Vortec 4.3

[Caver Dave]

A bud has a '00 Blazer w/ 4.3L V6

He says there's coolant leaking out between the upper & lower intake sections (chunk of gasket missing where they mate directly in the front behind the waterpump) . He's resolved to pull the upper, but not sure about the lower?

IOW, does coolant flow through the upper (plastic?) manifold or just through the lower? Possibly indicating the lower manifold>head gaskets are pooched also?

Given the issues with DexCool , should he bite the bullet and do all (head>lower & lower to upper) the gaskets?

 

[DemonDave]

There is no coolant flowing through the upper plenum, but while replacing intake gaskets look closely inside the plenum for signs of the MPI injector harness leaking or the fuel regulator leaking. (ie, clean spots) Would be much better to only have to go into it once if there's already other issues. I've had no issues with the head gaskets on my well beaten 01 4.3 Blazer, wouldn't go that far unless it's needed, A good intake se should do it.

 

[transman731]

just the lower intake gaskets is all you need to do. and tell him not to put dexcool back in it.(provided the injector harness is ok)

 

[Caver Dave]

There is no coolant flowing through the upper plenum

Cool!
Does that mean there *IS* coolant in the lower manifold? If so, does the gasket between the upper & lower cover/seal any coolant passages?

Trying to determine if the uper>lower gasket is responsible for the coolant leak or more likely the intake>head gasket?

 

[Caver Dave]

just the lower intake gaskets is all you need to do. and tell him not to put dexcool back in it.(provided the injector harness is ok)

Thanks Lee... shouldn't the plenum gasket be replaced (since there's a hole in it) also?

 

[lilfoot]

Yes deffinately.