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MG MGB Technical - Oil pump gasket, pressure, capacity – Revisited

After extensive check of the archives, I’m getting pretty convinced that I put the wrong oil pump gasket in during the rebuild. At first I suspected the gauge (with good reason) but yesterday I installed a mechanical gauge. I also switched the inverted spin on oil filter from a Fram (which was completely empty after sitting a half hour) to a Mann W917.

Still, on a cold start it takes 30 seconds to get oil pressure. Fully warm and cruising, it runs about 60 lbs. With a very low idle speed (to stop run-on) the oil pressure will falter for a while, and then drop to essentially nothing. I set it up to about 900 rpm idle and it will hold oil pressure.

Also, when I changed the oil and ran it a few minutes to fill the filter, etc, I checked the level there was a lot of air in the oil.

This is a GK series 5 main bearing engine, and I’m now running 4 ½ quarts total. The stick says it is full at 4 quarts (on change with new filter but not draining the cooler) and the Haynes book says it takes 5 quarts (U.S.) so I split the difference. A half a quart of the total is Lucas Oil Stabilizer, which I added for its clinging qualities to help lube during the cold start, and to boost the viscosity a bit. The oil is Valvoline 30 wt racing oil, which was the only thing I could find that clearly still contained ZDDP. The previous oil was old stock Delo 400, but I think all the new stock no longer has the ZDDP.

So, can anyone think of something I should try before I go pull the pan? This won’t be too much fun since I’m going to have to do it outside in an alley because I’m visiting Eureka, CA from Kentucky and don’t have access to my shop.

I think it is doubtful that I will find a gasket in Eureka without ordering it, and I can’t easily take the time for the order to come in. So, when I look at the pump, will it be obvious how to cut a new gasket for it so that it does not have the same problem?

I’m off to the store now to get gasket paper and some gasket cutting punches, but I will check on line when I get back before I pull the pan.

Thanks for any suggestions.
Charley
C R Huff

Charley,
From my (bitter!) experience if you use the wrong gasket you will get no oil pressure whatsoever.
It sounds more like a worn pump - did you renew the pump or rebuild with a new rotor when you rebuilt the engine?

David
David Overington

Charley, This link has a photo of both gaskets. See first question.
http://www.octarine-services.co.uk/faq.htm
Clifton Gordon

David,

When going through the archives, it seemed some people indicated no pressure, and some indicated delayed pressure. That's why I thought I'd ask it again before pulling the pan. Yes, the oil pump was new from Bob at Brit-Tek.

I'm thinking the people who got no pressure decided to give it up sooner than the people that got the dely. Also, I had primed my pump, and after seeing no pressure, I pulled the line, saw foamy oil, and put a temporary mechanical guage on it that did show pressure. Therefore, I suspected the sending unit or electric guage was whacked, so I continued on.

Clifton, thanks for the pics link. At least if I do pull the pan I will know for sure what I am looking for.

I do not recall seeing two pump gaskets in the set, but I will have to look again when I get back home.

Charley
C R Huff

I just built a motor with a O/E (thin) oil pump gasket & no pressure after starting it up. I pulled the pump & I saw some casting was left on the block, were the edge of the oil pump was not sitting flat on the block. Filed the pump were the pump set like it should on the block. I see were payen gasket is much thicker, & if I whould have used the payen gasket I would not had this problem. C.R. I would look to see if you are having the same thing happen. Wrong gasket = no oil pressure, you are getting air in the system with the oil.
Glenn Towery

Well, the jury is in, and it looks like I’m a bonafide idiot. But, I sure am a lucky idiot since I drove this car cross country for 2750 miles without damage.

I pulled the pan and the pump, and sure enough I had put in the wrong oil pump gasket. I cut a new one, bolted everything back together, and after four and a half hours work, I got oil pressure right away, with a cold idle at 64 psi.

I pulled the #2 rod cap and inspected the rod bearing and crank, and I used a flashlight to look at the cam lobes. Everything looks good.

So, if anyone asks if you can get any oil pressure with the wrong gasket, the answer is yes if you wait long enough.

Thanks for the help and support, and for the info in the archives.

About the 20th, I’ll head back to Kentucky from Eureka, CA. I don’t yet know if I’ll take the northern route through Nevada, Utah, and Colorado, or the southern route through Arizona, New Mexico and Texas. It depends upon the weather. But, if you are a British Gear Head on one of those routes, and want to send an e-mail to me to offer support if I run into trouble, it would be appreciated.

Thanks, Charley
C R Huff

Charley, Good to hear you found the problem. Thanks for posting the answer, I'm sure it will help someone in the future. Good luck on your return trip.

Clifton
Clifton Gordon

Charley, I'm glad to see that you and your MG survived our January 3rd storm. I live about 300 miles south of Eureka and many folks around here are just getting their power back on. Good luck on your return trip. Ray
RAY

Well Hello Ray,

I know what you mean. I came over the hill from Ukiah to Point Arena on Sunday morning the 6th, and I ran almost the whole way on tree debris. I guess I just got lucky and missed the actual storm.

Because of the storm, my friend who owns Kentucky Forge Works in Point Arena had left for places that still had power. If time allows, I’ll try to catch him on my way back south.

If that all happens, I will also try to stop at North Coast Brewery in Ft. Bragg for a pint of Old Rasputin (sp?) on my way through. Perhaps you would like to join me?

Charley
C R Huff

Charley,
Welcome to the bonafide idiots' club - there's standing room only.
Great to hear that you sorted the problem with no serious aftereffects.

David
David Overington

Charley, The North Coast Brewery mixes up some nasty ales. The roads should, by now, be nearly completly cleared up by now.I'm even considering taking the MG out of its coccoon today. Ray
RAY

This thread was discussed between 13/01/2008 and 16/01/2008

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