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MG MGB Technical - Oil Sump Query

Problem is my new sump from an SD1 has a bigger oil capacity than the original unique sump made for my 1974 factory built MGgtv8. My old sump had become porous and everyones advice was to replace this with one from the SD1 together with a longer pickup pipe. Original took 5.5 pints the new supposedly 7. 7 went into the engine after new sump was fit and the level now shows well overfull on the existing v8 dipstick. On the basis that the sum capacity is 7 pints it is now suggested that I need an SD1 dipstick but I have difficulty understanding why the old dipstick is not accurate on the assumption that any extra oil is needed in the sump to bring the level up to the same as for the smaller original sump and not to raise this. Has anyone any comments.
S Gash

Does the original dipstick not reach the bottom of the sump?
Dave O'Neill 2

Hi,

Assuming that the original dipstick is accurate and the top stop doesn't move, I would go by it as it is calibrated to the level that the engine needs. The size of the sump makes no difference to the level of oil required. I would even question whether a longer pickup pipe is necessary, though it would collect oil from lower in the new sump.

Herb
Herb Adler

Dave O'Neill 2, Solihull
Does the original dipstick not reach the bottom of the sump?
--------------------------

I have no idea but the new sump is deeper than the old which is why it made sense that more oil was needed. I still cant understand why the oil level comes above the max level on the old dipstick.





S Gash

Having had my sump off I can say that the V8 dipstick does not go to the bottom. I had a moments panic wondering what it was that was sticking through the baffle plate. You are quite right S, the original dipstick is the correct one to use as it is the position of the top of the oil that is important when using a different sump on your engine, not the level in that sump on its original engine, even though nominally it is the same engine.

My V8 always takes exactly 5 litres for an oil and filter change though, not 5.5. I did wonder if that was in the specs which would be for a dry engine, but the workshop manual states 4.54 for the engine and 0.28 for the filter, which is even less than I need.

Incidentally, what has gone porous? I changed my sump as well when it started leaking from the front, but that was because it was rubbing on the cross-member because whoever installed the engine got the mounting plates on the wrong sides, and they are handed, now corrected. The same person (presumably) also got all the right bank con-rods facing the wrong way, but that is another story!
Paul Hunt 2010

The dipstick doesn't measure sump capacity but oil level. It may well be that the SD1 engine, sump and dip-stick together do result in a higher level in the sump if that is what that engine needs. The deeper or greater volume sump on the MGB V8 almost certainly *will* need more oil to get the level up to the Max mark on the MGB dipstick, but won't necessarily need the same amount of oil as the SD1. You should have progressively put oil in past 5 litres until it reached the Max mark on the MGB dipstick, not whacked the SD1 quantity in all in one go. You need to drain some out to reduce the level to Max, as too much can be a problem as well as too little.
Paul Hunt 2010

Thats great, you are supporting what I think so I will now go back to the guy that fit it with a bit more confidence to argue the point. Thanks for the advice.
S Gash

This thread was discussed between 10/05/2010 and 12/05/2010

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