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MG Midget and Sprite Technical - Oil Leak

Have a small oil leak but enough to be of concern.

I am pretty sure its from the gearbox and read it up to find the rear seal tends to leak. However no oil in the transmition tunnel; small drip on rear of gearbox but not enough to have caused the small puddle on the drive in the week.
There is a lot of oil on the back of the bell housing on the passenger side, some on the back of the starter housing and the passenger side of the gear box. Drips have been going on the exhaust where it joins the down pipe and oil has partly coated under the passenger footwell. I have changed the gearbox oil during the week and ensured the rocker cover is not leaking or the filter. There is some oil on the sump and chassis rail by the breather but that seams to always be there and is not dripping. After two days tripping about since engine oil change the engine oil level seams constant and is fresh.
Checked both hydraulic reservoirs. No change in level.
So anyone know if its likely that the front seal of the gearbox is leaking? And is there anywhere else where lubricating oils could be leaking from at the back of the engine / the front of the gearbox in the bell housing vecinity?
Dave Squire (1500)

NO FREAKEN WAY DUDE!!!

an mg midget leaking oil... someone call "road and track" Magizine to.warn the planet... we need a total mg recall NOW, to get to tue bottom of this

oh dear god... the sky is falling...hell with the NK conflict... an mg midget leaking oil is un heard of

ROFLMAO

Prop

Prop and the Blackhole Midget

hahaha....oh dave you stepped into that one... dont worry it will wash off eventually...hahaha

a quick note... you mentioned the 2 hydrolic resevoirs... im assuming you mean the clutch and brake master cly...those fluids wont go into the transmission or the engine

if the clutch master or slave isthe source of the leak ... thats an easy fix

thr best way to find the leak is to wash is really good and after a ,50 mile run then crawel under with a good clean cloth and a good flashlight (torch)

remember oil does 2 things... it always blows backwards almost never forwards.

and a little oil goes ALONG way. aka a small spill just looks tragic

one of the goes of mgs is just learning to accept that mg midgets are going to leak... someone has to kill the planet and provide jobs for environmentalist... it might as well be us

agian... thanks for posting ... it made my day...sorry your the butt of everyones joke...it was just your time.

prop
prop
Prop and the Blackhole Midget

Ok Prop,

What I didn't say was that I had to put best part of a pint of oil in the gearbox today to top it up and the amount of oil being thrown on the underside of the passenger side of the car is definately a lot for a BMC gearbox of this type. (I had two back in the 70's in Itals).

I presume there is no other opening in the front of the casing apart from that? I can't see one on any of the exploded views I can see online or in Haynes. So I reckon its the front seal of the gearbox and I'm just being lucky with the clutch.
Dave Squire (1500)

Other than a leak from your engine rear main seal (which can pump out a lot of oil if it has been disturbed during a rebuild, or if the crankcase ventilation has been messed up by fitting an aftermarket carb or other some such), the transmission front seal is the next most likely cause of your concern.

Both of those seals are "above the water level" of your engine oil / transmission oil, so they won't leak while sitting still, only while running (or, most often, just after shut down, a few drips).

Both seals, if leaking, will drain out at the same place, where the split pin is in the drain hole in the bottom of your flywheel / clutch housing.


I did have a very annoying leak on a ribcase transmission once, from another cause: after I have fitted a new transmission front cover, supplied with a modern lip seal in place of the original scroll seal. This leaked all of the time (the whole transmission would leak down over the course of a year of sitting).

When I finally pulled it to replace that GD front cover I found that the hole was almost invisible. Some kind of casting defect where a couple of ribs met.


After installing a new one, I filled the transmission with oil and let it sit for a few weeks to make sure this one didn't have a defect, before going to all of the trouble of putting it all back together again!


By the way, if your leak began right after you re-filled your transmission, and you changed nothing else, then the first thing I would check is that it was not overfilled.
Norm
Norm Kerr

Not put any oil in the gear box previously Norm. Since passing its first MoT in years at Christmas it has done 750 miles. I already had the transmission oil ready to do a gearbox and diff oil change.

