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MG Midget and Sprite Technical - oil drip tray

Someone here, (possibly Jan?) mentioned making some sort of oil drip catch tray fitted under the rear crank area. Seems like a good idea if it doesn't lower ground clearance too much. Does anyone have some design details for this, and how is it then drained without getting oil running up to your elbow?
GuyW

Not on my Sprite, but on my Capri, in the same place for the same reason, I made/fitted a drip tray. More like small close fitting box really.

To drain, I welded in a nut, flush on the inside, to act as a drain plug, much the same as the sump drain on the Sprite. Draining it is very easy and doesn't get oil down your arm/elbow.

I shaped it using a cereal box, and then made the metal version. If making one for my Sprite, I have considered it, I'd fix it either side using a couple of sump bolts, and with a flange to bolt it to the bellhousing too.


From the archive.

"Robert (Bob) midget Turbo, England
Having been unable to stop the drip drip drip I have gone to plan B!!

I have fabricated a small drip tray that fits inder the gearbox bellhousing and catches all the drips.

The prototype works great so I am now making the real item so it should be fitted ready for our annual new years day run with the MGCC Lincs centre! hopefully with no leaks on our friends drive

Posted 11 December 2011 at 16:21:16 UK "
anamnesis

I use an old oven tray which was surplus to household requirements :) (not for the Midget but for an old VW).
Jeremy MkIII

Yes it was me who mentioned the catcher tank. They are almost standard fitments on T Series MGs. I attach a photo of the lash up tank fitted to my Sprite. I made if from an old tin of wood stain, just to see if it would work, before making something more elegant. My leak appears to be from the join between the back plate and bell housing rather than from the hole/split pin. I have fitted the tank to two of the bell housing bolts and it works superbly. There are absolutely no drips on the floor. Custom made ones are available for T Series cars but most owners fabricate them themselves. I will make one a bit more substantial than the 'prototype' tin can and put a bolt in the bottom so I can drain oil out periodically. A sponge in the tank stops oil splashing out. I have been using my lash up for about a month and clearance has not been an issue. There has been absolutely no drips on the drive or garage floor.

Jan T



J Targosz

Yes that's the sort of thing I was meaning. Not the oven tray, Jeremy - I want something affixed to the car to stop the embarrising drips on friends' posh driveways when I go visiting!

If a catch tank can be made from a woodstain tin that gives an idea of the sort of size. I was imagining something bigger, more akin to a sump guard, but see it doesn't have to be that large.

Oil is dripping off the bottom of the engine rear plate, which should be easy enough to catch. Unfortunately it is also running along the exhaust support bracket which is angled slightly downwards so it ends up with a secondary drip point at the outer end of that as well. But I think I have a plan to defeat that!
GuyW

Could try Tywraping a small nappy to the bellhousing ! or avoid posh drive ways !
richard b

It's not a bad leak, and probably nothing more than I should expect from a standard engine. I do have your pcv valve to fit it with yet Richard, and that may reduce the oil drip. But the car (Frog) looks so smart now that non-A series owners don't expect it to leak oil!
GuyW

The late John Mead mentioned to me that a frogeye owner he knew boasted about his car not leaking oil, John said it was the only one he knew where the tunnel was rusty.
David Billington

Well I didn't follow up on the drip tray idea, but today I updated the crankcase breather system and what a difference! It is an early 1098 engine so had one of the air extraction pipes from the front tappet chest straight down into the air stream. It didn't seem to do much other than produce the occasional oil drip but meanwhile quite a lot was coming from the rear crank. So today I fitted a manifold connected PCV and since this engine doesn't have a canister on the chaincase I connected it up to the existing pipe from the tappet cover. I took the car out this afternoon, about 40 miles. When I got back I put a sheet of card under the car and after 2 hours there is just one tiny spot of oil on it. So it seem that extraction PCV is doing its job.

Or maybe I have just run out of oil.
GuyW

How do you feel about the 1098 compared to your 1275 Guy? Does the 1098 feel more torquey? If that's the right word?
anamnesis

Not used /abused it yet Anam. It feels very soft though, compared to my 1275, but then that isn't exactly standard! It sounds nice, and is fine for tootling along, but the engine doesn't leap to 7k when I lightly blip the throttle, the way the other one does.
GuyW

Iy's a long time since I drove a 1098 in mk3 Sprite, but I remember it as being very punchy. Not azms free revving but nice.
anamnesis

Forgive my ignorance, but I have often wondered why there is there a PCV anyways?

A crankcase breather hose routed directly back to the rocker box would surely suffice to mitigate any crankcase over-pressurization/leaks?

