I don't know if this is bad ,but my radiator holds a lot of pressure. As soon as I start it it builds massive pressure. Then after I run it for a while and turn it off I can come back 20 or 30 minutes and take off cap and fluid pours out. It is not hot, maybe a little warm. On any other car when I do that it burps then settles. This does not. Also when I look in rad it seems fuller and that some of the fluid should go in overflow but does not. Now biengs overflow is just a rubber tube it should not be that complicated. It is possible tube is pluged but I don't know if that would explian pressure. I don't know if I should be conserned, but any feedback would be appreciated

 

replace your radiator cap with a "NEW" one...

 

I will give it a shot, but even when I don't have cap on it spews out like a volcano.

 

then either your radiator is plugged and or your thermostat is due for replacement... are you having in overheating issues?

 

No overheating, though I don't drive it but around town, but I figure that is when it would get hot. I replaced my thermostat a while back because it was overheating ( had 195 in it, and fan only worked when hooked to battery. Fan right now is always on till I get a switch which would keep it maybe a little to cool, but like I said I haven't got it out on highway. I will probaly just go and by one of those caps with temp gauge and I don't really trust my stock one, but like I said usually they burp then setlle down this one won't. I may flush it, just not looking forward to it. Northwest WA state . Windy and wet right now

 

could be a cracked head or head gasket,cylinder pressure getting into the cooling system.

 

I really hope not. That thought has crossed my mind. I have checked oil. Looks good. It does blow out white smoke when I start it and run it awhile but I do live in the Pacific Northwest and there is a lot of moisture in the air . It goes away after it warms up. So I am hoping that is not case. If I remove valve covers would I be able to see any coolent in there?

 

When you start it cold, or after it warms up?

 

i would take that as cold

you may or may not see antifreeze or oil mixing it depends on how, where and how bad the compression leak is.

 

Both. When it is idleing after I start it it spews out. Now really shooting, but on any other car I have had , when I check my coolent I will start it, and then let it cycle thru to check the levels. On this I can't because it just spews out. Does not just burp when I take of cap. The lat time I tried it had been siiting about 20 minuts and then probaly about a pint spewd out before it settled. Some times it also seems a little airy ( if that makes sense) . A lot of air bubbles

 

the other question i forgot to ask,is it pushing coolant out of the system over-flowing the overflow bottle or blowing the radiator hose off or anything like that?

 

How would I check for compression leak?

 

a lot of never ending air bubbles with the cap off and motor running is a very good sign of a head or head gasket failure.

 

Do a compression test, or a leakdown test.

 

No not blowing hoses or blowing into overflow bottle which is another issue

 

most of the auto parts stores sell a test kit for checking the cooling system for combustion gases.

 

I will go get this test you speak off. Kindof sucks about head gasket issue. I can take everything off and put back on, but I do not know how to adjust valves and stuff. And what is this leakdown test you speak off?

 

the valve adjustment is easy.i can pm you the way to do it with the engine off.

 

Sweet. I would apreciate that. I guess now I have a winter project. I may just get new ( used) heads anyways. I will see what mine are first. Problem is I have a 327 and I don't want to put to much money in it because eventually I would like a 427

 

if this were the case wouldn't he be complaining as well about poor performance?

 

I have only had car for about two monthes. I have been working out the kinks such as this so I can be a reliable cruiser so therfore I have not really been able to get on it to much. Just 10 miles drives in the outskirts of town, so I don't know if I am lacking in performance yet. I may give it a shot this weekend if it does not snow

 

it depends how much compression is getting out,if the entire cylinder was dumping into the water jacket yes because that cylinder wouldent fire but a loss of 10-30 psi would not be noticed.

like a very small crack in the head that lets pressure into the water jacket but still holds enough pressure for the cylinder to fire

its probably in the very early stages of the headgasket letting go.im sure if he kept driving it,it would get worse.

 

Let me ask this
If I do a pressure test and it was a gasket would all cylinders in one head have less prrssure then the other heads cylinders?

 

Probably not

 

Different cylinders will have different values.

 

So I guess my most important question before I rip off half my motor is how do I check for sure to see if I have a cracked head gasket.

 

 

i dont agree completely with a compression test for a headgasket.combustion gasses in the cooling system is a dead sign of a head or headgasket where a compression test you may have to make an educated guess as to a head ,headgasket,rings,valves.

a leakdown test is a little better but if the rings or valves are questionable will it hold enough pressure to bubble up in the cooling system.and at that point you need a rebuild or motor.

 

before you do anything stupid like tear the engine apart, check the overflow hose and canister, make sure its vented and not plugged in any way. My car did the exact same thing for ages, it would hold pressure in the system for weeks. Actually pushed out the waterpump gaskets and 2 freeze plugs.

It was all because my overflow canister, from canton, didnt have a vented cap, and would no allow the cooling system to regulate pressure. I vented the cap and all is well.

Make sure the radiator cap works as well, that pretty important too

 

86TA. Thanks for that info. I am going to do everything I can before tearing apart such as what you suggested and replace radiator cap. My evential goal to to build a 427 for it, but that will probaly take me two years so I would like to drive on this motor with as little expence as possible

 

Yes, compression tests lack specificity, but at least anyone can do it with just a compression gauge.

If the rings or valves are that bad, then you'll be tearing it apart anyway.

 

double post

 

the car running with the cap off and blowing coolant out and a never ending amout of air bubbles would have NOTHING to do with the overflow