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MG MGB Technical - Seeking help for a friend

I have a friend who owns a '79 Spitfire (hold on, I know this is an MGB site) who's having some oil pressure problems.

Since there's not much activity on their site, I'd thought I'd seek help from you guys, based on the level of expertise and knowing no one here would leave someone stranded (even if his loyalities are elsewhere).

He told me that lately he's been getting an oil light on at operating temperatures (no gauge apparently) and at idle but the light is staying on even up to about 2000 rpm. Plenty of oil (20W50) and seems to do it more often right after a change.

Oil pump on its way out? Any one have an idea what pressure the light is set to come on at? Any ideas gratfully acknowledged and will be passed on to the owner.

Thanks
Simon
Simon Austin

Fill it with dirt, park it in the front yard and plant flowers in it.
R. L Carleen

Ahh...thanks. I think it'd be easier to move if it's parked first, then filled with dirt. LOL

Any other ideas? I tried to tell him about MG's but there's no reasoning with some people.
Simon Austin

Simon-
Post your request on the midget Technical board. Late model Midgets used the Pitfire engine, so the Midget owners should be able to give you plenty of worthwhile advice.
Steve S.

This may be a question for the Midget board as they use the same engine (1500). Usually an oil waring light comes on at about 5 PSI, too late to stop any damage.
they oil light comming on could indecate a number of things; one is main bearing shot; two the oil pump is worn; three if there is an oil pressure relive valve then that could also be shot (but I do not know if the 1500 engine has one). four blown head gasket (unlikely given that you do not say it uses oil between changes)
Cecil Kimber

I think the oil pressure light comes on at about 15 PSI.

First thing to check is the actual oil pressure by installing a mechanical gauge at the switch port on the engine. If the gauge shows good pressure then the switch is bad. (you may also want to try a new switch first as it may be cheaper than a pressure gauge, however you may just want to leave the gauge in place of the light) If the switch is not the problem then there may be an internal problem with the engine.

If I remember correctly the Spitfire engine has a rear thrust bearing that tends to wear and allow the crank to shift forward in the mains. You can tell this by watching the crankshaft pulley on a running engine as someone works the clutch pedal. If the thrust bearing is worn you should see the crank move in and out slightly with the clutch movement. If you catch the worn thrust bearing early enough it can be repaired with out damaging the main bearings. I believe it can be replaced with the engine in the car.

Other than that, a worn rocker shaft can lower oil pressure, and of course the oil pump cold be going. Then there's always the main, rod and cam bearings, but I thought I'd start on the cheap end.

Good luck.
Bill Boorse

I agree with Bill. The first step is to install a direct reading gauge and find out if this is an actual problem or a sending unit problem. (One assumes that, when there is a light, there is an electrical sending unit.)The recommendations by Steve S and Cecil are an excellent idea, especially if the check with a positive reading oil pressure gauge shows an actual problem existing. They have a good group on the Midget boards and they will help as they can. Les
Les Bengtson

Thanks guys, all good advice. I'll pass it on to my friend.

Cheers
Simon
Simon Austin

This thread was discussed between 09/07/2003 and 10/07/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.