Idle problems - PeachParts Mercedes-Benz Forum

KrautWagonGTI · #1 08-11-2009, 10:55 PM

My car is a 1984 300D turbo with just over 300,000 miles, just recently the idle has been getting worse. its kinda rough at times with some hiccups, when I had the a/c on tonight it was shaking the whole car while stopped in drive and later on it stalled on me. I've put about 10,000 miles on it since I've owned it and never done a valve adjustment, set the timing or cleaned the tank screen. Am I just in need of a good tune-up?

here is my slow 0-60 run

http://www.youtube.com/watch?v=M1YzijgGfpA

Biodiesel300TD · #2 08-12-2009, 01:34 AM

I would start with a valve adjustment and changing the fuel filters. Then see if thing improve. If not you can start trouble shooting other things like rack damper bolt, injectors, timing, etc...

GWNorris3rd · #3 08-12-2009, 01:42 AM

Dude that is so slooooow... areyou sure it isn't a 240D? My 83 300D has only 147,000 but has one dead cylinder (160) and one sick cylinder (320) the others are 400, 420 and 380 and accelerates faster. You differently need some servicing that should help out. When was the last time you changed the filters?

KrautWagonGTI · #4 08-12-2009, 10:27 AM

It has been a couple months since I changed spin-on filter but I replaced the inline filter just the other day when the idle got funny and it seemed to help for a short while. I installed a boost gauge and it's pushing 10psi. After watching other 300D 0-60 times I did not realize how slow mine was lol

The guy I bought this from was running straight veggie oil right in the tank for a few miles but not many. I don't know where he got his oil from but the exhaust smelled like a french fried butthole

I have been running diesel since I've owned it.

jt20 · #5 08-12-2009, 10:32 AM

you will be amazed by what regular maintenance can do for your vehicle.

Biodiesel300TD · #6 08-12-2009, 11:00 AM

Change out the spin on filter. The prefilter only filters out the big stuff. The spin on really does all the work.

As for acceleration try cleaning out the banjo bolt on the firewall end of the intake manifold. It gets clogged with soot. And plugs up which prevents the car from accelerating like it is supposed to.

tbomachines · #7 08-12-2009, 11:07 AM

Quote:

Originally Posted by Biodiesel300TD

Change out the spin on filter. The prefilter only filters out the big stuff. The spin on really does all the work.

As for acceleration try cleaning out the banjo bolt on the firewall end of the intake manifold. It gets clogged with soot. And plugs up which prevents the car from accelerating like it is supposed to.

He is still getting 10PSI of boost though, not too bad. I would suspect something is up with the veggie conversion. Are all the fuel lines unkinked and in good shape? Was the conversion single tank or two tanks? Does your primer pump leak at all (old or new style - white screw-on or black spring-push)? How does the old WVO work look, shabby or professional? Have you tried tweaking your ALDA for more fuel? Does it smoke at all? A lot of people on here hate the WVO stuff, it can do some serious damage to the cars' fuel system if the fuel is not properly made. There's no telling what the PO did to it, but just cross your fingers and hope your IP is okay.

tbomachines · #8 08-12-2009, 11:08 AM

Although I need to add:

Do your valves, makes a huge world of difference, and run a diesel purge through the injectors to hopefully clean out any gunk. Keep an eye on your clear prefilter for any black gunk - that may be fungus.

Diesel911 · #9 08-12-2009, 11:58 AM

Quote:

Originally Posted by Biodiesel300TD

I would start with a valve adjustment and changing the fuel filters. Then see if thing improve. If not you can start trouble shooting other things like rack damper bolt, injectors, timing, etc...

add to above:
I does not matter when you changed a filter; if you tank is gunked up enough a new filter can get plugged in minutes. As part of your trouble-shooting change them and put the old ones in a Zip-lock bag or other container so you can reuse them if they turn out to be OK.

Air leaks due to the old style Hand Primer or old Rubber Hoses. It is only a few dollars to replace the hoses with 5/16 fuel hose.

To see if it is the Tank Stainer fill you tank 3/4 full and swap the positions of the fuel oulet and fuel inlet hoses that are on the fender well. This will draw fuel from a higher level in the tank and there is no screen. The caution is if you drive like this you will run out of fuel sooner and still show fuel in your tank. Use it only to trouble-shoot or keep the tank full.

