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Head Gasket vs. Bad Valve vs. Intake Manifold...???

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Old Nov 28, 2011 | 06:43 PM
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Question Head Gasket vs. Bad Valve vs. Intake Manifold...???

Hi all,

I bought a 2000 Blazer LS in May with about 163,000 miles on it (now has about 166,000), 2 DR, 4WD, 5 speed.

One hot day in June while driving home from work the engine stared missing. The temperature gauge was normal and everything was running fine, I just gently downshifted going up a hill on the highway, there was a little hiccup, and kazaam; misfire.

I took the Blazer to the mechanic that had done some work on my fiance's S-10, he hooked up to it and read that the number 6 cylinder was misfiring. He recommended that I do a tune up. Six new spark plugs, a wireset, and a distributor cap and rotor later, and she's still misfiring.

Then a friend of mine was looking over it and noticed that my coolant had oil in it. He voted that the head gasket was blown. His landlord (who is a mechanic and owns his own garage) took a look at it and told me that there was 0 compression coming from cylinder number 6. He voted either a bad valve or a blown head gasket.

I drove the Blazer down to my dad's place so he could look at it, and he talked to his best friend (another mechanic who owns his own shop). His vote was either a blown head gasket or the intake manifold.

I'm not sure what to do. i can't afford a new engine, and can't get a reliable answer on what the problem might be from anyone. Any advice contributed would be greatly appreciated.

Again, laundry list of symptoms are:

Miss on #6 cylinder
0 compression on #6 cylinder
Oil in the Coolant (not vice versa)
Unstable idle ( vehicle revs up to 2 or 3k RPM and back down to idle speed)

Never overheated in the time that I have owned it, even after the misfire occurred.

Thanks for the help folks, I've only gotten to enjoy this vehicle for a short time since I bought it, and with winter coming I'd really like to get her back on the road and enjoy her.
 
Old Nov 28, 2011 | 07:43 PM
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Zero compression on #6 means either a head gasket, valve issue, or ring issue. The intake doesn't enter into that question.

A leak down test on that cylinder will tell the tale. If you pressurize the cylinder with both valves closed (compression stroke) and hear air through the intake or exhaust, it is the valve. Through the crankcase breather, rings. Bubbles in the coolant, head gasket.
 
Old Nov 28, 2011 | 09:14 PM
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if it was the intake the coolant would be in the oil not the oil in the coolant i just went through that this spring good luck dude but i would rule out the intake imo
 
Old Nov 28, 2011 | 11:22 PM
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Thanks for the replies,

Would a bad valve or ring allow oil into the coolant, or would that issue be specific to the head gasket?
 
Old Nov 29, 2011 | 07:02 AM
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rings would cause blow by you would have had blue smoke from burning oil there needs to be a fault with a cooling part as well so i would think a bad head/gasket
 

Last edited by Valicswarrior; Nov 29, 2011 at 02:36 PM.
Old Nov 29, 2011 | 07:27 AM
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Oil in the coolant is typically a result of a leak in the oil cooler located in the driver side tank on the radiator.
 
Old Nov 30, 2011 | 09:24 PM
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hate to say this but no compression in cyl 6 and oil in coolant could mean a cracked head... new motor.
 
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