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Matt, Mechanical Engineer
Category: Jaguar
Satisfied Customers: 22255
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Hi, I have a s3 v12 e type in the workshop suffering from an

Customer Question

Hi, I have a s3 v12 e type in the workshop suffering from an excess of pressure in the cooling system.
The cooling system has been drained and refilled using a vacuum refill tool in order to eliminate any air lock.
Both thermostat s are opening at 82○c and there is even heat distribution throughout the radiator.
A cylinder leakage test shows nothing and neither does a test for combustion gases in coolant.
With a pressure gauge on the cooling system, warming the engine from cold, by the time the thermostat s are fully open ( 92°c) the pressure is showing 17 psi.
Any thoughts.

Regards Andy.
Submitted: 3 years ago.
Category: Jaguar
Expert:  Matt replied 3 years ago.
Hello Andy

if you haven't already then I'd replace the header tank filler cap as these are supposed to vent off at 14-15 psi

I' d also check that the small bore hoses that run back to the header tank are free flowing and not blocked
Customer: replied 3 years ago.

Cap has already been replaced and pipes are clear.

Expert:  Matt replied 3 years ago.
Hello Andy

in that case air must be pulled in somehow as the coolant circulates

usually the chief culprit is a faulty water pump seal that will allow air in but not water out

I'd also double check all the hose clips before fitting a new pump though

Matt and other Jaguar Specialists are ready to help you
Customer: replied 3 years ago.

Hi mat

I replaced water pump and all hoses.

Problem solved. Thanks


Expert:  Matt replied 3 years ago.

Glad you got it sorted