Burning oil?

[chembrad]

On my '94 V6 vortec cpi, I had a LOT of carbon choking passages all the way from my EGR down. When I pulled my lower intake manifold, the small rectangular passage in the center of the passenger side of the engine was almost fully choked with carbon (from burning oil???).

The same passage on the drivers side was clean.

Anyone have an idea of what this means and how to fix it?

[BlazerLT]

Have you ever replaced the CPI injector?

It was full or carbon from it burning that cylinder too rich.

[chembrad]

I just did replace the CPI/nut kit. I was just second guessing if there was something else going on in the engine than what I already found. I mean once I got the lower intake off, I'm almost tempted to go and replace the head gasket while I am at it... But if it's not broke...

[BlazerLT]

Replace "the" head gasket?

You know there is two head gaskets on a V6.

Don't replace it unless you are overheating, have coolant in the oil or visa versa.

[chembrad]

Yes a head gasket under each side. My bad.

Now back to the original question: what might cause such a carbon deposit on one side only of the intake?

[chembrad]

and in only that central port.

[BlazerLT]

CPI injector leaking excessive fuel into that cylinder causing it to burn extremely rich.

[chembrad]

OK. Thanks for the input.

[BlazerLT]

clean it out and it should be good from now on as long as the nut kit and injector have been replaced

[chembrad]

Actually that makes perfect sense now. The fuel injector was spilling into the passenger side manifold intakes and burning rich but only on the side of the leak (ie the passenger side). So the fuel lines/nut kit probably wasn't bad in this case.

But as it turns out, stripping the torx screw (using a T27 instead of a T30) and having to take off the lower intake manifold was a good thing. A fortuitous circumstance one might say. Because it revealed the carbon blocked manifold return port (or whatever that little one in the middle is called).

So if anyone reads this, after you replace your leaking CPI and you still have bad perfomance on the engine, your lower intake manifold return port may be blocked with carbon.

This is not a hard job, but it does take time.

Thanks for the help BlazerLT.

[BlazerLT]

True, but it was a smart idea to swap in he new nut kit anyways.