Got a phone call from a new MGB owner with an oil pressure problem. He says at start up the gauge reads 40# and once warm drops to 0#, but no engine rattles with 0 on the gauge. My responce was to try a differant gauge or sending unit, if it was really 0# the engine would rattle like crazy. It's a 78 and I think that year has an electric gauge? Anyone else had this problem or have any other ideas?

Hi wdp

As a first suggestion, have him watch the youtube, university motors video's and get John Twist's versions of the MGB oil pressure scenario's.
Below is the mgb one
http://www.youtube.com/watch?v=a7mVVvWnR34

Below is one on an MGA in which he explains the oil pump etc.
http://www.youtube.com/watch?v=YcBTTjLEvAg

I have found these of great help and encouragement.

Mark

My 78B came with mechanical gauge ....

Have him check to be sure that the rubber hose under the hood connecting from block to the line running to the gauge is in good shape. Also, be sure that the connection at the gauge is snug. You might inquire as to whether it is dripping oil on his leg.
There is a leather washer on the connection at the gauge best I recall.

Then like you say ... try a known good gauge.

Has any work been done on the engine? Is it possible the rubber hose is connected to the wrong spot on the block? I saw that on a B one time which resulted in very low readings on the gauge.

Or has filter been replaced and is possibly too short and blocking the internal tube?

Last thought - does it have proper amount of oil in it?

Just my .02 worth !

Don't know about the 78, but the 79 I had came with an electrical gage. If it has an electric gage, pull the sending unit and check it with any mechanical gage. If it's ok, install a new sender. What ever you do, make sure it's not internal! 40 psi at start up is low in my opinion. Is he using 20/50 oil?