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MG Midget and Sprite Technical - Engine out - parts list?

I've been using as much oil as petrol, price wise. It's about 2-3 litres of oil per tank due to leakages! I have therefore deduced that it would be cheaper to do an engine out and fix my oil leak!

So, as it's been a good 2 years since I last did an engine out, I would very much appreciate help with a list of things I need to order, to sort the rear seal (it /must/ be the issue!) AND to replace anything that's false economy not to.

I've got:
Clutch release bearing
Clutch fork pivot pins
Oil filter
Exhaust gasket
Some patience

...and the rear seal? What is this part officially called?

I'm not replacing the clutch plate unless it looks bad as it's a 7.5" one which was brand new 7,000 miles ago and I'm not made of money!

Anything else?
Rich Amos (1 Sprite 1 Midget!)

Did you do a leak down test to see if your rings and valves are sealing properly?
Trevor-Jessie

speedo cable and an earth strap ;)
Will Munns

Pilot bushing
Engine mounts?

If it is leaking that much oil through the rear scroll, the clutch may be saturated as well.
Glenn Mallory

would fit a peter may rear oil seal conversion kit myself and do away with the leak forever.
Alex Sturgeon

I haven't done a compression test yet no. I supposed I should better just to check!

I have been consdering the PM seal but is it THAT much of a difference that it is worth the cash?
Rich Amos (1 Sprite 1 Midget!)

I fitted a Peter May Oil seal to my early 1098(had it done properly by someone who knows what they are doing). It didn't stop the leak at all. I was later told by someone that if the crank is worn you can fit any seal you like and oil will still p*ss out.

So I decided to do the job properly....rather than taking the enigine out for a third time. I had it line bored and used the original scroll seal from the engine. Whilst it was out I had it rebored and cleaned up as well. Not cheap but as it was out worth doing I thought. If you can strip it down and rebuild it yourself it's not much money to have it just line bored.

A few months and a few hundred miles later no leaks at all. I know of a few other people who have done this as well and their engines are leak free as well. Just make sure you get someone who knows what they are doing.

I'm only fed up as my rear seal stopped me getting to Spridget 50. I had been losing a little oil from the area around the split pin in the drain at the bottom of the gearbox for a while. Decided to chance going to Spridget 50 and top up the oil on the way....that was until I got to just before Newbury services on the A34 and the seal decided to shoot oil all over the clutch :-( Still, my AA membership got some use.
A Harry

I think that those rear seals are only good for stopping SLOW leaks. If you have a big leak, then I'm guessing you have excessive crankcase pressure, or a worn scroll cap, or both.

I guess I'm saying: you need to fix the cause of the leak (they didn't leak that bad from the factory). Putting a seal on the flywheel flange may not be a good answer. That flange is not machined for a seal.
Trevor-Jessie

I had the same opinion of the PM seal. I'm not worried by minor leaks, I am worried by serious leaks, which it won't stop anyway.

My engine was rebored 7000 miles ago, it's just had a very expensive rebuild so this is obviously somewhat frustrating.

I don't know the innards of the A series engines very well, just the outtards!

To replace the rear seal am I looking at having to actually dismantle the engine? I figured it was something 'behind' the flywheel, am I wrong?
Rich Amos (1 Sprite 1 Midget!)

Did you use a cheap motor oil to help bed the rings into the clyinders....If not you may have "glazed" the clyinder walls and have a bad case of blowby...causing positive oil pressure build up and leaking .... If thats the case you will need to have the cly. re-honed to remove the glaze and new rings to do a proper ring bed in.

prop
Prop

BTW...Have you considard a cigar guaulatine...for removing excess fingers tip and knobs...much easier then a motor cycle chain....LOL

sorry...I just couldnt resist....LOL

prop
Prop

Rich

the rear seal "behind the flywheel" doesn't exist

what there is, which is where the problems come from is a very fine gap between the crank tail, next to the rear main bearing, and the engine block.

