12 replies to this topic

[Miniature]

Hello All,

My little '94 Mini Mayfair has started leaving some pretty big puddles of oil on the floor and I am a bit confused about where it is leaking from. From looking under the engine I can see lots of areas that are covered in Oil (see pic below)



I have sat with her running for a while and watched very carefully, and have spotted one area in particular where I could see the oil dripping and believe that this may be the "problem area" on my car... however I do not know what this object is that it is leaking from. It looks like some kind or engie sensor, as it is an electrical cable that attaches to a bolt which seems to be going into my engine, and the oil is literally dripping off this bolt. I have put a picture below which shows my whole engine, then a slightly more zoomed in pic, then even more zoomed in, until you can see the bolt with the oil dripping off.



Can anyone help me first in identifying this bolt and what it does? And secondly, advise me if this is something I will be able to fix myself or if it will need to go to a garage. Please explain this to me as if I am a 5 year old, because (as much as I try to pretend I know what I am talking about) and am quite new to minis and am not a mechanic. Any help at all would be much appreciated.

Thanks in advance!

[Mighty made]

It's the oil pressure switch that operates the lamp on the dash.
I think that it's a taper thread fit in the block.

You can try to seal it by unscrewing it and wrapping the thread with some PTFE plumbers tape
(just a turn or so) and then refit it in the block.

Above it is the oil pressure pipe (that goes from the block back to the oil filter)

Rover changed the fitting from a banjo to a cheaper (leaky) rubber olive type....

There is a kit that fixes it permanently using a braided pipe and some high pressure fittings.

[Ethel]

They're all good candidates - oil pressure switch (with the wire) and oil pressure relief valve (big bolt head with the domed centre).

Both have pressurised oil behind them so clean it and watch for oil seeping when the engine is running. you can also safely undo both with the engine off and try some thread sealant, or a new washer on the relief valve - just be aware there's a spring behind it.


I'd say the rocker cover is the most likely, but the oil can only seep out of there under gravity. They often get overtightened, wrecking the rubber bushes under the tube nuts.

[tiger99]

That is the oil pressure switch, and if you can use a spanner, you can replace it yourself. There is a hexagonal shaft behind the main body for the spanner. The Rover part number is GPS133 according to the Somerford Mini web site, but any Mini supplier will know what you want.

There should be a copper washer on it for sealing, you may need a new one. If not, you may find thatthe new one has a tapered thread, in which case you wrap the thread anticlockwise with a few turns of plumber's PTFE tape (available from DIY stores, usually under £!) before screwing it in to get a good seal.

I strongly reccomend getting a Haynes manual, as pictures are very helpful in identifying parts, and it will help you to be able to formulate the right questions to ask here.

[Black Pearl]

Clean the area with a paint brush and some washing up liquid..

Let it dry and run the engine again to see where the oil is coming from..

Mine leaked earlier this year..luckily i had a lambda sensor for another car with the same size copper washer..

Took two minutes to fix...

[jaydee]

The oil pressure switch when leaks it needs only replacing as it does not leak from the thread, it leaks from the switch itself. Overtorqueing will cause even more damage, for a part that costs a fiver, is it worth it to bodge?

[tiger99]

jaydee, well said! I was assuming that it was leaking from the body, as they always seem to do.

Actually, that is relatively a recent problem, the original design from about 1950, or whenever the first A series engines appeared, rarely leaked, but often failed electrically. Some time in the 1970s, the design changed, and they still failed electrically, but usually never leaked. I believe that it was in the mid 1980s, maybe due to worn out production tooling, that the leaking problems started.

I daresay that a new switch fitted today is going to leak within the next 10 years or so, while the 1950s ones are mostly still going strong. Such is progress.

[jaydee]

i've noticed the same thing, i've reported several failures on the later oil pressure switches leaking badly..

[Miniature]

Cheers guys! I do have a haynes manual, and I spent a lot of time scrolling through trying to work out what part I was looking at, but without knowing too much about minis I still struggled to work it out. Thanks for the advise jaydee, I dont like doing jobs by half so I will order a new switch tonight and get that replaced. This will sound like a very noob-ish question, but I assume that when I unscrew this bolt/switch all the oil in my engine is not going to come out?

I do not think it is coming from my rocker cover, as that has been replaced not too long ago, and I havent had any problems since replacing it (and I havent screwed it any tighter since). I was very aware that I could bend the rocker cover when I fitted it if I tightened it too much, so I was very careful. But then, if its not coming from my rocker cover then I am confused about all the oil around the top of my engine. I could physically see it dripping out of the oil pressure switch, so that is my main culprit, but then I do not know how the oil got from such a low part on my engine right up to the top of it.

Do you think it could just be the way the oil spreads when I am driving, or do you think I might have more that one oil leak happening?

Thats a shame that I have such a late model then, sounds like the earlier minis are much sturdier!

[jaydee]

This will sound like a very noob-ish question, but I assume that when I unscrew this bolt/switch all the oil in my engine is not going to come out?

No oil will come out, its an high point on the oil system and theres no pressure when engine is switched off.

The oil from the rocker cover could be coming from the bolt rubber seal, simply because once they've been overtorqued they deform and will leak.
Fix the oil switch issue first, then give a good clean and inspect further.
Oil on the drive i'd expect it to be from sump plug, gearbox rod seal, diff housing, timing cover.

[ibrooks]

By far the easiest way to find leaks is to clean the whole lot off and then watch where the oil appears again first.

White spirit/turpentine substitute is much more effective than soap or soapy water at loosening/dissolving oily deposits. Use a paint brush (or engine cleaning brush if we're going really mad) with white spirit to get rid of the oil and oily mud and then use soapy water to remove the white spirit. Personally I just wipe the white spirit off with lots of paper towel and let it dry unless I'm going to be painting afterwards. Be a little careful just what you drown in the liquids - the block can be washed with impunity but don't go pouring white spirit or soapy water over the dizzy - damp a rag with white spirit and wipe the coil and dizzy no probs.

Once it's clean and dry run it for 10 mins or so and look for oil re-appearing. If there is none then go for a drive and look again. Still none then run it for a couple of days and look again.

DO NOT use sealant on the oil pressure switch. Note it only has one wire. That's because the other part of the circuit is made by it's connection to the block. The threads must make an electrical connection so anything non-conductive in there is a really silly idea. If you tighten it enough then sure the threads will cut through the PTFE or whatever and make contact but... it's a taper thread so overtightening means there is a very real possibility of cracking the engine block. A taper thread should never need any sealant - that's the whole idea of the taper.

Iain

[Nu2mini]

I hope you'll be fitting one of the uprated 20 - 30PSI switches. It will warn you of any problems before doing real damage to the engine. If that amber light comes on somethings not right. Stop, switch off and find out what's wrong.

http://www.minispare...id=34094&title=

[tiger99]

That is just plain wrong. Taper threads, as used in plumbing, ALWAYS need some kind of sealant. They may make metal to metal seal if you do them up ridiculously tight, but usually not. The problem is that the thread profile always has a reduced tip, so it does not jam in the female thread, so there is always a leak path around the edge of the thread, all the way along, even if the thrust faces are in firm contact. If you make a thread with no root or tip clearance, it jams.

You are far more likely to break the engine block by forcing in a bare thread, trying to create the impossible seal, than by using PTFE tape and only gentle torque. The thread always does cut through the tape and allow good electrical contact, but the tape plugs the root and tip clearances to prevent the leals.