Blown Head Gasket? Intake? Other?

[tom73]

First let me thank everyone for this website. I have found a lot of useful info so far. However I have not found a specific answer to my particular problem.
I recently purchased a used 97 K1500 5.7 truck with 135K miles. It was running great but one day it started to pop out the exhaust with a significant loss of power. It only seems to happen under the following conditions:
1. Only when engine is hot
2.Only under a load. Under normal driving (1/3 throttle) it seems to run fine.

After trying multiple fixes including tune up (everything) fuel filter it has not improved. I was stumped so I took it to a dealer for a diagnosis. According to them the #6 cyclinder had fouled. They scoped the cyclinder and the mechanic said there is a sign of coolant entering the cyclinder through a cracked head or bad head gasket. They also did a compression test that showed 125 -130 psi throughlout the even side of the motor.

My question is the truck is not smoking. Also wouldn't the compression not be there is the head was leaking? Another friend had a Suburban with a bad intake gasket that he says is common on the vortec motors. Could this be my cause?

Thankfully I picked up the truck cheap but the cost of a head gasket replacement almost justifies putting in a new motor. The truck has 135K miles on it. I am afraid to put the intake gasket on to find out it was not that. Normally I wrench on my own vehicles however I do not have the time. Also the autos I worked on did not have all of the sensors and wiring that new ones do. I guess I am intimadated of all of the sensors.

Anybody have any ideas? Thanks in advance for all of your help.

[Matthew12M]

www.rxauto.com

its a head gasket treatment that runs through your coolant..

or "CRC head and block sealer" that you can buy in any auto store

[Fireplug]

Are you loosing any coolant? Running hot at any time?? Any white smoke or a sweet smell??
Any check engine light on ?? What is the fuel pressure reading while hot?? and cold?? What was replaced on the tune up?? Is it hard to start??

[tom73]

I don't seem to be losing any coolant. As for the temp I am not sure since the gauge does not work. I do not smell any anti freeze nor do I have a check engine light. I am going by the dealer mechanic who scoped the #6 cylinder and says he sees evidence of anti freeze entering the cyclinder. I have not checked the fuel pressure and it starts fine. During the tune up I did plugs, cap ,rotor, wires, fuel filter and PCV valve.
Seems odd to me that the cylinder would not have good compression with a bad head gasket.
The problem started last week all of a sudden. Thanks for taking the time.

[tom73]

Well guys I wanted to update you on my saga. After double checking the iginition on a recommendation from a friend I found that the #2 and 8 cyclinders had very little sprak. Since they are located next to each other on the distibutor cap I figured I would replace the cap. Sure enough it was the cap and it now runs great. Thanks everyone for your help.