1985 300TD Missing & Hesitating
My car ran fine on WVO for a year (20,000 miles). I have a two tank system, each with its own FM100 filter and booster pump. I have solenoid valves for switching tanks and switching return lines. I also have the sump kit and the coils around the FM100 filter under the hood. My car starts & idles fine and drives well at freeway speeds. My problem is under acceleration or going up a hill the car begins hesitating and sort of missing and loosing power regardless of whether I am on WVO or diesel. I switched out every WVO fuel hose. The diesel system is 3/8" hose. I removed the inner screens from both boost pumps. I changed out all filters and cleaned the little metal filter. I installed a new lift pump. I get adequate WVO flow at the engine (about 4 gpm) and about 6 gpm diesel at the engine. I am thinking that my WVO system has been fine all along and that something else is plaguing me. Could it be air in the injector lines or a timing chain about to go? What else should I be checking? Thanks.
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Fuel Injectors
Have you removed and cleaned your fuel injectors? Have you installed the new Monark nozzles that work much better on SVO than the original Bosch nozzles. The Bosch nozzles plug up much faster with running vegetable oil.
I would start there. If it is not your injectors then you might have a problem with your injection pump itself.
1985 300TD Missing & Hesitating
Still fooling with my 1985 300TD. I have about 6 gph of diesel to the engine. All new filters and fuel lines. New lift pump. Rebuilt injectors with Monark nozzles. The valve clearances were recently set. I ran two cans of diesel purge. Everything I have done seems to make some improvement, but the car still hesitates and misses at rpms above 3000 and when the engine downshifts going up hills. I have 190K miles on the car and ran WVO for the last 20K miles. I am thinking that the only other things I should be looking at are the timing chain and the injection pump itself. Is changing out the injection pump a DIY project for the experienced mechanic? What else can I do but take it to a MB mechanic?
Help!
Bill in Tehachapi
A few more things to check
Bill, I would go after your fuel injection pump last. Here are a few things -out of the box - to check.
1. Fuel tank vent- drive the car on your factory tank with the fuel cap loose or off and see what happens.
2. Exhaust system. How old is your exhuast system. It could be possible you have an internal restriction in one of the mufflers
3. Compression - go ahead and do a compression test and check your internal engine (chain timing) - you should rule those out now
4. There is a possibility you still may have something wrong with the way your fuel system is plumbed or switched. Try returning it to the original. Put diesel in your fuel tank and run it directly to the injection pump bypassing all your other hoses, switches and valves.
Report back your findings. Kent
1985 300TD Missing & Hesitating
Kent,
A couple of quick follow on questions:
How/where do I check the compression? Can I check it through the glow plug ports somehow or do I have to pull the injectors out? The injectors are just newly installed.
Checking the timing chain - do I just check/measure the slack or do I need to back off a tensioner?
Thanks for your help.
Bill
Compression test and timing check
Bill, you can check compression through the glow plug holes if you have the correct adapters. These are included in our compression tester.
Timing chain stretch is checked by noting the number of degrees that the timing marks are off. This is explained in my manual Diesel Performance Tuning and Repair.
Hope that helps... Kent