Low oil pressure

suffolkpete

suffolkpete

Member
The head gasket on my 2200SC blew recently. I replaced it and at the same time decided to renew the piston rings. On starting it I found the oil pressure is much lower than before, it used to be a solid 60 psi but now it's between 40 and 50 and when the engine is revved it rises slightly then drops back to a lower value than when it was idling. I replaced the big-end shells after this occurred but it made no difference whatever. Any ideas?
 
The gauge is a mechanical one with a capillary tube. Since it wasn't disturbed when I did the work, I can't see any reason to suspect it. The other thing I've found is that I can't get any oil pressure turning the engine over on the starter with the plugs out, although the light goes out immediately when I start the engine.
 
The 4 pot light sender puts the light on when the pressure falls to about the mid-20s psi IIRC so I wouldn't be overly concerned that the light won't go out when cranking. Replacing the big end shells won't do as much for the oil pressure as replacing the mains shells will. Is the bottom chain noisy at idle, and have you changed the oil since changing the head gasket?
 
Yes, I've changed the oil and the filter and there is slight noise from the lower chain at idle, but the engine doesn't seem to have any other untoward noises. The big ends and mains were changed previously about 20,000 miles ago and the big ends looked serviceable when I changed them since the the trouble started, but I did it as a precaution in case I damaged them when I put them back after doing the rings. I didn't touch the mains this time, so they should be all right unless the contamination of the oil by water damaged them. I can't help thinking it's something I've done, or failed to do but I've done these jobs before without problems.
 
I don't doubt that the lower pressure you've seen is genuine, I think you may be overthinking it and worrying unnecessarily. If you wanted to do something, I'd suggest dropping the sump and checking the mains shells in the caps, as they are the ones that take most of the load.
 
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