Hey guys, so I know I have a stuck exhaust valve on my 7.3 N/A and we're putting new heads on it. The blow by is very minor at idle from the oil fill cap and there's more when the motor shuts off.

I'm worried that I'm going to end up having the bottom end replaced also, because my truck always gives out white smoke when you give it gas, like a noticeable cloud. I'm pretty sure it's blue and not white, and there's a bit of black smoke when you get on it. Does this sound like the piston rings going or is it just that valve causing it, because we got the heads done to spec margins and the machine shop said that new heads on a worn motor will make the rings go sooner.

Any help is appreciated,

Thanks!

 

If you had sticking valves, you can't judge anything considering the engine wasn't running correctly.

 

Yup. The valve is stuck open on the driver side bank.

I told the guy who's doing the heads what my oil consumption is and he said that's not bad enough to think it's too worn, but I'm trying to make sure my rings aren't going also.

 

Put the heads on and run the engine. Worry about it when the engine stops running well.

 

The only thing that came to mind for me was a leak down test should have been performed prior to tear down; with the idea that the other 7 holes with good valves should give you an indication of what shape the rings are in. That said, I'm a rookie, and don't actually know how to do a leak down on a diesel...so I could be way off and don't take my thoughts too seriously. How many miles on the IDI?

 

It has 249,670 as of today. The guy who's doing the heads is a master tech who rebuilt his own IDI and has worked on them for most of his career. We got all new heads for it (didn't want to take my truck apart so we used cores he had laying around)

 

GoingBoarding,
You are correct, a leak down test would be appropriate, so would a compression test ... A leak down is basically the same on gas and diesel, just different tools/adapters.

DieselCamper,
Then you'll have good heads for your new motor ... Until then get the heads on before judging the condition of the lower end unless you have low oil pressure or obvious deep knock.

That valve is very likely feeding the cylinder with some oil, It would be expected to see some blue smoke!

I would guess that there have been millions of new/rebuilt heads put on old motors.

-Enjoy
fh : )_~

 

agreed. as long as you have at least 10 lbs oil pressure at hot idle put the heads on and don't worry about it unless the mechanic finds something he does not like when he opens the engine up.