Header tank filling and water bubbling

olliecast

Active Member
Hi all,
Just been out testing my newly mapped daughterboard and stopped the car to find my coolant was bubbling. also the level of coolant in the head tank was rising at a fair rate as the car was idling.
Could me water pump be knackered?

Cheers ollie
 

olliecast

Active Member
just looked again and the level is dropping in the header tank after squeezing a few of the hoses. I`ve head rusty coloured water for a while and the rad flush has been on the cards for a while. The header tank water has an ever so slight oily film on the top (not sure if its the gone off coolant or not).
Could it just need a flush and rebleed?
 

Shaun

New Member
It could just be a weak rad cap so try that first but if theres oil deposits in there then theres a chance of it being the head gasket
 

PobodY

Moderators
Staff member
It's one of two things:
Something is boiling somewhere (which might explain why you can 'burp' the system.
There's exhaust gas getting into the coolant. - If it's looking particularly rusty there's the chance that the jacket has corroded and there's a pin-hole leak for the exhaust to get through.

You could try a coolant flush just so see if there's a blockage somewhere... and whack a bit of sealant in the mix to block any small holes when you top it up again. Or just grind some black pepper into the radiator cap - it's an incredibly effective ghetto fix.
 

olliecast

Active Member
Shaun said:
It could just be a weak rad cap so try that first but if theres oil deposits in there then theres a chance of it being the head gasket
well i could hear hissing coming out of this when it was cooling down. how would it cause the header tank to fill then drain (apologies, this is my first dealings with coolant systems!)
 

olliecast

Active Member
PobodY said:
It's one of two things:
Something is boiling somewhere (which might explain why you can 'burp' the system.
There's exhaust gas getting into the coolant. - If it's looking particularly rusty there's the chance that the jacket has corroded and there's a pin-hole leak for the exhaust to get through.

You could try a coolant flush just so see if there's a blockage somewhere... and whack a bit of sealant in the mix to block any small holes when you top it up again. Or just grind some black pepper into the radiator cap - it's an incredibly effective ghetto fix.
there`s a small amount of "smeggy" crap around the sides of the header tank where the coolant level has been up before. i`ll try the flush and sealant thing as i ain`t loosing water and there`s no sign of water in my oil either.
 

PobodY

Moderators
Staff member
Yeah - my old Pintara used to do that (think of an R31 Skyline built for the Australian market with a CA20E engine in it). Good quality Australian block just corroded through and let exhaust into the water jacket... then it let go in spectacular fashion on the motorway.
My advice is to take notice of the coolant gauge.
 

Shaun

New Member
olliecast said:
well i could hear hissing coming out of this when it was cooling down. how would it cause the header tank to fill then drain (apologies, this is my first dealings with coolant systems!)
After a while the springs tend to go weak and as the water heats up it expands creating pressure as the spring is weak this will allow the water to fill the headtank whilst hot and will drain back into the system as it cools because the water shrinks as it cools creating a vacum and drawing the water back into the rad.On the other side,if the head gasket has gone from cylinder to water jacket the compression and combustion process over pressurise the water system creating the same symptoms.
 

markweatherill

New Member
If your friendly local garage has one of those exhaust gas 'sniffers' that look like a turkey baster, it's a quick and easy test for exhaust gas in the coolant.
 

PobodY

Moderators
Staff member
markweatherill said:
If your friendly local garage has one of those exhaust gas 'sniffers' that look like a turkey baster, it's a quick and easy test for exhaust gas in the coolant.
Oh yeah - good point, I'd forgotten about that. My brother-in-law is a plant mechanic, that's how I knew that it was exhaust getting into my coolant!
Change the cap first - probably is as simple as that. Also if the coolant is old, it's probably boiling when it shouldn't be (the anti-freeze is also anti-boil on the basis that molar depression of freezing point can also cause molar elevation of boiling point - Physical Chemistry 201).
 
B

benvquad

Guest
boiling up

i had the same prob, replaced my rad cap, no difference!!! it was the water pump. that stopped it!!! hope that helps
 
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