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Do I really need a new head gasket?

1K views 8 replies 6 participants last post by  dugcar 
#1 ·
My son recently bought a used 1995 T-100 V6 and began having overheating problems a week or so later. First, it overheated and the radiator developed a large crack and had to be replaced. Afterwards, it began overheating all the time.

A mechanic did some kind of "head test" on the radiator with a funnel, and observed bubbles in the coolant which led him to believe the head gasket is blown. He wants $1400 to replace it.

However, I did a compression test and the cylinders came out very consistent at 180, 178, 180, 180, 172, 180 psi so that makes me wonder, can a head gasket be blown and not affect compression?

Also, if we remove the thermostat it runs OK and does not overheat.

What I really want to know is, should I replace the head gasket at a cost of $1400 or not? Is this a reasonable hypothesis by the mechanic?
 
#3 · (Edited)
1..First, it overheated and the radiator developed a large crack and had to be replaced. Afterwards, it began overheating all the time.

2...A mechanic did some kind of "head test" on the radiator with a funnel, and observed bubbles in the coolant which led him to believe the head gasket is blown.

3..However, I did a compression test and the cylinders came out very consistent at 180, 178, 180, 180, 172, 180 psi so that makes me wonder, can a head gasket be blown and not affect compression?

4..we remove the thermostat it runs OK and does not overheat.

5...What I really want to know is, should I replace the head gasket at a cost of $1400 or not?
FWIW...just some thoughts & opins can/will vary. So...

1...Was "eng/old rad. completely flushed" before new rad. installed or just drained, new a/f coolant added? If not, inside might be contaminated? Maybe w.pump or ?

2...Bubbles in coolant could be "head gasket" leak. Check with napa auto or ? for "coolant exhaust test strips" If avail? Mine diff. brand, but bubbles in coolant & test strips=bad h.g.

3...Even with those #'s, its still possible a very slight loss of c. is happening=exhaust in coolant.

4...defective t-stat. or back to #1 ?

5...I really dont know. But, bubbles in coolant not good. Try test strips if u can get them?

btw..forgot to ask..have u needed to add make up coolant?
Good luck on outcome.
 
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#4 ·
Have you done a pressure/ leak down test on the cooling system?
That will tell you a lot.
 
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#6 ·
Welcome to the forums! :)

Who performed the radiator replacement? Was the engine filled with coolant first before filling the radiator? It's possible that the air bubbles were not removed completely. Did you run the engine with the temp control switched over to hot? ;)

X2 on pressure testing the coolant system. Harbor Freight has a testing kit fer about $85 Yer local AutoZone might have a testing kit fer free rental but don't expect the kit to be fully functional from abuse or all the components to be in the kit. ;)

Did you replace the radiator cap? ;)
 
#7 ·
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