Bad head gasket?

[hihok9]

I have the chance to look at a 91 motor that after running for about 20 min starts to push bubbles into the radiator, guy says it's the head gasket... does this sound familiar to anyone, and how can I check to make sure it isn't something worse like a crack... what else should I look for, check, etc... thanks!

Hiho

[GOLDCYLON]

I have the chance to look at a 91 motor that after running for about 20 min starts to push bubbles into the radiator, guy says it's the head gasket... does this sound familiar to anyone, and how can I check to make sure it isn't something worse like a crack... what else should I look for, check, etc... thanks!

Hiho


Without a tear down into the heads its hard to tell. You can drop the oil to look for the shaving cream appearance in the mixture. Depending on the leak it could be weeping into the galley and could be coming out of the rear drain tube. The exhaust also and offer clue which will collorarate the head gasket. A crack however not really until your start the tear down. GC

[bans25]

I have the chance to look at a 91 motor that after running for about 20 min starts to push bubbles into the radiator, guy says it's the head gasket... does this sound familiar to anyone, and how can I check to make sure it isn't something worse like a crack... what else should I look for, check, etc... thanks!

Hiho

The one down the cape? I was thinking of going to look at that one myself.. I will hold off if you are interested

[hihok9]

That's it. I might drop it in my next project.

[bans25]

That's it. I might drop it in my next project.

I think I talked to that guy selling the motor 5-6 years ago (maybe longer) when he was doing the install. I was thinking of getting it for a project as well but no real project on the horizon.. good price if it is just a gasket needed..

Did you buy all those other parts that were in Boston??

[hihok9]

Hi Bill,

Nope, I saw those parts but passed on them.

[Paul Workman]

Without a tear down into the heads its hard to tell. You can drop the oil to look for the shaving cream appearance in the mixture. Depending on the leak it could be weeping into the galley and could be coming out of the rear drain tube. The exhaust also and offer clue which will collorarate the head gasket. A crack however not really until your start the tear down. GC

I've had experience with a gasket leak resulting in water getting into the oil (chocolate milk), but if he's getting bubbles in the coolant, wouldn't a compression test possibly indicate a leak? Methinks that would be the nastier of the two as coolant would likely be filling the cylinder when the engine was not running. I'd wanna do a compression test.

Speaking of leaks, Marc Haibeck did a piece a while back on the effects of Dexcool on our gaskets. He showed me one of the gaskets exposed to Dex and the errosion of the gasket anywhere coolant touched it was quite evident. Ye 'ol GREEN glycol stuff is the one to use (Napa for one) is what I took away.

Well, here's a question for anybody... Assuming a new gasket that is compatable with Dex, is there any OTHER components that have to be considered if using the new Dexcool (orange) stuff?? (I'm wondering about the TB gasket and the coolant pipe gaskets. ARE JERRY'S NEW HEAD GASKETS DEXCOOL COMPATIBLE I wonder (out loud)?

P.

[GOLDCYLON]

I dunno stick with the green stuff and why take the chance to any of the other components? As to a compression check yes that one of the many things the potential buyer could due as he goes through the analysis process. My suggestions were basic troubleshooting suggestion before getting jiggy with it. Moisture on the plugs as well etc. GC

[Hib Halverson]

If you mean, when you say, "pushing bubbles into the radiator", that when you take off the cap, start the engine, then look into the high fill bottle, after the engine runs a while you see some bubbles in the coolant flow that enters the tank near the cap, if the bubbles are small, continue for a short period and don't smell like exhaust, I'd say that's normal.

However, if you suspect a head gasket problem, I'd run a cooling system pressure check, that will find a head gasket leak from the cooling passages to the bores.

You can also run a cylinder leakage test and find a head gasket issue.

If it's really bad you even can find it with a compression test.

Also, if you find someone with a borescope you may be able to even "see" head gasket problem.

If you have a head gasket leak from coolant into the oil, you have the baby s&%t looking creamy stuff on the dip stick.

[VetteVet]

A combustion leak tester would tell you for sure.

http://www.amazon.com/Lisle-75500-Combustion-Leak-Detector/dp/B0007ZDRUI

[Don in VT]

Hi,

Having just gone through the trauma of a possible head gasket leak and finding out the system was OK I would follow VetteVet's recommendation and do the testing to see if there are exhaust gasses in the coolant. Most auto repair have the test kit and the test does work.


If you have any further question you can feel free to email me.

Best Regards and Merry Christmas,

Don

:flag2:

[sdycke]

IMHO after doing the combustion gas in coolant test a few hundred times in a shop enviroment, it is not 100% postive. Maybe 85? And is very sensitive to clean (!) and correct test methods. I remember many times getting heads back (esp Chrysler!) from the machine shop that found cracks, albiet very small ones, that the tester did not pick up but were still the cause of overheating.

[scottfab]

I have the chance to look at a 91 motor that after running for about 20 min starts to push bubbles into the radiator, guy says it's the head gasket... does this sound familiar to anyone, and how can I check to make sure it isn't something worse like a crack... what else should I look for, check, etc... thanks!

Hiho

Have you road tested it? What are the systemic symptoms?
Does it in fact over heat?
I've always seen a few small bubbles in the high reservoir
I don't know that I'd run any other test at all till I know there is a problem.
.

[Marc Haibeck]

Because of the wet liners, a pushed back head gasket on an LT5 will initially result in coolant filling the white overflow tank to the top. As the failure progresses, exhaust gas will appear as a stream of bubbles entering the tank at idle. It's easy to observe the bubbles because the tank is semi-transparent. Finally, if HC can be detected in the overflow tank at over 20 ppm, that's the definitive diagnosis. Fuel should never be found in the coolant, not even a trace at 2 ppm.

I don't recommend DexCool because it causes the head gasket to swell. In addition I recently read that one of the organic acids in the the anti corrosion package has been identified as the cause of the intake manifold gasket failures that are so common on GM 3.8 V6 and Northstar engines. The silicone sealing rings get soft. This suggests that DexCool should not be used with silicone coolant hoses.

[LGAFF]

Owner of the company is a Callaway Corvette owner....

http://www.blockchek.com/

[Hog]

Those testers work great IMO, really quick way to see if combustion gasses are getting into the coolant.

peace
Hog

[scottfab]

The FSM indicates 14.7 gts for the system cooling capacity.

[scottfab]

Ha....OK....say.....does the 14.7 quarts include filling (2/3 full) the plastic coolant overflow container under the passenger headlight?
.....snip..
Cliff

No, I'm sure it doesn't and I've checked the FSM.
It says nothing about doing so. I never have. I think the most
I've put in there was maybe a quart. If one were to cram 3.3 qts
in there I bet it would be full. Filling your windshield wiper tank is
a good idea but filling the overflow? dunno about that.

[phrogs]

If this motor is still in a ZR-1 could it just be burping?

I have seen plenty of air make it to the overflow when the car is burping but who knows until you can get in and look around. Check the easy stuff, if it really has an issue there should be more evidence to be found.