compression testing a 7.3L turbo IDI

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May 20, 2015 | 07:48 PM

kelsodiesel

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compression testing a 7.3L turbo IDI

Having performance issues with my '94 IDI. The motor sounds good at idle but lacks power during use. I am having trouble even pulling a 37 ft 5th wheel trailer. My turbo has some wear to it and I have an exhaust leak on my up pipe could this be my problem of am I looking at more serious engine work, and with the turbo being oil cooled if the seals are bad would it put oil on the air filter? Thanks in advance.

May 20, 2015 | 08:32 PM

Macrobb

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I'd first turn the fuel screw up to max. It won't hurt, at this point. Then, try advancing the timing a bit, see if that helps.

An up-pipe exhaust leak will reduce turbo pressure, yes, which should result in smoke under load(and less power)... if you have enough fuel going in to not be burned cleanly.

Secondly, oil in the air filter/intake side of the turbo? Probably blowby, coming through the CDR.
Some people have replaced the CDR to fix it, but as these engines age, you just plain get a lot of blowby. And that blowby seems to like to pick up oil droplets.

You can do one of two things at that point:
1. Ignore it; Make sure the oil stays /in/ the intake and not on top of the engine.
2. Make a custom oil separator(basically just a can with some coarse plastic air filter media in it; oil gets caught in it and drops to the bottom) and route your CDR/blowby tube through it.

May 21, 2015 | 09:43 AM

Ford F834

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Definitely fix your up pipe leak. That is not helping. How many miles are on your injection pump and injectors? How many miles on the engine? As stated timing is really important and the timing shifts as injection pump pressure drops with wear, the injector springs weaken, etc., the injection timing and duration of the injection event changes with age. I would suspect that more than low compression. If your rings are shot you would most likely have blue smoke, ridiculous amounts of blow by causing oil to be forced past seals and gaskets. If it got bad enough it might also run rough from uneven compression between cylinders and become hard to start even with fresh glow plugs and a tight fuel return rail. Low power in itself is most likely another issue.

May 23, 2015 | 09:10 AM

kelsodiesel

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Roughly about 200,000 miles on engine and injection pump. No blue smoke, just black smoke under a load and no power under a load

May 23, 2015 | 09:12 AM

kelsodiesel

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This is my first diesel pickup I don't really know anything about them how do I advance the timing and turn up the fuel

May 23, 2015 | 09:33 AM

Chevy_Eater

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Quote:

Originally Posted by kelsodiesel

Roughly about 200,000 miles on engine and injection pump. No blue smoke, just black smoke under a load and no power under a load

If that truly is the original injection pump then it's due. They usually fail at just under 200K.

Can't hurt to do injectors at the same time.

You have plenty of compression though, @ 200K that engine is just broke in.