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No oil pressure!

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DavidAGO

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Hello, I'm fairly new to the forums, but have been messing with British iron for 30 years. I have a 77B that I bought as an unfinished project. The engine had been rebuilt by the previous owner and reinstalled in the car in 1999. He did tell me he used engine lube on the bearings and cam. I pulled the head and the pistons looked new and the cylinder walls had a nice crosshatch pattern on them, so I assumed he knew what he was doing. I have been working on it the past several evenings, getting it cleaned up and back in working condition. I attempted to start it a few evenings ago, timing was way off, the Weber DCOE carb is not working correctly, but I did get it running, but roughly. After almost 30 seconds of running at a rough idle, the gauge was still registering no oil pressure. I drained the new looking oil and replaced with newer, and disconnected the oil pressure line at the T under the hood and connected a gauge directly to it, attempted to restart, and still no oil pressure.

My main question is could the pump have been installed without the drive gear in place, and if there is any way to determine if this has happened without pulling the engine? If the cam timing is off I can correct that without pulling the engine, but not so the oil pump.

Thanks for any advice

DavidAGO
 
Or, the pump is so dry it will not pull a vacuum.
Step one, remove all plugs and disable spark (just to be safe).
No plugs means no load on rod bearings.
Crank it for pressure with oil line and any adaptors removed, as in, a BIG HOLE, to reduce any possibility of restriction.
If you get oil, stop.
If no oil at 30 seconds, stop.

Plug oil fill, and any crankcase vents, rags work, apply air pressure to crankcase (you can use a rubber-tipped nozzle in the dipstick port), while cranking.
Make sure something leaks....i.e. don't seal the engine up or you might pop a gasket.
If you can regulate the air, 20PSI is enough.

Crank it whiule applying air until you get pressure.

What you are doing is applying air pressure to the top of the oil in the pan, cranking it so the pump is turning, with an open port for it to vent from.
If you don't get it in 30 seconds, you won't get it, and surgery is required.
 
He could have failed to install the oil pressure relief valve, or left the spring out.
Could have left the oil pump out, but you'd not see that without the pan off (I actually ran into that once on another marque).
Drive gear...who knows at this point....

You should be able to get the pan off in-situ, I used to have to re-ring and re-thrust MGB's in shops all the freaking time.
At that point you could drop the pump and look.....

This a 3-main or 5-main?

I'll have to look and see....is this one have the distributor mount to the upper end of the oil pump?

I've seen so many cars guts over the last 45 years, can't remember...
 
There are two oil pump gaskets supplied with most gasket sets.

It is possible that he installed the wrong gasket.
 
5 main, the oil pump is driven off the camshaft on the left side of engine, dist on right side. I can't remember where the dist is driven off of. I have rebuilt MGA engines, but it has been years.

DavidAGO
 
If you do the open-port, apply pressure and crank, and it works, the moron...oooops....PO just used motor oil on the pump and it all ran out.

And, you need to go no further.
Cheap, effective, and allows you to get on with what you're doing.
 
Most of the time its as Rick said, Wrong oil pump gasket. If its been running for 30 seconds without pressure your bottom end is probably toast.(bearings wiped out and lines on the crankshaft) If you lost oil pressure on a engine that had pressure then it would not be so bad at 30 seconds. But a engine built 11 years ago and not started probably had very little protection left on the bearings. I hope it goes well for you. Bob
 
I would at least pull off a cooler line and crank it over to see if there is any flow.Perhaps the oil pressure switch line? If you crank it and see the actual flow happening it would be a good sign..Fingers crossed for you David,good luck. Mark
 
Thanks for all the suggestions, I'll get to try them out this weekend, but I think I'll get the engine hoist out just in case!

DavidAGO
 
I got sidetracked for a week, but started back on the B yesterday. It took longer to move stuff around in the shop and get out the engine hoist than it did to pull the engine. I tried pressurizing the sump, no go, decided to go on and pull it. Wrong gasket on oil pump. I pulled the third main cap, crank looks good, after I wiped off some goo. I dug around in one of the boxes that came with the car and found a tube of unilube engine assembly lube. The tube is now 11 years old, but it looks like it was used liberally by the rebuilder. I haven't pulled a con rod cap off yet, but it it looks as good as the main, I think I will button it back up, go on and check the cam timing, and reinstall it.

It has been several years since I have messed with British cars; my shop has the B, the parts B that came with it, my original two MGA's, and another project rescue I found, a 76 TR6. Time to finish this B, and start in on the next one in line until I see the back of my shop!

thanks to all who posted with suggestions.

David
 
DavidAGO said:
I tried pressurizing the sump, no go, decided to go on and pull it. Wrong gasket on oil pump. I
Click to expand...

Ding-ding-ding-ding-ding!

:thumbsup:
 
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