Hi everyone,

I've got a weird situation with my XR6T getting hot. The temp guage now gets to half way.. that doesn't sound hot but this car has always sat at 1/4 and it is not because if you stop driving suddenly you can hear it bubbling coolant out the overflow. If I let the car idle for a while after stopping the temperature drops a bit, but not all the way back to where it used to sit. considering the huge radiator and stuff in this car I'm puzzled as to why it would be running hot at all. There is a gauge in the lid of the overflow and that shows that the coolant is somewhere around the 100C point.. and it's never been anywhere near that point before.

The car has:
* newly replaced thermo fans. (did that trying to solve this problem.) cost was 20 bucks so WTH.
* 4 core radiator, only about 6 months old.. it's twice the thickness of the standard V8/turbo radiator. (which is twice the thickness of the standard radiator) so it only just fits in front of the engine with the fans on the front.
* Silicon hoses all round.. they came with the radiator. Seem pretty good as they don't get soft with heat the way the rubber ones do. There are no springs in them to hold them open and it doesn't' seem all that hard to collapse them so I"m wondering if I should source a spring for the bottom hose.
* New thermostat... did it yesterday. the old one looks fine but figured what they hell.
* No leaks and coolant is clean and green.

The water pump isn't leaking and doesn't' seem to have any slop or movement. If I put the heater on full when the car is hot it's so hot it burns your feet so there is definitely a problem of some sort.

Thoughts, I am concerned that the temp sensor on the block might be naffed and causing issues by not regulating the fans properly... at around the same time my external oil temp guage started reading 120 all the time which means either the sender has died or gotten disconnected or I have serious engine issues.

what else can I look at here that I have not already checked out? It's pushing two litres of coolant out the overflow every time I go for a decent length drive so it's driving me nuts.

cheers

Frank

I'd check the thermostat operation by putting it in a pot on the stove and using a thermometer to check what temp it opens at. The next thing I'd be looking at is the radiator. When the engine is hot, can you feel the coolant circulating through the top hose? Might need a rag to insulate your hand.

I replaced the thermostat with a brand new one.. no change.. both hoses top and bottom are hot and seem to be flowing.

I got an improvement in that it isn't losing coolant like before by changing the radiator cap.. the old one was letting pressurized coolant out the overflow too easily... but it's still running hotter than before.. gauge sits exactly between quarter and half but the engine even smells hotter now.

Gonna buy an aftermarket electronic temp guage and sender.. see what is really happening. It's peeving me because I've basically replaced the entire cooling system now.

Mothers wagon sits between 1/4 and half never smells hot tho. my xr6t used to sit on pretty much 1/4 all the time, i add a extra hole in the housing to help with air bleeding as well as remove the little brass pip from the thermostat. not sure if thats any help to you at all.

Good to know. I'm still looking for a problem first.. I'll worry about improving things later.. the fact that I'm no longer losing coolant is a good thing.

I've seen the odd new thermostat that didn't open fully or were incorrectly marked. But, it looks like you're on the right track with the testing, or replacing, the temp sensor for the fans.

the spring in the bottom hose is a good idea..
as silicone is ok for positive pressure ie boost
but for vacum ie in sucking the coolant up from the bottom of the radiator to the water pump not so good..

have you checked if that bottom hose collapse's with rpm?

It sounds like to me your old thermostat was opening well below the temp it should have, that's why your gauge was low, and your cap was not holding pressure. You put a new thermostat in, which is fully open at 103 deg, now your gauge is showing near half and your low speed fan will come on at 100 deg. Now your not loosing coolant with the new cap, get your self a temp gun so you can check the temp of the whole cooling system and check and make sure the high speed fan comes on with the air con and high temp.

yep, that's pretty much exactly what I figured. I already have a temp gun and I've also ordered an electronic coolant temp gauge and sender so I have permanent monitoring.

Oddly the old thermostat was only a year old itself and it looks fine.