190 2.5 diesel 1986 - engine labour on accelleration only

[Joseph]

I have a 190 2.5 diesel 1986. It proved to be a reliable car. Ever since it reached 100,000 km, (it now has 156K) upon accelleration, you can hear a vibration echoed through the, generally speaking, the body of the car, that seemes to be geared to how much load the engine is called upon to bear, i.e. to how much you press the accellerator pedal, and to how many passengers you have and/or which gear.

If you try to accellerate through gears, for example, it is less. If you can wait for it to accellerate slowly and prees more pedal slowly slowly, the noise is much less.

We did a compression test and the compression is fine.
The oil pressure is fine too.

I come from an engineering environment and understand how engines work preety well. But I am not experienced with such faults.

What I do know is that mercedes recomment injector replacement every 100,000 Km. When I asked why, I was told that the spring inside weakens, and that fuel gets inhected much earlier than it is supposed to, hence the burn gets closer to TDC which is a big strain on the engine.
But is this what I have ?

Or is it the mountings that after 18 years, have died down ?

Or what ?

If any one can help - I will appreciate it - thanks

Joe
jmbh@onvol.net

 

[190]

Re: 190 2.5 diesel 1986 - engine labour on accelleration onl

I have a 190 2.5 diesel 1986. It proved to be a reliable car. Ever since it reached 100,000 km, (it now has 156K) upon accelleration, you can hear a vibration echoed through the, generally speaking, the body of the car, that seemes to be geared to how much load the engine is called upon to bear, i.e. to how much you press the accellerator pedal, and to how many passengers you have and/or which gear.

If you try to accellerate through gears, for example, it is less. If you can wait for it to accellerate slowly and prees more pedal slowly slowly, the noise is much less.

We did a compression test and the compression is fine.
The oil pressure is fine too.

I come from an engineering environment and understand how engines work preety well. But I am not experienced with such faults.

What I do know is that mercedes recomment injector replacement every 100,000 Km. When I asked why, I was told that the spring inside weakens, and that fuel gets inhected much earlier than it is supposed to, hence the burn gets closer to TDC which is a big strain on the engine.
But is this what I have ?

Or is it the mountings that after 18 years, have died down ?

Or what ?

If any one can help - I will appreciate it - thanks

Joe
jmbh@onvol.net

The 190 diesels are very bad for engine mountings i would change them first .if you say the car is pulling ok in all gears they are £40 each from euro car parts [Dont buy them from german swedish they only do petrol ones but will sell you them saying that they are all standard]

 

[Joseph]

thanks for your input -

That is what I wanted to know really. I am from Malta, can I ask what you mean by - do not buy german - buy a set of mountings from Euro part. I was going to buy the originals from Mercedes in Malta - They have them in stock and asked me for Stg 43 each .

Should I also replace the hear box mouting. As i inderstand it from the service manual, there are the two at each side of the engine and a hear box one. Or would replacing the gear box one make no significant difference.

Thank for your help

 

[190]

Re: thanks for your input -

That is what I wanted to know really. I am from Malta, can I ask what you mean by - do not buy german - buy a set of mountings from Euro part. I was going to buy the originals from Mercedes in Malta - They have them in stock and asked me for Stg 43 each .

Should I also replace the hear box mouting. As i inderstand it from the service manual, there are the two at each side of the engine and a hear box one. Or would replacing the gear box one make no significant difference.

Thank for your help

If you can get them for that price from Mercedes go for it the reason I said about German Swedish is that they do not list mountings for the diesel model the say it?s a universal engine mounting for all the 190,s. Over here in the UK we have euro car parts & German Swedish what do most parts for Mercedes that are cheaper than the main dealers. Also it wouldn?t do any harm to change the gearbox mounting.

 

[Mikesmerc]

Joesph, try pulling or pushing the engine to one side when its running you should hear something if its the engine mounts. Have a look at the mid driveshaft bearing and rubber coupling just after the gearbox and any balancing weights which may be fitted to the driveshaft.
Regards
Mike

 

[Joseph]

Thanks Mike

I tried what you said, I switched the engine on - pushed/pulled the engine to and from as much as possible, but the verving or vibration does not echo through the body like when you accellerate.

Perhaps when you accellerate, the force against the mounting is much greater than I can ever push ?

Re the drive shaft - gearbox to rear diff - That is what we thought it was first. We replaced the center cross bearing and the rubber mounting and the vibration damper.

 

[Mikesmerc]

With the handbrake on, try putting the car in gear and slip the clutch without stalling the engine and listen for any noises. All in moderation of course :lol:
Regards
Mike

 

[Joseph]

Mark first of all thank for your time.

You are right - I did this and gave the mounting quite a push with the hand brake and barkes on. But NO it does not vibrate.
So that means that under a vacum or load its not the engine.
I always thought so. So it seem I now have a set of new mountings on the shelf. But at least this eliminated and narrowed down the problem.
Anyway, I always thought it was not the engine because its ideling and compression and temperate are just fine.

I took the car out and did some more analytical observations with my son's help or second eye.

1. I drove the car accellerating from o to 120 KM through gears using the indications on the spedo to reach max revs in each gear.
The noise is not there at all.

By this time the engine was hot and the gear box oil much thinner.

2. On ideling, you can hear a gear clattering and making a clattering mettallic noise in the gearbox, very much like the idle gear on a mini. If you rev the engine a little or you press the clutch it goes away too.

3. Moreover the vibration was fooling us. The vibration is not really touching the body. We took part of the carpeting off and you cannot feel it.

Moreover, it is there only if and/or when you change to top gear and wait till you reach 60 kilometeres in top and you accellerate. The noise starts at 60Km in top and remains there and most noticable till you reach 80km and if you continue to accellerate in top beyond 80 it goews away completely.

If, while accellerating form 60 to 80 in top, you change to 5th gear and do the same the noise/vibration (not with the body) is much much greater and to me it sounds like that gearbox clattering when ideling that we heard, only it is much much harder and much louder.

I am hopeless with gear boxes, but I have a feeling that this has to do with some worn out gear that is in the gear box - can make something out of these observations.

Its a bit of a challenge this issue.

One thing I should add. Everytime I tell the mercedes mechanic about this, he says, that only old 190 with a manual gear box do this. Automatics never do. So this seems a common complaint with manual gear boxes. Another thing I should say is that in Malta, by contrast to the UK, you are always changing gears since the roads are short while going up and down hills most of the time. There are very few flat stretches of road and definitely no highways. So the gear boxes have quite a job here.

I appreciate your help and have a nice day.

 

[Mikesmerc]

The symptoms you describe sounds like a failed engine/gearbox mount as the engine/gearbox at these speeds are at their lowest revs putting maximum strain on the mountings. The 'clattering' you are hearing could be a worn clutch release bearing but should not cause the problem you describe. Are there any balancing weights on the drive shaft?, if so they have been known to fail(rubber rotting and going out of balance) giving a nasty vibration.
Bit stumped now but I am sure there will be others giving more detailed adivice in the following few days.
Regards
Mike

 

[190]

Check the front coupling on the prop shaft at the gearbox it is also a vibration damper Hold the end going into the gearbox and try and turn the prop back and forward and observe the movement where the bolts go through the coupling. Also by any chance have you checked the exhaust mounting on the gearbox?