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MG Midget and Sprite Technical - Sump seal alternatives

I have been slowly rebuilding a spare motor for my 1275 Sprite and I am becoming increasingly paranoid.

(Whilst I'm building it I can't be proved wrong. As soon as its in the car refusing to run AND leaking like a seive I'll be gutted)

I've come to the point where I need to fit the sump. I've consulted the archive at length read manuals and searched on line and not found a definitive answer. How best do I fit it. Even one of my gasket sets offers two alternative end seal arrangements.

Do I use the preformed rubber seals or the cork ones? If I use cork, how much proud of the sump face should they be? I have two pairs of paper/card gaskets for the sump sides. Both pairs overlap the edges of the main bearing caps. Do I trim them back or are they supposed to fold at 90 degrees? Do they butt against the end seals or tuck up next to them? RTV silicon, Blue Hylomar, Three Bond?

Pic 1

Mark


M Crossley

Or pic 2. The rubber seals are different lengths to suit the ends of the sump. They protrude about 1/16"(1.6mm). The gaskets are about 1/64" (0.4mm)less.


M Crossley

I like the rubber seals best ...use the blue haymar just a dap and over lap the sump gasket on top...I also trim the U shape.piece flat with the top of the sump

Something I do, I never use my gasket set as gaskets...I keep them sealed and protected, and use them as templetes and just buy the composit gasket material and make my own ...that way ive always got a gasket and dont have to order and wait for it to arive and the cost of shipping

Also I set my gaskets up to be reusable...I permanently glued the sump gasket to the pan and then I use white lithium grease on the mating side and bolt it togather, when I need to pull the pan it just pops off and stays glued to the pan and the gasket is in perfect shape... just regrease and bolt it back on

You do have to retorque after 100 miles as the white lithium grease shrinks and that allows the hardware to loosen

Prop
Prop and the Blackhole Midget

I've never really found the sump gaskets to be the source of a leak - it's nearly always the front pulley and/or the rear scroll that needs the careful assembly.For the sump I'd suggest you dress both mating faces - the threads on the block sometimes pull up and the corresponding area on the sump can have high spots leading to pillowcasing between the fixings.I prefer to use cork ends cut square and 5mm proud.This together with Stag Wellseal should produce a leakproof sump, but it will need retorquing after a few heat cycles.
Fergus

I've done this a few times on my present midget already

I was told the rubber seal goes at the back and cork at front

you can get straight lengths of cork (I've got 6 spare if you need any) or you can get preformed semi-circle cork

in the old complete gasket kits I've had they came with two straight lengths of cork gasket

I've used cork gaskets at the front straight and semi-circled, definite the straight seal need trimming down, I can't remember with the semi-circle

first time I trimmed the cork seal down I felt I might have cut it too close so next time I left more on to allow for compressing the seal but even with two of us pushing on the sump pan it wouldn't offer up well until I trimmed more off

I've seen in Haynes it says to trim cork seals as required but the paper side gaskets are not trimmed and cover the ends of at least the front cork seal as I remember it

the oval washers can be a pain as they spin and catch on the sump pan lip so a long thin screwdriver helps to keep them located and getting at the rear small set screws is a little awkward so a 1/4" drive socket and longish extension bar is useful especially if its a wobble bar (which are still on my wish list)
Nigel Atkins

I've often found that you do need to trim the ends of the gasket or the holes won't line up.
Dave O'Neill2

The gaskets tend to be universal A series, which means the 10CC/1275 ones will need trimming for the bigger main caps. I trim the gasket end so the holes line up and trim the corner by each main cap a tiny bit so it butts firmly up against the cap.

I leave 8mm of cork protruding. Yes, it does require a bit of effort on the corner bolts to pull it down.

The sets I have used have cork both ends. this has worked well. However, I would expect the synthetic rubber to do likelwise.

I never use any sort of goo with cork or rubber. It can act as a lubricant and cause uneven squeeze of the gasket material and so localised losses of clamping pressure, leading to leaks.
(Oops, not quite true: I used to use goo on cork in vain efforts to stop leaks on the cam cover of my old Mk2 Jag. One day I didn't have time to do the goo thing - race meeting the next morning - and to my surprise it didnt leak. Worked out why, and have always had 100% leak-free results with corck & rubber ever since)

I do use goo on the gasket as many modern amterials seem to need it.

The one little exception to my no-goo-on-cork approach is to put a little dab in the corner where each main camp meets the block, just in case there is any gasket movement during assembly.

All this is fairly easy to do and I don't have leak problems with the gasket or seals.

I did have a leak once however - it turned out to be between the pressing which forms the groove and the sump itself. I had the particular sump dipped, and this removed the factory seam sealant. And that seam is on the oily side of the cork seal (the cork seal is tight top & bottom but may not be so on its sides) so oil sneaked past it.
Paul Walbran

Thanks Everybody,

I'll gird my loins stop finding excuses and get on with it.

Mark
M Crossley

One trick to keep the gasket in place, while you are fitting the sump, is to get four bolts of the same size and thread, and cut the heads off, fit these to the block finger tight, then fit the sump and gasket over these bolts, fit and tighten the remaining bolts.
Once the sump is in place, remove the headless bolts with pliers, and fit the correct ones.

Dave
Dave Barrow

Or slot the cut end for a screwdriver!
Alan
www.masckent.org
Alan Anstead

This thread was discussed between 19/02/2014 and 20/02/2014

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