Thread: Radiator caps

Both GEMS & Thor engines share the same cap (ESR1480) so maybe one has had a different spec cap fitted at one stage.
Fitting a higher pressure cap is a risk though as the extra pressure might make something expensive the fuse.

Factory spec is 1.0bar or 15psi.

Just checked on mine and there isnt a number on the cap...so cant help you

Originally Posted by Scouse

Both GEMS & Thor engines share the same cap (ESR1480) so maybe one has had a different spec cap fitted at one stage.
Fitting a higher pressure cap is a risk though as the extra pressure might make something expensive the fuse.

Factory spec is 1.0bar or 15psi.

Scouse, sorry to disagree with you but according to the RAVE manual:

The tank is fitted with a sealed pressure cap. The cap
contains a pressure relief valve which opens to allow
excessive pressure and coolant to vent through the
overflow pipe. The relief valve opens at a pressure of

1.4 bar (20 lbf.in) and above.

Gary

Have a close look at your cap, there should be two o rings, see attached photo of my old and new caps. On the left is the new one with both seals present, on the right is the old one, you can see the end has preished with heat and age, allowing the o ring fall into the expansion tank. I was able to fish out the old o ring which was sitting in the tank. This could cause coolant loss, I'm sure both o rings are there for a reason.
Cheers, Pete.

Originally Posted by mtb_gary

Scouse, sorry to disagree with you but according to the RAVE manual:

The tank is fitted with a sealed pressure cap. The cap
contains a pressure relief valve which opens to allow
excessive pressure and coolant to vent through the
overflow pipe. The relief valve opens at a pressure of

1.4 bar (20 lbf.in) and above.

Gary

I'm quoting figures from TOPIx:

COOLING SYSTEM - V8 ENGINE

System type Pressurized, spill return, thermostatically controlled water and anti freeze mixture. Vertical flow radiator with remote header tank and pump assisted.

Cooling fan 9 blade axial flow. Viscous coupling.

Pump type Centrifugal, impeller, belt driven.

Thermostat opening
Up to 99MY 88 C 190 F
From 99MY 85.5 C 185.9 F

Expansion tank cap pressure (system pressure) 1.0 bar 15 lbf/in

Scouse

What if we split the difference and go with 1.2bar . BTW, I checked my cap this morning 140. I'm wondering if somewhere along the way a Land Rover tech bulletin may have changed recommended specification to 1.0 bar?

Gary

Thanks Peter, My cap looks the same as your old one and no sign of the first O ring. It too is marked 140.
Having a good look at the cap end and the top of the expansion tank I can't see how the O ring would be able to seal against the tank in any event. The O ring is too small a diameter to meet with the sides of the tank. I note these caps are used in a number of other vehicles e.g.BMW and maybe for a different set up although I admit I have no ides how the cap actually works when excessive pressure is applied so may have nothing to do with sealing against the side.

Originally Posted by mtb_gary

Scouse

What if we split the difference and go with 1.2bar . BTW, I checked my cap this morning 140. I'm wondering if somewhere along the way a Land Rover tech bulletin may have changed recommended specification to 1.0 bar?

Gary

I wonder which is right, 5psi difference is quite a bit.