Quote:
Originally Posted by KS300
I have done A LOT of troubleshooting so bare with me... About a month ago picked up a 84 300d turbodiesel with 173k miles. started and ran perfectly but previous maintenance was unknown so I adjusted the valves (all exhaust too tight, most intake ok or slightly loose) fixed all vacuum leaks and replaced all fuel hoses along with the primer pump. Test start the car ran fine but the next day after a long drive it began idling badly and smoking greyish smoke at idle (especially while cold). i figured an injector was bad so decided to replace all of them with new bosch injectors, but this did not solve the problem. I narrowed it down to the number two cylinder by cracking injector lines one by one. it ran worse with each except cyl 2 which cracking the line did nothing. I tried swapping injectors around just in case and issue always stays with #2 cylinder. At this point i figure I must have messed something up with the valve job so I redo it entirely taking extra care at which were exhaust/intake and getting them PERFECT (slight drag with cam lobes in 1 o'clock position/90 degrees to platform lobe makes contact with). all were fine. I bought a compression tester and cylinders 1,3,4,and 5 were right around 400-425. cylinder #2 was 290. I poured a few ounces of oil into the cylinder let it soak for a bit and repeated the test with compression only going up slightly to 300-305psi. so I checked and redid cylinder 2's valves AGAIN with everything looking fin e and checking out. Additionally I have inspected the pre-chamber and it does not look particularly dirty with the ball and glowplug in there correct places. No oil in coolant no overheating issues smoke does not look or smell like coolant. I am about to pull the head and inspect the valves or just give up. Any ideas of what could be causing this? Prior to the compression test I was dead set it was a fueling issue but now I'm thinking there is not enough compression to ignite the fuel at idle on cyl 2.
TLDR bullet version:
-om617 turbo motor with essentially no blowby doing oil cap test
-has great power and runs PERFECTLY off of idle.
-cylinder 2 is not igniting fuel properly at idle causing misfire and puff of smoke
-brand new injectors and no air leaks in fuel
-Cyl 2 has 290PSI of compression (100PSI less than neighboring cylinders)
-car ran fine before valve adjustment after adjusting its almost like the valve no longer seats correctly.
-I have adjusted the valves 3 or 4 times at this point, Cyl 2 is Intake then exhaust and setting gap at .10mm and .35mm respectively.
Thank you for reading all this, any help or suggestions are greatly appreciated. Hoping someone out there has an idea i do not!
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I did not take the time to spell check:
Good job troublshooting.
When you swapped the Injectors and there was no changed as you said that indicated it was not the Injector.
You took the compression test and found a low cylinder.
You put Oil into the cylinder (which normally is not done on Diesel Engines because there is a chance that Oil pooled on the top of the piston could ignite a bit and ruin your compression tester gauge). So I think you have found evidence that it is not the rings/piston/cylinder.
Becaue normally oil in the cylinder would raise the compression if it was an issue with the rings/pistons/cylinder.
All that I can think of that is left is an issue with the not seating well or a head gasket leak.
If you have an Air Compressor (better if it has a water filter to keep water out of the compressed air) you could mod your compression tester adapter so you can apply compressed air into the Cylinder with the valves closed and it is supposed to be at TDC or close to that.
then you listen for leaks in the intake or exhaust maifold to see if it is a valve seating issue.
I am not sure how easy it is to here if air is leaking into the crankcase for a rings/piston/cylinder issue.
If the headgasket is leaking out side you might here the air hissing out.
If there is a head gasket leak into the coolant after you drive the Car sufficently get it good and hot; shut it off and park it for 2 hours or more. Afterwhich squeeze the upprer radiator hose. If that hose feels hard and inflated you have a head gasket leak into the coolant.
You also might be able to see bubbles in the coolant recovery tank or it could have that burnt combustion smell.
If everything is OK in the above tests all that is left is the Fuel Injecion Pump. Perhaps some issue inside the #2 element (if you have an MW Fuel Injection Pump don't loosen the 2 13mm Nuts on each side of the Element).