You had the valve cover off ,you might have simply miss located the bowden cable location .The bowden cable joint and the cruise control conrod joint are within an inch apart and are commonly misplaced especially if the cruise control has been deactivated (all its conrods removed)The slack, or lack of plays a big part in the engine and trannie recognizing each other.I had the same happen after doing a valve adjustment ,recheck the bowden cable .

This is a good thought, but I'm pretty sure the Bowden Cable is hooked up correctly based on an earlier thread I had where another member (Funola) very kindly provided images of his linkage setup for comparison. Mine was identical, although embarrassingly more filthy.

Another possibility is really poor fuel pressure to the base of the injection pump. Say a weak lift pump. Or the relief valve might be staying open.


Those are the two things I might checkout first. There are a couple of more things but not common.


A quick test is does the primer pump become more resistant as you pump it? If so the relief valve is working. Next have someone pump the primer pump with the engine running and see if the engine no longer quits when at hot idle. These two tests are not hard to do.

I'm guessing that whatever was causing your no start problem is causing this problem. Even though your no start problem was resolved it wasn't ever really clear as to what was causing it correct? Have you tried running it off a separte bottle of fuel with this current problem?

__________________
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

I think it was just air stuck in the lines that was causing the no start problem. Going back to that issue, it was running fine before I tore into the fuel supply system, but I had the hardest time getting all the air out after I put everything back together. Now it starts instantly even in cold weather and idles nicely.

Today I installed 2 new valves on top of the valve cover...I don't know exactly what they are called, but they are the white valves that distribute vacuum to the EGR valve, etc. I also blocked off the EGR valve. The car actually seemed to have more power than before but still very weak. It revved way past its shift points and then the shifts were very rough.

I also checked the timing marks on the crank and cam and they line up perfectly at TDC. There doesn't seem to be any slack in the timing chain. Again, I don't know the history of the timing chain so I probably will change it at some point, but there is nothing obviously wrong with it right now.

I'm skeptical about that. Didn't you try it on an alternate supply back then? I still think the problems are related. Too similar to be coincidental. Both are likely inadequate fuel supply.

__________________
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

A lot of air getting into the system? Usually if something goes wrong I pay attention to the last area worked on if it was not long ago.

No sense d***king around if you think it's air. Install a temporary clear PVC line in place of return to tank (aka cigar hose) line. You will see air if that is your problem.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

This is a great idea. I know you suggested it back when I had other issues and it did help then, but I'd since removed it. I will reinstall and see what I get.

Agreed. The lift pump, especially if just rebuilt, can *suck a golf ball thru a garden hose*.

The low pressure fuel supply system operates at below atmospheric pressure due to the intense suction from the lift pump. If there is a pin hole leak it will suck air.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

+1

Gruß
Volker

If I missed an already stated comment, my apologies ...

In the AM, when the car sat overnight, engine cold.

Does the car fire right up?

Does the engine idle smoothly initially?

Have you operated the throttle linkage by hand while the car is in park? If so, does it rev up? Does it remain idling after you rev it up a bunch?

So, the distinguishing feature / issue is placing it in gear and trying to drive it?

I don't drive it on a daily basis, it is still in repair mode and I only get to work on it on the weekends as I travel all week for work.

However, yes it does fire right up when cold and it idles nicely.

It does rev up very well when the car is cold and the throttle linkage is operated by hand. It does remain idling after I rev by hand a bunch when cold. I'm not seeing any smoke come out of the tail pipe that would indicate a head gasket issue and the cooling system leak down test and compression test returned good results. I did the compression test cold, maybe I need to do it again when warm.

There seems to be two (possibly connected) issues.

1. It has very little power when driving (when warmed up or when still cold). It way over-revs before shifting and the shifts are very rough.

2. Once it is warmed up, it tends to want to die after revving up. This doesn't seem to happen when it is still cold. This dying after revving when warm can happen after driving or when revving by hand. This issue definitely seems to be a fuel supply problem.

When I get home this weekend, I am planning to replace the cigar hose with a clear line to see if there is air in the lines. I am also planning to unhook the line to the shut off valve to see if there is vacuum misapplied there.

Any other suggestions are certainly welcome.

Typical behavior for the gearbox if the engine has only little power.


Yes, I also think the injection pump gets air instead of fuel


Don´t remove the ALDA
Block the EGR (you already did as I have read)


How old are your fuel lines?

What you describe sounds exactly like a pinhole in a fuel line like Jay_bob said.

You should replace all your fuel lines from the fuel tank to the injection pump housing including all hoses on the pressure side of the lift pump.
If there is a pin hole on the pressure side it is as bad as on the suction side. There will be no fuel leaking but air will get in.

If you are not 110% sure that every fuel line is perfect and as good as new, you should replace it.
Even a slightly slipping hose clamp can let air in but no diesel out!


Gruß
Volker

I am guessing I am stumped as you.

If it fires right up and revs/ idles nicely in the AM, I cannot see how there's "air" in the system at this point. Normally, if there was air, you would hear a metallic clang but that works itself out within 50 miles. However, you can drive the car without issue other than an annoying metallic clang sound.

However, once it warms up while in park, it will die?