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XFlow cooling


Crumpynut

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My flow suddenly overheated about 45 minutes into a spirited blat last year and has continued doing so ever since.

I have done all the usual flushed the engine and rad (almost new anyway) replaced the stat, pretty sure there is no air in the system but still after half an hour or so the system vents through the expansion cap leading to it overeheating.

Prior to this it generally sits around 80 on the gauge and fan kicks in as normal around 90.

Not checked or changed the sender but seems academic as new ors sure cap and stat should be doing their stuff without electrics!

Running with no stat seems to keep it under control but is not a great solution especially in winter.

Driven gently all is fine but then if I wanted to drive gently I'd have a Nissan micra.

Any helpful suggestions gratefully received.

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I would think that the thermostat was playing up.

 

You might be able to check by holding the top & bottom rad hoses as the engine is heating up. I seem to remember that x/flows like a 83deg stat? Especially if it is a tuned engine.

 

Jonathan

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If the coolant is venting through the cap before getting to too high a temp, and then overheating, I would think the cap is suspect?

 

This happens a lot on K-Series, with their crappy plastic caps (did it on my Elise a while back). New cap sorted it.

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Crossflow HG failure used to be very common. Since the quality of the gaskets has improved so the number of failures has dropped. If it is the gasket don't use a Ford one, ring Burtonpower and get one of the Cometic or Ajusa ones. £50-£100, but provided your head and block are flat its unlikely to trouble you again.

 

As others have said moving to a header tank sealed system works really well on a crossflow. Plenty in the archive about this and lots of us have done it *thumbup*

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Just to add that it is normal on a Crossflow to find an apparent 'blow' between nos 2 & 3, usually manifesting itself as a darkened area. This does not usually mean that there is an actual failure but a lot of people make that assumption. I've always felt it was caused by the design of the head given uneven clamping forces over the face. To back this up, a BDA with exactly the same block and gasket will not show this symptom.
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A couple of thoughts before taking the head off, have you checked the hoses, I have known them to de-laminate on the inside blocking some of the flow. Also it is not unknown for the pump to fail or damage the impeller. Both these are rare though.

 

 

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Thanks everyone, sounds like the head gasket is the most likely culprit, although this would not explain why it did not happen when running without a stat.

Am away this weekend so can't test again without a stat.

If it's OK without a stat, I would assume the head gasket is OK. Last time I had the head off and changed the gasket it was the standard issue item from Red Line so based on other comments could well be the culprit.

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