Morris Minor Forum

Hi… I am running out of ideas and wonder if anyone else has seen the same problem! I have a 1952 Minor, I’ve had it for 45 years, currently with a 948cc gold seal engine. The problem is when I park the car, engine off, the oil seems to run back to the sump from the oil pump. So when I restart it takes a little while for the pump to pick up the oil and circulate through the engine. Now I’m turning the engine with the starter but without the ignition being on until I see oil pressure only then will I allow it to start. At that time the pressure is good until I stop the engine and let I sit for a while.I’ve checked the pick up pipe isn’t drawing air, I’ve replaced the pressure spring, valve and copper washer I’ve also changed to a spin on filter but makes no difference. All I can think is the oil pump or the oil pump gasket. My next step would be to take the engine out replace the pump and check all the metal bearings that is unless anybody can suggest another course of action!
Thanks John Newcastle Co Down N. Ireland

Hi John - I am not sure if you have fixed this yet - Have a look at the oil pressure return valve and spring as it may have jammed. This is located on the side of the engine block and is close to the backing plate.
James (NZ)

James hi…. Thanks for your reply and for your thoughts. I did get a kit, a new spring, I think a ball bearing (to replace the valve) and new large copper washer but it made no difference. Back in the day on the old Minis we use to give the spring a little stretch to increase the oil pressure, I’m not sure if it really worked! I think I’ll end up taking the engine out and replacing the pump I have the notion it could be the oil pump gasket. It may be a good opportunity to replace the clutch and see what damage unleaded and e10 petrol is doing.
Thanks for your help…. John

Have you tested the actual oil pressure with engine running ? that would be the first thing to try..you should have +/- 50lbs of oil pressure at operating temp above 2,000 rpms... if it does not make the cut, most likely issue is a problem with the oil pump.. could be not fully tight or the gasket may be comprimised.. there is an oil plug on left hand side of the engine block right on the oil galley just ahead of the pump ..can be used to prime the oil pump on an engine that has been sitting awhile . If the pump is bleeding out, you can confirm by removing the plug, filling the oil gallery with a suitable oiling can, quickly replacing the plug and then immediately starting the engine.. if it has oil pressure right away the issue is likely pump related.. the early 948 pumps were 'vane' type and do not prime as effectively as the later hoborn -eaton rotor type pumps... general wear ( especially in main bearings) will also cause the oil to drain out of the galleries into the sump.. I have a very high mileage '67 with 1098cc engine and it takes +/-30 seconds to build up oil pressure if the car has sat for more than 48 hours.. the issue in this car that the whole engine is worn out..

Timothy…. Hi. I have primed the pump by removing the banjo type bolt from the pipe on the top of the oil filter housing threaded in to the block gallery at the back of the pump. I fill the pump by squirting oil in to the block while turning the engine in reverse. When all is connected up again there is instant oil pressure .. +60- this will be lost when the engine is off. I haven’t accurately tested the pressure my readings come from the factory Smith’s dashboard gauge but I know by the tone of the engine the instant oil is picked up by the pump when spinning the engine on the starter motor. The engine was bought by me many years ago as an unused BMC Gold Seal. To check I removed the head and the sump and looked at the pistons and bores, I believe it hadn’t been run. I took off some of the big end caps and everything was reworked perfect. The head wasn’t replaced but swapped for an unleaded converted item.
The more I write about this in the hope I have missed something very basic the more I convince myself that I need to strip the engine and check all the bearings and bores. Change the oil pump as a matter of course bearing in mind that turning an oil pump when it’s dry will damage it.
The car is only used for a few months each year, when it’s dry, when the sun shines and when there’s no salt on the roads that’s a small window in this country but when it is used it’s a pleasure to drive. It would be pity to take it apart and not find the problem… John

John.. BMC 'gold seal' units were built to high standard ( often they were in fact 'new' engines)..minimally had many new parts such as cylinder head and crankshaft.. but depending on date of build you may well have a vane type oil pump.. ( I believe the switch over point was early in '61) 60 PSI is healthy pressure if it holds at full operating temp..I'd check 3 things ;- (1) pick up pipe in sump.. make sure the gland nut where it bolts to block is tight, and inspect for any defects ( cracks etc in tube) ..if that does not reveal anything then (2) remove flywheel,back plate and oil pump.. check that the 3 retaining bolts are tight, and for any defects in gasket.. (3) if all else comes up good.. take the pump apart and check what type it is.. if it's a 'vane' pump, then ditch it and go with a burman/ hoborn-eaton rotary pump..( which superceded the old design and is all that is available now.) I'd not mess with bearings, given you already checked them, but if unsure, pull the centre main cap and if the lower shell bearing is good, (centre main commonly 1st to show wear) it should follow they are all good given the pressure reading and the fact you already checked it out .. BTW.. it takes +/- 10 psi for oil light to go out.. 6-8 revolutions at starter speed should provide that pressure..
You could of course just carry on as is and not fret about it.. seems you have good oil pressure..

Timothy hi. Thanks for all your information, I agree with all that you state. When I say that I have oil pressure +60- that is on start up and would probably drop to 30/35 on a run. A while ago I had removed the sump (with the engine in place) to check the strainer and the lift pipe and all seemed clean and tight however a tiny crack would be harder to find. I think it must absolutely be an air leak somewhere in the system. I did not touch the oil pump at the time I put the engine in as BMC would have replaced it routinely I’m sure that was the case in both Silver and Gold engines. I have a replacement oil pump from Mini Sport with gaskets and locking kit ready to go, I’ll give the whole engine “a good look at”
Thanks again
John

John..if your oil pressure is dropping +/- 30lbs between cold and operating temp, then you would be wise to re-check the bearings ..again..pull the centre main cap .. if the lower shell is comprimised you may need to dig deeper..