in a week or two, so I'll keep looking around to see if I can get a better deal (after all, I got that OEM IAC pretty cheap).
You remove both rocker covers, align timing marks on balancer and American passenger side cam, then measure in degrees on the balancer as you rotate engine by hand to align the mark on the drivers side cam. I was three degrees, as in three degrees of chain stretch, which is within tolerances, I don't recall the exact limit off hand.
I think I'll leave that to my mechanic.
 
#14 ·
I got my tensioner here,
Tensioner | Genuine Mercedes-Benz | 116-050-18-11
took about a week to get delivered to my US PO box, the rest of the parts I got from Autohaus who post next day every time I have dealt with them, the improved rails are from MB spares in Canberra Australia.

In your third photo you can actually see the mark where the chain has slapped against the head, scary stuff. :eek
 
#17 ·
How does one differentiate stretched chain from tensioner failure? After reading this thread it seems that installing a new tensioner may create fatal issues if the guide rails are not also replaced! I have 90,000 miles on my original chain and I am hard pressed to believe that it needs to be replaced. I am open to all suggestions. TIA.
 
#18 ·
You remove both rocker covers, align timing marks on balancer and American passenger side cam, then measure in degrees on the balancer as you rotate engine by hand to align the mark on the drivers side cam. I was three degrees, as in three degrees of chain stretch, which is within tolerances, I don't recall the exact limit off hand.
 
#19 · (Edited)
Tom you are correct that it will cause failure of the guides. I believe that's why mine failed.
 
#30 ·
Michael, I gave this some thought last evening and I wonder if Febi is being blamed for failure when the guide rails may be the problem. I removed the Febi tensioner (came with the vehicle from the previous owner) from my parts vehicle yesterday and I will replace it with the OEM tensioner that I removed from my low mileage vehicle last month. I removed the OEM because I was hearing a knocking sound at start up (infrequently). The parts vehicle Febi tensioner has never knocked while I have owned the vehicle these last several years. If the OEM tensioner does not knock in the parts vehicle then maybe the knocking that I am hearing in the low mileage vehicle is a result of something else.

I keep old parts just in case they are needed for a quick fix or become No Longer Available (NLA). I keep extra gaskets for multiple parts on hand at all times.
 
#23 ·
The driver side rail is the weak one and is the one that failed on my coupe.
 
#25 ·
Let me know if you need my help and PM me your email address and I will send you a master parts lkst for a 560.
Thanks! I'll PM you shortly!

By the way everyone, thank you for helping me (and offering to help me in person) with all of these issues. My car probably wouldn't have lasted a year without the information provided by the members of this forum.
 
#24 ·
Let me know if you need my help and PM me your email address and I will send you a master parts lkst for a 560.
 
#28 · (Edited)
2 to 3 days. If you have everything.
 
#31 ·
Well I believed that the left side guide failed because of the increased tension and because the left hand to guide is a bad design. It is long and flat and snaps in half at the mounting point. At least the ones that I have seen have. That guy in Australia made that one much thicker. After years in the car, they get old and brittle. Once they are Hershey chocolate brown its only a matter of time.

Tick tock....
 
  • Like
Reactions: Currumbin SL
#34 ·
All right, I bought the MB chain tensioner from eBay since it was $50 cheaper.

Here's everything I purchased which, based on the info I received from everyone here, should be everything.
OEM MB Chain Tensioner
OEM Cam Oiler; Camshaft Oiler Kit; 10mm (these came in a kit of 2 supposedly on Autohaus)
Iwis Timing Chain; Double Row 198 Link with Master Link
VictorReinz Timing Chain Tensioner Gasket
OEM Timing Chain Guide/Rail; Left Cylinder Head; 143mm (these also came in a kit of 2 supposedly on Autohaus)
OEM Timing Chain Guide/Rail; Cylinder Head Inner; 172mm
OEM Timing Chain Guide/Rail; Clamping Rail/Lever
 
#35 ·
Good because I was going to tell you that buying a cheap tensioner is like buying bargain condoms. You might get it on and use it for a time, but you'll never know when it will fail, and when it does it'll cost you a fortune....
 
