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Dek
05-05-16, 07:18 PM
32948

Been trying to find a slight oil drip and noticed the top of the oil pressure switch was oily and dripping onto the back of the block. I took it off and noticed it's got what appears to be an oil reservoir at the top with a tiny pin hole in it. The pin hole would obviously let air out to let the oil in under pressure but this is where the oil is leaking from. Can anyone explain what should be happening here?
Cheers.
Dek

StewbieC
05-05-16, 07:39 PM
I've had oil pressure switches go and start to leak. I'd imagine there's probably a diaphragm in there which has got hard and split. Just chuck it and buy a new one.

Dek
05-05-16, 08:52 PM
I've had oil pressure switches go and start to leak. I'd imagine there's probably a diaphragm in there which has got hard and split. Just chuck it and buy a new one.

Yes a diaphragm would explain it and you're probably right, replace it. Am I likely to get it at a local motor factor?
Dek

kdavies3
06-05-16, 07:56 AM
depends what engine you have.
most of them are fairly generic, take it with you to the factors and see if they can match it.
I bet they ask for your registration number. about as much use as a chocolate fire guard to them. LOL.

Dek
06-05-16, 07:34 PM
Yes gone are the good old days when they were happy to go and have a look out the back. Now all they want to do is use the computer and then still give you the wrong part! That's why I always take the old part with me if possible.
Dek

StewbieC
07-05-16, 04:31 PM
You could try a motor factors but I'd imagine that tinterweb may be your friend. Thread will probably be NPT if it's a yank block. Definitely if it's a Ford.

Dek
07-05-16, 08:11 PM
You could try a motor factors but I'd imagine that tinterweb may be your friend. Thread will probably be NPT if it's a yank block. Definitely if it's a Ford.

Thanks Stu, it's a SBC so perhaps I should have a look on evil bay .
Dek

tonym
07-05-16, 08:20 PM
If it's a switch for the oil light then any one will do but if it's for a pressure gauge then it'll need to be correct for that gauge :-)

Dek
07-05-16, 08:41 PM
If it's a switch for the oil light then any one will do but if it's for a pressure gauge then it'll need to be correct for that gauge :-)

It fits on top of an adaptor with a side feed to a SW gauge Tone. Looks like I might struggle. What about that American Auto store near you on the A5? They were quite helpful last time I went to them.
Dek

tonym
08-05-16, 08:54 AM
To be honest Dek, it looks like a rover oil switch similar to this one http://www.ebay.co.uk/itm/LAND-ROVER-SERIES-2a-3-2-25-Oil-Pressure-Switch-90519864-/391018601400?hash=item5b0a865bb8:g:UkoAAOSwwTlUps7 Z

Dek
09-05-16, 10:03 PM
Thanks Tony, it does indeed. If only they gave the thread size. I'll see if I can find out.
Dek

Dek
28-07-16, 06:23 PM
Having no luck sourcing a new oil pressure switch from several local motor factors in spite of it having 'made in England' and a number stamped on it. One of them thought the number related to a John Deer tractor! Would it help if I knew the thread size and how do I determine it? The thread is actually tapered (presumably to seal it) and measures 0.368 inches at the base and 0.405 inches at its max. There are 12 threads over its half inch length. It's screwed into a T piece which also connects to the Stewart Warner gauge. Any suggestions anyone?
Cheers.
Dek

StewbieC
29-07-16, 06:57 AM
I would have guessed 1/8 NPT.

does this help? https://mdmetric.com/tech/thddat19.htm

if you google 1/8 NPT low pressure switch plenty will come up.

aaronjb
29-07-16, 10:43 AM
A bit of trig to double check and I'd concur; the maths says that a 1/2" long 1/8 NPT fitting should have 13.5 threads, be 0.405" at it's widest and given a 1ยบ 47' angle be ~0.389" at it's narrowest end..

Dek
29-07-16, 10:24 PM
Thanks guys that's really helpful! Now I've got a starting point.
Cheers.
Dek

Dek
11-08-16, 08:29 AM
Just a quick follow up to say after a couple of futile visits to local motor factors who asked "what's the reg." ? I found one who looked at it and said " 1/8 NPT that's a 50500". Well done Northants Auto Parts and Service (NAPS) and you guys for all your advice. Job done!
Dek

StewbieC
11-08-16, 12:37 PM
Glad you are sorted Dek.
Shows that a problem shared can be a problem solved.

Dek
11-08-16, 05:49 PM
Glad you are sorted Dek.
Shows that a problem shared can be a problem solved.

How true!
Dek