Overheating Issue! - MG-Rover.org Forums
 
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post #1 of 7 (permalink) Old 04-03-2014, 15:39 Thread Starter
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Overheating Issue!

Hello!

Well I have had an absolute nightmare. Last night at 7pm I set of for Scotland yesterday to go on my holidays! Got just past Lancaster and the heater went dead cold, I glanced across to my temp gauge and it was just hitting the red. looked in my rear view and steam was everywhere. Hazards went on and ignition went straight off!

Called green flag and they were straight out to me (they were excellent - A company called Macadams Rescue!) The guy looked at my F and instantly said HGF. I suppose this is the reputation our cars have.

So we filled it back up with water and drove down to the next junction. Exactly the same thing happened. Loads of steam and the temp guage rocketing to red! So I pulled over and the guy sorted out recovery back home to brum. So much for being on holiday. Finally got back about half 4 this morning and got some sleep.

This morning I walked down to Metroman and picked up a pressure expansion tank cap. Put this on to replace the old one. FIlled it back up with water and coolant and ran it for a good hour. It did overheat but not as bad and would go down when the heater was on. Im thinking this is airlocks. Turned it off and left it a while. Checked coolant level again and started it up. No overheating.

Ive taken it for a good run and left it another 20 mins running. No overheating so im thinking it was the cap. Is there anything else I should just double check? I have never heard the rad fan kick in but did notice a blip in revs as if the fan was kicking in, I just couldn't see or hear it! Also the engine bay fan wasn't working??

Im pleased its not overheating anymore. I just thought id let everyone know what had happened to see what people say.

Thanks
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post #2 of 7 (permalink) Old 04-03-2014, 15:49
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All you can do at this stage is bleed the system at the usual 3 points,rad top, heater bleed nipple and the screw on engine then give it a run. it is possible that one of the jiggle valves is stuck or worse case has a small leak past the fire ring on the head gasket, a run over 30miles it would show up with air in system again,ticking over in my experience for 3hours doesn't allways show up, a sniff test would allso diagnose the same but not allways accurate in my experience. A hgf doesn't allways give water oil mix. Hope your lucky and have no hgf but its not difficult or too expensive if it is.
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post #3 of 7 (permalink) Old 04-03-2014, 21:57
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Sounds very similar to my old freelander and it was the jiggle valve sticking! Cleaned it and it stuck again. Cleaned again and same thing so in the end knocked it out and it ran perfect!
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post #4 of 7 (permalink) Old 04-03-2014, 23:16 Thread Starter
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Thanks for advice. How do you clean the jiggle valve? Why does it stick?
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post #5 of 7 (permalink) Old 05-03-2014, 07:25
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It seems it's common to remove the daft jiggle valve when replacing a head gasket or inlet gasket.
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post #6 of 7 (permalink) Old 05-03-2014, 09:24
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The jiggle valve is just a small tube with a ball bearing trapped in it. The ball bearing is free to move and restricts the flow of coolant whilst allowing air to travel freely.
The problem is that old radweld and other gunk block up the valve which means that the air cannot get to the header tank and is forced further round the system causing air locks and potential overheating.

It can be cleaned when the inlet manifold is removed. Try using interdental brushes, cotton buds or anything that will get rid of the crud. Clean all the other coolant galleries that you can reach at the same time - including the hoses.

As Plezier says, many people remove the ball bearing altogether. I am not sure of the long term negative effects of this but it seems to work for many.
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post #7 of 7 (permalink) Old 05-03-2014, 09:35
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Replace rad fan under bonnet with 20 amp (from memory)

Once car is up to temp check rad under bonnet is actually hot..

Ie.. Proves stat is opening
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