Author Topic: Wet Sump  (Read 1006 times)

Offline Howard

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Wet Sump
« on: 20.04. 2012 19:31 »
My old A7 wet sumps if I leave it with-out starting for two weeks or more. I have fitted a drainable sump plate. But would I do any damage if I start it with out draining the excess oil ? won`t it just pump the extra oil back to the oil tank ?

Offline lawnmowerman

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  • 1959 Super Rocket. Kent, England
Re: Wet Sump
« Reply #1 on: 20.04. 2012 19:38 »
Oh if it was that simple. It really depends how long you have left it and how much has drained into the crankcase.

I had a one way valve on my SR which I removed because there were bad reports about them on the forum. At the same time I changed the oil from straight 40 to 20/50.

OK if used at least once a week but after a couple of months I started her up and she dumped about a quart of oil out the crankcase breather and on the garage floor. Also filled up the primary as it was on the prop stand.

I am now going back to straight 40 and fitting an oil valve on the feed pipe with a built in mag kill switch.

1959 A10 SR
1938 Wolseley 14/60
1955 Ferguson TEF20 tractor
1965 Ferguson 135 tractor
1952 Matchless G80 rigid
1960 BMW R60
1954 Matchless G80S
1955 Ariel 500 VH
1951 Sunbeam S7DL
1960 Matchless G12 with Watsonian Monza
......and loads of lawnmowers

Too old to Rock and Roll but too young to die  (Jethro Tull 1976)

Offline Beezageezauk

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Re: Wet Sump
« Reply #2 on: 20.04. 2012 19:48 »
Hi Howard,

If you leave too much oil in the sump you could over pressurise your engine and, at least, blow gaskets.

You say that you have a drainable sump plate so you can already save yourself a lot of time by draining the oil prior to starting the engine.  I don't think it's worth taking a chance with the other option, it could cost you a lot more time and money in the long run....for the sake of a few minutes work.


Offline bikerbob

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Re: Wet Sump
« Reply #3 on: 20.04. 2012 20:00 »
Hi there I have a1963 A65 which does not wet sump and a1957 Gold Flash which does, on both bikes I use Halfords Classic oil 20/50 I found out with the Flash by trial and error if I leave it for 3/4 weeks it starts okay but you get a bit of smoke out the exhausts for about a minute but if I leave it for 6 weeks you end up with oil on the garage floor so I try to start it up every 2 weeks through the winter months and have no problems.
56 A7 s/a
63 A65

Offline Goldy

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Re: Wet Sump
« Reply #4 on: 20.04. 2012 20:18 »
Howard.   I fitted a sump drain and thought it would be easy to just drain it each time, but it does become a bit of a pain so I purchased an SRM oil pump and solved the problem.
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline Rich

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Re: Wet Sump
« Reply #5 on: 20.04. 2012 20:44 »
still have my one way valve fitted 5 years + still ok