The excessive oil on the driveway and on the underside of the car started about 10 days ago. The leak does not continue to flow while the car is stationary. Any excess leaked oil drips off the underside of the car at the end of a run. I have wiped down the underside of the engine, gearbox, and bell housing previously and the oil seems to come from the base of the bell housing but obviously has to be flowing there from somewhere else.

The transmission was quite noisy just running up to about 4 weeks ago when it miraculously went quieter. I assume this was gearbox noise. First gear is still sort of noisy from time to time.

Yesterday I topped up the gearbox and intend going for a run out today to see what happens. I will change the gearbox oil when I get back anyway to see if it makes a difference. If PO put wrong grade of oil in the box years ago and it is the box leaking then I am thinking a proper oil change may fix it.

I am not usually that lucky with noisy gearboxes though so hence the question about seals in the bell housing area. The last time I had a noisy gearbox it was in a car I already owned when the noise began and that was a bearing fused to a shaft wearing the casing out. The mechanics found out when the box was out.

I assume that if it continues to leak badly the only real way to check any of this is to take the box out?
Dave Squire (1500)

dave ... I hate to say it, but I think your locked in, unfortantly its an engine out job to get to the seals

if it were me, id take the oppertunity to freashen up all the gaskets and seals while the engine and transmission
is out

the problem i always have is figuring out where to stop when the engines out as I fall victem to... "while the engine is out, I might as well...." this and that

what I would avoid it oil additive that fixes leaks... that a reciepet for disaster

just for grins... watch areas like around the dissy, the oil pan gasket, the front engine cover ...those are areas that can have hidden oil leaks

prop
Prop and the Blackhole Midget

hmmm... how cold is it where the car is

with so few miles driven 750 ??? and if its really cold maybe the seals have gotten hard and no pliable and oil is leaking past

prop
Prop and the Blackhole Midget

Yes Prop and I hate to think it but ...... £$%^7*

Oil pan (sump) gasket is a good suggestion. I'l have a closer look in a minute. Another quick wipe down while the car is up and then a trip out to warm the gear oil and come back and look again and change the oil.
Dave Squire (1500)

Do you park with the car pointing downhill? If so the bellhousing/gearbox seal can leak if it is the scroll type seal when parked on a hill as the oil just runs out the front of the gearbox.

Mal.
Malcolm Le Chevalier

Norm's advice is good, except he is describing an A series engine & ribcase box. They leak for different reasons and in different places.

The start point would be to clearly define if it is engine oil or gearbox oil. Best done by accurately checking both to see if the levels are dropping. But as Prop says, a little oil goes a long way and so what looks like a serious leak may not actually be lowering the level in either unit by very much.

It could be your mainshaft seal at the front of the gearbox. The design of this was modified part way through the 1500 production, presumably because the early one was prone to failure. I may be dreaming this, but some months ago when you first were worried about excessive gearbox oil didn't you find that the oil level was low? Maybe it had drained out over the years and the leak had never been attended to? Of course, if it is the gearbox front seal it is an engine out job to fix it.

If it is engine oil, then the crank seals on a 1500 are not too bad at all. More likely, - and easier to fix, - are sump gasket or the bottom of the timing cover (if oil starts that far forward). But if it has only recently started, can you relate it to any work that you did on the engine? e.g a common fault is failing to get the rocker cover cork gasket seated properly after adjusting the rockers. Oil then leaks out at the rear of the cover, runs down the bellhousing and appears at the bottom so it looks like a gearbox leak!
Guy Weller

I was going to do the gearbox oil a few weeks ago but got waylaid by water leaks so hey ho.

Topped up gearbox last night. Wiped everything down and checked gearbox filler plug in properly this morning. Then went for a 20 mile ride.

The gearbox sounds great. In fact it is less sounding and more quiet. I am :-).

I think the oil is coming from under the engine. Looks like it could be the sump to block joint or the timing cover. I topped up with thinner engine oil a couple of weeks ago as it was all I had at the time (not for far or long) and I reckon it could be the washing action that has caused it. The lower grade 10/40 oil definately caused lower oil pressure and the engine sounded a bit different. The old new oil when it came out and I replaced with 20/50 was full of carbon and the cyly head valve gear is now much cleaner). The sump could do with coming off and a manual clean out anyways so its either make or buy a gasket (I've got quite good at making gaskets over the last few weeks).

