KrustyKustom

So I got my GL350 back from the timing chain/parts replacement. Luckily no surprises, everything looks to be back exactly in the correct spot under the hood barring a couple of smears of dried black silicone (probably valve cover sealant).


The upper sprocket on the passenger side showed the most wear (closest to tensioner), the other side looked better but I only saw old parts so not much to compare to. The slider on the tensioner side had some good grooves in it, the other side looked unworn.


All and all a success. I have only had one cold start and it sounded good so I think it is fixed. The Technical Service Bulletin explains the method of measuring the timing chain "slack" by putting crank in TDC and turning cam sprockets and measure the "slop". They even have a chart that compares mileage with expected wear so the TSB looks to be targeted to exactly this issue without a doubt.


Engine sounds completely smoother at all rpm, especially in Park and holding 1500rpm, just sound smooth now.


Having a German beer tonight, and hoping for 150k miles +.........

samiran

Another update. Vehicle still at dealer.

Unable to find the reason for hesitation that occurs when accelerating from a stop (was a suspected transmission valve body issue, then it might have been related to the leaky fuel injector). They are thinking now it is "carbon build-up" in the engine, and going to do a compression test. They are waiting for a tool to do the compression test.

Seems unlikely to me, since the issue wasn't present prior to the engine service.

I'd appreciate it if anyone had any thoughts/suggestions.

KrustyKustom

Carbon buildup is doubtful I would think as it did not exist prior to the chain replacement?


Is it displaying any codes? Maybe they got something off one tooth on the chain? Other idea is something related to the mass airflow sensors, they are sensitive and perhaps they did not fair well through the disassembly process on top of the engine?


The Mercedes software is so crazy thorough it seems they would be able to see if a sensor(s) are out of spec. Maybe some more driving would throw a code?

samiran

Krusty, wanted to say I was glad you got your vehicle back in working order

For my issues, I've done some more homework, and I'm guessing that if there is an actual compression issue (new), it is related to one of the cam timings being off slightly (hopefully not far off enough that there is piston/valve damage).

My guess is, if there is actually low compression, that there is uniform low compression, and that a leak test will show the same class of leak on all cylinders (all exhaust leaks, or all intake leaks, etc . . . .)

The likely hood of piston/ring wear at this mileage (89,000 ish) seems really unlikely, and would be a pretty unique issue. This is especially the case since this is a "new" thing.

Unfortunately, if the timings are off, it seems like a really big job to fix it; and one that the dealer should take responsibility for. Based on my discussions with them, they were moving in the direction of blaming low compression on carbon-build-up, but that seems like a serious stretch. It sounds like the want to claim it (carbon-buildup) is an unrelated issue, and needs to be fixed at my cost. Based on my reading of carbon-build-up issues, this is tantamount to an engine rebuild. If that is their final conclusion, I've got to pickup the vehicle, and take it to another mechanic to verify the valve timings, and get a second opinion.

If it is truly "carbon-buildup", I've read that running the engine hard and hot (Italian Tune-up), should really help on an engine with minimal wear. That being said, I regularly drive highway mileage (60+ trips at 75+ mph), and would not think that the "extreme sooting" of a babied diesel engine would apply to me.

If anyone has any recommendations for MB diesel "gurus" (to borrow a term from the VW people) in the Midwest (or really, anywhere in the US), I would really, really appreciate it.

Based on my reading from the Sprinter-Source forums, it also seems like the heli-coil repair of the injector hold-down bolt won't last, either, and that a deeper insert into the cylinder head is required. Between this, and the "compression" issue, my confidence continues to decline.

KrustyKustom

I feel your pain in your situation. If in fact is just a soot issue there is a product made by LubriMoly that is the best on cleaning the soot from a diesel. YouTube Lubrimoly DPF Cleaner, they usually put it directly in the fuel filter for maximum concentration (recommended).


I think from your explanations that the dealer has not done work one would expect from a factory trained mechanics. They need to make it right for sure.


My money is either a valve was dinged when the chain went on or off a tooth. No way it is the rings, these engines are solid on the bottom end. They use a laser honing process to have a super hard surface on the cylinders, no way with your mileage those are bad. The OM642 gets sooty from sitting and idling or lots of city mileage but on the Sprinter forums problems are not seen until over 250k miles.


Keep us posted,

samiran

We continue to make no progress.

Car still at dealer. Still experiencing "hesitation". Compression test was "marginal, but no red flags".

Now they are doing a "socket box test", to test "engine resistance". I asked if this was air/exhaust related, and the SA indicated it was fuel and other related. Couldn't give me any other details.

Anyone know what a "socket box test" is? This is nothing I've ever heard of, and a bit of Google-fu reveals nothing.

KrustyKustom

Never heard of a socket box test...sounds like a "widget"...

BlownV8

They need ignore the socket box and focus on the blinker fluid. MB uses unobtanium and it has probably run out and simply needs refreshing. Throw in some 30 weight ball bearings and it should run better than new.

samiran

That's kind of what I was worried about :/

At this point, I think I just have to go in, pickup (possibly tow) the car, and take it somewhere else to have the timing checked.

