Lubro Moly Diesel Purge - Did Nothing to Solve my Problem
 

Here's the facts:

1983 Mercedes 240D. Factory Crate Motor with only 25,000 miles. Idles like crap and gets worse around 1150 RPM with the engine shaking wildly from side to side. Above this RPM, the engine smooths out and runs fine with lots of power.

I ran 2 cans of Lubro Moly Diesel purge through a seperate container, with absolutely no effect whatsoever. Still idles like crap.

I called Ditmire Motor Works which are Mercedes Diesel Specialists not far from where I live and I told them my situation and given the fact that Diesel Purge did not help me at all, I suspect my timing might be off. They said the timing on these engines almost never needs to be adjusted during the life of the engine. He was certain that one or possibly all of my injectors are dirty and need to be cleaned - which I thought the Diesel Purge would have done for me, but it looks like I need to tear into the injectors now. Can I clean these things, or is it better to buy new ones?

At 25,000miles, they will not be very dirty unless you got some REALLY bad fuel.

How did you break-in the engine?

Could be the rack damper bolt is out of adjustment.

Dave

Ditmire said the same thing, but I reminded them that this is a 240D, and the 4cyl non turbo engines don't have a rack damper bolt.

When I purchased the car, the engine had 12,000 miles on it already. But I have all the service records and the oil was changed during the first 600 miles.

Shame on me. A friend offered me some filtered WVO and I mixed it with my diesel fuel for about 6 months in a 50/50 mix. Starting to think that was a BIG mistake. Whatever I saved in fuel, it will probably cost me double that for new injectors.

Tell us more about the history of your car/ engine. Have you done a compression test? Have you cracked open each injector line one at a time with engine idling to see how the idle is affected?

Even more for the injection pump if its damaged as well. Yes, BIG mistake using it unheated.

I've never seen IP timing affect idle quality. Engines that are 12 degrees late seem to idle just fine.

I'd agree with the mechanics..........the condition of one, or more than one injector is probably your issue. You can clean them with specialized knowledge and specialized tools...........neither of which I possess.:o

Try to isolate the bad injector by cracking the injector lines one at a time. Either the idle will get noticeably worse..........or it won't. If it doesn't.........that's your suspect injector. For further confirmation, swap that injector with the adjacent injector. Now do the procedure again and see if the problem follows the injector to the next cylinder. If so, you've nailed the issue. Replace the injector and you're done.

Were the engine mounts changed with the new engine? Really rough idle with a lot of engine motion visible is very likely a mount problem well along the road to a broken mount. I speak from experience on that. And broken mounts can lead to all kinds of "collateral" damage, including a literally broken starter.

How does it start in cold weather (not that you have any real recent experience given the weather across the country lately)? If there are no other performance issues (smoking excessively at idle, hard to start, etc.) I would not be focused on the injectors or the injection pump. Mounts or air in the system or some other routine problem would seem more likely than injectors or injection pump.

Good luck and I hope this helps, Jim

I agree with Jim, how are the mother mounts and the engine shocks. My engine thrashed around and idled badly until I changed both the mounts and shocks. The mounts had degenerated and the shocks had lost their lower bolts making them useless When you shut down do you get a loud clunking sound? That is another sign of bad mounts.

Good or bad motor mounts should have no affect with a properly running engine. I ran an engine without mounts and it ran smoothly.

I agree. Engine used to idle like a swiss watch and was smooth at ALL RPM's and that was just 10,000 miles ago. If you saw how bad this motor shakes at 1150 RPM you would agree that motor mounts are not my problem. It is not firing correct at low RPM. I have minimal smoke though and lots of power, but an engine with 24,000 miles should have good compression.

I think I need new injectors. What else could it be?

.........one single injector...........

The injectors are easy to remove and disassemble. Do not mix parts from one injector with another. DP will not clean heavy deposits. I've had good luck soaking the parts in carb cleaner over night.