Engine Radiator "Burst"

[Lotus26R]

We have a '98 2.5 Boxster that suddenly developed an engine coolant leak. Investigation reveals that one of the radiators has "burst" - looks like the internal pressure got too high. Question, is the filler cap (mine is blue) solid or is it supposed to have a pressure relief function? If solid, is there pressure relief elsewhere in the system please?

[RFM]

Yes the filler cap have a pressure relief function.

[Lotus26R]

Thanks RFM - seemed that it should. Now I just need to work out how the pressure got high enough to burst the rad.

[berty987]

Are you sure it burst ? All 911 and boxsters suffer radiator corrosion from leaves and debris building up on the bottom part of the rad. Could it be it simply rotted through to a point where the rad popped ?

[jcorallo]

As mentioned above, the front rads on these cars collect leaves which rot leading to leaks.

If you are worried about over-pressure, yes check the coolant cap, but also get the air in the coolant header tank 'sniffed' to test for cylinder head gasket leaks (after the engine has been run for a bit).

On my old VW Golf VR6, the heater matrix deep in the dash blew apart (fun - not) because the head gasket had gone and was forcing combustion pressure into the cooling circuit.

Jules