p38 intermittent overheating

Hi
I've got a 1998 4.0se with an intermittent overheating problem. Works OK most of the time but occasionally overheats. When it does, the hoses are rock solid with the pressure. I can usually cool it back down when driving by having the heater on full blast. I've looked for the viscous fan check thread but can't find it. However I can stop the fan with a tightly rolled up newspaper but it takes a while to do it. Any ideas? Thanks

Datatek has an Aircon mod that will rule out the VC being at fault. Given it is a V8 more often than not it is the head gasket.

Couple of things a do you have any coolant loss prior to the overheating b does it run on gas

Hi
Seems to have a small amount of coolant loss, maybe half a pint every 300 miles or so. I've just converted it to gas so the systems brand new

My guess is that the coolant is being lost on the t pieces where it was spliced into the cooling system for the vapouriser once air gets in it will pressurise and lose more vicious circle. Make sure all the clips are on correctly and make sure the hpipe from top of rad to expansion tank isnt airlocked

When it pressurised first time did it go into the red ?

Caught it before it got to the red each time. I'm paranoid about it overheating so never take my eye off the temp gauge!

Viscous fan check is in EAS "How To" at top of page. Sounds like it is knackered change it.

wammers said:

Viscous fan check is in EAS "How To" at top of page. Sounds like it is knackered change it.

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+1, if you can stop the fan with a hot engine it's knackered.

Thanks for the replies.No external leaks at all. I've just picked up a new viscous coupling so I'll try that and let you know how it goes

timmy264 said:

Thanks for the replies.No external leaks at all. I've just picked up a new viscous coupling so I'll try that and let you know how it goes

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And add the aircon fans mod as back up for next time

how do you do the mod?? i've searched but can't find it!

timmy264 said:

how do you do the mod?? i've searched but can't find it!

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PM me with an email address and I will send you details. It's very simple to do

Thanks for that. Pm sent

Well,changed the viscous fan but still the same. Went to fit a new thermostat but found it was missing so someone's obviously had problems before I got it. Re filled the system. Water circulates and comes out of the 2mm return pipe but its not going through the rad. Hoses hot,rad cold so I suspect its blocked. A new water pump was fitted a few months ago. I'll order a genuine one on Monday. When its sorted I'll do the air con mod as a backup. Thanks datatek