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Oil capacity


Ken G
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We started the engine on Saturday, with no difficulty whatever, in fact a bit of an anticlimax, until we noticed that the oil gauge was reading zero. To cut a long story short, the service manual says the oil capacity is 3 Imperial gallons (3.6 US), but on a slight downward slope that amount didn't even put enough oil in the pan to let the pump operate nor reach the end of the dipstick. Having now put in 5 US gallons (4.2 Imperial), I get oil pressure but the level is still well below the dipstick mark. I guess that it will take at least another half gallon.

Reading the instruction book, the stated 3 gallons seems to apply when you have simply drained the oil via the drain plugs. I have had the engine apart, removing all trapped oil, and there are certainly places where oil would be trapped when you simply drain from the bottom (notably the wells below the cam-shaft and rocker arms). However, I wouldn't expect that trapped oil to amount to 1.4 US gallons plus whatever I still need to put in to get up to the dipstick mark.

This is a mystery to me. Does anyone with experience of old engines have any ideas? Is it at all likely that trapped oil would account for about one third of the total capacity?

Ken G, 1925 Rover 16/50 (San Francisco)

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My '15 Stellite took 5 qts with 1 being held in the piping with a 1.1 liter engine and the Vauxhall takes 7 altogether with a 4.5.liter mill, took me awhile to properly judge the capacity of both. Are you establishing oil capacity with the dipstick only, which may be misleading or are you judging by "guesstimate".

If in doubt you may wish to contact the National Motor Museum in Beaulieu, Hampshire UK. They have been very helpful with info on the Vauxhall and the Beardmore.

And have supplied me with facsimile reprints of original owner's manuals and spec sheets. {for a fee of course}

Just a thought. Best of luck, Carleton

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Carleton,

Many thanks for your reply. Perhaps my surprise is mistaken. Your examples suggest that it would not be impossible for the trapped oil to be one-third of the total.

I don't think Beaulieu could help except in a theoretical way, because I am sure they haven't got one of this model; there are only about three in running order, none there.

I have the original owner's manual which in fact has a section for the owner on how to drive the car and routine maintenance, and a much longer section that constitutes the service manual (with excellent drawings). The latter has of course been invaluable, although it is written for an experienced mechanic and therefore assumes a lot of prior knowledge. For example, it hardly ever mentions gaskets, and I have had to cut dozens of them!

Having had the oil pan off, and seen the depth required in order for the oil pump to work, I think the mark on the dip-stick makes sense. The end of the stick nearly reaches the "floor" of the pan, and after putting in the 3 Imperial gallons specified in the instruction section (not the service section) of the book, the oil scarcely reached the end of the stick, certainly far too shallow for the pump to work (it pumped mainly air). Having put 40% more than the specified quantity, the pump works, but the level is still perhaps an inch low on the dipstick. With the large oil surface area, an additional inch is still a lot of oil.

Ken G, 1925 Rover 16/50 (San Francisco)

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Ken -

Is this the car that has an open oil sump shared by the engine and transmission? If so, I can believe that you would need more than 20 quarts US to fill a dry system. If memory serves me correctly, my 57 Jaguar had something like a 12 quart engine sump. Must have been needed to compensate for the Lucas electrics. <img src="http://www.aaca.org/ubbthreads/images/graemlins/grin.gif" alt="" />

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Leadfoot (!)

Thanks for your comment. Yes, the engine and transmission share the oil. I have now received a laconic message from my cousin who last tore into this engine, a few years ago, merely saying that he "too found that it required more than 3 gallons" (Imperial), so I think that is just the way it is, and the book is wrong or at least deceptive. I have decided, with encouragement from several sources, that only way forward is to add oil until the level reaches the dipstick mark, and not to worry about the quantity (which is 4.5 or 5 Imperial gallons rather than 3).

Ken G, 1925 Rover 16/50 (San Francisco)

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Pretty sure. The pan and dipstick are original (the car is complete and has been in the family from new, so there are no bits and pieces collected together from other vehicles). Unfortunately of course the people who would have known the answers, my father and his father who bought the car new, are long dead. I had the pan off. The dipstick reaches almost to the floor of the pan, and the mark corresponds to perhaps two inches' depth of oil. The oil pump is mounted on the floor towards the back of the engine, and needs at least an inch or so of oil to operate at all. Even with oil at the dipstick mark, there is a tendency on steep down-slopes for the oil to slop forwards, away from the pump, leading to a temporary loss of oil pressure; that is a design flaw from new. If the dipstick mark is wrong, if anything it errs on the side of being too low, not too high!

No, I am now convinced that the actual capacity from dry is 4.5 or 5 Imperial gallons (5.4 to 6 US), and the book's figure of 3 is either wrong or just possibly refers only to how much to put in when you have drained only using the plugs on the bottom of the engine and gear-box.

Ken G, 1925 Rover 16/50 (San Francisco)

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There is a dam between the gear-box and the oil pan, trapping about 1 gallon (all Imperial gallons, 20% bigger than US). When the engine is running, some oil is pumped into the box, the dam overflows, and oil returns to the pan.

The only references to oil capacity are in the instructions-to-drivers section of the book. With the benefit of hindsight, I think it is saying that if you drain the engine and/or gear-box (separate drain plugs), you need to put back 2 gallons in the engine and 1 gallon in the box.

I had the engine apart and removed all trapped oil. I find that I need 5 gallons total (6 US) to bring levels up to the marks, and then I get proper oil pressure. I conclude that the figures in the book do not apply when you are filling from dry. Either there are 2 gallons of trapped oil (possible but it seems a bit unlikely) or the book is plain wrong. Anyway, I think all is well. I drove around the block on Saturday without incident; definite progress.

Ken G, 1925 Rover 16/50 (San Francisco)

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