Cylinder head/gasket dilemma

[redfishsc]

So i discovered yesterday that my 1999 5.7l Suburban has an apparent intake gasket leak despite having the Felpro metal framed version installed hardly 2 years ago. I keep losing small amounts of coolant, truck steams from exhaust pipe more than you'd expect when warming up, cylinder misfires on the driver's side (especially when cold, especially #5) and yesterday I noticed (while doing radiator flush) steam and exhaust odor coming from the radiator fill (coolant was cold at that point) .

This seems to be the source of the misfire I've been dealing with.

I haven't pulled compression numbers yet so this could still be head or head gasket issues but thankfully the oil stays pristine.


So here is the dilemma. 225k miles, probably original head gaskets still on it. If this turns out to be just the intake..... Should I yank the heads, check for cracks, reinstall? Heads don't leak oil onto the valves, no smoke at startup.

I'd LOVE to put better heads on this but that's a lot of money on an otherwise unmodified engine. Anyone suggest reliable aluminum heads that won't set me back $800?

Im hoping to avoid having to rebuild the heads myself, I really liked being able to just drop reman heads on my other truck (blueprint engines reman, cast iron, but discontinued)


I am really hurting for time to do this, but I have done it before (my other 99 Suburban). I just don't know how long the head gaskets last on these old beasts.

Oh, and it will definitely get the upgraded MFI injectors either way

 

[shorepatrol]

No chance I'm doing the head gaskets as PM. I'd do the intake and MPFI while in there and call it a day

 

[L31MaxExpress]

Intake gaskets are not going to put combustion gases into the cooling system. You have a blown head gasket or a cracked head.

I built a set of 200cc Assault racing heads, however they are every bit of $800.

I discovered they are copies of Dart Pro1 platinum head. They call for .100" longer valves but I also found that Dart builds their castings with both standard and .100 longer valves depending on the valve springs used.

Not using the double springs and longer valves and using 3/8 rocker studs would drastically cut the expense.

 

[shorepatrol]

Intake gaskets are not going to put combustion gases into the cooling system.

I don't see that anywhere in his post.

 

[redfishsc]

I don't see that anywhere in his post.

It's in there. When flushing the radiator yesterday (water was cool) and the truck running, I noticed a little vapor coming out of the radiator fill neck and it smelled a bit like gas. It increased a little if i revved up to 3k rpm.

Wasn't much, but I definitely saw a little vapor and smelled exhaust. Radiator (water, at this point) was not hot enough to steam.

 

[ddaxe]

I'm not sure if you used high temp RTV on your intake bolts, as they can be prone to leak., sometimes leaving little puddles on the intake.. (even oil in some cases) or can leak into the engine by getting past the gaskets because the cooling system is pressurized @ about 15 psi... plus the vacuum created... as for an exhaust smell.. the crossover passage could be forcing exhaust gas through the bolt as well.. I have run into this on more than 1 Chevy engine I've had my hand on...

 

[L31MaxExpress]

I'm not sure if you used high temp RTV on your intake bolts, as they can be prone to leak., sometimes leaving little puddles on the intake.. (even oil in some cases) or can leak into the engine by getting past the gaskets because the cooling system is pressurized @ about 15 psi... plus the vacuum created... as for an exhaust smell.. the crossover passage could be forcing its way through the bolt as well.. I have run into this on more than 1 Chevy engine I've had my hand on...

Vortec engines do not have exhaust crossover passageways.

Also cold misfires that seem to go away with a warm engine are also indicitive of coolant getting into a cylinder. I bet if he pulls cylinder 5 plug it is super clean.

 

[redfishsc]

I'm also betting I find lousy compression on #5 as well.

What is a fair price typically for having heads rebuilt? Best price I can find on new ones is like $350 each for stock cast iron Chevy Performance or Summit versions.


I really don't like the idea of just reusing the old ones if they aren't cracked.

 

[Oldblue98]

Am I wrong ? This is more a question than an answer ! But in my experiences in life and it has been a while since my engine building days, but when you are working with a high mileage engine,and worn cylinders and rings, and you start building heads or more compression up top, does that not lead to more blow by and or oil consumption ? Just a question ! I know in older high mileage engines something as simple as a fresh valve job could create this.

 

[redfishsc]

Am I wrong ? This is more a question than an answer ! But in my experiences in life and it has been a while since my engine building days, but when you are working with a high mileage engine,and worn cylinders and rings, and you start building heads or more compression up top, does that not lead to more blow by and or oil consumption ? Just a question ! I know in older high mileage engines something as simple as a fresh valve job could create this.

I put new stock heads on a 99 last year that's doing quite well, 234k miles