Below is a pic of the Bosch Injector Nozzles for you Engine. The Central Hole in the Pintel and the Cross Drilled hole can get plugged up with carbon. The Central hole is there for use at idle and low fuel quanities.

In my origional Injectors and most of the ones I have pulled from the junkyard the central holes were plugged. Often you can see they are plugged just by pullling the Injector and looking. The one in the thumbnail pic appears to be OK.

barry123400 · #10 08-12-2009, 12:28 PM

I tend to build up a foundation of troubleshooting on a new or recent vehicle with running problems. I start with a compression check after a valve adjustment or check.

In your case I would also clean the fuel tank and its strainer if the tank strainer was loaded. He could have loosened up a lot of gunk back there with his vo..My theory is almost anything of a preventative nature is better than being stuck out on the highway.

KrautWagonGTI · #11 08-12-2009, 01:58 PM

From what the PO told me, all he did to run the veggie oil is strained the crap out of it and dumped it in the tank with the diesel, after a while the tank was 100% veggie. When I got the car it still had 1/4 tank of veggie and I filled it all the way up with diesel and ran until the oil was gone. I also changed the filters about 8 times within the first 2 weeks. I guess the good news is he only put about 300 miles on the car when he owned it and not all of those miles were veggie. I guess I need the get the old triumph running and park the benz for a few days so I can catch up on all the work that needs to be done. When I first got the car I wanted to run veggie but it scared me and I did not want to take any chances. besides, diesel is only $2.43 a gallon right now.

Diesel911 · #12 08-12-2009, 03:03 PM

Quote:

Originally Posted by KrautWagonGTI

From what the PO told me, all he did to run the veggie oil is strained the crap out of it and dumped it in the tank with the diesel, after a while the tank was 100% veggie. When I got the car it still had 1/4 tank of veggie and I filled it all the way up with diesel and ran until the oil was gone. I also changed the filters about 8 times within the first 2 weeks. I guess the good news is he only put about 300 miles on the car when he owned it and not all of those miles were veggie. I guess I need the get the old triumph running and park the benz for a few days so I can catch up on all the work that needs to be done. When I first got the car I wanted to run veggie but it scared me and I did not want to take any chances. besides, diesel is only $2.43 a gallon right now.

Both of the above give you some idea why the PO did not drive very far on Veggie.
If you had to change the filters 8 time with 1/4 of the tank on VOand 1/4 Diesel you can imagine what it was like with 100% VO.
It also tells you that his filtration method was no good.
I am still unclear if the PO was using waste veggie or not? Waste would be even worse as it also has meat fat mixed into it.

tbomachines · #13 08-12-2009, 03:14 PM

Quote:

Originally Posted by Diesel911

Both of the above give you some idea why the PO did not drive very far on Veggie.
If you had to change the filters 8 time with 1/4 of the tank on VOand 1/4 Diesel you can imagine what it was like with 100% VO.
It also tells you that his filtration method was no good.
I am still unclear if the PO was using waste veggie or not? Waste would be even worse as it also has meat fat mixed into it.

Sounds like PO had no clue what he was doing. It also sounds like there was no VO conversion done at all, just dumped into the tank, water and all.

Biodiesel300TD · #14 08-12-2009, 03:22 PM

Quote:

Originally Posted by Diesel911

Both of the above give you some idea why the PO did not drive very far on Veggie.
If you had to change the filters 8 time with 1/4 of the tank on VOand 1/4 Diesel you can imagine what it was like with 100% VO.
It also tells you that his filtration method was no good.
I am still unclear if the PO was using waste veggie or not? Waste would be even worse as it also has meat fat mixed into it.

I would think if he was straining out the crap, he was using waste oil.

I would try switching the supply and return lines like stated above. If the sluggishness goes away then the tank strainer is likely clogged. You should pull it and clean it. I'd put money down that it's clogged since you've been through so many filters. The worst thing for these cars are the lazy WVO'ers.

KrautWagonGTI · #15 08-12-2009, 03:46 PM

I'll pull it off the road tomorrow to check the tank screen. Thanks for all the help and I'm sure I'm going to have more noob questions lol