190 5 cyl turbo surging @ highway speed - PeachParts Mercedes-Benz Forum

Brooksie43 · #1 11-09-2005, 12:22 AM

I'm new to this list and hope I can find help. My '87 190dt (325000 mi) 602 engine, started surging at highway speeds. Cruise control is inoperative. EGR system removed years ago, "motorized flap" assy. in air cleaner housing tossed years ago also, throttle linkage lubricated, filters changed, good vacuum, no visible fuel leaks. Started surging at 65 mph requiring constant footwork to keep at steady speed. Disconnecting ELR actuator drops the idle speed but surging remains. Disconnecting ALDA corrects surging but, of course power is gone. Adjusting the ALDA one turn in or out raises or lowerers the surging speed (and power) but it still surges. Removed ALDA, opened, all seemed fine (seals & bellows) flattened cover and housing, resealed with silicone sealant under and on gasket ring. Still same surging problem. Tried without wastegate hose, same. Suggestions?
Thanks

1983/300CD · #2 11-09-2005, 05:35 AM

Maybe you have a 5... 4... 5... 4... 5 cylinder engine.

Compression test?

t walgamuth · #3 11-09-2005, 07:09 AM

not thnik that a low cylinder would cause surging.

seems more likely to be fuel related to me. possibly an air leak into fuel line or plugging from algae (fungi).

tom w

Jetmugg · #4 11-09-2005, 08:26 AM

I've got an '87 190D 2.5T also. It surges too. My surge is mostly at idle. Car has 240K miles. When I open the hood and watch, the "stop" lever moves up and down with the surge.

My ELR seems to be working (If I unplug it, the idle drops). If anyone can solve this surging issue, my car will be like a dream come true.

SteveM.

Brooksie43 · #5 11-09-2005, 12:40 PM

Thanks for prompt responses.
I will check for fuel suction leaks again but the car will accelerate smoohly and quickly to a speed faster than I want to go (130 mph or so) this is when the engine should be most suseptable to fuel starvation from filters & suction leaks. No. it only surges at a steady 65 mph with or without cruise control (when I can get the cruis working). If disconnecting the ALDA stops the surging, don't you think it has somthing to do with the ALDA or its vacuum source? What I didn't do, now that I look at the diagram, is disconnect the line from the ALDA "Y" fitting to the vacuum control valve (65). I know this will effect the shifting but maybe that part of the system if causing a ALDA problem. What think you?
I am that close to discarding ALL the control system stuff and turning this into a real, troublefree, diesel as it should be!
John

1983/300CD · #6 11-09-2005, 01:17 PM

Is it possible that heavy acceleration would suck the air through, but steady acceleration causes a constant air leak that can't pass through and it just builds up until it is a problem?

Brooksie43 · #7 11-13-2005, 12:09 PM

I did follow your suggestion and check/replace everything remotely suspicious on the suction side of my fuel system. No difference in surging while trying to hold a steady speed at 65-70 mph. As an aside, these systems are basicly self bleeding anyway. I still suspect something with the ALDA or it's vacuum line because, as I mentioned originally, disconnecting the ALDA is the only thing that stops the surging. Fuel price complainers (and I'm one) take note, a tank of fuel lasts indefiniately with the ALDA is disconnected...

Brooksie43 · #8 11-22-2005, 03:47 PM

For what it is worth, I solved my surging problem by bypassing the overload solenoid. Problem solved. The pressure switch was OK but the solenoid (switch over valve) must have been fluttering. This is the forth control system I have discarded on my engine only to see it run better. I have a wastegate and a boost gauge to control boost pressure; this was overkill. I hope this helps someone else.
John

300DPETE · #9 11-30-2005, 07:16 PM

Quote:

Originally Posted by t walgamuth

not thnik that a low cylinder would cause surging.

seems more likely to be fuel related to me. possibly an air leak into fuel line or plugging from algae (fungi).

tom w

I'm on a mission to rid algae from the diesel dictionary....

Fungus, fungus. Not algae. I know too little about my MB, but I know that a fungus is not an algae. Algae requires light to survive (can be a plant or a symbiotic creature that has photosynthetic cells). As far as I know, no light reaches the fuel unless you have a clear acrylic hood and a clear pre-filter.

P.S. If anyone considers this spam, please let me know and I'll refrain from posting again...just figured that this could finally be nipped in the bud (...or in the thylakoid as the case me be).

Pete.

t walgamuth · #10 11-30-2005, 10:40 PM

you are really a fungi!

wait, is that politically correct? must be ok if you said it first, right?

tom w