Hey folks,

I'm looking at removing the head of my 7.3. I believe I have bad valve stem seals (awful blue smoke on deceleration and a major loss of power. I either am blowing black smoke trying to get anywhere or blue smoke trying to slow down) and I was wondering what else I should do in there while I have it cracked open (suggest anything... it can be performance or preventative maintenance) Any suggestions will be taken into consideration. Thanks in advance.

Goose

 

send the heads into a machine shop. they will do valve grind & install the valve seals which will come included with the head gasket set. Head bolts are supposed to be one time use. Head studs are a big upgrade for a couple more hundred. R&D idi performance sells them.

 

the IDI head bolts are not torque to yield bolts.
which means they can be reused.
however I would purchase head studs.


a few things we need to know before any more suggestions.
is this engine turbo'd?
what is the budget?
how old is the fuel system?

 

The engine was replaced. I dont know when but the fuel system is quite old. I'm going to replace the fuel lines soon. My budget is probably around $500. I'm doing all the work myself so that cuts costs a lot. I need to save money for a transmission rebuild, so the cheaper the better... but if a good idea comes along I won't say no to it.

 

also engine is n/a

 

Valve seals are likely not your problem. These engines don't have a vacuum in the intake like gas engines, so the diagnosis for those don't always work. I bet once you pull the air cleaner you'll see the intake full of oil thanks to a bad or clogged CDR. It's burning that oil all the time, it just burns completely with fuel. Modern oils that are resistant to burn off tend to smoke more.
I would recommend a pump and injectors, especially if the injectors have grey paint on them. These are wear items, and do need to be replaced eventually, usually between 100000 and 150000 miles.

 

I'm going to say you have fuel system issues, and that's probably all. at 21.5:1 compression ratio, the 7.3 IDI can burn just about any oil you throw at it cleanly, if your timing and fueling is happening correctly.
The blue smoke is going to be retarded timing. I've seen this multiple times on multiple trucks. Advance it a few degrees and it'll go away.
Remember that as the fuel system wears, the timing ends up more and more retarded over time.


As an aside here, I had an exhaust valve guide go bad due to incorrect machine shop tolerances.
It had a good 1/8" of play to it by the time I noticed. Lots of gap there, and obviously there was no seal anymore. It did not smoke, just ticked a little. It had enough exhaust leaking past that guide(due to backpressure from the turbo especially) that it discolored the valve cover above it from the heat.

If *that* won't cause noticeable smoke, a bad valve seal sure won't.

Oh, and actually, when I swapped in a different head on that motor, I decided to simply get rid of *all* the valve seals. Didn't make a bit of difference, to be honest. No extra oil being burned, no extra smoke...


I don't know that I agree with this. A perfectly good CDR will dump lots of crankcase gasses(carrying oil droplets) into the intake. It's just typical. The only time the CDR closes is under heavy vacuum due to running at heavy throttle with a restriction from the air filter... and even if you *did* suck oil in at heavy throttle, you wouldn't notice it at all as it would be burning perfectly well.

Remember, people *run* IDIs on WMO. Which is straight up engine oil.

 

smoke on decell could be bad, if this started suddenly could be broke ring or rings, if it was running fine , its not timing. or valve guides, possibly a injector, however it would miss or nock funny, do a compression test, it is the only way to test combustion components as a hole, not related to fuel system, compresion tester fits in glow plug hole, do it on hot engine, use antiseze on glows when reinstalling them, wash engine first to remove debris, or use air gun, remove all glows, test, reinstall glows.