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Old 03-21-2007, 11:45 AM
psfred psfred is offline
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Hmm.

There is a line from the turbo outlet housing to the wastegate controller. This must be intact to prevent over-boosting (else you toss a rod, not a pretty sight!). Fairly large hose, check for integrity.

The boost signal line on a 617 engine runs from the rear of the intake manifold to the ALDA, again it must be intact or you don't get added fuel.

Check to make sure the wastegate control link is installed, otherwise the wastegate will be open all the time and you don't get boost, or very little, even though the turbo is fine.

Later model turbos (85 california, 86 49 state engines) have an air recirculation valve that vents boost back into the air intake duct -- this is both to keep the turbo up to speed and for the trap oxidizer that you don't have. On the KKK it's on the front of the housing, I think somewhere else on the Garret, but I'm not sure. Just leave the vacuum line off, you don't need it in your application.

Limit boost to 13.1 psi unless you a willing to risk "greatly reduced engine life" -- on an engine with lots of miles, read hours of operation, not weeks or months with more boost. Under no circumstances exceed 14 psi, you risk very rapid rod failure, that engine just wasn't designed for that much hp.

How did you measure vacuum pump output? I thought those pumps (post 76) vent into the crankcase, not the intake manifold, so there is no accessable output. If you are getting 40 psi from the TURBO, you need to attach the wastegate control pressure hose or the solenoid to wastegate link, the engine isn't gonna stay together long!

If the engine won't shut off with the brakes applied, you have a split diaphram in the booster most likely. However, you should also make sure the check valves and plastic section in the vacuum line from pump to booster isn't cracked (they get very brittle). If in doubt, replace the entire line, they aren't expensive. Also verify that the other lines (shutoff, door locks, ACC) from the main line hold vacuum and fix or cap -- they should have restrictions in the lines (little yellow "butt connectors" or small orifices in the main line fitting) to limit the effects of leaks, but who knows.

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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