My 1991 350 SDL is a great car but it's really slow. I'm wondering if the turbo is working, is there a good way to check this? are there a top 3 things to check on this car with this prob? it runs pretty good, on level ground, with enough time the thing cruises ok at 90, but getting there takes a while.

thanks

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe

In no particular order:

There is a line from the intake manifold to a switchover valve on the firewall to a device atop the injection pump. If that line is clogged, there is no signal for the injection pump to increase fuel in relation to turbo contribution.

A restricted fuel system will restrict engine performance. Check the fuel filters in the engine bay and the strainer in the fuel tank. Does the small filter upstream of the lift pump have a clear case? If so, can you see through the filter element or is it clogged?

To round the hat trick, move the throttle linkage in the engine bay by hand to see how far it extends before hitting the limit on the injection pump. Have someone put the pedal to the floor and see if that corresponds with the linkage getting as far you are able to move it by hand.

Sixto
87 300D

thanks, i'll try these things tonite

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe

#1 the function of the ALDA
#2 the function of the ALDA
#3 the function of the ALDA

To see if it is functioning correctly remove it, or at least loosen it and leave it in place. If you notice increased throttle response after removal, it was not working properly. If there is no change, then the problem is something else.

http://www.peachparts.com/shopforum/diesel-discussion/69422-om603-alda-removal-instructions.html

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

I found that unplugging the lines and switchover valve made mine run much better. Then I turned the pump up

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

compu_85, when you say "unplug the lines" are you r u referring to the lines to the switchover valve?

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe

I think he means unplug the EGR valve and cap the supply line, and separately, bypass the overboost protection solenoid between the manifold and ALDA.

Sixto
87 300D

I was referring to removing the plug inside the ALDA lines... they were plugged solid with soot on my car. Disconnecting the EGR... for testing... doesn't affect the speed of the car.

My overboost protector is bypassed right now because it plugged again. I deleted the boost / transmission modulator a while ago so a simple line from the intake to the ALDA is sufficient.

When I got my car and the ALDA was plugged, the throttle linkage was set wrong, transmission shift cable was wrong, and the IP was not set correctly. It would hardly go 80! It's much faster now: http://www.youtube.com/watch?v=srXc2xV0fO8

Thanks,

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.