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[harpersimon]

My coolant drops a bit.. do these cars 'use' any?
Would a new expansion tank cap be useful?
I noted it does get a bit hot, fans cut in and bring it back to 80 from near 100, but the other day I noted it chucked some out the overflow when cooling.. why would that be?

[tunnie]

define 'a bit'? No they should not use any, mines not used any in 8k since i changed it.

Most likey cause is HBV 

[dbug]

My coolant drops a bit.. do these cars 'use' any?
Would a new expansion tank cap be useful?
I noted it does get a bit hot, fans cut in and bring it back to 80 from near 100, but the other day I noted it chucked some out the overflow when cooling.. why would that be?

Overfow - it should be a sealed system!!  Do you mean the vent in the cap?  If so its probably been overfilled.

[harpersimon]

Hello - yeah I wouldn't think coolant useage is normal :-) - and have read some bits and pieces about the Heater Bypass Valve..
There are no obvious leaks - nothing under the car after sitting or being used..
(By overflow I meant is there some pressure driven valve to let some out if there is too much pressure/coolant?)
what happens is:
the car has plenty of coolant - up the tank seam when cold.
Runs with apparent normal temps
Then when its cold, appears to 'expand' a hell of alot back into the tank - to the point the tank fills up. Its not over full if the fillmark when cold is accurate!?
not sure whats going on.

[tunnie]

The fill mark is the ridge to the expansion tank, it should be at this level when cold.

The only possible escape for coolant is via the cap on this tank, or the cap on the rad (bottom of rad passenger side) So not sure what this pressure driven valve is you refer to?

[harpersimon]

The fill mark is the ridge to the expansion tank, it should be at this level when cold.

The only possible escape for coolant is via the cap on this tank, or the cap on the rad (bottom of rad passenger side) So not sure what this pressure driven valve is you refer to?

Hi - sorry maybe I am not clear - I didn't know if there WAS a valve for expelling pressure/coolant on these, I am not saying there is an issue WITH mine, just asking IF there is one - to try and work out where some of my coolant goes :-)
I have normal coolant level, filled to the seam / level mark when cold as you mention.
Run the car no issue (gets warm when stood in traffice but fans cut in ok)
Seems to expand too much back into the tank when switched off, and some then escapes.
So I guess the question is why does it expand loads of coolant back into the tank,  when it has the correct level when cold?

[tunnie]

Sorry both getting confused there, no there is no release valve, as mentioned above its a sealed system.

Has anyone ever put rad weld in the cooling system? Also when its up to temp, does the big pipe from the top of the rad to engine get hot?

[harpersimon]

can't answer those but will check . No Rad weld to my knowledge, but bought from dealer so no one is going to mention that if they had. Rad and hoses etc look in good condition on general inspection. I'll have to check the top hose temp when next running the car, as its near cold now. Assuming it ought to be hot?

[tunnie]

can't answer those but will check . No Rad weld to my knowledge, but bought from dealer so no one is going to mention that if they had. Rad and hoses etc look in good condition on general inspection. I'll have to check the top hose temp when next running the car, as its near cold now. Assuming it ought to be hot?

Yup, will tell if its hot going into the engine....

Rad weld signs are silt/crap in in the expansion tank /under the cap, if your coolant is nice and clear its never had it 

[harpersimon]

mm I feel a flush coming on then, as its pretty crappy in there.. browny sort of residue. Think I will pull the bottom hose, drain and refill at some point. Any special bleeding techniques, or literally drain it and refill it? (I'll also remove header tank and clean out)

[tunnie]

mm I feel a flush coming on then, as its pretty crappy in there.. browny sort of residue. Think I will pull the bottom hose, drain and refill at some point. Any special bleeding techniques, or literally drain it and refill it? (I'll also remove header tank and clean out)

Oh 

This sounds like oil cooler failure 

[harpersimon]

really? mm not so sure. no oily smell, no oil in water.. no loss of oil.. I'd say more silty/crap than oily brown colouring. Hard to tell I guess when you aren't looking. How else would I check the oil cooler incase?

[tunnie]

really? mm not so sure. no oily smell, no oil in water.. no loss of oil.. I'd say more silty/crap than oily brown colouring. Hard to tell I guess when you aren't looking. How else would I check the oil cooler incase?

'brown residue' said oil cooler to me, but either way its going to be cause of over-pressurising.

The oil, or rad weld, has blocked up the rad most likely causing too much pressure.

Post up a picture of the inside of your expansion tank 

[harpersimon]

good call.. Ill have a pop at doing that..when I am able to get near the car again in a maintenance capacity (new baby :-) )

[tunnie]

good call.. Ill have a pop at doing that..when I am able to get near the car again in a maintenance capacity (new baby :-) )

Women can sort that out  (waits for sexist replies  )

If it is silted up your right in your previous post, lots of flushing is going to be needed! Not sure how handy with spanners you are but if rad is nackered need to pop the rad out, fill it with hot water and feel for cool spots.