190E 16V timing chain rattle

[Jim Herold]

I have a 1987 190E 16V with 167,824 miles . Approximately 11K miles ago, at 156,199, I installed the upgraded timing chain tensioner because I was getting timing chain rattle after starting a hot engine, When I made the upgrade, my timing chain was tight and timing was within about 1 degree of TDC with the marks aligned on the camshaft sprockets. I concluded my chain was good. The chain rattle totally disappeared after the upgrade.

However, after only about 11K miles the rattle on start-up returned. The noise has gotten progressively more noticeable--a key difference is that the rattle now occurs almost always on startup, whether the engine is hot or cold.

What might have failed??

[mbdoc]

The tensioner is the most likely problem.

I did read that you already replaced it.

[t walgamuth]

I would also look at the sprockets for "waving", the wear pattern that makes the teeth non symetrical, and look carefully at the chain for wear at the link axles.

Just because it was not appearing worn before does not necessarily mean it is not worn now.

Tom W

[Jim Herold]

Thank you both for the responses. I would normally check both the tensioner and chain condition myself and repair whatever is necessary. I'm not in a position to do this now so I am anticipating what a repair shop would suggest.

Could the rattle also be caused by wear on the timing chain guide that the tensioner pushes against? Or would a worn guide cause noise beyond just the rattle at start-up?

Jim Herold

[t walgamuth]

I think you can have quite a bit of wear without much noise on guides, you know until things start breaking off.

Tom W

[BenzMacX]

If you have a big problem with your guides you can most likely see it if you pull the valve cover and look down. The guides themselves are plastic and probably would not make a rattle noise if one were to break off and be rubbing against the chain. However, if one is almost off, it will eventually come off, drop into your oil pan and you will start getting low oil pressure after a few min of driving. I know this because it happened to me, and took me a few months to diagnose and fix (actually ended up with me giving up and sending it away to a mechanic...).

The timing chain tensioning rail is aluminum with a plastic coating and the chain does rub on this. The tensioner pushes this rail into the chain to created the tension on the chain. I highly doubt this happened to you, although it did happen to me as seen here: http://web.ics.purdue.edu/~smithjs/Site/190E_2.3-16v_Head_Job_Part_II.html

I would take a look down there for your self, taking the valve cover off is a 2min job. I doubt that this would have happened to you, because it only happened to me when my injectors were leaking gas after the car shut off , into the cylinders, and down into the oil. This made the oil less viscous and probably softened the plastic rails, letting the chain chew up the tensioning rail. (Also, the car had a lot of chain slop when I bought it. One of the first things I had to do was replace the tensioner, but that was too late and it had already claimed one guide rail...)

This is a worst case scenario, but I figured that I would pass along my experience with it. There is a lengthy posting on my repair job here: 1986 190E 2.3-16 Chain Guide Rail Replacement

[mbdoc]

Tensioner bleed-off is the most likely cause that would allow for rattle & then pump-up & make that rattle disappear.