Thermostat? Headgasket? Or other?


Hi guys

Well... after looking into replacing a head gasket, i realised its no job i would be able to do with me feeble skills and i'm not going to pay more than the value of my car to get it changed... and further more... i'm not entirely convinced it is the headgasket.

I'm HOPING that its a faulty thermostat.

Here's the symptoms:

- Overheats after a long journey the coolant reservoir BOILS and bubbles over
- The radiator is never boiling hot when it overheats, but the coolant it
- Air is not being blown into the coolant reservoir, it is just getting too hot
- There are no visible traces of oil in the coolant res. but it did go very slightly green when i looked at it the other day
- the exhaust dribbles out a very very small amount of water

that's about all i can think of right now! can anyone help? thanks a lot SmileSad


hi domdino, what car have you got,which model Daihatsu?


Hi George, i have a sportrak

Hi George, i have a sportrak 1990 ELi

Sad god i hope it's not the headgasket SadSad

water leaking into the cylinder block would screw up my engine though right? the oil would mix with water? There doesn't seem to be any trace of water in the oil... The car drives absolutely fine but on slightly longer journeys (15miles+) is when it really starts overheating...

Compression gas.

NB ..... Don't anticipate its water leaking into your cylinder block. It could easily be compression gas from a cylinder which is creating an 'air' block in the coolant. Try sniffing the reservoir water ... does it stink of exhaust fumes?

It does sadly sound like the

It does sadly sound like the HG, If it is using water I'd guess its almost certan.
What you could do to make sure is remove the thermostat altogether and run it for a while. Assuming it still does it you could try bunging some rad weld in as occasionally that cures it though temporarily, After that you have the choice of repairing or breaking the vehicle

Watch you dont blow a hole in the cylinder head.

If the water coolant reservoir is boiling then its a blockage. Could be the thermostat, could be the water pump is not working. If those are proved ok then the head gasket is leaking into the cylinder block and prevents water circulation - so the coolant boils.


hi domdino, sounds exactly like the symptoms i had a week after i bought my spotrak elxi.Sorry mate but mine was headgasket, i found out on here somewhere that the H\G usually goes between the cylinder and the waterway on a sporty so this is how i found out... Remove the radiator cap and top it up full of water. Then start her up with the radiator cap off... mine pushed the water out hard enough to hit he bonnet with force lol, and sure enough it had gone on no.4 cylinder.Done mine myself and shes running sweet, its not as daunting a task as it looks if you get a good manual,