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Old 08-27-2004, 01:39 AM
psfred psfred is offline
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Sounds like the wastegate control spring is shot and the wastegate is open all the time. The link between the boost control servo and the wastegate should be sprung fairly stiffly towards "closed" (I think that is toward the front of the car, but I'm not sure).

Make sure the fitting in the intake manifold is clear -- if it it plugged, you willl have boost but it won't do anything without extra fuel, and you won't get extra fuel unless the boost signal line is intact (white plastic between intake in the center and ALDA -- note that it goes through a switchover valve on the firewall and to the vac amplifier for the tranny shift controls).

Blow through this line after detaching from the intake. If it won't hold pressure, find the leak. Most likely is a blown overboost protection switchover valve -- it must not vent out the top when unplugged. If it does, replace it. If it does any time the ignition is on, the pressure switch is bad, replace that.

Otherwise, look at all the connections (the boost line has clamps everywhere) to check for broken rubber connector bits or cracked lines. Don't ignore the tranny amplifier, it must hold pressure too.

The wastegate control servo can be fixed by a competent diesel injection service, this shouldn't be too much.

However, it is possible that the turbo is bad -- if you feel intermittant resistance while spinning the turbo compressor wheel, the bearings are shot and it isn't making much if any boost even though it turns. It has to go pretty fast to make boost, after all!

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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