Thread: Head gasket and head crack questions.

I have an '07 gt. 145k miles. Just got this car. Out of the blue it had overheating issues.
After water pump, thermostat, coolant flush, radiator, extensive bleeding, and radiator cap, not in that order. It still over heats.
So now I am the point I see I have compression or exhaust in the cooling system.

Kind of wondering before I pull the heads to see if I should just plan on using some stop leak and dump the car.

Am I just facing a head gasket or are cracked heads common?
I would assume there are cracks but are there acceptable cracks if they are not leaking?
Is it most likely the head or heads are going to be junk?

Is the front and rear head the same? Meaning if I get a used one will it work in either position?

How many hours you think I am looking at in labor?
I plan on jumping in tonight and hope to have a head off before I stop.


Thanks for the help.

I have no leaks.
Clean oil.
Exhaust in coolant verified
I also have a cylinder #4 misfire code so I think I know where the problem is. Just wondering what to expect when I get there.

Dropped heads off at machine shop this morning.
No visible cracks. No obvious areas of compression leakage.
It almost looks like it was leaking on 5 of the 6 cylinders, but as we were standing there looking at the heads and old gaskets we noticed one exhaust valve is really seated deep compared to the rest so we did a quick leak check on them.
5 of the 6 exhaust valves leak badly. 2 of them bad enough they should have caused a misfire.
So now a valve job and maybe a couple seats.

I am very disappointed with GM.

He is tearing them apart, then he will crack check them again. After that he will tank them and put them on the mill and we will see how warped they were.

That's true I guess most engines are probably worse off than anyone knows and with electronic controls the computer compensates best it can for the wear.
Of course I haven't had to do any head gaskets on any of my fords so there's that.

No word from the machine shop. He probably got behind or it wasn't as bad once he got it torn apart.

Originally Posted by BillBoost37

You never owned a Ford with a 3.8L. Everyone did a head gasket or 5 on those.

We get em in our shop all the time. 50/50 chance the heads are cracked too. i'll stick with GM myself!

My heads are cracked in four cylinders.

All six exhaust valves were worn out.

Replaced them all and it runs just like it did before, just fine.

Still some unusual driveability issues, but the tune does some interesting things and they're all controls I have no access to like IAC control and idle spark.

Got the heads back from the machine shop today.
No cracks, not really warped. He did a valve grind and surfaced them.

Car is back together tonight. Drove it out of the shop.
Will purge air and do an oil change tomorrow before the big test drive.

I hate not finding anything wrong. I suppose it could be a cracked block but I would think we would have gotten hydrolocking at some point or steam out the exhaust.

Hope it is all good when I drive it. Stupid GM.

Original radiator cap tested at 15 psi, first new replacement tested at 15 psi and second new replacement tested at 15 psi. LOL

Car is running, seems like a head gasket just let go. Couldn't find anything else wrong. Seems to be running fine now and not overheating. We will see if it makes it through this week.

Normally you pull a head and see the damage to the gasket or at least one combustion chamber that looks way different than the rest.
Not so in this case. It is being driven everyday. So I hope it holds up.

It was hard to tell with all of the left over dexcool mud. We did watch the gaskets and made sure the whole were clean and empty but taking it apart could have dislodged a flake or chunk blocking the passage through the head gasket. The holes are what 3/16" big?