380SL Noisy Startup and Timing Chain Question - PeachParts Mercedes-Benz Forum

jkford13 · #1 11-28-2007, 12:30 PM

~1 year ago, my SL started making a clattering noise on startup. It is a kind of clackity-clack. It only happens on occassion; not every startup and not only warm starts or cold starts. Based on some searches for similar problems, it appeared to be caused by broken oiler clips, so I bought a kit with the clips and seals.

However, when I pulled off the valve covers and replaced the oiler clips, I did not discover the damage that I expected. One or two of the clips on each side were a little loose, but not cracked, or broken.

After finishing the job, i began searching for more info, and have seen reference to cracked timing chain guides. I just realized that I have the guides but didn't replace them. Looks like i have a new project for this weekend.

Based on this setup, i have a couple questions:
1) Could faulty chain guides result in the described noise?
2) Some posts have said if you're gonna replace the guides, you might as well replace the chain while you're at it...do you concur?
3) Once I pull off the valve covers, do i need to replace the seals again. It is obviously not old or warn, but not sure if seals can only be tightened once before they can lose ability to seal.

Thanks for your help.
Justin

230/8 · #2 11-28-2007, 03:31 PM

Timing chain guides/rails, chain tensioner, and chain...double row chains - replace at 100K, single row - replace ASAP and then watch like a hawk for 50K. You don't want to see the repair bill if your chain breaks or throws off the sprockets.

230/8

JFawcett · #3 11-28-2007, 03:36 PM

How many miles on the car? Does it still have the single row timing chain? (Some have been converted aftermarket to dual row).

The 380SL should have the timing chain inspected, if not replaced, every 50-60,000 miles. The replacement/service should include upper rail inspection or replacement and tensioner replacement. My 420 SEL tensioner failed and ate up half the engine. The chains stretch over the useful life and will become more prone to skipping sprockets and running your pistons into your valves....not a good thing.

The noise you describe is possible broken rail or slack in the chain....both will dramatically increase chances of big problems.

Chains don't always have to be replaced - it is a good idea, but the chains rarely break - the tensioners and guides fail before the chain.

jkford13 · #4 11-28-2007, 06:19 PM

I've had the car for about 3 years, and it's closing in on 200k miles. Not sure when the last timing chain inspection/replacement was done. I bought the chains today, and plan to replace them with the upper guide rails over the weekend.

You both mentioned the chain tensioners...how do i determine if they need replaced? The cost of these parts isn't trivial, so I wouldn't want to replace unless I knew they were an issue.

I believe another symptom that might indicate chain slack from another post I read is engine power. Especially when I hit the gas from a standstill, i will push the gas pedal and sometimes get no response for 3 seconds or more...pretty scary when making a turn across traffic!

Thanks for your help!!!

jkford13 · #5 11-28-2007, 06:20 PM

Oh...and my 380SL is an '84 with a dual row chain.

meltedpanda · #6 11-29-2007, 09:15 AM

so on my 450SL , how do I visually inspect for problems, what do I look for?

bbeberness · #7 11-30-2007, 05:52 PM

My '84sl has the same problems with the rattle. If you do the repair yourself, it would be interesting how long it took you. I probably would just take it to a MBZ mechanic and have them do it. I have been priced from $600 to $1500 for the total replacement. Still much cheaper than another motor. Mine had been replaced by the original owner because of a slipped chain at 75,000 miles.

ctaylor738 · #8 11-30-2007, 08:00 PM

IMO, that's very good advice to do the chain, rails, and tensioner at the same time. It's an excelllent and satisfying DIY.

But if the noise you are describing is more of a "clack" than a rattle, you may be hearing noise from a ball stud that's leaking down and allowing the rocker to slap the cam lobe until it pressurizes.

jkford13 · #9 12-01-2007, 06:59 PM

I've discovered the source of the noise, or at least what I assume is the source of the noise. The inner chain guide on the driver side is broken. Both the upper and lower pins still hold the respective halves of the guide.

Now I have a problem needing promt assistance. In trying to remove one of the pins holding the broken chain guide, per a method I had read, the screw sheared off. The screw is flush with the pin, and there is nothing to grab on to. I have tried to drill the center of the screw out with a colbalt bit, and it is being stubborn. I have an easy-out, but i do not think the hole in the center of the screw is deep enough for the easy out to catch. I think i'm hosed.

Any help to remove this pin is greatly appreciated. I don't want to concede and take it to a Mercedes repair shop...but i'm running out of ideas.

Thanks,
Justin

aam · #10 12-01-2007, 07:42 PM

Quote:

Originally Posted by jkford13

I've discovered the source of the noise, or at least what I assume is the source of the noise. The inner chain guide on the driver side is broken. Both the upper and lower pins still hold the respective halves of the guide.

Now I have a problem needing promt assistance. In trying to remove one of the pins holding the broken chain guide, per a method I had read, the screw sheared off. The screw is flush with the pin, and there is nothing to grab on to. I have tried to drill the center of the screw out with a colbalt bit, and it is being stubborn. I have an easy-out, but i do not think the hole in the center of the screw is deep enough for the easy out to catch. I think i'm hosed.

Any help to remove this pin is greatly appreciated. I don't want to concede and take it to a Mercedes repair shop...but i'm running out of ideas.

Thanks,
Justin

Justin,
What you can't undo you cut, or replace.
What do you think a pro. is going to do, more then you?
If it is not coming out he will replace the necessary parts at your expense.
Kip working on it, don't give up.

jkford13 · #11 12-01-2007, 07:51 PM

Thanks! I was debating that as a next step. Any suggestion on how to keep the debris out of the engine? that's my priary concern at this point. Once I get that set, I think it's sawzall time!

Cheers,
Justin

meltedpanda · #12 12-02-2007, 04:14 PM

I have rigged up a shop vac with an extension to suck out crap as I have taken dirty bits off on my engine. You can also put a strong magnet nearby for any flying metal bits

jkford13 · #13 12-04-2007, 02:25 PM

Ron,

Thanks for the suggestion. I will definitely give that a try. I figure between the shopvac and rags covering the engine opening, i should be pretty safe.

Thanks again.
Justin

Arkansawyer · #14 12-10-2007, 08:04 AM

Greetings--I'm new to this forum. My question is how do you check/measure the slack in the timing chain? Seems like this would be a good way to see if it needs to be replaced. Thanks. Regards....Arkie

meltedpanda · #15 12-10-2007, 08:50 AM

this will get you started

http://www.peachparts.com/Wikka/M117TimingChain