The crankshaft tail has a very fine "pseudo thread" with an anticlockwise set to it so that with the engine rotating clockwisedly any oil that gets into the void between crank and crankshaft is spirited back into the engine by the reversed bias of its thread

no more

no less

obviously the sump has its gaskets and the rear and front mains caps have their seals too but for an actual seal in the rotating bits the A series relies on the scroll (the threaded portion) pushing the oil "uphill" back inside the sump

if you look at the picture of Toby's crank you can see the scroll "thread" cut into the crankshaft just to the left of the flywheel flange at the right hand end of the crank

http://tinyurl.com/6yz3y6

wich is why I fitted a PM seal kit a few years ago

which even after much (much) abuse is still generally doing the job I paid for

My power unit has oil leaks but I have no reason to think there are any of these coming from behind the flywheel, most smell like Ford gear oil...


I hope this helps you some!

Never shown on pictures, diagrams or in chatting about these engines Lara's crankshaft actually had a square section O ring hidden behind the three holed bridge piece. This didn't touch the crank but nestled tidily in the square section cutaway in the block

Someone will pop along soon to tell me/us that that is the required seal, I hope, but as it didn't touch any rotating engine part I hope we can get the way it should have worked explained...
Bill

Wow, my ignorance spans that far!

Thank you so much Bill.

So given the absolutely chronic leak, there must be something seriously wrong with the engine as I'm 99% sure it's not from the sump gasket? I have no idea what though!
Rich Amos (1 Sprite 1 Midget!)

If you're going to take the engine out, get a new set of hoses. It's a pain when one breaks and you don't have a spare. If you don't normally carry spare hoses, get two sets.

That's a lot of oil to lose - half the engine's oil in 200 miles. Do you have a visible leak point?
Nick

Yeah, I normally do although I renewed the hoses very recently and have a few spare 'just in case' some go - specifically the smaller ones which are a nightmare usually from past experience.

I can't see where it's leaking from. I can see a lot on the clutch slave fork arm 'boot' and I can see a lot all under the engine from back of sump backwards, though it's different to when I once had a leak that just splayed it 'everywhere' (i.e. right down both floorpans). I just can't figure out where it's coming from, but if I can't see or reach it, it's not going to be fixable without an engine out! It loses so much that even just as I drive in up the drive it'll leave a splodge every 3 metres or so.
Rich Amos (1 Sprite 1 Midget!)

I had the same oil loss (every tank of fuel = 1 litre of oil, oil pressure 70 psi max, crank vents clean, no other leaks on the unit) as you detail and all from the rear of the crank, and turned out to be a very small amount of wear in the rear cap mating face with the oil return scroll and bad fitting of the rear cover. This oil leak is common on A series engines if not assembled correctly or with wear in the cap, guessing mine had run with worn main bearing at some time in its life causing this wear and was a gold seal unit what did very in quality. The 1500 engine has an oil seal and can only guess that BL did this to remove a known fault on the A. I would fit the PM seal as a belt and brace measure.

If the engine has been running as well as it did after the rebore rebuild I would leave the top end and the pistons alone, maybe pull a main cap and have a quick look to see if you have any wear in the bearing and take it from there, you could also fit a five speed box at the same time!!!!!

Alex Sturgeon

how about the seals on the sump front and back?

Some use a fitted rubber seal others use cork seals that fit in the void between the sump and engine (Moss catalogue gives me part numbers CAM 6270 for front seal and CAM 6271 for the back) ISTR that they fit up to the mains cap and give the essential final sealing bit

If its the cork one it needs cutting slightly long to provide "squish down" when the sump is fitted

if not long enough when beginning its life (some people cut the cork flush and as it shrinks under engine heat find a new leak) it can easily be the source of your trouble.

The sump can be removed in situ, just

then these seals can be checked out

Sorry but I cant remember how much squish to leave on new corks

been a long time...
Bill

Did your engine builder line bore the mains and rear scroll?

For that amount of oil to be pissing out I would think that it is something else..

Do what Alex suggests and pull a main cap off or if you pull the engine then check at that point...
Toby Anscombe

This thread is delivering! Thanks for all the comments so far.