So its a crawl under and see what can be done. I see its possible to remove the sump with the engine in the car so that is a good thing. I'l start there. Probably a job for next weekend. Should be OK till then. Got plenty of oils of all correct types now. Reading begins tonight, grand kids here this afternoon so happy families for now.

Thanks all.

Dave Squire (1500)

Dave,
You probably know this, but be careful about how you re-tighten the sump mounting bolts on the 1500 engine. Most go into the steel of the crankcase, and are no problem. But the front 2 (or 3, cannot remember) go into the alloy bridge piece across the front crank main bearing. Being alloy, just when you have got used to tweaking up the others nice and tight, you then hit the alloy fixing ones and promptly strip the thread! Be warned, it is very easy to do!
Guy Weller

Thanks Guy, no I didn't know, and yes I would have done the steel ones first! eek. (and of course that could be the problem from the PO). Will do the front ones first and be careful. Some engine oil down on the dip stick after run out today so looks like it is the one to go for.

I still can't get over how quiet and nice the transmission and gearbox is with oil in it (like my itals from years ago). Definately getting happier even though I am having to keep at it.

Cheers.
Dave Squire (1500)

Dave,
I think you may find that those front ones use a different thread to the others. It would be normal practice to use a UNC thread in alloy, rather than the more normal UNF thread into the steel block. I haven't checked the handbook (sinner) or Haynes, but they may list different torques for those bolts.

I know you were planning on removing the sump for a good clean up, but if not then you may find you can reduce or stop the leak just by checking the sump bolts are all done up to the proper setting. They can work their way loose, or the gasket can compress, in time.

If you do remove the sump, check the flange itself for flatness, using a steel rule. Often the sump flange will become distorted around each bolt hole, especially if it has been overtightened in the past. A little time spent with a hammer and some sort of flat dolly to dress the flange flat again is well worth while.
Guy Weller

if your going to have the pan off... you might as well replace the thrust bearings... common replacement item ever 30 to 40 thousand miles

btw... giving all the hardware a good snug is a great idea

I purchased one high quality gasket set, but never use them except as templetes for making new gaskets....with as many times as I pull my engine apart...it saves alot of time and money

prop
Prop and the Blackhole Midget

The order is made:-

MG badge clips
Small toggle switch
Pedal box seal
Door mirror mount
Accelerator cable
Radiator cap

Oh', and two gaskets, one for the timing chain cover and one for the sump. :-)

I am still amazed by how relatively cheap some of the most important bits are (and I don't mean the badge clips Prop).

Shame the car is untested after the latest hose fix at the weekend; just had to go to Nigels town and back in the modern.
Dave Squire (1500)

Dave,
I'm not sure where you're getting the toggle switch from or what you want it for but the cheap ones can be rubbish

if you're coming to Northampton let me know and I'll let you have a go in a 1275 to see how it goes and how hot a heater can be especially on your feet

I'd probably be able to find a few bits that might be useful to you to bride you into liking me for a few seconds too

Nigel Atkins

"to bride you into liking me"

Dave I'm not sure what that means but is sounds distinctly iffy to me. You know that they always advise that you should never agree to meet people you contact on the internet. There are some very strange characters about.
Guy Weller

you missed off the 'for a few seconds bit'

it's true there are some very strange people on the internet but we continue to converse with each other






. . . . and them
Nigel Atkins

Quite right Nigel. I should have alerted him to the perils of short term relationships as well.
Guy Weller

I thought hello, sounds familiar, it's Papa Lazerou!

http://www.youtube.com/watch?v=s2F4ZWTjwTU
Pete Ottewell

so nigel,

what.happens AFTER the.1st few seconds are complete...

creepy creepy.creepy

so do you purchase owners manuals or do you make them from scratch B-)

prop
Prop and the Blackhole Midget

I'm just yearning for friendship and acceptance and you lot turn it all nasty and sordid

League of Gentlemen, as many comedies have, started on Radio 4 'the home of comedy' before going to be 'discovered' on TV
Nigel Atkins

Dave

My views, for what they're worth are:- Yes you can remove the sump in situ but it's a pain, if you can get an engine hoist remove the engine and gearbox as a unit, it's easier than it sounds. This gives you the chance to separate the engine and gearbox and get a better idea if it a seal that's causing your problem, you could also check the state of the clutch while you're at it.

