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MG MGB Technical - oil pan question

I have a 1969 MGB with the original motor and an oil pan that is noticeably caved-in at the front; like the PO ran it up on a rock or something. I plan to replace the pan or bang out the dent when I have the engine out of the car, but for now it doesn’t leak from the dent and so I drive it as is. The dent seems to reduce the capacity of the pan (the volume it can hold is decreased by this, right?) because when I refill after a change (including new filter plus I detach and hang the cooler to get a complete drain) it takes 4 US qts and the level on the stick is about ½ inch above MAX, even after I run it and let it sit. I’m afraid to put in more in, even though the specs call for it, because I am already over MAX; but also afraid to put in less as it might be insufficient oil. Am I safe to continue with the 4 qt refill or am I doing damage? I do watch the oil level and keep it at its current mark to assure 4 qts. in the pan. Thanks in advance for responses.
James Novak

Yes, you can run the engine with decreased capacity, though it would be best to have the oilpan repaired or replaced eventually. RAY
rjm RAY

James. The sump and engine are never completely drained of oil during an oil change. While the factory workshop manual lists the capacity of the sump as being 9 US pints, it does not take that to refill the sump during an oil change unless it is an initial start up. Models having a can type oil filter will vary, slightly, depending on what size oil filter is used. The cartridge type filters (replaceable elements) are somewhat more consistent in replacement volume.

My method is to drain the old oil while hot, allowing about a half hour for as much to drain as possible. You will still have a few drips when you wipe off around the hole before installing the drain bolt. (This wiping off only removes oil. You clean the area around the drain bolt, carefully, before removing the drain bolt so that no oily dirt or sand remains.) With the drain bolt installed, replace the oil filter. Refill the engine with three quarts of oil. Let sit for a while. Top up the engine oil to the top mark of the dip stick. Run the engine until you have good oil pressure and, then, check for leaks. If all is good, shut off the engine, allow it to sit for at least one half hour, then top the sump up until the oil level is just at the top of the full mark.

Some people will turn the engine over with the coil disconnected until they have oil pressure, believing that this is easier on the engine. Others dispute the need for this, pointing out that there is oil on the bearings and turning the engine over for an extended period on the starter is hard on the starter.

The distance between the min and max marks on the MGB dipstick represent about three cups (1.5 pints, 3/4 quart).

Refilling the sump above the maximum line on the dip stick can be a bad thing because there is a potential for the crankshaft to hit the oil in the sump. This is not a good thing for a number of reasons, so do not over fill the sump.

Les
Les Bengtson

Thank you both. So, Les, are you saying that its better to refill with 3.25 US quarts, as this would bring met to MAX with my dented pan, than potentially overfill with 4 qts? The difference between the two amounts is maybe not that significant? What are the syptoms of the crank hitting the oil? Thanks.
James Novak

If the crank hits the oil it could cause aeration or foaming and you could affect the oil pump operation, ie pumping gas.
Art Pearse

Having it no higher than MAX is better than putting a specific quantity in and being over. However with the reduced capacity the oil will circulate more frequently and so 'wear out' sooner. It should be marginal, but better to sort out the sump. The other issue is, are you using the right dip-stick? There were several, but I have never see any definitive 'depth of oil from the sump floor' measurements.
Paul Hunt

Paul. There were three dipsticks, two oil pans (sumps), and two "tube, dipstick in block". I suspect that the difference in dipsticks may have been the fact that the last models had a seal attached as part of the dipstick while the early ones had a rubber cap which slid over the rod itself.

I can say what an 18V engine uses (same sump as any other five main bearing engine, perhaps indicating that the relationships between the sump and dipstick are the same.).

The dipstick projects 3.930" below the bottom flange of the block.

The "max" mark is 2.070" from the bottom flange of the engine block.

The oil pan is 4 5/8" deep from the inside, bottom of the sump to the bottom of a straight edge laid across the top of the sump.

Cannot say how far the crankshaft projects below the bottom of the block, and at what point it might strike oil if the sump has been over filled, until I have a chance to examine an engine having the pan off and crankshaft installed. But, this is a start on providing some information that I have not seen published before.

Les
Les Bengtson

James,
My 69 gt had a similar problem- the whole bottom was dented in. I never filled it above the full mark and never had a problem. you do not want to overfill, as stated above.
when I pulled the engine to replace the clutch I successfully banged out the big dent. I placed it on a 4x4 piece of lumber, and used a hammer to hit a 2x4 to take it out. I just took it slowly and it worked great- no leaks!

Don
don g

I've also removed a dent using the same process described by Don. Take it easy and there should be no problems particularly if the edges of the dent are not sharp but are smooth curves.
Richard Coombs

I have a later sump (75-80) on my 66 B. It was the only one I could get on short notice when the chain snapped while removing the engine and put a hole in the sump. It only holds 6 pints as opposed to the 9 pints the orginal sump held. The one I have now has the drain plug pointing toward the rear of the car instead of the side. I now have the correct type and will be replacing it this fall.
Tony
Tony Shoviak

What with all of the cases of dented pans, I would be concerned with the state of the oil pump pickup tube screen assembly as it
sits just above the bottom of the pan.
Daniel Wong

"it sits just above the bottom of the pan"

Indeed it does. I well remember some years ago someone writing about loss of oil pressure at high revs in competition, albeit in an A. The investigation showed there was only about 1/8" between sump and pickup, and a phenomenal rate of flow through the pump at high revs, so much so that for whatever reason it started sucking in air when it couldn't pull that volume of oil through the small gap.

My V8 sump needed repair but not from denting, it had been resting on the crossmember because the engine mounting plates were on the wrong sides which put the engine 1/2" too far forwards and wore through.
Paul Hunt

This thread was discussed between 26/10/2009 and 29/10/2009

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