Most bikes just have a hose - exiting open ended at the rear of the bike - though on a Matchless I once owned, it exited above the rear wheel - not good!
Oggers

A hose from crankcase back to the rocker box cover wouldn't do anything! They both connect to the same internal spaces of the engine so there would be no suction or reduction of crankcase pressure.

I do remember British bikes often terminated a breather pipe just above the rear chain for added chain lubrication. Maybe your Matchless one had been wrongly mounted!
GuyW

Oggers, on my AJS which had the same engine as a Matchless the breather was on the drive end of the crankshaft and was timed, it pointed directly at the chain, It seemed to work as the engine was reasonably oil tight. The problem I had was with the gear change shaft, I never could stop it leaking.

Bob
R.A Davis

Bit late to the party but here's the drip tray I made for the A35. It covers the back of the sump to the gearbox, and uses 40 x 50 oil absorbent pads full length and width, and attached with springs so it can be quickly uncoupled for the nappy change.


f pollock

Great to see the PCV being put to such good use !

R.
richard b

Yes, thanks Richard. I should have acknowledged the source.
It was good to apply theory into practice and get a good instant improvement, and with no other changes.

There is still a slight drip so I may add a catch tray or maybe a sump nappy like Fergus'. I like the Special Tuning lettering too!
GuyW

Guy


Surely rocker box is virtually at atmospheric, whilst crankcase isn't? Pressure would thus equalize. Regardless, I am still not understanding the need to have a PCV if you had an open ended breather.
Oggers

Oggers the rocker box connects to the crankcase via the pushrod tubes so is at the same pressure as the crankcase. Crankcase pressure is elevated above atmospheric partly by the piston movement, but mainly by piston blow- by. There might potentially be a very slight pressure gradient but not sufficient to pull the fumes through and since part of the need is to get rid of the build up of acidic fumes you wouldn't want to feed it back into the engine internals anyway!

The second reason is to produce a negative pressure in the crankcase which reduces the oil loss via the rear crankshaft scroll "seal". The negative pressure pulls oil back into the crankcase and assists the flow of oil caused by the scroll which works like an Archimedes screw.
GuyW

Guy

All understood - thanks. It was me being a bit a twerp in assuming PCV meant Pressure Control Valve - as it does in the oil industry and elsewhere - and not Positive Crankcase Ventilation!

Yes quite right, simple breather hoses do either exit from rocker box or crankcase, and Mr Bernoulli provides the negative pressure - though admittedly not much.

I wonder though if the closing of the valve (at presumably idle and quite possibly a bit above) is still detrimental to the crankcase oil seal actually sealing due to the crankcase pressure not being ventilated until such as time as the valve opens at higher revs?
Oggers

Oggers, maybe there is a difference between pcv and PCV then?

On these, the Control Valve works the other way round from as you describe. It is normally pen but when connected to the intake manifold the suction is too great at times when there is a high vacuum in the manifold - as on the over-run. When the suction is too high, the valve shuts off else it would be liable to pull oil up the breather pipe. Its "natural" state being an open valve, not closed.

1275 engine systems drawn by vacuum at the carbs (ported) don't need a PCV as the vacuum at the carb body never gets that high.
GuyW

Guy

I think the type of valve in a positive crankcase ventilation system is actually a vacuum (vac) valve. I believe these are normally closed at high vacuum at the manifold - as you say it would probably draw in oil and lean out the engine otherwise. All other occasions it is open and thus lowers the pressure in the crankcase by drawing gases into the manifold

A Pressure Control Valve basically regulates system pressure upstream of it. Not much use in a positive crankcase ventilation system I don't think.

Unsure about not having a vac valve on the positive crankcase ventilation system drawn by carb manifold for a 1275. My old mk3 deffo had one.


Oggers

Oggers, my '71 car connected to the carb port without any sort of valve. Ported vacuum is too low to require one.

Where there is one, I will continue to refer to it as a PCV. That is what it is listed as. I was never sure if this actually stood for Positive Crankcase Ventilation, in which case one might say it was a PCV valve, or alternatively it stood for Pressure Control Valve, in which case one wouldnt repeat the word "valve". Semantics!
GuyW

Hmmm. Personally I would refer to the valve in a positive cranckcase ventilation system as a vacuum valve. The acronym PCV definitely refers to Positive Ventilation System - it really cannot be anything else as the alternative acronym of pressure control valve would not make sense to the valve employed.
Oggers

Inspired by this thread I have just bent my own drip tray up from aluminium. Have added a drain plug too.

Hoping to keep my newly painted garage floor a bit cleaner.





Simon Wood

Extensive!
GuyW

That'd be a bit misshaped with some of the roads I go on.

And I'd need a bigger one for the gearbox supplied and fitted by the "specialist experts".
Nigel Atkins

This thread was discussed between 25/06/2021 and 17/07/2021

MG Midget and Sprite Technical index

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