ErnestSw

I have the air intake off of my 91GT for powder coating. The intake itself seemed to be pretty clean, but all eight air intake ducts in the heads have a fair amount of black carbon residue in them coating the sides.
Where does this come from, does it mean anything, and, other than some paint thinner on a rag, is there any other way to clean them?

Jay Wellwood

The black resiue likely comes from the oil cross contamination along with whatever may slip past the air filter - this is apparently normal for the 87+ models.

The configuration of the oil breather and the cam cover hoses premits a bit of oil to enter the Intake - where it plates out on the Intake runners to the cylinders.

In as far as removal - get some Kerosene and some disposable shop rags - the Kerosene will cut the stuff pretty easily - but be very aware of the potential for ignition.

hth-

ErnestSw

Thanks Jay,
I'm glad it's normal.
Ernie

BrianG

Apparently it's normal for the earlier cars too. Upon disassembly of my '86 induction system I found the discoloration running all the way down into the intake ports of the head and was afraid that it was combustion chamber reflux...... like past a poor intake valve. Wally disavowed me of that notion, informing me of the oil and fuel residue.

Further, the detachable plenums (plenii??) on the 85-86 cars each contained 2-3 ounces of clean engine oil....... apparently of the same source.

Worse, however, was the 1/4" or more of dark, dirty oil sludge in the horizontal intake tube that runs between the MAF sensor and the throttle-body. It was like tar!!
<img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" />

A bit of varsol and some elbow grease cleaned it all up nicely prior to the powder-coating. All apparently "to be expected". <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

ErnestSw

VARSOL!!
Haven't had a good swig of Varsol since I left Canada. They haven't discovered it down 'ere b'y.