Intake gaskets 1995 L19 7.4

[termite]

So, I'm gearing up to pull the intake and valve covers on my Suburban to reseal it. Doing this all in hopes that my slight coolant contamination is from a leaking intake gasket into the valley and not a cracked head. If nothing else I'll fix some oil leaks and clean the egr passage in the intake.

My goal is to knock this out in a day, but will likely have some mission creep and distractions stretching it out to 2-3.

My question: Are any of the intake bolts on the 7.4 TBI through holes requiring sealant? I looked through the FSM and saw nothing about applying sealant on assembly. Any other advice or tips are welcome.

 

[1997]

no help on your question, but i'd guess yes.

why don't you suspect a head gasket?

 

[termite]

no help on your question, but i'd guess yes.

why don't you suspect a head gasket?

Maybe just wishful thinking. I don't think I'm losing oil beyond leakage outside of the engine and no oil on plugs I recently replaced. Coolant in radiator appears clean, from what I can tell looking down the filler neck engine off and running.

I'm open to suggestions on chasing it down if you have any.

 

[someotherguy]

At least run a chemical test on it to see if there's combustion gases present in the cooling system. You might get it down to the intake gasket level and not find conclusive evidence of intake gasket failure. Might as well get all the info you can before you tear into it.

Richard

 

[termite]

At least run a chemical test on it to see if there's combustion gases present in the cooling system. You might get it down to the intake gasket level and not find conclusive evidence of intake gasket failure. Might as well get all the info you can before you tear into it.

Richard

That crossed my mind last night when cleaning up my disaster of a shed and saw the combustion gas tester hanging on the wall. Reckon I'll do that today. I'm not sure I want to tackle head gaskets myself with everything else in life going on. Time will tell.

 

[termite]

Did the chemical test for combustion gases in coolant just a few minutes ago.

Attempt one, failure. Didn't have enough coolant drained out and sucked it into the chemical chamber.

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Attempt 2 after draining more coolant, started out blue, collapsed upper radiiator hose after 70 seconds (using a hand vacuum pump). Burped the collapsed hose and restarted. Three minutes later and still blue fluid.

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Proof of concept to confirm chemical is still good.

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Going to rule head gasket failure out. At least on combustion gas leakage.

 

[1997]

was the engine up to temp?
do any of you plugs get fouled or tips look white?
any indication of burning oil?

my 95 (SBC) had similar symptoms to yours, so i replaced intake and head gaskets, never did find the evidence either was "blown". my combustion chambers on 3, 5 and 7 had "crap in them", maybe have a look inside the cylinders with a scope.

The Stupid Engine Questions Thread

Yeah, I remember you going through that. My mistake, I was referring to TBI trucks. Well, the oil pressure sending unit going out, did inadvertently lead to getting the long crank/hot start issues rectified. When it went bad, the "check gauges" light was coming on at idle and low RPM, and I...

www.gmt400.com

95, all the gaskets a getting pretty old.

 

[termite]

was the engine up to temp?
do any of you plugs get fouled or tips look white?
any indication of burning oil?

my 95 (SBC) had similar symptoms to yours, so i replaced intake and head gaskets, never did find the evidence either was "blown". my combustion chambers on 3, 5 and 7 had "crap in them", maybe have a look inside the cylinders with a scope.

The Stupid Engine Questions Thread

Yeah, I remember you going through that. My mistake, I was referring to TBI trucks. Well, the oil pressure sending unit going out, did inadvertently lead to getting the long crank/hot start issues rectified. When it went bad, the "check gauges" light was coming on at idle and low RPM, and I...

www.gmt400.com

95, all the gaskets a getting pretty old.

Was fully up to temp. Idle in park guage is about 195. Plugs were all decent looking to my eye. Unknown mileage on them as they came in the engine. I'll look into laying hands on a scope ome way or another.

Left to right Top to bottom across the handle are 1-7.

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2-8

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[1997]

not an expert, but agreed, plugs don't look bad.

 

[someotherguy]

Did the chemical test for combustion gases in coolant just a few minutes ago.

Attempt one, failure. Didn't have enough coolant drained out and sucked it into the chemical chamber.

You must be registered for see images attach

Attempt 2 after draining more coolant, started out blue, collapsed upper radiiator hose after 70 seconds (using a hand vacuum pump). Burped the collapsed hose and restarted. Three minutes later and still blue fluid.

You must be registered for see images attach

Proof of concept to confirm chemical is still good.

You must be registered for see images attach

Going to rule head gasket failure out. At least on combustion gas leakage.

Good catch on confirming the chemical will still turn yellow. Sounds like you've been down that road before with bad test chemical that stayed blue regardless.. (I have too)

Richard