#37 ·
saving $120 can cost $400 plus the cost of the original part but take note, your labor was free at least and your cost of getting wiser was less than the local University. Then again it has been said here over and over again; the most expensive car you will ever own is a cheap Mercedes....
 
#38 ·
Just thought I'd provide a small update:
  • The parts I ordered on Autohaus are coming in tomorrow, so that's good news.
  • The tensioner I ordered on eBay 2 days ago still hasn't shipped out. I'm going to post a picture of it on here just so everyone can see it (since it's $50 cheaper from this seller). i hope it ships out soon.
  • liviu165 actually recommended that I purchase a mechanic's stethoscope a while back, so I ordered one before I created this thread. It's coming in today.

I might not be able to take you up on your offer, mclare, although I'm still looking into it. While my AAA coverage is able to tow it that far, it's more of a time constraint issue for me at the moment. I'll let you know what I decide to go with.
 
#39 ·
Understood, lmk.
 
  • Like
Reactions: Vizezeul
#40 · (Edited)
The tensioner I bought from the eBay seller finally came in the mail today. I double-checked it for the Mercedes logo (as I heard Febi's and knock-offs don't have it) and it was there. I think it was pre-oiled as it both feels and smells a bit oily, which was a nice touch in my opinion.

Here are a couple of pictures of it below.



Mclare, I've made the decision to just pay my indie for this repair. The only time I would be able to take the car up to Lancaster, stay there and work on it is in December, although I need the car up and running by early November. However, if the offer is still on the table, I'm going to need to rebuild the front end of my car sometime next year due to a bunch of worn rubber suspension parts. I'd rather not pay my mechanic for it (It would be around $1,000 for parts and labour I think), so if you wouldn't mind me heading up there early November, perhaps we could work on it and I could cross that one off my list. Of course, I'd have to look further into doing this one as well, but this would be more for a cost assessment rather than a time thing.

I had a couple more questions for everyone if you guys don't mind answering them:
  1. I noticed that nobody mentioned changing out the camshaft sprocket when doing the timing chain. Is it necessary to replace the sprockets, or can I get away with skipping those? You can see the condition of my current sprockets in my first post in this thread.
  2. This next one is a bit silly. Is there anything I should expect from letting the car sit for another week or is there anything I should do? I disconnected the battery for now and no surprise leaks have happened yet, although I believe I read a thread on here about transmissions leaking excess fluid from the torque converter. This is actually the first time since I've owned the car that I've let it sit for more than a week.
 
#41 ·
The camshaft sprockets seldom need to be changed. I think there is some benefit as wear affects the timing slightly and probably wears on the chain more quickly, but it's not going to cause a failure. I replaced mine "just because," and they're not terribly expensive; might make more of a difference at your mileage.
Sitting, in my experience, doesn't cause any more issues with our cars than any other. I used to deploy for 2-3 month periods and not even disconnect the battery without issue. Nothing to worry about there.

The tensioner does have a "charge" of oil already in it. Slightly beside the point, but my SEC (Liesl) is the cat of nine lives. Or was until it hit a deer, but my brother was driving... When I got it, there was some unusual noise from the engine. I drove it for a month or so before I got everything together to tackle the timing chain, tensioner, and guides. When I took it apart, I discovered that the left upper guide had split in half and was riding on the chain (even had some wear marks on it, who knows how long it was like that). How it didn't jump into the waiting teeth of the sprocket is beyond me. Fast forward about five years and a top end rebuild (among much other work). I'm driving from VA back to OK, having put around 2500 miles on it since finishing all the work. Quite randomly, I notice it's down on power and running rough at idle and low speed. Strange, but it's doing well enough, and I'm 500 miles from home. I get back and start looking for a culprit. After some preliminary fuel and spark checks, I pull the valve covers and discover that the right cam has somehow jumped a tooth or two. Nothing broken, and no further issues in the 10,000 miles since. I replaced the genuine tensioner from when I replaced the chain with another genuine one, and that tensioner is now sitting in Schrodinger's box - anyone want it?
 
