Hi Guys,

Excuse the rambling but I hope someone can help...

A few months ago I installed a rebored and rebuilt 2.0 Pinto (more power than the existing 1.8) in my Seven as a short term measure until I get the Zetec in. Unfortunately it had been stood for a while and the block had corroded inside where the coolant circulates around it.

I flushed and flushed again (a good 10 flushes getting the car to temperature by driving it at high revs with the understanding this would get any crap dislodged) using cooling system flush for the first and last flush until the water was clear. Refilled with 50/50 coolant/water and all was fine for a couple of months until I did a track day. The car was driven hard for a good few hours (not continuously obviously) with no problems but towards the end of the day it started to overheat to the point where water was overflowing from the top of the expansion tank. It is not a pressurised system.

My solution to keep me running for the last couple of hours of the day was to empty the coolant (it had rust in it I guess from more crap being dislodged by very hard driving) refill with water and remove the thermostat. Problem solved and I finished the day with no further problems.

I have since flushed the engine again and refitted the thermostat and filled with coolant/water. Unfortunately the car will not stop overheating (happens within 10 minutes) and the end result is that the expansion tank ends up being full of water and the fan is running permanently once hot.

I have tested the thermostat and it opens about 1/4 of an inch in boiling water (it is rated 82degrees). Is this enough or do you think I need a new thermostat? Can anyone tell me how far it should open? Googled with varying answers ranging from 1/4 inch to 1 inch.

If the general consensus is that the stat is the problem then I will change it. Otherwise if you guys think it is down to more crap lodged inside the system I will run it without a thermostat for its last track day. Will all be replaced in the winter anyway so don't want to spend more than a few quid on a repair.

Thanks for any help. And I may change my signature to 'why use 1 word when a million will do'

To flush a rad you take it out the car and turn it upside down put a garden hose in the water outlet (bottom hose) and turn on the tap flush.

To flush an engine remove the thermostat, put the garden hose in and flush from the top water out let to the bottom.
Assuming you have by-pass circuit and your thermstat is Ok and the pressure cap is ok then I suspect you have either stuck stuck mechanical advance or a blown head gasket.

[Edited on 8/10/11 by britishtrident]

What he said ^

Flush the rad, I'd put money on that.
Check ignition advance.

i thought the pinto was meant to run a pressurised system? your wasting your time flushing a pinto out i had the same issue on mine and i didnt matter how many times i flushed it out it always went mucky again. adam had the same on his pinto in his track tiger also.

Ok thanks. Will run with no 'stat for its last outing and hope for the best...

Just to update...

Set the timing properly and bingo no more overheating!!

Thanks for your help guys!