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#1
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My head is SPINNING
I have a 1983 Mercedes 240D with a 4spd, (manual). My engine has 24,000 original miles on it. It was purchased as a factory crate motor from MBNA and came complete with everything including the injection pump, etc...
Recently I have begun to notice that after my engine warms up, it idles poorly. Slightly revving the engine makes it worse. It shakes and misses terribly. However, above 1,400 RPM it runs smooth as silk. I adjusted the valves to factory spec and replaced the fuel filters. No difference. The engine has plenty of power with no smoke. At highway speeds, engine appears to run perfectly. One other observation, which happened by accident when a friend gave a 5 gallon jug of veggi oil to try in my benz, is that if I run thicker fuel, like vegetable oil, the problem completely goes away. but if I go back to diesel, the poor performace at low RPM comes back. My conclusion is that my poor idle is the result of timing chain stretch which caused a slight change in IP timing, something I would have expected since the most chain stretch occurs within the first 20 to 30 thousand miles of an engine's life. I am guessing that the thicker fuel (vegetable oil) ignites more slowly than the diesel and my timing being off is compensated by the delayed ignition of the thicker fuel, (veggi oil). So what I would like to do is test and adjust my injection pump timing. I did a search on IP pump timing and came up with all sorts of buzz words like "drip method", "well method", "milli volt", "RIV", "woodruff key", "RD bolt" and even "give the IP a slight bump toward the block" What I would like to know is: 1. What is the best way to test my injection pump timing, (assuming I need to do this) and 2. How do I go about adjusting the IP timing so it runs better on diesel? Is there a way to adjust the IP timing while the engine is running so I can get a feel for where my engine idles best? Can I do this, or is not advisable? I really appreciate your help and advice. You guys are great! Thanks! |
#2
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Have you considered the possibility of an air leak into the fuel system? Does it run any better on an alternative fuel source such as is used during a purge?
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#3
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You should have ZERO chain stretch at 24,000 miles.
Have you done a diesel purge yet? Also, have you checked for an air leak? Fuel lines will still dry rot over the years. My car has about 4 degrees of chainstretch at 237,000 miles. I'll be replacing the chain at 250,000 instead of using a woodruff key.
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RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K 90 Dodge D250 5.9 Cummins/5 speed. 400K Gone and still missed...1982 w123 300D, 1991 w124 300D |
#4
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Kerry Edwards,
If I had an air leak, I would assume I would see air bubbles or a low fuel level in the pre filter, (my pre filter is clear), but I do not. It is full with diesel - no air and no air bubbles. When you say a purge fuel, do you mean something like diesel kleen or some other fuel injector cleaner? No I have not. Do you think my problem is caused by dirty injectors? If so, wouldn't a dirty injector perform worse on a thicker fuel like veggi oil? |
#5
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Quote:
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#6
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rrgrassi,
I was told that the majority of chain stretch occurs in the first 20 to 30K miles. Is that incorrect? To the best of my knowledge my fuel lines are original, but they appear good. Everyone seems to recommend a diesel purge. I drive my 240D to work every day and it's a 90 mile round trip. Most of these miles are a constant 80+MPH, which in a 240D is about 4,000RPM, so I assumed my injectors and conmustion chambers are pretty clean. |
#7
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kerry edwards,
When I "purge" in this method, do I use a special fuel, or just plain diesel? Also, assuming I wanted to experiment with my IP timing, how do I do this? Is there a good thread someone could suggest? |
#8
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Quote:
Have you replaced the air filter?
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#9
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It sounds to me like you have an injector problem. With your engine idling crack each of the injector lines one at a time. Each one should change the idle the same amount. If one changes/decreases the idle less than the others that injector isn't working right. There are multiple options for repairing... the easiest is to take it to a Bosch shop to get the injector tested and repaired.
The Diesel Purge is an actual product name. Its made by LubroMoly (I think thats the correct spelling). You put about two cans in a jar and disconnect the fuel supply and return lines. Put both of them in the can and run off of straight diesel purge. This is supposed to clean the injectors, but it doesn't work for everyone (myself included). For some people it works wonders though! The 'proper' method of timing your injection pump is to use the drip method. If you have a Factory Service Manual CD (if you don't they're $20 and are very much worth every penny!) you can find the procedure there. Should also be able to find it on the forum somewhere too. It does require a $20 dollar tool or you can make one yourself. Hope that helps! ![]()
__________________
John Robbins '05 E320 CDI - 240k '87 300TD - 318k |
#10
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Tymbrymi,
I will pick up a couple of cans this Diesel Purge this weekend and see if that helps. I assume the idea is to run the engine on straight "diesel purge" until all of it is used up and then reconnect the hoses back to the stock fuel system? I assume it will take a while to burn up 2 cans of this stuff. One question still lingers though....if the miss at low RPM were caused by a dirty injector(s), why does it run fine on a thicker oil but runs worse on a thinner oil? Wouldn't a thinner fuel spray better from the injector? Also, this problem only occurs when the engine warms up. When the engine is cold, it idles fine. ![]() |
#11
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not to highjack the thread but by curiosity:
How much money did you pay for a crate OM616 ?
__________________
------------------------------------------ Aquilae non capunt muscas! (Eagles don't hunt flies!) 1979 300SD Black/Black MBtex239000mi 1983 300TD euro-NA. White/Olive Cloth-MBtex 201000mi. Fleet car of the USA embassy in Morocco 1983 240D Labrador Blue/Blue MBtex 161000mi |
#12
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Quote:
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NC Benz Fuquay-Varina, NC 1979 300D 1983 300D Turbo 260,000 Miles 1984 300D Turbo 345,000 Miles (sons car) OBK #31 1998 Ford Expedition 5.4l (fer Haulin'!) 145,000 1973 19' SeaRay with 115 Mercury TOWER OF POWER! Club Car Golf Cart 36V Ex toys: 1967 Mustang 289 (First Car) Fiat 124TC 1975 Honda CVCC 1980 Audi 5000 Turbo |
#13
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Quote:
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Not sure on the hot/cold thing... hopefully others will chime in!
__________________
John Robbins '05 E320 CDI - 240k '87 300TD - 318k |
#14
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Quote:
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__________________
John Robbins '05 E320 CDI - 240k '87 300TD - 318k |
#15
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Quote:
How long has the car sat before you got a hold of it? Did you check the tank strainer? A diesel purge using the lubro moly stuff, or some sea foam helps to clean out any build up or deposits left by the fuel that sat so long before you got the car. Also check the tank venting. A vacuum in the tank can also cause poor fuel delivery after a few minutes of running. Diesels really need to be driven, and your 90 mile round trip is actually good for that.
__________________
RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K 90 Dodge D250 5.9 Cummins/5 speed. 400K Gone and still missed...1982 w123 300D, 1991 w124 300D |
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