Morris Minor Owners Club

I have noticed a small oil leak on inspection it looks like the drain plug from the gearbox, it’s tiny about the size of a tangerine I’ve tightened the plug slightly but I’m cautious in case it sheers off ,
Should I just leave it and keep an eye on it or grasp the nettle and tackle it full on?
I’ve attached a couple of pictures

Sorry don’t think the photo attached to the post

You have to ascertain where the oil is actually coming from. It tends to drip down to the lowest point. See if there’s any oil coming from the bell housing jiggle pin hole. Also you can remove the bell housing bung and try to peer in. Check the filler plug and where the speedo cable joins the gearbox. If it really is just the drain plug then don’t overtighten it. The thread is tapered and you could in theory make it far worse by being heavy handed. I had a very slow leak and it was just the drain plug. Whilst doing another job on the gearbox I drained the oil. Before refilling I wrapped the drain plug threads in plumber’s PTFE tape. Problem solved. My diff has a near identical leak and I had the same leak on the previous gearbox.

Stephen

I agree with Stephen and I suspect it's not from the Drain Plug.

Look at the photo and the area at the top of the photo, i.e. forward of the Drain Plug, has clean oil drips on it. The oil seems to be running back towards the Drain Plug.

**Edited to add photo**

2 drips not on the drain plug, and incidentally, that gearbox steady cable is too slack. See arrow.

geoberni wrote: ↑Mon Mar 31, 2025 6:07 pm I agree with Stephen and I suspect it's not from the Drain Plug.

Look at the photo and the area at the top of the photo, i.e. forward of the Drain Plug, has clean oil drips on it. The oil seems to be running back towards the Drain Plug.

Agreed. Needs further investigation. Suggest removing the bung on the gearbox (opposite side to clutch fork) and looking in with a torch and previous suggestions of speedo drive entry, filler plug etc.

See this photo of my gearbox which shows the location of the bung I am referring to and the split-pin (the purpose of which is to keep the oil drain hole clear).

If there is oil coming from the split-pin hole then it is either leaking from the front cover of the gearbox or the rear of the engine. The oil in your picture looks extremely clean and this does suggest it is gearbox oil and not engine oil. The standard gearbox has a scroll in the front cover to reduce oil leaking out. This is not a seal and oil does leak out especially if the car is parked nose facing down hill. So some oil is to be expected but not much. If the scroll is worn the rate of oil loss increases. Some cars have a modified front cover with a standard lip oil seal. This can obviously leak if old or high mileage but would not normally be expected to leak.

Stephen

Thanks for your help not having much experience with gearbox and certainly not leaks with regard the picture just to confirm
The area I’ve highlighted in yellow is the bung and the area highlighted red is the split pin

Yellow is the bung yes. Sometimes this is missing. Split pin is at the bottom of the bell housing. I will load the picture again with an arrow. What you have highlighted in red is the clutch fork and carbon release bearing.

Stephen

You will see the split pin dangling through on the outside.

Ah ok I will take a look tomorrow

Thanks again for your help

Speedo cable attachment. The filler plug is above (not in the photo). Filler plug usually accessed by removing bung in passenger footwell but if you are looking at the speedo attachment you can see it from there and see if there are leaks.

In an ideal world there would be no leaks, but reality is that the majority of these old cars have some degree of leakage. As others have stated, being clean, the oil is unlikely to be engine oil. We don't know how much oil is leaking of course, but unless you want to spend a lot of time on this, it may be best to just keep an eye on it. If it turns out to be a significant leak then, yes, it does need sorting. My own car always seems to have a drop of clean oil on that drain plug but I very, very rarely ever have to top-up the gearbox oil when checking, so I don't worry about it.

A useful thing is a large tray to go under the car. I have a large stainless steel tray made by the tool company Laser. It not only stops oil drips from going on the garage floor but it’s easy to clean and helps to identify what is leaking and by how much. Of course I used cardboard to start with but this kept blowing away. I use the same tray to do messy jobs like disassembling the Purolator oil filter.



Stephen

I've edited my post from yesterday afternoon to add something: viewtopic.php?p=706732#p706732

geobernie posted an additional comment about he noticed in my picture the gearbox steady cable looked loose, I’m due to get underneath the car at the weekend and sort a couple of things this is an addition to my list,
Having not adjusted this cable before can anyone give some tips/advice on what to do a little knowledge and all that

Stevie R wrote: ↑Thu Apr 03, 2025 6:55 pm geobernie posted an additional comment about he noticed in my picture the gearbox steady cable looked loose, I’m due to get underneath the car at the weekend and sort a couple of things this is an addition to my list,
Having not adjusted this cable before can anyone give some tips/advice on what to do a little knowledge and all that

I added the photo to highlight the drips that are nowhere near the drain plug...
But I then mentioned the kinked 'steady cable'. The relevant instructions are in the workshop manual.
When I say 'the workshop manual'' I refer to the Morris/BMC/BL one, AKD530. I've no idea if Haynes bothered with the information in their book.
If you don't have the Manual, you can search 'AKD530 pdf download' and you will find libraries where it can be downloaded for free.

To quote the manual, the cable is "tensioned so as just to prevent any forward movement of the power unit relevant to the chassis. Care must be taken not to impose too great a tension or roughness will be felt with engine vibration."

Note that you have to use two spanners when adjusting the cable, so as not to twist and damage it.

thanks geoberni that’s helpful

Having done some investigating it looks like the leak is at the speedo cable attachment

Ok. If you are lucky it is just that the speedo cable is not screwed on properly. See if the leak is resolved by screwing the connector up (maybe it is loose). Don't over tighten it. If this doesn't help that it may be the oil seal (see diagram part 88). Having never replaced the oil seal I am not clear on how it is done.

Stephen

https://www.moss-europe.co.uk/en-gb/ext ... 14--05--01

svenedin wrote: ↑Sat Apr 05, 2025 2:55 pm Ok. If you are lucky it is just that the speedo cable is not screwed on properly. See if the leak is resolved by screwing the connector up (maybe it is loose). Don't over tighten it. If this doesn't help that it may be the oil seal (see diagram part 88). Having never replaced the oil seal I am not clear on how it is done.

Stephen

https://www.moss-europe.co.uk/en-gb/ext ... 14--05--01

Interesting; the original Parts Book doesn't illustrate a separate oil seal, only the 'Bush Assembly - Pinion' Pt No 22A 71.
A seal is mentioned but annotated NSP (Non-serviceable Part).
The Moss Pt No, NKC105A, is listed far a great many applications.

Yes I've never even seen the "oil seal" but I can say that I replaced the speedo cable and didn't screw the gearbox end on tightly enough which then leaked oil.

Stephen