Peugeot 306 XSi - Overheating: head-gasket / thermostat / other?

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Thu 30 Aug 2012 13:37
Peugeot 306 XSi - Overheating: head-gasket / thermostat / other? - RichF75

Hello all,

Problem which I 'think' I know the answer to, but Im not very car-savvy!

4 days ago, noticed a small leak of water directly under the coolant-tank. Filled it back up, didnt think anything else of it and car has been running fine...until yesterday morning when I heard a constant clicking sound from under the bonnet and noticed 110° on the temperature gauge.
Immediately stopped, pulled car over, opened bonnet: smoke coming from oil-tank and water.coolant tank.

Left it for 4 hours to cool and carried out following tests:
1 - re-filled water-coolant tank, left cap OFF and started engine - left for 2-3 mins - water just constantly bubbling away at same level
2 - replaced water-coolant tank and started engine revving on-and-off for 1-2 minutes - water pouring out of overflow-pipe in side of coolant tank.

Also noticed light-grey smoke coming from exhaust-pipe with some water residue - although this smoke only appeared when I really revved the engine.

It is an OLD car, mid-90s...what other specific tests can I carry out to identify whether this is radiator-based or head-gasket?

Many thanks for any/all advice

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Thu 30 Aug 2012 13:54
Peugeot 306 XSi - Overheating: head-gasket / thermostat / other? - Peter.N.

If you have pressure building up in the header tank it will either be the head gasket or head that's leaking. A leaking gasket doesn't in itself cause the engine to boil just that the pressure blows most of the coolant out, then it boils. Look round the filler cap and overflow pipe for signs of dry antifreeze.

If the thermostat has stuck closed it will boil and eject the coolant but takes sometime to do that, if the radiator is geting hot then the thermostat will probably OK. The temperature that your engine reached will probably have caused the gasket to fail anyway.

Drive with your heater on, if the gasket is leaking the heater will go cold before the coolant boils.

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Thu 30 Aug 2012 14:53
Peugeot 306 XSi - Overheating: head-gasket / thermostat / other? - RichF75

Peter.N.
Thanks for your reply. I forgot to mention in my original post that the actual interior-heaters have not worked for the last year!
Anyway, the only thing I did notice was when I re-filled the coolant/water tank, replaced the cap and ran the engine for a couple of minutes with the occasional over-rev, when I stopped the engine and slowly removed the cap, the water poured out over the rim and contained deposits of light-brown-sludge - but this might just be rust.

The only problem I have is - this car is now parked at work, 12 miles from home - Im not sure if/how I can get the car back to my local garage to make any further checks. (short of doing the journey in two parts, LOL)
Ironically there is a scrap-metal merchants 500 yards from where it's standing...

At the end of the day, Im going to scrap this car as it's pretty much now at the gates of 'The Great Car Park In The Sky'...I just thought if I could repair it on the cheap I can use it to look for a replacement motor!

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Thu 30 Aug 2012 22:54
Peugeot 306 XSi - Overheating: head-gasket / thermostat / other? - Peter.N.

If its expelling the water that quickly that you cant drive it far I would say definitly the gasket, possibly a cracked head.

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