help please temperature issues

Hi can anyone help please. My range rover p38 4.0 v8 temperature gauge keeps going from normal then shooting to the red. The car engine is not hot I can put my hand on it so engine isnt really hot. I've changed the temperature gauge and sensor. Also changed the radiator both thermostats and expantion tank cap also flushed the system and new coolent put in but still the same problem. I don't know if there is a air lock as there is no bleeder valve. Can anyone shed some light on this for me please or no the best way to bleed the cooling system. The cab heaters do get hot inside someone said something about a heater matrix or something. Any help would be really great full. The car stills pulls strong and goes well no smoke etc and not leaking any coolent but the radiator hose is building up a lot of presure. Thanks

I had the same thing after I replaced the expansion tank. It only stopped after slowly undoing the cap every time the gauge went into the red, only enough to get the coolant to fill the tank. I guess it had a air lock somewhere.

Sounds like your air locked alright you can fill from the rad top hose take the expansion cap off poke ur hose into the rad hose and fill once you got water coming out the expansion bottle and the top of the rad quickly connect the rad hose. Run it up and let the coolant level settle. Works for me.

I expect you have the common problem of an air lock in the stat easy fix is to drill a 3mm hole in the outer rim of the stat it doesn't have a wiggle pin like old style stats so traps air.

Sounds like an airlock somewhere, some P38s are easier to bleed than others, usual way is to park it facing up a hill, then carefully open the cap and 'burp' it. There are loads of threads on here - use the search facility.

Have you checked that the thin pipe from the top of the rad to the expansion tank is clear? - this lets any air at the top of the system bleed out into the tank. Blow it through.

Other than that, if it's pressurising and makes the hoses really hard, you may have a leaky head gasket. You could get a sniff test done which will identify exhaust gas in the coolant, or do a compression test.

Good luck.

PS - 2 thermostats ??? there's only one in a plastic body with about 4 hoses coming out of it, low down near the oil filter.

Unless you mean temp sensors, there are 2 of those . . .

Alastair

Thanks for all the advise guys I'll give it ago tomorrow on a hill. Should I drill a few holes in the thermosat that sits in the housing or just the one. Thanks

Woooo....2 threads....

Posted this on the other one....

Saint.V8 said:

Do a hydrocarbon sniff test on the coolant.....building pressure is either serious overheat, or combustion gases getting into the system!



From normal to into red is only a matter of 10-15 degC if not a tad more, it is not a linear gauge....



Best way to bleed system is to raise the side of the vehicle with the expansion tank on as much as possible (jack or ramp) to make the tank the highest point of the system, this way the air should rise to the tank.



Lots of coolant, burp the hoses and keep topping up the system....once done, leave to cool over night and re-check the level when cold.



I'd do a sniff test first to rule out combustion gasses in the coolant circuit...if that is clear, the overpressure must be due to overheat!

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Keep to one thread please!

switch on & load all electrics, lights, heaters, wipers etc etc if temp shoots back to normal its a fault with the becm (failing) had the same issue on a old p38 10 odd years ago

mania08 said:

Thanks for all the advise guys I'll give it ago tomorrow on a hill. Should I drill a few holes in the thermosat that sits in the housing or just the one. Thanks

Click to expand...

Just the 1 hole will do it

biketeacherdave said:

Just the 1 hole will do it

Click to expand...

Just make sure the hole is to the top in the housing.

Hole in stat works for the diesel....

The V8 stats are a plastic assembly mounted low down in the pipe work from the rad....difficult to drill holes in!

Saint.V8 said:

Hole in stat works for the diesel....

The V8 stats are a plastic assembly mounted low down in the pipe work from the rad....difficult to drill holes in!

Click to expand...

Had a few tipples by the time I posted, what's your excuse Dave?

Nobody has mentioned the viscous fan, check that it is locking up when hot.

Did this start suddenly or has it gradually developed? Some more history would help in the diagnosis . . .

A

Saint.V8 said:

Hole in stat works for the diesel....

The V8 stats are a plastic assembly mounted low down in the pipe work from the rad....difficult to drill holes in!

Click to expand...

difficult but not impossible iv done it to my spare stat thats sitting here ready to fit should i need to