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? tranny mounts? dirty injectors? i recently did a valve adjustment but it barley affeted idle only i saw a difference in acceleration. my car doesn't smoke (or at least i dont see it) so i assume the injectors are fine.

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

I am not sure which "it" you are turning?

If you are in the US there should be a sticker on top of the Radiator Support Frame/Cross Member.
On the Sticker should be the proper Idle Speed range and what gear it is adjusted in, Timing and Valve Adjustment specs.

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84 300D, 82 Volvo 244Gl Diesel

If you are getting a lot of shaking when you put the car into gear I would look at the trans mount for sure and engine mounts if you haven't already. If you have to maintain a high idle at when the car is just idling to keep it smooth, I'd look at injectors and compression.

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By "it" i meant the rpm adjustment knob, and i dont think my car has bad compression because when warm and not in drive or reverse it can run really nice at the lowest rpm setting in park and it doesn't smoke, could the car still run nice and not smoke if the injectors are dirty? i was planning to do a diesel purge some time.

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

Under any loading the engine is not as free running. Since you own a 240d I would check the pressure in the fuel system in the base of the injection pump.

A quick and dirty test is to close off the return line from the injection pump temporarily. If no change at all overall especially while taking the car for a short drive. It is unlikely the fuel pressure is adaquate to open the relief valve. If a change is noted at least the system is capable of developing enough presure to open the relief valve. The actual pressure that the valve is opening at is still unknown. It should be 19 pounds in an ideal situation.

This area is neglected maintenance in my opinion on most 240ds. In my opinion it is very important even if it turns out to have no bearing on your current issue. It at the same time can impact your issue to some extent.

Read the thread on the relief valve by Cervan. At worse it is a nominal expendature to do this properly. Also it in my opinion is quite managable by a newer member.

You also should learn enough that if fuel delivery problems arise in the future you will have a head start. Also for a rough loaded idle situation like yours have a look at the primary fuel filter. There should be an air bubble there but not a stream of bubbles transiting the fuel filter. Air in the fuel can roughen up a loaded idle as well. Also have a good look around for anything That may be physically making noise.. Like poor mounting of the air filter container.

THe rational to the above checks is the engines fuel injection pump can deliver unequal amounts of fuel from each injector in a seriously low feed pressure situation. Plus the injection pump is deprived of the flow of cooling fuel as well. Overall power is down to what is possible. Not that you need or want all that is potentially available..

What rpm smoothes things out?

See Thumbnail: On the Stock Nozzles it is possible for the passages #14 and #15 to be compeletly plugged with Carbon. And, that passage is there for the Idle Fuel and the low speed fuel quanities.

I found the above problem on the Injectors on my Car with rough idle and in fact the Nozzles were actually needed replacing (I have had a Pop/Nozzle Tester since 1992 when I bought my Volvo Diesel). I also did not have any unusual smoke.
I believe the Ball Pin in the Prechamber allows the bad Nozzles to remain in service longer. Besides atomizing the fuel that physically hits it when it is hot and Fuel hits it must be a big aid to igniting the Fuel. When the Nozzles are worn one of the things that happes is the Fuel Squirts out in a stream instead of a spray pattern. So if the stream of fuel makes it to the Ball Pin it will get atmized more and if the Pin is hot vaporized and ignited.

Anyway, rebuilding the Injectors took away the bulk of my shaking.
The next thing that helped most was the Valve Ajustment; which you did already.
After that it was changing all of the Mounts
lastly the Idle Damper Pin (that you do not have) took out some more shake.

Air leaks can also cause shaking.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

I'm having similar problems with my 240...I'm trying to understand what is supposed to happen when you close off the return line. I tried this on my car, and saw no noticeable difference in idle quality/performance. Is this normal, or does this indicate a problem? I'm assuming the "problem" would be a weak relief valve?

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

Thanks for all the responses, my fuel filters were replaced as when i first bought the car it was ran on wvo or what ever that barrel was in the trunk, i disconnected it and i had to clean out the fat/Gunk in the fuel tank then i replaced the fuel filter again... I'm going to try that plug the return line thing and see what happens, but a while ago one of the return lines broke and i did see a difference in driving. But it could even be the injectors since my car was a veggie car and diesel911's volvo ran with out smoke and it was the injectors.

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

i think i plugged the wrong line, i'm suppose to block the bigger line to the injection pump right?

