Magna TL 2004, 250,000Kms:
I have recently had some issues with temperature - broken radiator fan (the bigger one, now replaced) and broken radiator cap (now replaced).

The temperature gauge shows I get spikes (up to 3/4 on the dial) in temperature until the smaller fan kicks in. The temp then drops to about half way. Over time, after a couple of hours it slowly heats up more and more until I switch off to let it cool.

It used to be that the gauge would always sit at the halfway mark.

I have checked for white residue on the oil cap and there's none. The coolant *looks* fine (but I'm not sure if I'd be able to tell) and the oil looks fine.

When I run the engine with the radiator cap off and rev the engine, coolant gushes out. Lots of it. I gather the opposite is supposed to happen - it's supposed to be sucked in.

If it's a head gasket, what other symptoms would confirm?

Could it be the water pump or trapped air in the system?

Also, my driveway is on a slight incline - only about 2-3 degrees. Would it matter which way the car is pointing?

Thanks in advance for any help!

well for starters when you runningvur egine coolent in the radiator will become hot and under pressure, if u notice under the cap there is a spring with a plug type set up. this is to allow the pressurised coolant to push up and flow out into the overflow bottle. if your having heating issues i would suggest u look into yoi thermostat. head gaskets symtons include signs of oil/coolant leak around the block, white smoke out ur exhaust continous, milky oil, hard to start....

if it was ur water pump there would be no movement in your radoator and when you feel the top hose to see if coolant is returning to radiator u would find its cold. is your coolant level dropping after u go gor a drive. a bad water pump should cause the car to overheat and if the seal has failed there should be coolant leak visable under the car

may also be a clogged radiator as no coolant should not overflow when you first start ur car

may also be a clogged radiator as no coolant should not overflow when you first start ur car

Thanks for your comments. It only overflows when I rev the engine. I mentioned the radiator cap broke. The rubber seal and possibly other fragments (part of the release mechanism) may well have found their way into the radiator....

I don't have a lot of equipment for testing etc. Maybe I should just replace the radiator anyway seeing it's done 250,000Kms.

BTW, I am not losing any coolant.

So you confirm that no coolant is being lost? That rules out water pump leaking.

No milky residue in the oil or foamy stuff in the coolant? Doesn't rule out head gasket. The gaskets are metal type so they very rarely crack. What happens instead is that the heads warp. The only sure-fire way to check is to do a compression test on all 6 cylinders.

Next is the thermostat. Thermostats often break in these cooling systems. Check that the thermostat opens and closes at the appropriate times. This is where I would bet your issue is coming from.

So, considering you have diagnostic equipment, check the thermo and do a comp test. if both come up good, you have a blocked radiator. Get a new one or grab one from a wrecker.

when u first start the car does the coolant overflow..... or is it only after it warms up? basically coolant shouldnt overflow when the engine is cold

Check that the thermostat opens and closes at the appropriate times.

I said I do *not* have testing equipment, unfortunately. Is there any way I can check the thermostat without special equipment? I do know the big fan comes on when the temp gauge hits 50% and the small fan kicks in at 75%. I don't know if they are controlled by the (same) thermostat you are referring to.


when u first start the car does the coolant overflow..... or is it only after it warms up? basically coolant shouldnt overflow when the engine is cold
No, it never overflows unless I rev the engine. Only then does it overflow. And the engine is not very hot right then.

Also, the car is otherwise running well. No loss of power.

Sorry mate misread that.

Take the thermostat off the car. Chuck it in a pot of water. Cook the thermostat. If it opens at 88 degrees or so (just before it starts to simmer), it works, if it doesn't then it's buggered, get a new one. (Don't cook it all day, just till it boils and you get a reading)

thats not a bad idea, defiently keep that one in mind

Thanks guys. @dreggzy - I haven't had a chance to do the thermostat test, and I'm really thinking I might get my local mechanic to do that - even though that multi tasking recipe looked delicious! :happy: I don't know why you took it down.

Anyway, here's one more question. Does the image below look right in terms of how a brand new TL radiator cap should look?

http://s9.postimage.org/bb2h8mn57/Radiator_cap.jpg (http://postimage.org/image/bb2h8mn57/)

It has "16psi / 110 KPA" written on the top.

When I warped the head on my ex-magna the mechanic, who also does radiators, used a liquid carbon monoxide tester on the radiator to check for head warping. The liquid changes colour if it's detected. You may be able to get one at a Supercheap or similar though I'm not sure, may be cheaper just to go get it tested by your mechanic.

Good luck!