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Radiator cap op. pressure

johnwager
Posts: 74
Joined: Thu Feb 11, 2016 3:26 pm
Location: Thundersley, Essex

Re: Radiator cap op. pressure

Post by johnwager »

Steve
I have always found that with the V8 saloon you need to let it find it's own water level, which is usually at the bottom of the horizontal fill tube.
If I ever fill over that,it always pushes the excess out, then settles and never goes down further.
The engine and radiator on that car holds a large volume of water(3 gallons), which needs room to expand.
I think you will find that even with a 9lb cap it will do the same thing.
If everything runs normally I would tend to leave it.
John

Flinty
Posts: 90
Joined: Mon Sep 24, 2018 7:34 pm
Location: Scarborough

Re: Radiator cap op. pressure

Post by Flinty »

Thank you John.
I have only just acquired the car which is an SP so I will take your advice and run it for a while and see what happens to the water level after the first spill.

Steve.

Vortex O'Plinth
Extra-Wise Man
Extra-Wise Man
Posts: 1065
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: Radiator cap op. pressure

Post by Vortex O'Plinth »

Flinty wrote: Thu Oct 18, 2018 3:23 pm Thank you John.
I have only just acquired the car which is an SP so I will take your advice and run it for a while and see what happens to the water level after the first spill.
SP's typically run with the coolant level just above the cross-pipe in the header tank. If the tank is filled to the top, the next time you check it will be down to that level again. The temptation is to refill the tank again and begin an ongoing cycle of refilling and re-losing coolant. It's worth checking to see if the level does stabilise just above the cross tube before doing any mods. If it settles below the tube there is the risk of drawing air into the system.
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

lioneleast
Posts: 33
Joined: Thu Feb 25, 2016 8:47 pm

Re: Radiator cap op. pressure

Post by lioneleast »

I always check the level when the engine is hot and never top it up when the engine is cold. In this way you don't need an expansion tank.

Regards,

Lionel

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