KrustyKustom

Samarian, have they kept you in a loaner car all this time?

Another thought came to mind, you mentioned they replaced the entire balance shaft, not just the sprocket. Perhaps this is out of sync? The bummer is the cams may be timed with the crank but I wonder without disassembly how the balance shaft timing could be verified?

The other idea is one cam sprocket runs the other on the same head (tooth to tooth). It is a possibility that the exhaust cam (running on chain) could be spot on but the intake cam is one tooth off?

It totally has to be something related to this if it is not a cold air intake measurement issue.

Feeling' for ya my Diesel brutha...

samiran

Yup, loaner car for most of this time, which just makes the whole thing stranger to me.

Especially because they keep running "tests", and not finding anything, I continue to suspect that there is a timing problem, but they won't fess up to it; I'm not sure if they are re-doing the repair, or if they are just exploring other avenues.

I spoke with a buddy of mine, who is a non-MB mechanic, and his view was that the issue was very consistent with the timing of the cams being off.

He mentioned that similar things have happened to him, and in his shop before, (being off a tooth), and its' typically a result of a junior mechanic being assigned to a job that is just too big for him. The outcome should/needs to be that they redo the job, and do it correctly. In his view (depending upon the number of cam teeth), it was unlikely that there would be valve damage resulting from being a tooth off.

That being said, it was also his view that it would be trivial to bend a valve during the repair, depending upon the procedure.

I'm looking for another update from the dealer today.

EDIT: Found out what a socket box is (not from the dealer, but from another buddy of mine). Apparently, it is a special MB toolkit used to test the various wiring harnesses throughout the engine. It provides feedback on fuel injection, pumps, sensors, and virtually every electrically operated part of the vehicle.

It is, apparently, a PITA to use, because A) they are rare, and typically have to be ordered from Germany by vehicle, and B) they need to be attached at the ECU and at the various harnesses in question, which are located throughout the engine.

It seems to be used when they suspect an odd ECU error.

samiran

Argh.

Still haven't heard back from the dealer.

I stopped in today after work, (~6:00 PM), and neither a manager nor my SA was there.

I did talk to a different SA. I introduced myself by saying that I was looking for information on my car, and I hadn't heard back from "Joey" in a week.

My car must be notorious there, since his immediate response was, "Oh; the diesel GL?", followed by a pause, followed by, "I don't know anything about your car, sorry."

I think its time to throw in the towel on this dealer. I'm going to pickup the car tomorrow, come hell or high water, and find someone else to diagnose the current situation. If it is timing related, I'll send these guys the bill.

KrustyKustom

Holy Cow, that has been what like 6 weeks?

I wonder if you try someone up the food chain at the dealer or try MB service help line?

Seriously, these guys can't just keep putting this off. They gotta fix it if they messed it up for sure.

alx

a tooth off on some interference engines will result in many bent valves and scored piston faces.

KrustyKustom

So...whats up with the ol clacking OM642? still in the shop?

FastMoneyPlaya

I had the same problem at 60K miles on my 2011 GL350... had the clank noise at startup and tranny felt a little rough... thankfully I bought the extended warranty so everything is covered, but timing chains shouldn't go so soon - this sounds like a flawed design.

Here's the diagnosis on my GL:

"Concern about the hard start is caused by a stretched timing chain. This is covered by warranty

Concern about the harsh downshifts of transmission is a defective torque converter. This is also covered by warranty

In addition we found an incredible noise when idling from the engine caused by a defective main bearing. The half of the bearing where the crankshaft rotates on in the center of the engine. In short there is play and wear and tear. Covered by warranty. Note: this required taking the engine out of the car and breaking it down. Should be complete next week."

KrustyKustom

This timing chain issue seems to affect 2011 models and it has a Technical Service Bulletin on it describing the issue. The design is not defective exactly they just had a run of bad timing chains that prematurely stretched.


Your main bearing problem is a whole other issue, that's major!


Since I had my timing chain replaced my car is awesome. Smooth as silk and great mileage again. I got 32mpg the other day.


Are they replacing the sprockets as well on yours?

FastMoneyPlaya

I'm not sure exactly which parts are being replaced, all I know is what the service adviser emailed me. I can post all the details once the job is complete and I see the summary. I'm not too upset about it since it won't cost me a dime, but I would really be angry if I didn't have the extended warranty. Especially since this seems to be a common problem, and Mercedes owners shouldn't be expected to shell out $5K or more to fix their engines at 60K miles.

B Marques

Can someone record noise at startup. I bought my 350 used and not sure what is normal and what isn't. Thanks

KrustyKustom

I do not have my sound recorded from before it was fixed but it is simple to detect. On mine if it sat overnight or at least 8 hrs the when you go to start it it will for 3 to 5 seconds make a distinct metallic slapping or dry rattle sound, then it will soften and go away. Hot starts are not an issue.

