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MG MGB Technical - Oil Pressure Help

I just started my engine after a rebuild which was completed about 5 years ago. I seem to have little to no oil pressure. I have read through the archives and see that priming the pump from the oil filter tube gets you started.I did that but my question is shoud there not be lots of oil into the rocker cover after running for a few seconds? Also I removed the oil filter line and started the engine and only get some air out, I expected the oil to shoot across the shop. I also read that the wrong gasket may cause this but since I purchased the oil pump with the gasket I would assume that the proper gasket was given. I may have no choice but to remove the pan but I just thought I would give it a last ditch effort and see if anyone has any better ideas. BTW my car is a 70 B.

Thanks Joe
Jh Clark

Don't assume. If you did indeed get the 3 main bearing gasket you will never get any oil to pump up. RAY
RAY

Joe if the engine has sat a long time and never been started the pump will be dry so. Put an extra gallon of oil, and I mean a gal, in the sump, enough so the pump is under the oil and try again with the plugs out. This is the safest way to do it as the high oil level will cause the crank to throw oil every were helping avoid damage from oil starvation and the pump will prime. If you dont get oil pressure then follow Rays advice. You could disconnect the oil gauge to get a quick idea of your success. Dont forget to get the extra oil out as soon as you can as over time it could cause problems. Dont run the engine with the extra oil.
Denis
Denis4

Joe,

If the gasket you got with the pump was right for the pump, you may have the wrong oil pump.

This was the case with a BGT I bought once. I believe, though I have not verified, that the 3-main bearing engine uses a pump about 1/2 inch shorter. At least that is what was in mine. This allows the pump gear to just barely cam. Then if the engine kicks backwards, it can lift the drive shaft out of the pump and the oil pressure goes to zero.

Charley
C R Huff

I had this exact problem and it was the gasket between the oil pump and engine. The gaskets are very similar but make all the difference!
Ian Jackson

Thanks everyone for your help I tried the tip from Denis about the extra gal. of oil and still no pressure, so I guess it's off with the pan. I'm hoping this can be accomplised with the engine installed without too much trouble.
Joe
Jh Clark

Joe,

Yes, you can pull the pan with the engine in place. You may need to release one or both engine mounts to raise the front of the engine a bit to get to the bolts on the front if the pan. You can remove the engine mount bolts, jack the engine up a bit, and stick wood in between the mounts and mount point to keep it up enough to reach the bolts.

After you pull the pan, and before you pull the pump, look with a flashlight to see if the drive shaft for the oil pump has extra space above it where it rides in the block. In other words, is it possible for the pump drive shaft to move upwards into its bore in the block? Also, look at the engagement of the cam/pump gears to see if they look centered. It is possible that you have the wrong pump.

Charley
C R Huff

Thanks Charley, I'll be sure to check that. I will let you know how it turns out in a couple of days.

Joe
Jh Clark

On the removal of the sump, i managed to take mine off without raising the engine at all, and hence leaving engine mounts etc in place. The front 4 or so sump bolts were tricky but it is possible, I used a modified 7/16" ring spanner for the front bolts with the ring end ground down to aid access. Good luck....

Ian
Ian Jackson

I would have to disagree, very strongly, with the concept of adding and extra gallon of oil to the system, then starting/trying to start the engine. This is twice the system capacity and would raise the level of the oil to the point where the crankshaft would be hitting oil each time it rotates.

Most people, when young, have done a "belly flopper" into the swimming pool. We quit doing it because it hurts. Water is incompressible and, when struck with a large, flat object does not easily part to allow that object to pass into it or through it. Excessive oil in the sump acts exactly like this. The crankshaft is doing a series of belly flops into the excessive oil. Yes, it will spray oil all over the place. It also has the potential to damage the crankshaft, connecting rods and the bearings associated with each.

Not a good idea.

Les
Les Bengtson

Thanks all for your comments and help, I dropped the pan this morning and sure enough the wrong gasket was in place. Changed the gasket reassembled and I now have oil pressure, not sure yet how much because the dash is out and the gauge is disconnected but there is oil throughout the engine while cranking.
Joe
Jh Clark

Some 35 years ago, I took the oil pressure fitting into an auto parts shop and they built up a positive reading pressure gauge for me. A gauge that reads up to 80 or 100 psi, a foot long piece of high pressure rubber hose with fittings to fit the gauge at one end and the oil pressure take off on the other. Very useful over the years. I would never run an engine that I did not have a pressure gauge attached to. Especially, an expensive, newly rebuilt one.

Les
Les Bengtson

This thread was discussed between 05/06/2009 and 10/06/2009

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