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

Yes the one that is closer to the hood...

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

ok so i did the plug the return line from injection pump and i drove for a while then it shut off my car and i needed to put the line back in to turn on the car. ahh shoot nvm i plugged the line going from the primer pump oops...

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

Actually it was my Mercedes that ran without smoke yet the Injectors were no good when tested on the Nozzle/Pop Tester.
And, the little passages #14 and #15 in the pic of my previous post were plugged solidly. Also I live in Southren CA so it does not get too cold here.

I guess I should not have thrown in that part about when I bought the Pop Tester. Bought the Volvo in 1992 and the Mercedes about 3 years ago.
My main point was that in my case Rebuilding the injectors fix the largest part of the shaking.
However, changing the Mounts is cheaper than rebuilding the Injectors.

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84 300D, 82 Volvo 244Gl Diesel

Ill have to talk with my dad because he knews what hes doing...and i know small stuff like i just figured out which line to block... but i got some new injector tips on hand, but do you think a diesel purge would do the job?

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

so i cant do anything about the mounts and injectors since my dads on vacation, so ill try the plug the return line to the injector pump and about the air leaks- i have black vaccum lines that lead no where one that comes this black box that is on the passanger side in the engine bay and one that leads nowhere that comes into the drivers side.

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

Remember with the return line closed you also want to drive around the block to see if there is a difference as well.
Do not assume weak relief valve. It is just one of many possibilities. In your case probably just something to check in the process of finding what is really wrong. By shutting off the return line your base injection fuel pressure should have risen to thirty pounds. You would have seen a major difference in performance. That pressure is too high to live with but it will do no harm to just test with it.

No change at all indicates the supply pressure is low itself. You really need a gauge to get this right.

If no differance was noted the pressure being supplied by the system to the injection pump is not enough even to open the relief valve. Or is at best only marginally so. The pressure needed will sag even further under load in a situation like yours.

With symptoms as you have described it is best to get a liquid dampened pressure gauge with a calibration of 0-30 pounds and start investigating what is really going on. In the process you will learn a lot.You should be able to find that gauge for about ten dollars.

Low pressure has many effects that are well documented. With a two fourty and three hundred series diesel the effect not documented. The potential loss of the number one rod bearing over a long period of time running with substandard pressure on the two forty especially. Your car is happiest with 19 pounds pressure in the base of the injection pump.

You really want to get there. The additional power alone is worth the effort mind everything else. You will never regret paying attention to this area. There also will be no lack of help on site as the importance of this is only really becoming accepted in the last year or so.

Causes of low pressure in the base of the injection pump. Relief valve is gunked up by running wvo and basically is not regulating properly. Spring is tired with age realeasing too early at too low a pressure. Clean it in solvent and inspect.

Unfortunatly for the people that close off the return line and there is no difference it alone is not the problem. It comes into the equation later when you have pressure to regulate. With the no change of running quality by closing the return all you know for sure is the general pressure unregulated is too low. It again should be about thirty plus pounds. This also allows the excess pressure to remove heat from the injection pump by feeding a portion of the fuel entering the injection pump back to the fuel tank.

Causes of no change by closing the return off. Fuel filters are basically partially plugged up. This can be checked by moving the pressure gauge to the output of the lift pump.You want thirty pounds or better remember . Tank screen or weak tired older lift pump can deny you this at that location. The lift pump rebuild kit is cheap enough if needed. I guess junk accumulated in the fuel line might also do this. Blow it out with air.

The liquid filled pressure gauge is basically cheap. It enables you to put the supply system in top condition. If you only have one diesel I would install it in a permanent fashion. It will tell you when to change out filters and many other things as needed in the future before they become problems.

The reason idle can be better is that all elements of the injection pump recieve the right amount of fuel with good pressure. Under low pressure this is not occuring.

I for one am more than willing to assist in any clarifications required to help anyone understand what you are doing at any stage. If you are not sure of any step all you have to do is post on this thread. Many will help I believe.

I also have a couple of 240ds. It does no harm to read the thread about the pressure relief valve by Cervan. As long as you understand the relief valve is not the total picture. It can only perform it's proper function if the general fuel pressure is high enough to enable that function.

Again thats why when closing off the return line with no noticeable difference. Is just a quick and dirty test to indicate the operational pressure required for good running as the manufacturer intended is not present .