Originally, when the 276 cam was fitted, the engine was line bored. This was about a year before the engine was rebuilt most recently (some of you may remember it blew up the bores after an air leak). Should it have been again?

I have come up with an alternate reason to what the potential problem may be. Since the rebuild my clutch has been over throwing to the point that if I push it to full travel, it stalls the engine. It's not just 100rpms it loses, it's more like 500. Someone suggested a while ago that there is .. too much play/tolerance in the crank?

Would this movement cause wear in the end of the crank and cause this kind of leak there?

Dare I ask, What kind of disassembly do I need to undertake to get to the main caps?

It's hard because I'm trying to plan my route of attack! If I get the engine out I will be somewhat limited to what I can do without tools x y and z at the ready, if I leave it in I could end up replacing bits and disturbing bits I don't need to disturb!
Rich Amos (1 Sprite 1 Midget!)

Jack up car
Take off sump
Pull center main & inspect

All without pulling the engine!

Lots of travel on the clutch and stalling sounds like a thrust washer issue -sure you don't have a 1500? ;-)

If it was line bored and you have not changed the crank then it should be ok.


It would be handy to get under the car with a rag and some washing up liquid (or degreaser of your choice) and clean it up to try to establish where the oil is coming from. Front plate and running round the sump lip? Rear cork seal (would have to be a really bad rear seal!) - you need to find the source..

http://tinyurl.com/632ysr shows you the rear seal - the only other place it can come from thats above the sump is the oil pump.

http://tinyurl.com/5hpe9t the green thing at the top of the picture is the cap for my oil pump; if yours was loose and the tin 'cover' not fitted to the backplate then that *could* chuck enough oil out..
Toby Anscombe

aerosol carb cleaner rocks Rich

a good spraying with that will offend against something they all said in Osaka or some other place

but will clear the way for an onslaught

Peter May requires (if nothing else) that the oil pump cover must be on the back of the lump or there's no chance of it working, when you buy a seal kit

I "glued" mine in with RED Hardening Hermetite gasket goo
Bill

The best RTV (room temperature Vulcanizing) liquid rubber I have found is from Ducati (the motorbike people) as they don't use any paper gaskets and all metal to metal surfaces are sealed only with this stuff. On the air cooled engines even the head to barrel seal (normally a head gasket) is metal to metal with only o rings sealing the oil-ways

A good steam clean and after dry cover with french chalk or your mums talc around the suspect leak will leave a very clear tell tale mark
Alex Sturgeon

As Toby says - if your crank is moving backwards and forwards every time you depress the clutch, yes - the back end might just leak oil.
Nick

Rich,

I fear from what I have read above, that you may just have a crank thrust issue, caused probably by the clutch throw. I think this may require more than just pulling the engine, but an investigation into the clutch mechanism too. Are you using a std set up or a five speed?

I would be more than happy to take a look at things for you but... I'm 'Up North' and you... 'Down South'. Maybe Alan Anstead or Toby would be able to cast an eye over it, but bite the bullet and get it out and inspect it properly.

Mark.
Mark T. Boldry

Mark,
Thanks very much for your comment. I fear that it could be the crank thrust issue - I am running a standard A series gearbox and have no intention (nor money!) to convert to 5-speed in the near future. Am I looking at having to do any significant parts replacement if this thrust issue is the case?

I think I will remove the engine and bit the bullet somewhat and have a proper look.

Rich
Rich Amos (1 Sprite 1 Midget!)

I think thats a wise plan rich..."in for a penny in for a pound"

It wont take that long to pull the engine, you can have a really good look, and much easier to fix, plus you will be able to see if there are any other issues..(On a midget---PLease, that could never happen...LOL)...I think the additional time spent will pay off in the long run.

BTW...did you get a chance to see if you got blow by caused from glazed cylinders...its suprising how many new engines builds devolop that with in 10,xxx miles


prop
Prop

This thread was discussed between 02/11/2008 and 05/11/2008

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