Coolant pushing out of the cap?

Neelsonwheels

Neelsonwheels

Donating Member
Hey guys,

Recently drove the truck slightly hard and when I got back the radiator cap released some coolant. I let her cool down and the next day started it without the cap on. Within 30 second
coolant was coming out of the radiator cap opening. I drained the coolant and changed the t stat and both radiator hoses. Then refilled the system. It didn't take 2 gallons? no matter what. I burped it by squeezing the upper hose and everything. I also have a new cap. No white smoke,no frothy substance in the oil. I know a head gasket can cause this issue but I find it hard to believe since it didn't even get above normal operating temp while I was driving it and the fact that I have Cometic MLS head gaskets. Could this condition be caused by a clogged radiator? Also the coolant that was drained looked nice and clean. Any thoughts??
Thanks in advance.
 
D

Damian

Member
Re: Coolant pushing out of the cap?

Are there any air bubbles coming out the radiator cap? A leaky head gasket would have a constant supply of them and they are usually smaller in size. If not, might be your thermostat. It might be stuck wide open. I'm using this one: http://m.summitracing.com/parts/bra-330-160, it keeps equal pressure on both side of the thermostat. I like it so far.
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

With cap off the coolant overflows within 30 seconds. I guess I could try to run it with the cap on to see what happens??
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

Okay I am pretty sure it's head gasket. :(.
Did everything I can think of and all the classic signs are there.
I guess I just didn't want to admit it. Coolant overflowing from radiator,
Decent amount of condensation from the tail pipe, I did run it with the. So on and it stayed cool and still steamed out of the cap. I now have to decide to tear it down here or have so one do it. I do have new heads and I take on the way. Decisions decisions.
 
D

Damian

Member
Re: Coolant pushing out of the cap?

I always jack uo the front end of the truck as high as I can and run the engine with the cap off to get all of the air out. Try that and see if you get a bunch of air coming out.
 
IGottaSy

IGottaSy

Active member
Re: Coolant pushing out of the cap?

YouTube head gasket diagnosis. Shows how to perform pressure test to determine which side needs replacing. There is also a block checker chemical test available at the auto Parts store. Pressure test will tell you exactly which cylinder(s) are affected before you tear into the task.
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

Thanks,
I am headed out to work on things now. I'm going to throw a 160 thermostat in it,
And try to make sure there is no air in the system. I am not sure still if I don't have a clogged
Radiator. I don't feel that it took enough coolant even though it all seems full.
I may just buy a radiator and change it out to be sure.
 
gstacky

gstacky

Member
Re: Coolant pushing out of the cap?

The way I always add coolant is by leaving the t-stat out, fill with coolant watching where the t-stat goes and fill it up to the top there, then put the t-stat in and tighten, then fill up the rest of the way, that will get most of not all the air out every time.
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

That is exactly how I do it. I worked on it last night and managed to get it to run and push heat through the vents. The temp was normal and the fans came on and brought the temps back to below 180 and shut off. The cap didn't let go or pass steam. I am heading to the parts store to grab a radiator. I just going to swap it out to be safe. I have no idea how the one in the truck has been maintained anyway. At least I can enjoy the truck until winter project time!! Thanks for all the posts and suggestions.:tup:
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

Its a blown head gasket for sure.:tdown:
Now I need to find out what my plan of attack is.
Is it easier to pull the heads while the motor is in the truck or to pull the motor and then
replace them? I was hoping to enjoy the truck a little more this year but it is what it is.
Any suggestions on which gaskets to use? The ones on there now are Cometics.
Thanks
 
Black Knight

Black Knight

I Glow Therefore I am
Re: Coolant pushing out of the cap?

Oh yeah, pull them in the truck.

No big deal, you can have it fixed and running again on a Sat.

You could even go L35 heads while you're at it :)
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

Cool. I'll give it a shot. I am running vortec heads now.
 
Last edited:
Quickstop [UK]

Quickstop [UK]

Combating adversyty.
Re: Coolant pushing out of the cap?

We did a head gasket swap on a weekend. Assuming no other damage, it's not too bad. Bummer though. Good luck!

I have cometics so if they blow, my engine will probably be toast too.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Coolant pushing out of the cap?

Tooky, blew one of his cometic MLS head gaskets and it didn't appear to damage his motor.
 
Neelsonwheels

Neelsonwheels

Donating Member
Re: Coolant pushing out of the cap?

Yeah it does. I'll take care of it. Thanks Jimmy!!
It's part of the game right?
 
You must log in or register to reply here.
Top