|
|
|
#1
|
|||
|
|||
Squeaky Timing Chain
I ran into a strange situation yesterday while doing a valve adjustment on my
'83 240D. Halfway through the procedure, which I have done many times, I noticed a very audible "springy" squeak when I manually turn the engine as in rotating a cam lobe to the right position. It first occurred after I had left it for a while about halfway through the job and had come back to it later. I'm sure I did not hear it until then and I believe it is loud enough such that I would have heard it the last time the engine was running the day before I removed the valve cover to start the job. A check of timing chain stretch at the start of the routine showed ~4 degrees. I'm not aware of anything falling into the timing chain recess, no nuts, washers, or other parts are missing, and as far as I can see into the recess with a bright light I can see no foreign items. I thought perhaps it was coming from one of the peripheral items in the belt system, e.g. alternator, etc. but the sound appears to be emanating from the chain recess or the cam area. It is consistent with each rotational movement of the engine crank/chain. I thought perhaps it was due to lack of oil on some surfaces due to drain down, but that should be somewhat typical as any shut down period. At this point, I'm a bit reluctant to button it up and fire it up. Has anyone had a similar experience or any suggestions? One thought is that it could be vacuum pump noise, but it certainly seems strange that it would first occur halfway through a valve adjustment.
__________________
Okiebenz |
#2
|
||||
|
||||
I vote the vac pump. can you use a stethoscope or stick to listen to it and narrow down the location?
__________________
1984 123.193 372,xxx miles, room for Seven. 1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven. |
#3
|
|||
|
|||
how many degrees of movement @ the crank cause the noise?
@ which degrees on the crank does this occur? how are you turning the crankshaft? definitely inspect Vacuum pump as suggested. |
#4
|
|||
|
|||
Squeaky Timing Chain
Quote:
The noise occurs with any degree of movement and any rotational position, whether turning the crankshaft via the crankshaft bolt or via the belt system (turning of PS pump). I suspected the Vac pump, but it was very strange to have occurred halfway through a valve adjustment.
__________________
Okiebenz |
#5
|
||||
|
||||
Thats not the chain or vac pump. That squeak is air being compressed in one or more cylinders on its compression stroke, the air slowly escapes around the rings (due to such a slow movement) and makes a squeaking sound.
Its 100% normal!
__________________
-diesel is not just a fuel, its a way of life- '15 GLK250 Bluetec 118k - mine - (OC-123,800) '17 Metris(VITO!) - 37k - wifes (OC-41k) '09 Sprinter 3500 Winnebago View - 62k (OC - 67k) '13 ML350 Bluetec - 95k - dad's (OC-98k) '01 SL500 - 103k(km) - dad's (OC-110,000km) '16 E400 4matic Sedan - 148k - Brothers (OC-155k) |
#6
|
|||
|
|||
Squeaky Timing Chain
I'll try to find a way to isolate the noise. With 240K on the odometer, I had replacing the original vac pump on a list of upcoming things to do from just a preventive standpoint although it has never made noise and delivers a costant 22". I have heard tales of catastrophic results from vac pump bearing failures, i.e. timing chain, etc. What has been your experience in that regard? I measured timing chain stretch as ~4 degrees before starting the valve adjust.
__________________
Okiebenz |
#7
|
||||
|
||||
We posted at the same time....see my post above....
__________________
-diesel is not just a fuel, its a way of life- '15 GLK250 Bluetec 118k - mine - (OC-123,800) '17 Metris(VITO!) - 37k - wifes (OC-41k) '09 Sprinter 3500 Winnebago View - 62k (OC - 67k) '13 ML350 Bluetec - 95k - dad's (OC-98k) '01 SL500 - 103k(km) - dad's (OC-110,000km) '16 E400 4matic Sedan - 148k - Brothers (OC-155k) |
#8
|
|||
|
|||
Thanks for the response, and I'd sure like to think you are right about that. It's just strange that I have never heard it in the many times I have done the procedure and this time only when I was halfway through. And it sure sounds mechanical and from the chain area. But no doubt I will learn something one way or the other when I button it up and fire it up in the next couple of days!
__________________
Okiebenz |
#9
|
|||
|
|||
That whistling noise should be discernible from squeaking / scraping to someone who has done the valve lash on numerous occasions.
I still do not understand the nature of this sound, but if I was able to repeat a mechanically based anomaly with EACH movement of the crank... I would certainly not be running the engine until I had inspected the critical moving parts that may be related. Don't forget, Vacuum pump lobes: 2 ratio of rotation to crank: 1:2 sound of your diesel squeaking its last squeak: pricey |
#10
|
|||
|
|||
Quote:
__________________
Okiebenz |
#11
|
|||
|
|||
i think the tensioner is also a good assumption - whether the rail in the cavity, or a broken spring in the tensioner itself.
good thinking. |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|