Oh, boy.
In 2016 I was replacing the timing chain and had chain noise after replacing the chain and all the guides.
I posted links to videos I had posted on Dropbox (since removed) where I solicited opinions on the noise source. No responses.
While replacing the front crankshaft seal, I noticed a LOT of slack in the timing chain on the uptake side of the crankshaft. Enough to cause the timing chain to wear a hole in the upper oil pan and cause an additional leak source- replacing the seal with NOT stop this leak.
Kent has a posted video describing the problem
being caused by a defective timing chain tensioner. I installed a new tensioner unit (Febi) purchased very close to this site. Apparently the "new" tensioner unit was "as good as old", and didn't function properly. Out it goes.

I got to thinking about the additional issues that could cause excessive slack, including sprocket wear. I would be nice to have someone make up some steel or aluminum "go no go" gauges that you could stick in the sprockets.

Since this doesn't exist, I will probably be safe assuming I will be breaking the "new" chain and replacing the cam sprocket, the idler sprocket, and the crankshaft sprocket; the timing device has another sprocket but a replacement timing device isn't on the menu. With 3 out of 4 sprockets replaced along with a new FUNCTIONING tensioner I should be able to correct the chain noise, and it's attempts at ventilating the upper oil pan further.
Kent patched the hole in his oil pan by using long-cure JB Weld on the inside and outside of the hole in the upper oil pan.
So kinda back to square 1, back to breaking the timing chain and hoping to get sufficent slack to remove the camshaft sprocket, the upper oil pan is RIGHT THERE under the sprocket and the chain can not drop far enough to clear the upper pan to allow the sprocket to be pulled without slack, I will find out how far I must go!

Cheers

Stan

IIRC you have to suck oil into the tensioner when replacing. Was that done and tested when you replaced?

https://www.tonk.ca/models/w123/w123CD2/Program/Engine/615/05-310.pdf

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

Correct

__________________
84 300SD
85 380SE
83 528e
95 318ic

Can’t help with the timing chain but if you want to see real world tests of JB Weld and other epoxies, check out project farm on YouTube. He just tested putty epoxies and JB Weld did very well. He even patched a lawn mower cylinder head with it.

And he got a little silly with a chain, a rusty pickup and a large tractor.

Michael

Yes indeed

Had the "new" tensioner out at least twice, each time I stuck it in a quart tub full of fresh 15w40. but it in the drill press and pumped it until no bubbles appeared. Each time it was reinstalled the chain racket persisted. No change. Went through several new tensioner gaskets I recall. Budget for repairs exhausted, I buttoned it up and drove it for about 4 years occasionally. Racket remained unchanged.
Finally returned recently to replace leaking crankshaft seal that didn't seem to be leaking
(after pulling the balancer, it was going to be replaced anyway). As I was surfing for videos I found Kent's leak video, so I checked my upper oil pan. Sure enough, there was a hole, didn't look to be more than a rock chip in a windshield, but oil still slowly dripped there. Cleaned area with MEK, then sanded with 3M rough sandpaper to give the slow set JB Weld something to hold onto.
Since I am going back in I will take a pic of the sprocket as it sits with the excessive slack laying in the uptake side. Replacing the tensioner and the sprockets should pick up the chain slack.

Stan

Which engine are you referring to?

Helps to put this info in your signature.

__________________
1981 240D 4sp manual. Ivory White.

OM 616

Sorry. I need to find my other password and continue as "snapped_bolt", even though I sold the car with the snapped bolt due to mid-body rust attack. Car a one time t-boned and repaired, but the welded-in "frame" under the doors wasn't treated internally against rust. I found the rust when removing oil-soaked carpets (previous owner must have had the job of hauling full torque convereters)

1979 240D Auto mechanical shift

Stan

That would explain the chain tensioner that required priming.

Something I’ve been wondering is whether we’re able to use the 617 chain tensioner.
That thing is much less complex and is serviceable without removing the assembly.

.

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1981 240D 4sp manual. Ivory White.