  • Like
Reactions: Vizezeul
#46 ·
Yeah, these sprockets seem a lot sturdier than those nylon-tipped sprockets used in some cars, so I figured they wouldn't need to be changed as often.

Ah, thanks for clearing up the sitting issue for me! I was always worried that if I let the car sit too long, the car would develop some sort of seal-related issues.

Those timing guides sure can do a lot of damage. It makes you wonder why Mercedes didn't make them thicker, back them with metal like the banana rail, or even make them sturdier like the lower guides to begin with.
I agree with the above, that the sprockets very seldom need replacement. There are indeed cases when they do, a chain with stuck roller(s) for example can prematurely wear out the sprockets. However, what nobody has mentioned so far (in here as well as in another recent thread) is that if we accept the idea that the sprockets are worn out, then the crankshaft sprocket would have to be changed too, not only the camshafts ones. This one would have the most wear because is the only chain's driving sprocket. Why discriminate, just because is not easy to get to that one???

Where I have a different opinion, is the statement "they're not terribly expensive" (the camshafts sprockets that is). I am assuming we are talking about new OEM parts as replacement. Well, if that is correct, they would be more than $500 both. That, for me, is expensive. Just my personal opinion.
At 1/10 the price of a new MB sprocket, I would stay with the original ones unless with a new quality chain I would have the timing off by a lot, in which case I would go with MB used ones. At 1/10 the price I just have a hard time trusting their quality (I know what machining is involved to make a sprocket and I just can't see how somebody can make a quality one and make profit within $25/pc.).
I'll have to take a look at them next time I have the valve covers off and see what they look like. They've got around 35,000 miles on them, so if they're inferior quality they should should show significant wear by now. Genuine is virtually always preferred, but it's not a terribly complicated part, certainly not $250 complicated. A premium racing-spec timing set for just about any american V-8 costs less than that.
I noticed those cheap camshaft sprockets over on Autohaus. It's the only option they have for some reason.

I'm going to leave this link here so that I can reference it later.
http://www.benzworld.org/forums/w12...2057-chain-guides-upper-all-timing-cover.html

I was searching for information related to catastrophic engine failure due to worn lower guides, and I found that thread to be informative.
 
#42 · (Edited)
I agree with the above, that the sprockets very seldom need replacement. There are indeed cases when they do, a chain with stuck roller(s) for example can prematurely wear out the sprockets. However, what nobody has mentioned so far (in here as well as in another recent thread) is that if we accept the idea that the sprockets are worn out, then the crankshaft sprocket would have to be changed too, not only the camshafts ones. This one would have the most wear because is the only chain's driving sprocket. Why discriminate, just because is not easy to get to that one???

Where I have a different opinion, is the statement "they're not terribly expensive" (the camshafts sprockets that is). I am assuming we are talking about new OEM parts as replacement. Well, if that is correct, they would be more than $500 both. That, for me, is expensive. Just my personal opinion.
 
#43 ·
For better or worse, I used the Swag cam sprockets, they're $25 each. Given the price difference, I can't imagine they're re-boxed OEM pieces, but they're German-made (or were at least). It is a good point about the crankshaft sprocket, it stands to reason that it would see twice the wear of the cam sprockets. I found a little more info in this thread, which contains a link to this if you're really interested in the intricacies of chain drives.
 
#44 ·
At 1/10 the price of a new MB sprocket, I would stay with the original ones unless with a new quality chain I would have the timing off by a lot, in which case I would go with MB used ones. At 1/10 the price I just have a hard time trusting their quality (I know what machining is involved to make a sprocket and I just can't see how somebody can make a quality one and make profit within $25/pc.).
 
#45 ·
I'll have to take a look at them next time I have the valve covers off and see what they look like. They've got around 35,000 miles on them, so if they're inferior quality they should should show significant wear by now. Genuine is virtually always preferred, but it's not a terribly complicated part, certainly not $250 complicated. A premium racing-spec timing set for just about any american V-8 costs less than that.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top