Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Coventry Climax oil pressure valve

I remember reading some history of the Coventry Climax engines a long time ago. The design was as a fire brigade water pump engine which had to be light enough to be carried in a cradle, and capable of being started and run at maximum rpm from cold. So the design was quite loosely put together, such as the fit of the pistons in the bores, which caused oil consumption - not important on a fire pump engine. I guess that the oil pressure relief system was also designed with that in mind.

Dave that was the later FW engine as you say used in fire pumps. Later modified versions being used for racing in the 50s and 60s.
Coventry Climax stopped making the IOE around 1938 but it was continued to be manufactured under licence by Triumph. I think that's the reason Morgan switched to Standard.
If Morgan had switched to the FW that could have been interesting.

There is some data on the Coventry Climax engine on Morganatica that you might be interested in .

Try https://sites.google.com/site/morganatica/engine/coventry-climax

Good stuff Andy G

Simon, what was the grade of the oil you're using - are you getting the same problem with straight 40 oil too?

Do the oil pressure problems seem to be temperature related? My cold and warm oil pressure was fine (1938 Coventry Climax), but I was getting quite a lot of fluctuation when hot, until I realised the coolant level was slightly low so wasn't thermosyphoning correctly so was probably getting a bit too hot.

I also checked the ball valve on the side of the pump for contamination and pitting but it seemed fine; I'm going to have a look for the other one now!

I don't see any reason to bleed the gauge.

I used to use 20/50 but changed to Castrol R 30 after a rebuild. On start up from cold the pressure would be high and lower when the engine was hot. The gauge would fluctuate with engine revs with both oils. If the radiator was low on water then the temp gauge would read low but didn't make much if any difference to oil pressure.