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523 Random Overheat!!!! Please help!!!

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4.1K views 5 replies 4 participants last post by  westbay1000  
W
#1 ·
Ok, when idling/or in traffic it will rise and rise, but when I drive away it will fall, sometimes virtually straight away to normal temp and sometimes slowly back to normal temp, then as soon as I stop again it will start to creep up.

Oil is not creamy, Oil cap has no sludge, no bubbles in expansions tank and car drives like a dream - so presumably not head gasket.

Thought it might be the fan clutch, but when cold, the blades are how they should be - turning like in a thick syrup. Not ceased and not freewheeling.

Could it be the thermostat?
I was always under the impression that if these went wrong the temperature would never fall.

Thanks for your help!
 
R
#2 ·
I have exactly the same problem and I have taken it to 2 garages who really have not had a clue what is causing it. However, it has recently got worse leading to a severe overheat and a radiator leak. I must now find the cause before I can mend and use the car again.

Some threads here and on other sites suggest various possible reasons. These include water pump impeller breaking, head gasket leak, poor thermostat or viscose fan coupling.

I too would appreciate any help and any links to instructions for replacing water pump and also for do head gasket.

Cheers,

Roger.
 
W
#3 ·
Roger I feel such an idiot now!!!

Obviously someone suggested has it got enought water?
When I took the cap off yesterday while the engine was warm it looked like the expansion tank was full to the brim.
I've gone back to it this morning when cold and found the expansion tank was virtually empty (I hadn't checked the water level since I bought it 4 months ago!)

I've topped it up and found everything is now fine!!!!

I don't know if you've tried anything as obvious as this! I thought I was sort of car savvy, but obviously not lol!
 
R
#5 ·
Same Problem

Roger, I had the same issue with overheating at low rpms. The temp guage would rise until I held over 3000 rpms for 30 seconds or longer. The stealership and INDY had no explanation and replaced the thermostat twice with no lasting effect. The third shop immediatley recognized this problem and replaced the "Heater Valve/AUX, Water Pump" and fixed the problem. It was sticking closed at low pressure and not letting the coolant circulate. I don't have the knowedge yet to explain what that part exactly does, but the new one fixed the problem. I'll be happy to pass along the number of the shop if you'd like a better explanation from them.
 
W
#6 ·
Its definately air!!!

Although originally I said the expansion tank was empty - well it only looked like that!!! after turning the bleed screw on the expansion tank it filled right up ... so I hadn't lost water after all.
It was fine again until last week...I've bled the system once and it's better but not perfect so i'm going to attempt it again!
 
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