Over Heating Previa!

[Paulietheprevia]

Hi thanx to those who helped me with my last problem it was the break fluid level!!

i know have a new and different problem. on a recent trip to London (last week) which is bout 250 miles from where i live, the car started to overheat a bit (the gauge moving from quarter to, to ten to). this was about 100 miles into my journey. when i stopped i noticed that there was some water leaking from underneath, this when tested was not overly hot, on opening the bonnet found the whole of the bay soaking. when i opened the expansion bottle, there was no water at all and was steaming. i checked the engine oil and the water that was leaking, there was no water ( or mayonaise) in the oil, or vice versa. being used to driving old cars i had water, though no radweld, filled up the system and went off again (without coolant). after 80 or so miles, started to heat up a bit more pulled over, did my checks again all ok, no waster in bay with radiator, there was water still in the header tank, but it was low so i topped it up a bit more. there was water leaking underneath again this was again not overly hot.

rest of the journey was fine, no over heating, even sat in 2hrs of London traffic. it leaked while there a bit so i put radweld in for the journey home.this seemed to work fine no over heating or leak etc.. till i was bout 30miles from home, so again checked oil etc.. there was water underneath again, and again not overly hot, so when i thought it had cooled a bit i opened the expansion bottle which proceeded to still boil over. i filled the system up with water again and made it home, have been useing it since and no over heating locally, stil leaking water somewhere. and now the heater is only blowing warm not hot when on max!

so am not sure exactly what the problem(s) are, i know i have a leak somewhere, but not sure why there is such a big temperature difference between the water leaking out at the bottom and water boiling over at the top? oil and water are not mixing at the moment, and i have no loss of power, so the head is fine as far as i can tell? could it be the thermostat sticking, or my water pump? or a blockage?

so if anyone has any ideas i would appreciate the help, as at the mo my regular mechanic is busy, and i need the car working right for my holiday at the end of september

thanx for your time, neil

[bothwell_buyer]

Its a kind of common problem with these cars - especially the diesels.

My petrol 1997 Previa suffered the same and I eventually changed the cylinder head. 3 years later it happened again but this time it was the radiator - the radiator fins corrode and blow out leaving just the water columns which don't cool down as efficiently. Check the radiator for leaks and missing fins (the wavy metal bits between the columns). If the head gasket has gone, then it could just pressurise the cooling system... to the point of blowing the water out.

Another one to check is that the fan comes on when the water is hot. And check the water thermostat in case its jammed.

[dazzagh]

I have excatly the same problem, although my temp went up driving away from london up to the lake district. I called the RAC out while i was at the lakes, he said the rad looked a bit wet at the bottom & told me to try a new rad & filler cap. I got a new filler cap, have ordered a new rad, im also going to change the thermostate (do you know where abouts the thermostate is).

Thanks Darren