I know this seems like a newb question, but in my years, i have never personally dealt with this situation. As the car heats up, it builds what seems like excessive pressure. Squeezing the upper and lower hoses, they get hard. Which i know is normal. Everything is normal, car runs fine, doesnt smoke, doesnt use coolant, doesnt over heat. There is no mixing of coil/coolant. But i noticed last night after the car was completely cooled down, like 12 hours after it was running, there was still pressure. I pulled the radiator cap and it was a big release of pressure. Not sure what would cause that. Everything i read said it was a head gasket issue but being a head gasket issue, i would think it would be going through coolant or something...over heating....something lol. Only issue is its holding pressure for a long period of time. So...any insight?

Its a golden eagle sleeved block, 84mm, 8.5:1, B16 head, Honda head gasket.

 

Do a chemical block test. If combustion gases are seeping past the head gasket into the cooling system that will find it.

 

Wouldn't hurt to put a new OEM rad cap and t-stat in it to know they're good. Cheap and should be done periodically anyway.

 

Its got a new thermostat and the cap hasnt been replaced recently. But the spring in the cap and plug seem to be fairly easy to push so im not sure why it wouldnt be pushing the cap open.

And its got an eBay aluminum radiator in it so an OEM cap wont fit. Im gonna have to go to the parts store to find a cap.

And still doesnt make sense why it will hold pressure overnight or longer.

 

for what its worth, a customers car with an ebay radiator was doing the same thing and found that the cap was getting stuck on the neck of the radiator and not allowing the spring in the cap to compress

 

I think it may be a blown head gasket unfortunately. When its cold it builds pressure almost instantly and coolant has been heating up alot quicker.

 

So i went a got a new cap. Drained all the coolant out and put water in it since thats whats supposed to be in it at the track. Noticed that its not building pressure like it was before, but i am noticing that with the cap off, its got quite a few bubbles coming up...at first it was bigger bubbles, now its little tiny ones and seems like its producing less and less. Just not sure when i completely drained the coolant and blew air in and flushed every bit out, how much air will be coming up. I let it run for about 30 minutes.

 

Had a buddy put gsr head studs in a b16 years ago and it did the same thing your explaining, car never over heated just built UN normally high pressure and never released

 

once again if you think it is a blow head gasket do a chemical block test

http://www.napaonline.com/Catalog/Ca...006_0361073538

 

It was a leaking gasket. The gasket was a cheap one from auto-zone thats over a year old ona car making over 700hp.

 

^thats pretty good life

 

Going to say, if the radiator cap is good... it is the head gasket.

Been in the same position, you hope it is not the HG but it usually is.

 

Why was an autozone headgasket used on a 700 hp build ?

 

i use them on my car^

 

Cause i normally use Fel-Pro gaskets. And the day i pulled the head off, i couldnt find one locally for a decent price. I wasnt going to spend $150 on a head gasket. The only one i could find was the no name one at AutoZone. I want the car to get back out to the track the next day so i used the no name one. And almost a year later, it finally failed. So im not bitching.

 

i use the blue felpro ones work pretty good.

 

You dont happen to know the part number for the 84mm blue one do you? Thats the one i wanted, but cant find a definitive part number for the blue. Settled for the standard one for now.

 

The blue PermaTorque 84mm is Fel-Pro part# 26159PT

 

Head gasket is the result....not the cause. You likely lifted the head from detonation, weak head studs, or bouncing hard off the rev limiter or something. The head lifts and scorches the gasket, lets coolant past and there you have your pressure issue.

Replacing the gasket may only be a temperary fix if one of the above are present.

 

Thats the part number i used and it wasnt the PermaTorque Blue...it was the standard black.

 

And yes i know....i did a big 3rd gear burnout in a parking lot bouncing off the limiter is when im sure it happened. But i think a nice name brand gasket wouldnt have failed under the same conditions.

 

i run the 81mm gaskets since im still on stock bore,i just borke a gasket testing out some crazy timing at the track since my gate springs wouldn't allow anymore than 34 psi and 147 mph was too slow.

anyways i think these perma torque gaskets may not be the best but they fail almost instantly when something goes wrong.ive been on the same head and rotating assy for 3 years but ive been threw some head gaskets. i just think of it as a fuse. i replace it ever now and then.