[nsayers88]

Hi all,

I am a newbie, so please bear with me. I have a 69 chevy c10 that does not coolant. This is the question, I fill the radiator to the neck, and start the engine. About a minute later, the radiator starts spitting the new coolant out the overflow, until the radiator is about half full. I just got this truck, so I have no history on it. Can anyone help with where to start, if it maybe a pocket of air, or another problem?

Thanks in advance

Nsayers88

 

[NXS]

It is a pocket of air alright and it's probably coming from your headgasket.

 

[advanced design]

I agree with NXS. Pull the spark plugs to see if you have coolant in the cylinder. If so a head gasket is blown.

 

[nsayers88]

There is no coolant in the oil.

Let me specify when I found this problem. I first noticed that the coolant was leaking out when I replaced the water pump. It was leaking on the top of the water pump, most likely it cracked from being in a yard on the coast.

Is it possible that there is a pocket of air somewhere in the path, besides the head.

 

[Restore60s]

Leak

Put a pressure tester on the radiator to see if you can find a leak somewhere, even an internal one but I agree with NXS & advanced design you just about described a head gasket problem.

 

[nsayers88]

thanks NXS, advanced design, and Restore60s, I will try a pressure test on the system.

This truck runs great, that is the reason that I don't think that the head gasket is the problem, however that is why I am posting.

Thanks for all your wisdom

 

[NXS]

Anytime and best of luck! Oh, and keep us updated on what you find.

 

[advanced design]

The cooling system pressure tester is a good way to go for further diagnosis. Let us know what you find or if you need any more advice.

 

[GoneNova/406]

did you check to see if your thermostat is good?put it in a pan of water and boil it to see if it opens.you could leave it out also just to see if the water system flows with no restrictions.if it still does the same thing at this point you've got a head gasket out.whether or not you put a new thermostat in it you can drill 3 3/16's holes in the edge of the stat to make sure that there is no air pocket at any time.it also keeps you from burning up motors when the stat doesn't open.

 

[454me]

When ever you change the thermostat look at the new one and see if there is a hole through it. If there isnt I would drill a 1/16 inch hole in it. The hole will allow air out so you eliminate the air pocket and if there is a air pocket at the thermostat it will never open no matter how hot the car gets. It has to be in liquid to open. It does sound like a head gasket to me if it starts spitting water as soon as yuou start it. Pull all the plugs and see if any are white looking almost like brand new plugs if there is one its getting water in that cylinder.

 

[nsayers88]

I think you may have something GoneNova/406 and 454me, when I replaced the water pump I replaced the thermostat (which was missing when I got the truck). Let me try a 1/16 hole in the thermostat.
I will also try to pressure test the system, found my tester late last night.

 

[nsayers88]

Thanks all for the advice...

The one thing that I did not even think of is the radiator cap! I used a radiator tester and followed the instructions. I tested the cap, which tested to 13 PSI, then tested the system, and it held strong at 16 PSI. I then followed the instructions that came with the tester, to rule out the head gasket, which told me to run the system to normal temp, and check the reading. It was holding steady a little above 16 PSI. I will try and replace the radiator cap , maybe that might change everything .

Anyone know what cap actual belongs in a 69 Chevy C10 w/out AC running a 350?

 

[85 vette]

If your engine is spitting out water within minutes like you said then it can't be the radiator cap. You didn't state whether the coolant is boiling that fast or is it shooting out cold. Even a system with a blocked thermostat takes longer than a minute to overheat to the degree of shooting out the overflow. Try this. When the engine is cold have someone crank or start the engine with the radiator cap off and your hand over the opening. If you feel any pressure against your hand you have compression in the radiator which equals a blown head gasket. I had an Acura that was so blown that whenever you cranked it the plastic overflow along with the hoses would blow up like balloons. Also check and see if your bottom radiator hose has collapsed . It can collapse internally without looking bad on the outside. Anyway, if your bottom hose is collapsed your coolant can't circulate and the waterpump is going to send it to the path of least resistance which is the overflow or radiaqtor. good luck