Oil Pressure Gauge

[James k]

Hi,
I've got a Durite oil pressure gauge that I'm trying to fit. The problem I've got is that the ESM oil pressure pipe doesn't fit into the back properly. It starts screwing on but then gets too tight to turn. I'm guessing that there's a thread mismatch. Any ideas how to sort it out? Has anyone fitted one of these gauges?

Thanks,
James

[aupickup]

is it a tapered thread like the temp fitting in the head

[James k]

It's not tapered, the nut has to go fully home. It just seems to be the wrong thread pitch.

[amgrave]

If you do a forum search you will find a couple of threads that cover it. If memory serves there is two screw threads that are very similar and it sounds like you have a mismatch between them but you will be able see what the two threads are.
Good luck.

[philthehill]

See my post below.

[James k]

I've currently got the pipe screwed into a smiths oil pressure gauge (which I've borrowed and must return ASAP). It fits fine on the smiths gauge but gets too stiff on the new one. Is it possible that it has a different thread?

[philthehill]

James
I think that I have got to the bottom of your problem.
The threads on the back of your Durite oil pressure gauge are 1/8" National Pipe Thread Fine (NPTF) at 27 TPI. See the attached link:-
http://autoelectricalpartsuk.co.uk/prod ... 53316.html
The threads on the rear of your Smiths oil pressure gauge are 1/8" British Standard Pipe (BSP) at 28 TPI.
I have confirmed the threads on the rear of a Smiths oil pressure gauge by using a 28 TPI thread gauge, screwing a 1/8" BSP 28 TPI oil take off adapter onto the rear of the gauge and screwing a 1/8" BSP plug tap into the take off adapter.
Therefore if the pipe supplied by ESM is 1/8" BSP at 28 TPI it will not fit the Durite gauge without difficulty.
I would suggest that If you want to use the Durite gauge you will have to use the correct pipe.
See link:
http://www.durite.co.uk/ItemDetails/Ite ... ber=053398
Phil

[James k]

Thanks for that Phil, I suspected that the threads were wrong. I really wanted to avoid using the copper pipe (which was supplied with the gauge) as it seems more fragile and more hassle than the plastic. Perhaps I can get a pipe adaptor.

[Declan_Burns]

James,
You need a Male/Female BSP/NPT Adaptor.
Something like this
http://www.ebay.co.uk/itm/Brass-Male-Fe ... qCwRegards
Declan

[philthehill]

If you want to use the ESM oil pressure gauge pipe you will need to make sure that the BSP male threads on any adapter are not tapered as the straight threaded female unions on the end of the pipe will not fit the taper threads very well.
You could use the adapter if the adapter screws directly into the block or oil pressure adapter 'T' piece as in the photo attached.[frame][/frame]

[James k]

Hi,
I've been searching ebay for the correct adapter and the best I can come up with is the combination of these two:

http://www.ebay.co.uk/itm/1-8-NPT-Femal ... SwbqpT20~J

http://www.ebay.co.uk/itm/Straight-Bsp- ... 2wibtgG40g

One is a BSP to NPT female-female adapter and the other is BSP to BSP male-male. My idea is to screw the female adapter onto the gauge to convert it to BSP female then to use the male-male adapter to couple the pipe to the gauge. Is there any reason why this wouldn't work? I've tried to find a single adapter to do the job but I can't find one that's correct; they all seem to have tapered BSP.

[philthehill]

James
What you are proposing as regards the adapters is good except that the male/male connector should be tapered thread/straight or parallel thread.
The ESM pipe connector will only fit a straight thread so what you will need in conjunction with the first part quoted above to allow it all to fit together is this:-

http://www.moss-europe.co.uk/union-oil- ... soc=417423

I have one of the MOSS type connectors in front of me as I write this but it has a male taper / male parallel thread which has a countersink to receive the pipe union and is made from brass (removed from a 1275cc MG Midget engine). If both the MOSS connector threads are straight it is of no consequence as the connector will fit the female/female adapter. Just secure with LOCTITE Seal and Lock, you may not need the fibre washer and its requirement would be dependent upon the depth of the female threads.

You may need two - one for either end of the pipe but numbers will be dependent upon what block fitment you have.

Phil

[James k]

Hi Phil,
what is it that the tapered thread is for? I thought it would need to be parallel in order to fit both the pipe and the female-female adapter.

[philthehill]

James
The taper thread is to ensure an absolutely oil tight fit and the tighter you screw it in the better the seal.
The male taper thread can be screwed into a female parallel thread without any worries.
Here is a photo of the MOSS type adapter.
It has a taper thread where it fits into the 'T' adapter which has a parallel thread to accept the MOSS type adapter.
The 'T' Adapter has a taper thread which screws into the block which has a parallel thread.
The other union connection is also a parallel thread.




Phil[frame][/frame]

[James k]

Okay, so the taper thread is to screw into the female-female adapter?

[philthehill]

James
Correct.


Phil[frame][/frame]

[James k]

Ah, I've got it properly now. The female-female adapter will give me an 1/8" BSP fitting at the back of the gauge so I can use the same adapter to connect the pipe to the gauge as I did to connect the pipe to the T-piece. Is that right?

This is the one I bought:
http://morrisminorspares.co.uk/shop/pro ... ac2e72267d

[James k]

Brilliant picture! That makes it very clear. My only problem now is that the female-female adapter I found is NPT and not NPTF. I'll look around for another one.

[philthehill]

James
I suspect that the NPT side of the female/female adapter listed in 'e' bay is actually NPTF - so one and the same.

See: http://www.bing.com/images/search?q=nat ... ajaxhist=0

The 1/8" NPT has the same number of threads per inch (27 TPI) as 1/8" NPTF so the adapter should work.

Substitute the MOSS adapter with the ESM adapter and it should be plain sailing.
Phil

[James k]

Thanks,
I've ordered both pieces now. I got this straight adapter since it was cheaper than ESM or Moss and had free delivery: http://www.ebay.co.uk/itm/181841694480