My guess is you'll have a scroll seal at the front of the gearbox, these don't wear but could leak if parked on a steep slope nose down or the gearbox is overfilled (don't ask how I know).

One simple check you might want to try, unless you're sure it's engine oil leaking, is to get underneath the car and put your hand up and feel the top of the gearbox cover. I had a problem with oil coming out of the gearbox breather that's in the top cover. The oil sat in trough that's formed by the raised edge of the cover until that was full, it then ran down the side of the gearbox. I never did figure out why it was doing this and I only managed to cure it by replacing the breather with a pipe and catch tank.

Contrary to what prop would have you believe these cars can be made pretty oil tight, I wouldn't say they don't leak any oil but mine's parked on a block pave drive and there are no noticeable oil marks.

Bob
R.A Davis

Right, OK.

It looks like there is an oil leak from the head gasket (the rocker gasket no longer leaks and the heat of the last few days running has got the head clear of oil) and I had some grey smokiness yesterday at over 60 (the water level went down more than previous and I now have creamyness and water drops in the rocker box) so it looks like my assesment from just before Christmas was probably right and the head gasket is gone. (there was rusty water, as well as the oil we had poured in, in the seized cylinder, that came out of the spark plug hole when we turned it on the starter for the first time after the lay up so it all fits).

All tools and gaskets are on their way and the missus is at work all weekend.

I know from the other things I have done on the car that chances are this hasn't been appart before. (On the other hand all the head bolts are now nice and oiled up from the rocker leaks).

I have read the BBS archive threads as much as I can to get an idea of whats what with this job and seems straight forward if somewhat precise and daunting.

Can you all comment on the likelyhood of what will fail as I take it appart and put it back together?
Or of course the shortcomings of the instructions in the Haynes manual?
Dave Squire (1500)

Should be a simple enough job. But as I recall the awkward bit on a 1500 is removing the manifold from the head - the middle two nuts are very difficult to get at. You may find it easier to undo the exhaust connection and lift the head off complete with the manifold. But that only works if the 3 exhaust bolts aren't seized up.

Personally, I would choose to do a compression test before starting to dismantle. It should give you additional information about engine condition which can be useful in any subsequent decision making.
Guy Weller

you've got some of the signs of HGF and it would explain the coolant that keeps dropping but Guy's suggestion is good if you have a compression tester or can borrow one

there are quite a few signs to HGF but they are often easier notice with hindsight
Nigel Atkins

I was thinking beyond checking that it is HGF - although it does sound like this. Using a compression tester would confirm if it is HGF, but would also give you information on the state of valves and rings as well. So later, when you have removed the head and are wondering if you should be dismantling further to check and lap the valves, you will already have the answer. Or at least some helpful clues!

There are probably better ones, but this is what I use, a Halfords offering:
http://tinyurl.com/d9btnwq

Guy Weller

yeap I caught your drift and thought I was agreeing
Nigel Atkins

Yes, I thought you were. Weren't you ?
Guy Weller

it wont cost anything or take much time to retorque the head and see if that does something

prop
Prop and the Blackhole Midget

It does do something, its much better after just torquing it up (one nut moved over a full turn). Only been up to 50 mph on 10 mile run but seams OK. Will let it cool down then do the back them off a quarter turn and retorque.
Question is how cool is cold? That is the question?
Dave Squire (1500)

gee dave,

your just not happy till you get everyones panties in a bunch are you....hahaha

cold torque vs hot torque... let the blood bath begin

im intrenched into the hot torque camp myself, but others have differant belifs...but then agian, im not a cat loving panty wearing coffee drinker ither...hahaha

id run it up to normal operation temp, then torque it down to spec...followed by a check of the valves tappets clearance

others will definatly disagree

prop
Prop and the Blackhole Midget

This thread was discussed between 06/04/2013 and 13/04/2013

MG Midget and Sprite Technical index

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