Mystery Eng. Stumble..Altitude?

[seafood54]

Ok...OK..now it's happened again..

Here in OH, my 300TD has an engine stumble at low RPM's and is a bit tough to start, even when it's warm. BUT..when I drive to Savannah GA to visit my daughter, the symptoms are MARKEDLY reduced..and even disappear. Last spring I had only a few mins to visit the wonderful Diesel Dr there in SAV, Dietmar Strohmetz, Autobahn Service Center. He said the injector timing was not the problem, and it was hard for him to diagnosis without experiencing it and having the car a while, which was not possible.

The car acted wonderfully as soon as I got to Sav. again this weekend. .. and again began its mystery stumble after leaving Sav and getting into the higher hills of NC.

It suffers NO loss of power at any rpm over, maybe 1200, *guess because, tach inopperative*

Now, is my engine:

1.) Suffering from some altitude sickness like, maybe Diesel Bends? *cough, sorry*

2.) Patently Petrified of Herr Strohmetz, and so cant 'be bad' within his radious of influence?

3.) Simply likes hanging out In Sav with all the other older cool MB's and hates Zanesville because it's in the only 300TD within 3 parsecs.

Feel free to adorn, complicate or solve the riddle.
Thanks.. Fish E Frank

[whunter]

Originally Posted by seafood54

Ok...OK..now it's happened again..
Here in OH, my 300TD has an engine stumble at low RPM's and is a bit tough to start, even when it's warm. BUT..when I drive to Savannah GA to visit my daughter, the symptoms are MARKEDLY reduced..and even disappear. Last spring I had only a few minutes to visit the wonderful Diesel Dr there in SAV, Dietmar Strohmetz, Autobahn Service Center. He said the injector timing was not the problem, and it was hard for him to diagnosis without experiencing it and having the car a while, which was not possible.
The car acted wonderfully as soon as I got to Sav. again this weekend. .. and again began its mystery stumble after leaving Sav and getting into the higher hills of NC.
It suffers NO loss of power at any rpm over, maybe 1200, *guess because, tachometer inoperative*
Now, is my engine:
1.) Suffering from some altitude sickness like, maybe Diesel Bends? *cough, sorry*
2.) Patently Petrified of Herr Strohmetz, and so cant 'be bad' within his radius of influence?
3.) Simply likes hanging out In Sav with all the other older cool MB's and hates Zanesville because it's in the only 300TD within 3 parsecs.
Feel free to adorn, complicate or solve the riddle.
Thanks.. Fish E Frank

This is only a wild guess!!!
#1. Rack dampener pin is bad.
#2. Plugged tank strainer or filters.
#3. Tank vent plugged = vacuum stumble.
#4. Air leak in fuel feed lines = cracked hoses or lines.
#5. EGR jammed open by carbon/oil sludge.
#6. ALDA needs to be tweaked.
#7. Bad valve adjustment.

[seafood54]

well, whunter..,.thats more like 7 wild guesses..

I have changed or cleaned all the filters including that incredibly messy one in the bottom of the fuel tank itself.

Just by the feel of it, (needing to crank a few times even when hot, after being off for 5 mins or so, I got the feeling that there might be an air leak in the supply, somewhere along the line. Is there supposed to be an air bubble in the clear in-line fuel filter? Would that be an indication of an air leak or is it normal?

The Master in Sav said that the valves were not out of adjustment, because it has great acceleration and power. ( I had posed the possibility to him)

Ive tested the bad tank vent theory by removing the fuel tank cap, with no result. Should I be checking the vacuum system some other way?

How would I check the ERG? (Is it the semi-shiney silverish round thing kinda near and infront of the air cleaner?

You mention the ALDA, but if it were out of adjustment, wouldn't that diminish power? This car has great power and top end.

this leaves the rack dampener pin, of which I know absolutely nothing. Sounds like the bacon-stretcher I was sent to get, back a few decades, in the Boy Scouts.

Whunter, I want to thank you for trying. another hint might be that even in 45 degree temps, this thing hates starting. SO unlike my old 300sd, from so long ago.

Franko

[seafood54]

Wunter.. One more query... Why does it run so well in Savannah? I dont get it. It still wants a little help to start there, but it runs so well. I mean, it's like silk there....smooth even idle, like a metronome, puuurrrfect as can be..and then,,,back in Ohio..Bump bang choke miss..
It tore out the motor mounts here, it was so bad. (replaced)

Franko

[tangofox007]

The rack damper pin (aka governor idle pin) is located at the very rear of the injection pump, just forward of the oil filter housing. It looks like a bolt with a locknut. It contains a spring loaded pin. If not adjusted properly, the engine will either run rough or it can be hard to start and develop inadequate power. I believe that a search will provide info an adjusting the pin.

[whunter]

Hello Franko

New wild guesses!!!
#1. Rack dampener pin is bad.
#2. Bad valve adjustment.
#3. EGR jammed open by carbon/oil sludge.
#4. Air leak in fuel feed lines = cracked hoses or lines.
#8. ALDA needs to be tweaked.

Good. RE: Changed or cleaned all the filters including fuel tank screen.

An O ring, missing aluminum seal washer or loose secondary fuel filter will fit your symptoms on start-up; also a failed glow plug system will cause this issue, and bad valve adjustment will contribute to this. RE: Just by the feel of it, (needing to crank a few times even when hot, after being off for 5 minutes or so, I got the feeling that there might be an air leak in the supply, somewhere along the line.

Normal. RE: Is there supposed to be an air bubble in the clear in-line fuel filter?

He used calibrated ears???
Do your own valve lash check , and consider a new mechanic, one misadjusted intake valve can do strange things , ask “1985 300SD Sady” how easy it is to check the valves, he is 15 years old . RE: The Master in Sav said that the valves were not out of adjustment, because it has great acceleration and power. ( I had posed the possibility to him)

Good. RE: I’ve tested the bad tank vent theory by removing the fuel tank cap, with no result.

No. RE: Should I be checking the vacuum system some other way?

Remove the silver tube clamp, cut a soda can, use at least two layers between pipe and valve, reinstall clamp and test drive. RE: How would I check the ERG?
Yes. RE: Is it the semi-shiny silver round thing near and in front of the air cleaner?

Last resort IMO, but still possible cause. RE: You mention the ALDA, but if it were out of adjustment, wouldn't that diminish power?

I would need to drive to confirm. RE: This car has great power and top end.

There are many threads on this subject, and it is DIY simple. RE: This leaves the rack dampener pin, of which I know absolutely nothing.

No relation to silly jokes. RE: Sounds like the bacon-stretcher I was sent to get, back a few decades, in the Boy Scouts.

This sounds like glow plug system failure. RE: Another hint might be that even in 45 degree temps, this thing hates starting. SO unlike my old 300sd, from so long ago.

Atmospheric pressure and temperature are different. RE: Why does it run so well in Savannah?

Where are you in Ohio, PM me, there may be local help. RE: I don’t get it. It still wants a little help to start there, but it runs so well. I mean, it's like silk there....smooth even idle, like a metronome, perfect as can be, and then back in Ohio; bump bang choke miss..

This sounds like a classic rack dampener gone bad. RE: It tore out the motor mounts here, it was so bad.