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MG Midget and Sprite Technical - Oil surges, Peter May baffled sump

I think this came up in light conversation here a while ago, but I just wanted to clarify. My car with a 7k mile engine has, somehow, god knows how, managed to get a tiny oil leak. Not much, but it's got one. Good old A Series.

Anyway, the minute the oil level drops from 'full', I start to get oil surges all over the place. If I pull to a heavy stop, the needle races towards 20 (sometimes 0) and then crawls back up. As soon as I fill the oil a bit more back to 'full', it's absolutely fine.

Does anyone else get this with these sumps?
Rich Amos (1330cc Blaze Red '72)

With a standard sump, it's never been a problem. I am very suprised to hear about your problem with this sump as it should hold enough depth of oil under the pickup to stop this.

Check that your dipstick is at the correct height..are you underfilling?

Failing that, you may have a problem with the pickup pipe.

It's certainly not normal and needs checking out before your main bearings make a bid for freedom.
Robin Cohen

Agree with Robin

Blowing air into the bearings isn't what you want. As a temp measure, I'd over-fill a pint or so.

Mine use to have a pressure dip on application of full brakes when near the empty mark; I used to use this as a signal to add oil.

A
Anthony

My standard sump gives this behaviour as well. Its OK when on the full mark and not OK when on the low mark.

MOT day tomorrow.......

Roly
Roly

Mine does it too, less when full but still does it when hot.

I'm getting a baffled sump on the next rebuild.
Tarquin

I have a baffled sump (Mark Turner, not PM) and mine does exactly that. Keep it topped up!

I have a spare for sale btw if anyone is interested - never used since modified. We just ordered too many by mistake.
John Collinson

Driving fast and braking hard with a modified engine and brakes can see an alarming dive in oil pressure on my engine.

However, the only time it was a real problem was when I had a 40 grade oil in the engine so I 've stayed with a 50 grade (15-50) ever since.
Daniel Thirteen-Twelve

I'm interested John.
Nick

John is that one of those works of art I saw at the Classic Cars Show last October/November* at the NEC

very nice


*I'm old, I'd forget a date with Kate Moss even...


p'raps
Bill

Nick, I think I paid £30 for it, so yours for that if you want it - mail me at john.collinson2@btinternet.com
Bill - not sure! Mark's stuff is all top quality though.
John Collinson

I was the one stood drooling at the whole stand

made my worn out knees go all wobbly

I really did mean works of art

ta John
Bill

So I've topped it up substantially today and have had much better readings from the gauge, but it does seem that you get all number of issues with the engine if it is below the 'correct level'. I'm not even sure the 'correct level' is enough!
Rich Amos (1330cc Blaze Red '72)

Yet another part I've missed!
John do you have anything else that I could have first dibs on!?

Matt
Tarquin

You sad beggar! :)

Btw, shouldnt you be concentrating on a rover 3.5ltr V8 engine?
Arie de Best

shurrup!
dropped the rear disks & hubs off at the machine shop last week, so should have the rear end back together ina week or two. Trying to find some decent golf gti rear calipers which are aluminium, so nice and light.
Tarquin

Matt, most of what i have is probably what everyone has; used bits of engine I will never use (why do we keep used cam followers??), second hand brake shoes i can't bear to part with, etc. One or 2 nicer bits. We are having a clear out of the pig pen so I'll see what we have.
John Collinson

John

I'm rebuilding (in spare time) a maestro block into a 1380. I have pistons and want to get the block sorted and crank/flywheel balanced without having to take the old one out. I could do with a flywheel, which will get machined to take a Ford 7.5" clutch cover, and maybe lightened a little. I need a baffled sump too. Other than that there isn't anything else I really need, the alloy backplate sounded nice tho!

You know I had a thought the other day. When balancing the assembly does the crank & flywheel get balanced first, then add the clutch cover and balance that? Otherwise if it all gets balanced together only once, when a new clutch cover is fitted the balance will be out of whack.
Tarquin

Rich

Does your dipstick sit on the block on on a plastic sleeve?

A
Anthony

No sleeve. It just sits there metal on metal. Which I always thought was a bit strange.
Rich Amos (1330cc Blaze Red '72)

Rich, when you do an oil change, how much oil do you put in to get to the MAX mark?
David Smith

Sounds like an Ital block - is it ribbed?
Daniel Thirteen-Twelve

David,
I cannot remember for the life of me how much I put in when I do a change. I think last time I tried 3.8 litres, but I have the slight issue of having an oil cooler too so I usually add a bit more! I just fill it until the thing says max on the dipstick.

I'm not sure what block I have. Can someone gather it from these crap old photos?

http://farm1.static.flickr.com/156/387201699_9243d1eb29.jpg?v=1171235346
http://farm1.static.flickr.com/129/387202036_971633dec4_b.jpg

Awaiting answers with anticipation! Otherwise, tell me what to look for and I'll go have a peek.

Rich

Rich Amos (1330cc Blaze Red '72)

It's not an Ital block where the dip stick does sit on the metal of the block itself.

Your car's block looks to be a 12V block which has a metal sleeve inserted into the block rather than the plastic sleeves fitted to the earlier blocks.

The dipstick should be a really tight fit with the metal sleeve unlike the looser fit with the plastic sleeve. I also believe the dipstick for the metal sleeve is different from the one for the plastic sleeve.
Daniel Thirteen-Twelve

With the type of sump John has we usually run just below the X of the MAX on the dipstick with no problems. Hard braking is the only time you get a surge, but in over 5 years of using the same sump ive never run my bearings yet due to surge, the only time ive done that is when I broke the crank across number 4 big end, but thats what prolonged 8000rpm does!!!!

Cheers

Mark
Mark Turner

Have a PM sump on our 1380 (not Ital) and get the same problem - need to keep the level up to the 'Max' and maybe 3mm above to be sure under braking.
Richard Wale

This thread was discussed between 11/07/2008 and 18/07/2008

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.