Now overheating.........
 

Can't seem to catch a break at the moment. it has decided to overheat twice within a couple of weeks. Both times I have let it cool down and then it seems to be fine. Both times I had been driving for a while then it suddenly shoots up. Not loosing coolant, could it be a dodgy pump or thermostat or is this the head gasket going.

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Water pumps are fairly reliable - Thermostats are designed to fail in the open position so shouldn't cause over heating but could cause slow warm up.

I'd start by dropping the coolant and then refilling using the Bottom up method to try to eliminate airlocks (Water would be fine for a bit as a test).

Do you get any bubbles in the Overflow tank and is it filling excessively when hot if so the usual culprit is a HG failure allowing exhaust gasses (combustion chamber) into the coolant it's quite rare that the coolant and oil mix in the flat 4.


Bottom Up coolant re-filling method.

1. Drain from the rad drain plug, or remove bottom hose. Set heaters in car to hot while it drains, leave them there.
2. Inspect rad for the core turning to dust, if it's bad, replace it, internet ones are fine.
3. Use a decent quality anti-freeze, as at a motor factor for one suitable for an alloy engine and having anti-corrosion added. Dilution is usually 50/50.
4. Replace plug or bottom hose!!!
5. Remove the rearmost pipe from the metal header tank on top of thengine, remove the cap from said tank. Jam a funnel down that hose and fill SLOWLY via the funnel, do NOT allow it to gulp.
6. Watch for the header tank to fill, once it reaches the top, remove funnel and replace that pipe.
7. Now, with cap still off, start engine and allow to warm up until fan comes on. Watch for bubbles, top up or mop up as necessary.
8. Once fans start, switch off, replace cap, drive round block, leave to cool.
   When cool, remove cap, check level, top up if necessary, replace cap, job's a good'un.

It takes a while, but bear in mind, THERE IS NO KNOWN WAY TO BLEED THE SYSTEM IF YOU AIRLOCK IT.

Be prepared for head gaskets . It's very comman on the 2.5 get it checked asap and change oil asap if signs or mixture the water gets in and washes the crank.
I know this as my hawk sti did this!

Thanks for the replies, I'm going to get out there tomorrow and have a look.

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Ordered a new water pump, cam belt kit and tensioners, don't think it's hg as the oil is clean, no water contamination and it's not loosing and fluids. I will let you know the outcome.

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They usually fail as exhaust to water - check for bubbles in the overflow tank or do the washer test!

Get the engine up to full operating temp, take the overflow hose out of the tank and add a length of hose to it so that it pokes out of the bonnet in view of the driver or passenger then go for a drive and put the car under heavy load to really spool the turbo up to full boost for prolonged periods. If the hose squirts large amounts of coolant when under boost it’s almost certainly a HG issue (cylinder to water jacket).

if it fails water to oil you have major issues in general terms............

the way the blocks are structured the cylinder is surrounded only by water so you don't get the "mayonnaise" effect you get with more traditional upright 4's...........

Went and checked it this morning, all levels are fine, no leaks, hoses getting hot that need to, top to start with then bottom after a while, fans come on. Temp level staying the same. Hot air blowing. Just seems like something stops working after a while but not on every journey.
New pump, belts and tensioners going on this week.


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Usually When headgasket starts to fail you can start them an leave them sat running on the drive an thay will be fine. What thay tend to do is blow threw the compression ring in the headgasket an blow into the coolant which results in either bubbling in the overflow or it pushes water out the overflow but thay only do that when there under load. It will sit running on the drive for hours fine. Either way it won’t actually overheat till the coolant level is low after it has pushed it out. Il bet pound to a pinch of salt one of your headgaskets is starting to fail unfortunately

Use the test I mentioned earlier where you extend the overflow pipe and run the car on boost to check. I think changing the cam belt and water pump/tensioners will be a waste of money unfortunately and this way you will find out for sure.

If it was the head gasket failing would it not overheat all the time I drive it?

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In my experience under load.

Its overheated twice in a couple weeks but before, between and after it's been fine.
I have now replaced the pump which had a little play, the thermostat looked well worn and had marks down one side, looks like it was trying to push in/out at an angle....
I also noticed the radiator had bowed out on either side so replaced that as well.
Cam belt was the original so changed that and the tensioners.
Should have it filled up and ready to go tomo.

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fingers crossed mate...

All in and running fine, no overheating issues. Now to sort out the original issue of the stutter...

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