Valve spring replacement?
 

'83 300 TD

I was speaking to a very well-seasoned mechanic friend of mine, about the fact that I keep having to adjust the valves on my OM617. After I do, it is pretty damn smooth; not perfect, but pretty damn good. But the longer I drive it or if I rev it at say 4K for a minute In Park, it will get worse. He suggested that carbon on the valve seats is not my problem, but that either my valve springs are broken, or weak.

I searched around and didn't see a whole lot of talk about this, and he approached it with the idea that it if they are weak, it is a fluke, but... He also suggested perhaps I did not lock the adjustment nut down properly, which I double checked, leading me to think that something is wrong.


I'm thinking I will need to replace the springs and valve seals all at once, which does not appear to be too tough a job; I Will inspect it again to see if something is broken, or obviously wrong, just putting out a feeler here to see if I can benefit from others' experience.

If you look back through the archives you can see that I have been preaching replacing the valve springs any time you replace the valve stem seals... they are cheap.... you have already done the labor to get to them..... just logical....
There are some people who claim metal does not ' weaken' ... but that is not true.... and many of our engines spend some time... sometimes years... sitting without being ' turned over'... meaning that some of the springs compared to the others of the same age are in compression .. the others not....
This is also like someone being too cheap to replace the throwout bearing when doing a clutch job... it will cost a lot more in the future if you have to do all that labor to go back in just to get to the throwout bearing...
and the rotators are right there too..under the springs...and also cheap.....and are valuable for keeping your valve seats round...
The FSM also suggests replacing the cap and lock nuts on the top of the valves.. they are subject to a lot of pounding and new threads on them can influence how long a valve adjustment lasts....

I wonder if there are any behive or high silicon steel springs available to improve performance, and reduce cam wear?

Stock MB springs will do just fine...
There is no advantage to be gained in a low revving diesel engine... dual springs help only on gas high rpm engines which may reach the rebound limit of single springs...

I agree with your assessments, LM...

So are you saying after you drive at 4K you have worse Engine vibration at idle speed?

After the Car sits and cools off does it vibrate less?

If you Valve Stems and or the Valve Guides are worn or the Rocker Arms where they pivot or worn you Valve Adjustment will not last. At least it is like that on the Bigger Diesel Engines.

When I had hot idle shaking it was moslty caused by the Valves not being adjusted and next was the Injectors that needed to be rebuilt.

People have also had issues with the Fuel Pressure Relief/Overflow Valve and the old style Rack Damper/Governor Idle Pin.

I also needed Motor and Transmission Mounts to get rid of some more shaking and I had a small Air leak that only showed up we it was hot under the Hood.

Sorry, I corrected your question for clarity, will edit my original post for any newcomers...

No, it only worsens, no improvement later, hot or cold.


That's a scary thought... I don't have a lot of blow-by, in fact very little. Only thing I can smell is unburned fuel... Perhaps I will make a video to show what it is like?

I do have concerns about the injectors too, since this thing has 205K on it, no way to know if they have been touched... However, that isn't all of my problem.

I have considered getting Greazzers HiPo return spring, but I hate to muddy the water if I have problems.

I can see that one of my mounts is slightly compressed, but not bad. I have a new set on the way. I also have no dampeners on mine, but I know that is more for shut-down versus running...


Someone in my research suggested that it might be worn or weak adjustment screws, that the threads can be tweaked on the nuts and therefore loosen too easily (Bergsma said it). This too seems possible, but I hate throwing parts at something, esp when it is my daily.

Some of our Members have also said replacing the Delivery Valves in the Fuel Injection Pump fixed their vibration. However, that was after the other stuff was tried.

On mine the 5th Cylinder has 50 psi less compression then the rest. It nails some until the Engine is warmed up but I don't have anything close to bad vibration.

If you have the Fuel Pressure Relief/Overflow Valve that can be taken apart you can try stretching the Spring till you end up with a free length of 27mm, check the Ball Bearing that acts as a valve to see if it is pitted or not.

If it is that valve then that has helped others.
If you look at your Fuel Pressure Relief/Overflow Valve and see a Ball Bearing pressed into the head of it; it cannot be taking apart without a lot of trouble.

Thanks, I will check each of those.... And BTW, I used to own an '86 240 GL gasser. Good car, but man was that a parts-whore... I Wanted to find a Diesel engine and put it in mine too, but they were hard to find in OK.

I did a diesel purge, and it seemed to get a Lot quieter; didn't seem to affect my vibration though.

BTW, will the fuel coming from the return pulse? Mine was.