Reconditioned OM617.952 - rattle at front of engine when first started. - PeachParts Mercedes-Benz Forum

TonyFromWestOz · #1 01-31-2008, 09:06 PM

I am from Australia and the OM617.952 is a rarity here.
I obtained a used one of these engines a couple of years ago and had it reconditioned at some great cost with a view to installing it in one of our fleet or 300Ds.

Over Christmas, I managed to remove the original engine and in January, I installed the reconditioned engine.
I have primed the injection system, filled the oil, PS pump and coolant and fired her up.

There is a loud rattle at the front of the engine which sounds like chain rattle, along with some clunking.

I have searched thru the online FSM (copied from a website which has since been closed down) and find there are some differences between the OM617.912 and the OM617.952 in relation to the chain tensioner.

The 952 appears to have a ratcheted tensioner and the 912 does not. My engine does not appear to have this facility. As the non - ratcheted tensioner performs well in the 912 series engines, I doubt that this is the cause of the rattle and clunk. The tensioner appears to be working correctly in my engine.

Can anyone shine some light as to the other possible causes of this noise?

If anyone has the parts listing for either of these engines, I would appreciate copies of the parts list and exploded parts diagrams of the timing and oil pump chain regions of these engines. Please PM me for my email address or provide me a link to this material online.

I appreciate your assistance.

Regards,
Tony

barry123400 · #2 01-31-2008, 10:53 PM

Harmonic balancer installed correctly? All the bolts tightened up properly. It would not make chain like noises but could be clunky.

Diesel911 · #3 01-31-2008, 11:58 PM

I bet you know this already: Get a 3 foot piece of broom stick and put it on the area you think the sound is comming from put your ear on the other end and you will know where the sound is comming from.
I think your engine is too expensive not to use the correct chain tensioner! The FM I have said that the ratchet is there to hold the chain tensioner in place during starting until the oil pressure builds up behind it. Which brings up another question; if the wrong chain tensioner is on the engine are the oil passages/gasket holes matching up?
See if you can access this site:
http://www.pauldrayton.com/uploadfiles/merc/Service/Library.html

Dusty-NZ · #4 02-01-2008, 12:01 AM

Could it be a vacuum pump noise, again the broom stick stethescope is a good tool to help isolate noise locations.

Diesel911 · #5 02-01-2008, 12:20 AM

I was looking at the service manul and the OM617.912 chain tensioner comes in 2 types one uses a paper gasket and the other "O" rings; neither have the ratchet feature. On both there it appeared there was instructions about filling them with oil before installation.
I then looked at the OM617.952; besides the differance of having the ratchet the piston has a oil passage in it that I did not see in the OM617.912 tensioner and only the paper gasket type.

http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Engine/615/05-310.pdf

http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Engine/617/05-310.pdf

MBeige · #6 02-01-2008, 12:22 AM

I too have a rattle that only makes its presence known in the morning at first start, and I usually hear it on the right side near the firewall. I haven't had the time to check but the air cleaner is tight so next is the oil return tube, or the heat shield, are my second guesses. Any time during the day after it's warm and I start it - no rattle.

compress ignite · #7 02-01-2008, 12:37 AM

'sounds like a chain rattle to me.

I'm getting foggy,but I believe the 617.952 HAS the ratchet type tensioner.

See if running the engine # through the Russian website gives you anything.

http://www.detali.ru/cat/oem_mb0.asp?TP=1

Diesel911 · #8 02-01-2008, 02:23 AM

Quote:

Originally Posted by compress ignite

'sounds like a chain rattle to me.

I'm getting foggy,but I believe the 617.952 HAS the ratchet type tensioner.

See if running the engine # through the Russian website gives you anything.

http://www.detali.ru/cat/oem_mb0.asp?TP=1

I agree. If you look at the cross section line drawings of the the tensioners for the 2 different engines you can see they are different. The 617.952 having the ratchet. I would not expect them to interchange.

TonyFromWestOz · #9 02-01-2008, 06:47 AM

Thanks all for your rapid responses.
It looks like I need to remove the tensioner completely and verify its correct operation outside the engine.

How much pressure should be required to move the tensioner (3 Bar?) past each detent?

rrgrassi · #10 02-01-2008, 11:06 AM

Check the vacuum pump also. If it pukes it's innards, it can cause the timing chain to break, and the recondition engine will just turn into a reconditioned paper weight. To be safe, check everything else as suggested above.

Ken300D · #11 02-01-2008, 12:46 PM

I would strongly recommend you get the correct ratcheting chain tensioner for this engine. It is a superior design and the ratchet helps to prevent a loose chain at startup. A loose chain can scrape against the valve cover, or some other spot, or even worse, skip teeth and cause big problems.

The ratchet holds the chain firm even when there is no oil pressure. The non-ratchet design has a spring to do the same thing, but the design is not as effective. On a 240D (non-ratcheting tensioner) you start getting the chain rattle at start up when the chain has worn and elongated. If you're getting that now with a freshly rebuilt 617, I'd get the right tensioner in their as soon as possible.

Ken300D