My 93 factory turbo is blowing white smoke, oil in the rad, etgs are higher than they should be, the compression is down on one cylinder 250, and it has been using lots of oil. But it still starts and runs fine (not for long I guess).
So I am guessing that I should just replace the motor, I found an 89 7.3 for a good price with low miles. Is this motor compatible with mine? I guess that I would have to swap all the accessory's and just use the short block... It appeared that the heads my be different?

 

The biggest differences are the wrist pins are bigger on most of the factory turbo engines and the oil cooler has a few more plates per inch.

Can you just swap the turbo and or fuel system, yes.
Will it bolt up, yes.

Would I swap heads, not without having them magnafluxed and reworked.

Oil in the radiator could be an oil cooler issue, blown head gasket, cracked head or a cracked block.
Excessive oil consumption could be a bad CDR.
Excessive EGT's could be the engine oil burning, motor oil contains more BTU's than diesel does.
White smoke could be coolant or unburnt fuel, what does it smell like?

Are you seeing excessive pressure in the radiator?
Is the coolant recovery tank running over?
Do you have any coolant in the oil?
Milky sludge on the dip stick indicates coolant in the oil.

 

its coolant smoke for sure no milky oil but quite alot of sludge under the rad cab. Could a blown head gasket cause low compression and excessive oil consumption? Seems to blow more white smoke under engine braking. I was hoping for a blown head gasket at the best...

 

oh the cdr and turbo are new

what is a wrist pin??

 

Wrist pin connects the piston to the connecting rod.
1" on the NA motors, 1.3125" on the turbo motors.

Just more reciprocating weight in my book.

Blown head gasket and low compression go together.
Depending on where the gasket failed, high oil consumption may or may not go with the blown head gasket.

Cracked head or block, high oil consumption, coolant loss, low compression and oil in the cooling system again may or may not go together, depending on where the crack is.

My first test would be air pressure into the cylinders through the glow plug hole.
Which cylinder puts air into the cooling system and can you hear air going into the crankcase from one of the cylinders.

Before you apply air, fill the radiator to the top, leave the cap off, apply air.
When the radiator runs over, that is a problem cylinder.

At the same time, leave the oil fill cap off, can you hear air in the crankcase.

That would tell you iff all of the problems are from the same cylinder.

 

A leakdown test is better than a compression test for diagnosing diesel engine problems.

On a Cat diesel it is recommended to test each cylinder at TDC, as far as I am concerned either TDC or BDC is just as good.

With 8 cylinders it would be a major pain to locate TDC for each cylinder. When you put air to a cylinder the engine will turn over, when it stops, put it in gear to lock the engine and test each cylinder that does not have a valve open. Write down the results. When done find a cylinder that will turn the engine and lock it again. Keep doing it until you have been able to test all cylinders.

Tom

 

Testing a 7.3 IDI block it is better to test at BDC.

On the 7.3 cavitaition is a very real concern.

If you let each piston rotate to BDC, when you apply air pressure to each cylinder, you are testing the head, head gasket, rings and cylinder walls.

Yes, that leaves a lot of places to look in the cylinder, but at least you have eliminated 7 other cylinders.

Also testing at BDC using air pressure from a shop compressor is much easier, if the piston is somewhere other than BDC the engine will rotate that piston to BDC unless the crank is restrianed by some method.
So when you use the shop air method, be prepared for some rotation when you apply air to each cylinder since the fan and belts will move.