There are a couple of other mid rpm sounds that it made with the bad chain as I have another vehicle with the same engine to compare to.

Technical service bulliten says fom 36k miles to 120k it can develop.

FastMoneyPlaya

Here's an update. The GL350 is still in the shop for the above listed problems - it's been 2 1/2 weeks. The last we heard, they rebuilt the engine, etc, and it is still running rough - the dealer is trying to figure it out.

I must say, this is my first Mercedes, and I'm not impressed at all with the engineering. This is the second time my vehicle has spent an extended period in the shop. The first time was over a week to fix an AdBlue warning that kept coming on repeatedly. Good thing I've got the extended warranty and a free loaner!

jasonjeross

It's also on the 2012 GL350s. Read my story.

I guess more people should have believed me when the exact same story of pain over a year ago.

Of course "Alx" thinks you are lying and full of it. Funny...must be a lot of foolish owners out there eh?

Nope, more like people that bought a brand that WAS quality and is now an overpriced Ford (that's not really fair, Fords are more reliable).

Once again.....glad I traded the POS in while it still ran. I feel sorry for the sucker that bought it used. I couldn't floor my new truck fast enough out of the dealer when we were done. F-you very much Mercedes.

READ AND LEARN!!!!

FastMoneyPlaya

Here's the latest on my GL350 - it's been in the shop for 3 weeks now:

"Sorry for the delay. I spoke with the shop foreman regarding the engine repair. It most definitely didn’t go as planned and we had to tear down again to replace the intake manifolds as it was running rough. We are waiting for them to get here and should have more info in the AM."

samiran

Hi All, I know a thing or two about this problem now :-)

B Marques: For what it sounds like, there is a ML350 thread on Vimeo that has EXACTLY the same sound:


That is actually a gas version, but it is a very similar problem. In that case, the oil powered chain tensioner leaks down overnight, letting the chain go slack. Pressure rebuilds when the car starts, which takes up the slack.

If you have this problem, my strong suggestion: Find a dealer in a low-labor cost area. This job is a LOT of labor. The parts aren't THAT expensive (between $400 and $1100). But if they have to pull the engine, that can easily become 30+ hours.

Unfortunately, for our vehicles (my diesel, anyway), the issue was not actually the tensioner, but the the chain, and various other timing components, being worn. I suspect a poor quality of metal in the chain. Dealer, of course, blamed it on "bad oil", but that is a very fishy explanation if you ask me.

An update on my vehicle:
I picked it up two days after my last post. The dealer indicated that it still had the "lagging" problem, but I wanted to get it out of there, and take it for a drive.

They gave me all the paperwork for the testing that had done, and it was pretty exhaustive in terms of the subsystems that touched. Having said that, I did learn that some of the testing they did was not necessarily conclusive because of the test method; for example, the compression test was not done with an actual compression tester, but was done use the STAR diagnostics and the starter, counting the number of revs. This is a reasonable way to do a first test, but it doesn't actually measure the compression in the engine, and can lead to inconclusive results if the battery is low (within spec, but low), or if the car doesn't sit long enough between revs, etc . . .

I've been driving the car since, and it seems to be in pretty good shape. I did notice the lag intermittently, but honestly, previously it had been something I typed up to being a turbodiesel. It was very different from when I had picked up the vehicle the first time; the lag associated with the fuel leak was dramatic.

I have since switched diesel brands AGAIN, and the lag seems to be totally eliminated. I'm very strongly suspicious of US diesel quality, and I'm pretty convenience (after having talked to some guys at work with VW diesels) that virtually no diesel in the US meets MB standards.

Some of the guys here use PowerService fuel additive with their VWs, in order to bring the diesel cetane number into range for these engines, which I am considering. Right now, I'm filling up with "Gold" premium diesel, which is closer to the cetane range recommended for the OM642. My understanding is that the X164 Bluetec series requires(strongly recommends?) a cetane rating about 45; and that in Europe diesel fuel typically has a cetane rating of 50-60. But I digress. . . .

FastMoneyPlaya, I'd be really interested to know what "running rough" means. At one point, they thought that my vehicle had a problem somewhere in the transmission as well (to explain the lag, perhaps the valve body), but eventually concluded that it was an engine problem; possibly a "carbon buildup" problem. For whatever reason, my problem seems to have been "solved" by switching to a different diesel.

FastMoneyPlaya

My GL350 ran rough at startup for about 30-60 seconds, then seemed fine. Originally, they replaced the timing chain, main bearing and torque converter... Then they replaced the intake manifold, but it still wasn't totally right... So they tested the diesel fuel, and said there was some contamination, and they found some metal clogging the fuel injectors. They suggested that I bought bad fuel at some mom and pop station, but I checked my credit card and proved that I'd pretty much filled up at the local Shell station which is one of the highest volume stations in my area. It literally took over one month to do all the diagnosing, trial, error, engine rebuild, etc... But thankfully all was covered under my extended warranty, I had a GLK loaner the whole time, and the GL350 runs fine now...