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  #1  
Old 04-22-2012, 07:24 AM
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Vac Pump Failing? Front Rattle OM617

Hello Everyone,
I’m sorry to make my first post a cry for help, but I’m in need of some advice - I hope that I can make some useful contributions in the future!
I’ve a recently acquired OM617 Turbo with a rattle towards the front of the engine bay.
Could anyone identify what’s causing it from the Youtube recording, please? Sorry it runs a bit long!
OM617 Turbo - YouTube

There’s also a leak in the fuel primer – see the last few moments of the video. What problems will this cause – it does seem a little sluggish but flies when the turbo kicks-in.
The second vid is my low mileage om617 na, just for a comparison.
OM617 131,500kms n/a - YouTube

I’ve had suggestions that it may be the vacuum pump – I can’t even find it! Is there an easy test for this, or does it simply have to be listened to closely or touched to feel the rattle?
If the pump was failing, would there be other symptoms?

Update:
I've just had another good crawl around underneath, the propshaft continues to turn (auto-box) because the plastic selector bushings are shot, it might be the noise is from there?
Thanks in advance.
Cheers,
Paul

Last edited by isobars; 04-22-2012 at 10:03 AM. Reason: Update
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  #2  
Old 04-22-2012, 12:29 PM
Diesel911's Avatar
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The Rattle could be the Vacuum Pump Failing. If you want to pull it off and inspect the Arm and Bearing and the face of the Fuel Injection Pump Timer.

What in particular causes vacuum pump failure?
What in particular causes vacuum pump failure? - PeachParts Mercedes ShopForum

New Vacuum Pump Ruined due to too much Timer/Intermediate Shaft End Play (the title from my notes).
second vacume pump, help! on a trip-Toronto - PeachParts Mercedes ShopForum

On mine I had a rattle at the Front of the Engine and it turned out to be that the upper most stamped Sheetmetal Timing Chain Guide; the one that you can see if you can see on the drivers side of the Engine when you pull off the valve Cover was loose and rattling.

The Air Filter support and the Studs have been know to cause all kinds of noise. When you are driving the noise can sound like it is comming from different places.

This is not likely but Hunter had a photo where he visually inspected the whole length of the Timing Chain by turning the Engine by hand. He found some of the Pins on the Chain had backed out.
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Old 04-22-2012, 12:35 PM
macdoe
 
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FAILING harmonic balancer also rattles at the front.
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Old 04-22-2012, 12:57 PM
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Many Thanks for the tips!

Crikey!!What is a harmonic Balancer for? (and where is it hidden?)

Cheers,
Paul
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Old 04-23-2012, 06:34 AM
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The thing that puts pressure on the T chain doesn't sit face to face, could that be connected - no noise from the chain.
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Vac Pump Failing? Front Rattle OM617-cten.jpg  
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Old 04-23-2012, 02:03 PM
macdoe
 
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A harmonic balancer dissapates torsional forces in the rotating mass of the engine=crankshaft..... there is a better description on wikipedia so check it out....to make a long story short it is attached to the front of the crankshaft and is attached to the big pulley that all the accessory drive belts are driven off of. (it is behind the big pulley and is the interface between the pulley and crankshaft))

There are many threads on this subject (harmonic balancer) and they have been known to fail, causing catastrophic damage to your engine. I have had it happen to mine and was able to repair it for now (knock on wood). I ended up fixing it three times now. It started with a slight noise that I could best describe by a ticking at the front of the engine under idle. I unfortunately continued driving the car for the rest of that day and it only made it 30 kms before it failed....spinning on the crankshaft nose. It is not a pleasant experience at all. I was lucky that the last fix took to the repair cause if it did'nt I was looking for a new engine. I actually have found myself a new crank (shortblock) for when the inevitable day comes that my repair job fails....I am expecting it. Do yourself a favour and find the noise before you drive the car.

I am not saying this is the cause of your noise cause I cannot hear it and it could be something entirely different. I only posted cause it could be and it would be a shame for you to go down the same road.

With the engine off... grab the balancer and try to move it in and out. there should be no play at all. check your belts too.

I think that your pic of the timing chain tensioner contacting the tab on the guide rail is normal but someone will chime in and confirm this. I don't think it is all that important that it lines up perfectly from what I remember reading but am just not positive. One of the more senior mechanics will be here to help you. I am not a mechanic.

Last edited by macdoe; 04-23-2012 at 02:30 PM.
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Old 04-23-2012, 02:06 PM
macdoe
 
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Forgot to mention that the clutch on the front of the air conditioning compressor can make funny noises too. It happened on my 85 wagon so I just cut the belt off.
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Old 04-23-2012, 02:38 PM
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Quote:
Originally Posted by isobars View Post
The thing that puts pressure on the T chain doesn't sit face to face, could that be connected - no noise from the chain.
There has been a lot of comments on them not being centered on the Timing Chain.

I cannot recall anyone saying it was either good or bad.

The back of the Timing Chain Tensioner Rail appears to be cast Aluminum and it is not likely to make a tinking type of rattle due to the material it is made of.

You can get a Mechanics Stethoscope cheap at Harbor Freight or you can use something like My favorite; a cut off piece of Wooden Broom Stick.
Put you Ear on one end and the other; watching for moving parts on the Part you want to listen to.

I have a Mechchanics Stethoscope; it fell out of favor with Me bacause you sometimes have to get your Head too close to stuff. One time it resulted in me burning my Cheek on an Exhaust Pipe.
Since then using 3 foot Broom Stick keeps me at a distance from stuff.
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Old 04-23-2012, 02:45 PM
macdoe
 
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Good thing you mention to keep it away from moving stuff. I envision a broom stick through the ear as an alternative injury.
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Old 04-23-2012, 04:05 PM
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Thanks again to you both for the tips and info.
I'll get my ear to the pump and push the balancer.
It does sound more like a clacking than a rattling.
At least I can listen to a good pump on my na and compare with the suspect one.
Cheers,
Paul
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Old 04-24-2012, 04:10 AM
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I'd like to give my opinion on the whole turning the crank via the power steering pulley thing.

Please note - I'm not jumping up and down saying it should never never ever be done! We're all free men here (I hope) we can all do what we want. But I do think it is bad practice for the following reasons

1) The power steering pump and pulley is designed to be driven rather than designed to be the "driver" - turning the crank this way applies unnecessary force to the system.

2) Over tightening utility belts can / might / could damage bearings even if it is done for a short time.

3) OM617s have a pretty well known achilles heel - that crank pulley system and crankshaft balancer is known to fall off. I think that that is a good place to visit during routine maintenance. Hopefully with frequent visits to that area a mechanic would notice that something was loose / wrong in time to avoid a costly repair. If you don't go there you don't know!

So I say use a 27mm socket on the crank in preference to any other method.
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Don't leave that there - I'll take it to bits!
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