Blown Head Gasket On New Motor

[Devin]

I was just about to hit 500 miles on my rebuilt 4ac when the temperature spiked. It was running great and keeping cool for about an hour of driving and then it's like a a switch went off and it climbed super fast. I pulled off to the shoulder and let it cool down before it hit the red( luckily it was freezing out). Eventually I had to take the hood off to keep it cool enough to drive to our cabin where I had to leave it.

I can see where coolant leaked onto the block by the distributor. The #4 plug had some rust on the threads and was a little more orange than the others.

The oil on the dipstick looks like normal oil. I was expecting milkshake color. And it didn't just dump coolant. It overflowed a little from the radiator overflow bottle but the radiator itself remained is totally full. I also didn't notice much loss in power while limping her home. It starts and runs fine too.

Why would a brand new Fel Pro head gasket fail so soon? And I wonder why I dont have coolant in the oil or loss of power?

[dlb]

was it torqued correctly? did you do petros' head gasket mods?

not all bad head gaskets manifest the same way. depends where the break is and what direction things are going. you can do a compression test, and also just try cranking the engine with the spark plugs out (unplug the dizzy so there is no spark though--no fires please).

[larry mcgrath]

How cold was it, did the rad freeze up? Larry

[Devin]

I made sure to torque all the head bolts and I did do the Petros mods. When I go back up to the cabin I will take my compression tester. I don't mind changing the head gasket but I hate to put a new one on before I know what caused it. It's like the gasket blew which caused it to over heat. It's not like it steadily climbed because I was pushing too hard. I was watching the gauge super close since I was still breaking in the new motor.
It was pretty cold Larry, maybe 20 or so. The temp gauge was in its normal place right up until the spike though.

[larry mcgrath]

did you have any antifreez in it ? rad will freez up first ,water stops circulating ,then engine over heats.Larry

[dlb]

I made sure to torque all the head bolts and I did do the Petros mods.

could your torque wrench be out of spec? i know that happened to another member on this forum before.

i personally would not alter any head gasket i was installing.

[larry mcgrath]

DID you have ANY ANTIFREEZ in this ????????????????????????????????? Larry

[Devin]

Yup it has antifreeze in it.
I am thinking it is a head bolt torque issue like you say dlb. I reread Petros' write up and I realized I did not use any bolt lube. When I started the engine for the first time, there was a little outside leakage that sealed up after a few heat cycles.
I don't get what about a blown head gasket makes it overheat though. I think it's a water jacket to outside failure, and I don't see that causing the spike in temp.

[dlb]

if there is a failure that both prevents coolant from reaching the temp sender at the front of the head and allows a pocket of air to form, my guess is that the temp gauge will spike when that air pocket reaches the temp sender since the air pocket will be much hotter than the coolant.

[Petros]

you may have had a small coolant leak unrelated to the head gasket, seeped out until not enough to keep it cool and overheated. make sure you actually need a head gasket before you pull it apart, and check all other possible places you could be losing coolant; hoses, radiator, by-pass tube o-ring, other gaskets, heater core etc.

[teranfirbt]

It's critical to clean out the threads with a brush and carb/brake clean. Blowing them out with air isn't enough. It's also critical to lube the threads on the bolts, oil works fine, although a touch of anti-seize is more consistent, but you'll want to drop the final torque value by about 10 ft-lbs to get the correct tension (anti-seize lubes threads a lot better than oil..)
The last time I did it I found it only took about 20 miles before a re-torque was needed, although that seemed to set it. A second re-torque gave me the same bolt position after as before.

[Devin]

Well I made it back to my stranded Tercel. I retorqued the head bolts and that seemed to seal up the head gasket. I have driven it probably 6 hours and pretty hard and no leaks. Hopefully it stays sealed for good!

[TURTCEL]

Good vibes to you and the car that it is all good. Redoing a head gasket job right after doing it may be faster but it is frustrating to do twice.

Peace