I have a 1985 126 diesel engine 617 that gives me a lot of noise and griefs.
Difficult to start-up in morning, Then during the day it makes a large noise at start-up as well as when I turn off the engine. When it runs, I can feel some light vibrations trough the steering wheel.
As I use the car, it runs perfectly, and there are no misses or noticeable loss of power.
Looking for potential problem with air leaks? Vacuum control? Injectors? Fuel pump? or Glow plugs or any combination of problems.
It drives me nut

 

Just worked with a friend with his diesel Benz.

He changed out the fuel injection pump and it ran better but he still had hard starting problem.
Then he changed the glow plugs and man, that made world of difference. That thing runs smooth and quiet(for that era of diesel and compared to when it wasnt running right)

Sometimes thise injection pumps on the diesels go with age and mileage and acts strange. It can be a fairly pricey part.
Start with glow plugs first if the havent been changed in a while.

vibrations in the steering wheel might be from the steering damper or old motor mounts or possibley some other loose front end component. Annoying problem but the steering vibration usually aint hard to fix once tracke down. Also if you do the damper, make sure th steerign gear boxis bolted dow tight like it suppose to as this can also caue vibrations especially the slight ones if it rattles.

 

Thanks for the reply.
Sorry about the delay, computer problem. Priority first.
Tomorrow I will performe a Diesel Purge and change all fuel filters, then purge the line. I found the way to do it on DieselGiant, with pictures. I will then check all Glow plug for continuity then change any bad ones.
By the way, is it best to change the bads only or do you recommend changing all at once on a 200.000 mi engine? About changing the injectors or rebuilding them? I read somewhere they are good for 100,000 Mi. and I know nobody ever bother until I got he car.
I understand the connection with the damper but will check the engine first as the unusual vibration were connected with it.
The shocks and damper are on my list of things to do anyway.
That do you think about an air leak into the fuel line. I noticed some fuel leaking from the hand pump, would it be significant to produce the engine shaking.

Thank you again
Chris

 

If the injectors havent been changed in a 200,000 mile plus car, that is about time to do that as they lived about double life.
Glow plugs up to you. Some people change them as they go but I would change them as a set.

You dont want air in the lines too much. Even though it's best to find how it gets in there. The pressure in diesel lines eventually get to a very high pressure, about 30,000 psi irrc. and I would guess in that case that especially that air is not good thing as too much air in the mixture can cause running issues. Usually air trapped in the line is out the system within a few cycles unless there is a continious flow of air that really should be fixed.

 

OK. Thank you.
I don't know at this point if the air could be THE problem but I will purge the line just to make sure as .
I will replace all glow plugs now and the Injectors as soon as possible.

 

Update:
Found problem with starting; several glow plugs are bad. Will change them shortly.
Performed a diesel purge. A lot of crap came out of the exhaust.
The shaking noise is due to a broken front engine mount. I bit to mush for me to fix. My mechanic (independent) will fix them for $ 100.00 bucks for both (front only) very low price.
Fond one sub-frame bushing broken. He will replace them also at he same time.
I do not undestand the purpose for them as they are mounted on a rocker type bracket and the linkage to the front well goes to the midle connection between them.
Any reasons for this design? Just curious!
I can give my mechanic address to anybody in the in the L.A. area. He is more than reasonable and very good.

 

motor mount is something any mechnic worth his wrench can do.

I dont know the "real" reason they designed them that way but according to corp. lit., it was the best design that can be made to reduce engine vibration from goign through the passenger compartment while at the same time reducing stress on the other drivetrain components giving them a long life and exceptional durability. Something like that.

When you fix them glowplugs, and mount you will have one smooth (for a diesel) ride. In fact, Mercedes diesels inside are one of the most interior vibration free diesel cars I've been in. Check out any other diesel of that era and even some up to mid 90s and you'll see what I mean. Apparently that mount design have some truth to it.

 

Thank you for all your inputs.
I do know about the car as I have it for three years now, and intend to keep it running for a very long time. It is by far the best car I ever had.
My 450 SLC is very nice too, but it is a different machine and more fun driving into the local mountains.