MEX351

I not long did a head gasket,exchange head timing chain, radiator rebuild (new tanks and a flush) and the bloody thing still sporadically gets hot!Not all the time or everyday just 1 every 2nd or 3rd week.Let it cool and check the coolant level, top up if needed 3 times so far and then it's fine again for another couple of weeks.Did a pressure test on the cooling system and it seemed okay.
There is a little evidence of coolant on the alternater but I tightened the hose clamp and fixed that(the bottom radiator hose sits above it).The cap seems fine and tested okay.

When the car gets hot it rises slowly to about half way then just screams up to hot in no time and the temp warning beeper comes on and then the fun stops.The fans apear to be working but I don't know if they are going at full speed or just slow.The coolant loss concerns me as there is no new stains down the side of the engine and the pressure test was alright I'm stuck to know what else aside from taking it to a shop to be fixed/looked at.

The way it gets hot in a hurry when it does makes me think it's the thermostat.As they are $29.50 for a new one I don't want to buy somthing if I don't need it but I would like to fix it at home if I can before I send it to the mechanic.

Any ideas or help would be great,If there are other threads that have delt with the same issue point me in the right direction and I thank anyone that can help.

atec77

If the thermo doesnt fix it then I expect its the radiator being blocks , you can get a new unit for under $200.00 so might pay to save

CraigS288

I pulled apart a 4 litre engine not so long ago and something that puzzled me was the fact the head and block have water galleries up each side and at the ends, but the head gasket only has corresponding holes on one side and the ends.
Why would there be a head gasket in there that blocks off half the water flow?
Did your head gasket have holes for the water galleries in both sides?

garth04

Don't want to throw a dampener on things here, but if your loosing coolant, and its not a visible leak around the motor, then you could be loosing the fluid down the exhaust, o oh cracked head....(maybe the exchange head wasn't crack tested)

Did you do the cyl head swap yourself or did a garage do it?

Might pay to stop by the garage anyway, as they should have a sniffer that checks thru the radiator cap hole for combusted gasses in the cooling system.

Thermostats will play around like that if there is an air bubble trapped behind them.

TO CraigS288; Head gasket is like that to create a flow characteristic because of the length of the motor, ie to flow across and from rear to front. If all the holes were open the fluid at the back of the motor wouldn't flow forward. V12's are like that too.

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MEX351

[QUOTE=garth04]Don't want to throw a dampener on things here, but if your loosing coolant, and its not a visible leak around the motor, then you could be loosing the fluid down the exhaust, o oh cracked head....(maybe the exchange head wasn't crack tested)

Did you do the cyl head swap yourself or did a garage do it?

Might pay to stop by the garage anyway, as they should have a sniffer that checks thru the radiator cap hole for combusted gasses in the cooling system.

Thermostats will play around like that if there is an air bubble trapped behind them.

[Didn't even check that.But it's just strange that it's not getting hot all the time.Will check that out,thanks for the tip.

notty

THERMOSTAT

theres your problem and if a thermostat costs you almost 30bucks you are at the wrong place the last thermostat i bought wast 12bucks so try somewhere else and always ask for trade price!
the thermostat will have a bit of shit arround it and it will cause it to get sticky thats why sometimes it will get and sometimes wont get hot also if the warning is comming on you are playing with fire and for the lost coolant have you ever thouight that you are actually boiling the engine and its comming out of the overflow?

cheers notty

MEX351

The car was loosing coolant when it was running fine and not boiling so going out the overflow I don't think so.We were checking it every 3-4 days so we would know.Also what sort of car do you drive?Mine is a EF and the cheapest price I got for a thermostat was $22.50 (I live in Wagga Wagga) the dearest was $31.50.They are a dual acting unit also.Where did you get it?

I have got the cooling system tested at a radiator shop and they removed the thermostat and it looked fine as did the radiator cap.But over the last week it has not used coolant or got hot at all so I checked the hose clamps and everything else I could think of and panited the side of the engine with a fesh coat of paint with a white strip to see if any is leaking out the head gasket and so far so good.

Thanks for your reply Mex351.

notty

i also drive a EF falcon
i got my thermo stat from Natrad in Thomastown
and a mate told me he just recently bought one from Bursons for $18
cheers

MEX351

Man our Bursons said $27:50,that sucks.And we need an account to get trade discount.

Thanks anyway Mex351.

notty

they are money hungry bastards!