1983 240d idle question - Page 2 - PeachParts Mercedes-Benz Forum

whunter · #16 07-30-2010, 05:56 PM

Quote:

Originally Posted by diesellac

when my 240D is warmed up i can run it on park on the lowest setting but when i put it in drive i have to turn it most of the way to the left or else i would get heavy rattle on the hood. so i was wondering what is a normal set up for the 240D? and if it is running on too high rpm then what could be the problem? transmission mounts? dirty injectors? i recently did a valve adjustment but it barley affected idle only i saw a difference in acceleration. my car doesn't smoke (or at least i don't see it) so i assume the injectors are fine.

It sounds like the idle is to low = 350-599 RPM, normal idle is 600-800 RPM.

other possible issues:

My head is SPINNING
http://www.peachparts.com/shopforum/diesel-discussion/193309-my-head-spinning.html#post1556256

Fuel injection pump starvation with good a good lift pump
http://www.peachparts.com/shopforum/diesel-discussion/247039-fuel-injection-pump-starvation-good-lift-pump.html#post2133911

Fuel pressure relief valve adjustment
Fuel pressure relief valve adjustment

lift pump test
1979 300td -- Can anybody walk me through a lift pump test?

fuel pressure
http://www.peachparts.com/shopforum/diesel-discussion/249082-fuel-pressure.html#post2156755

Diesel Injection:
Diesel Injection:

Have a great day.

diesellac · #17 07-30-2010, 06:55 PM

ok so i blocked the return line and took it for a drive and didn't really see much of a difference... but then when i took out the blocking piece i heard a pop, could that be stuck pressure or just a rubber unloosing pop?

barry123400 · #18 07-30-2010, 07:09 PM

Just indicates available fuel pressure is low or very little higher than the relief valves opening pressure at best. Whatever that really is. It is an unknown at this time. Stretching the relief valves spring will do absolutly nothing for you at present.

Time for a gauge to see what you have. Again this is good stuff to work on as it's both cheap to do and really educational. Fairly easily understood if you think about it while doing it as well.

Another simple test. With the return line open and not connected there probably will be no fuel coming through from the injection pump to return to the fuel tank with the engine running. Thats if the supply pressure is lower than the relief valves present opening pressure. If you find this to be the case it would be prudent to check it out better. This is a process of learning in many simple steps.

diesellac · #19 07-30-2010, 07:36 PM

ok so i took the car for another spin with the plug and actually the performance is better and when i took out the plug when its running fuel is getting through.

and also i broke the yellow return hose and was wondering if a hose with a smaller hole would work and made out of rubber?

barry123400 · #20 07-30-2010, 07:59 PM

Thats better. At least you have overflow pressure. The actual pressure the relief valve is opening at is still unknown at present without a gauge.

At least your pressure is not so substandard that it will not open the relief valve. The only way to truly verify the actual opening pressure of the relief valve is still using a gauge.

There is so little return fuel pressure on the return system that almost any line repair you try will probably be okay. A replacement line is probably reasonable in cost as well. I also suspect your base pressure is high enough to not influence the idle.

If it was not the closing off of the return hose would have made a huge change. I still personally advocate a gauge in that circuit. Best performance occurs at 18-19 pounds pressure.

whunter · #21 07-30-2010, 07:59 PM

Quote:

Originally Posted by diesellac

ok so i took the car for another spin with the plug and actually the performance is better and when i took out the plug when its running fuel is getting through.

and also i broke the yellow return hose and was wondering if a hose with a smaller hole would work and made out of rubber?

Plastic fuel lines, injection pump, OM616, 617.912, 617.952
OM616, 617.912, 617.952, Plastic fuel lines, injection pump

diesellac · #22 07-30-2010, 08:06 PM

ok cool but i want to figure out if its working properly, to do that what kind of gauge would i need and where could i find it? autozone?

and thanks for the parts link

barry123400 · #23 07-30-2010, 08:19 PM

I purchased mine at princess auto for about ten dollars in Canada. Your equivelent more or less is harbour freight. Just make sure it is liquid dampened.

They are a chinese gauge of reasonable quality and appearance for the price. By installing the gauge you are going to verify that optimum conditions exist or you can make them so.

All along I have felt that with the two forties you really want the optimum conditions and to maintain them as such over time. The three hundred five cylinder series can get along easier with less. They just have more power.

Well I just pulled the centre consul on a kia of ours to find the automatic transmission cable snapped. So I better try to source one and get out to the cottage.

My fault as I forced it before unseizing the transmission selector rod. I should have known better. I guess I do know better just in too much of a hurry.

diesellac · #24 07-30-2010, 08:31 PM

same here when it comes to me for every job i do that is new to me there is always something that likes to break and its always something i could have avoided if i just gave it a deeper thought.