BMC 1.5 engine coolant pressure cap

[SimonA]

My BMC 1.5 has been leaking coolant from the overflow pipe when the revs are above 2000rpm. Yesterday I nipped into the chandlers and picked up a new pressure cap but the only one I could get was rated at 13psi which i think might be too high for the BMC? It has stopped coolant leaking from the overflow. The old one was rated at 7psi.

I am risking damage by running with the 13psi pressure cap?

 

[nedmin]

My father used to have a 1954 Morris Oxford (petrol) which is basically the same engine as the BMC 1.5 Diesel.They were that well made that they were able to make the petrol engine into a diesel.The workshop manual doesn't give the thermostat relief pressure but would have thought that a decent motor factors might be able to tell you what one is suitable. Its based on the old "B" series engine.

 

[The Dogs Pollacks Brother]

Not sure of the risk, but check out asap as they usualy stock a few.

 

[sailorman]

could also be a head gasket blowing & over pressurizing the cooling system

 

[vyv_cox]

I believe the main reason for an increase in cap pressure is to enable the engine to run hotter without boiling, in conjunction with a higher rated thermostat. In your case I am guessing that you have not changed the thermostat, so the temperature will remain the same. I doubt very much that there is anything on the coolant system that will fail at 13 psi but survive reliably at 7 psi.

 

[30boat]

I don't think there will be any problems if you increase the pressure in your engine.14 psi is not a lot.

 

[Lakesailor]

The question is "Why was the old cap leaking?"
Had the spring weakened? Had the seal hardened? Have you a head gasket failure?

 

[TQA]

Well in moving from 7 psi to 14 psi you are doubling the internal pressure on all your primary coolant circulation components.

In good condition they would all cope just fine but the extra pressure will expose any weak hoses or suspect joints.

Have a very careful look at system when it gets up to operating temp.