Fitting an oil gauge.

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amgrave
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Re: Fitting an oil gauge.

Postby amgrave » Sat Jun 06, 2015 12:04 pm

Thank you everyone for the answers, most illuminating and surprising. Can the answer be added to the thread size chart at the top of this section for future reference?
EDIT: Just found the size mentioned halfway down the page about thread sizes, oooppps :oops: :roll:


Wadams
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Re: Fitting an oil gauge.

Postby Wadams » Tue Feb 04, 2020 2:24 pm

Hi Guys

Would you mind helping out a complete novice please? I have had a 1965 Morris Minor saloon for several years now and my father in law was teaching me all about the car up until he passed away a year ago. I have bought a water and oil gauge from David Manners and I have managed to fit the water gauge without any problem. However, The oil gauge is working fine as a gauge but I cannot attach the light cable unless I have a T piece and a threaded bar into which I can screw the pressure gauge then attach the light wire.

The problem I have is the pressure switch seems to be an unusual thread size that does not appear to fit into standard connections. Can anyone advise what the thread size and type is likely to be and where I can get a T piece that will allow me to have the gauge and light working at the same time please?

Thanks in advance.

Wayne

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philthehill
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Re: Fitting an oil gauge.

Postby philthehill » Tue Feb 04, 2020 3:29 pm

The thread is 1/8" NPT.

Here is an adapter 'T' piece suitable for the Minor 'A' Series engine.

https://www.ebay.co.uk/itm/Classic-Mini ... SwuuVd3p~9

The majority of thread sizes including the oil pressure connection (read - oil pressure switch) are listed at the top of the Mechanical section.

Phil


Wadams
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Re: Fitting an oil gauge.

Postby Wadams » Wed Feb 05, 2020 5:42 pm

Hi Phil
I have looked at the T piece you showed in your reply but there doesn't seem to be anywhere for the electrical spade connector to fit on. Also, can I assume that the flexi hose connector fits this T please?
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Wadams

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Re: Fitting an oil gauge.

Postby Wadams » Wed Feb 05, 2020 5:42 pm

Hi Phil
I have looked at the T piece you showed in your reply but there doesn't seem to be anywhere for the electrical spade connector to fit on. Also, can I assume that the flexi hose connector fits this T please?
Cheers
Wadams

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philthehill
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Re: Fitting an oil gauge.

Postby philthehill » Wed Feb 05, 2020 8:17 pm

You have to fit the 'T' piece adapter into the block, then the oil pressure warning light switch into the 'T' piece and then the warning light electrical connection attaches to the switch. The 'T' piece is only there to provide the duel facility for the oil pressure gauge/oil pressure warning switch.
The oil pressure gauge flexible pipe and the oil pressure warning light switch can be fitted into either hole of the 'T' piece but use whichever hole is suitable for either switch or pipe.
You may have to fit an adapter piece between the 'T' piece and the flexible hose. Some kits provide the adapter and some do not.
The adapter piece screws into the 'T' piece and the flexible pipe screws onto the adapter.
Here is a suitable adapter:-

http://www.minispares.com/product/Class ... o%20search


ampwhu
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Re: Fitting an oil gauge.

Postby ampwhu » Sat Feb 08, 2020 8:02 am

oil pressure.JPG
oil pressure.JPG (45.57 KiB) Viewed 609 times
I use the combined water temp and oil pressure gauge from a mg midget. the other end of the braided pipe goes to the back of the gauge. the connection is 1/8th BSP.

ampwhu
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Re: Fitting an oil gauge.

Postby ampwhu » Sat Jun 27, 2020 9:36 am

coming back to this, there is i think an easier way of doing this. These pictures are from my A35 engine.

If you remove the banjo bolt at the rear left side of the engine, it's the ideal place for connecting.
adaptors.JPG
adaptors.JPG (56.12 KiB) Viewed 427 times
i guess your all familiar with the 'gold' coloured adaptor that you can get from all the mini suppliers. Well i've fitted these in the past but find them too fiddly and have lost a few leather washers trying to get the damn things on. Then there's the dizzy in the way etc.... so with the banjo bolt you have the option of fitting the pipe there.

If you drill a 8.5mm hole down the middle and tap it to 1/8"NPT, you can either screw the adaptor in there or the pressure switch. I thought that there was no point moving the switch.
Oil pressure tube.JPG
Oil pressure tube.JPG (66.83 KiB) Viewed 427 times
upon start up I had 60psi oil pressure and after a 20 mile run, it had 30psi on tick over. Job done.

pgp001
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Re: Fitting an oil gauge.

Postby pgp001 » Sat Jun 27, 2020 6:54 pm

What a good idea.
I have just been out and removed the clumsy Tee piece from my spare engine that is nearly finished.
I have done exactly the same as you and tapped a hole in the banjo bolt, it is a much neater solution.

One thing I found was that those fittings are not NPT as has been stated a few times.
1/8" NPT is 27 TPI, but I measured mine with thread gauges and they are all definitely 1/8" "BSPT" ie 28 TPI.

The only thing I do not like about your idea of tapping the banjo bolt, is that I didn't think of it first :D

Phil

ampwhu
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Re: Fitting an oil gauge.

Postby ampwhu » Sat Jun 27, 2020 7:13 pm

all the other oil pressure fittings i've used from ESM and all the other MG suppliers have defiantly been 1/8"NPT. the exception is the braided hose which is 1/8" BSP. This goes from that little male/male adaptor to the gauge itself.

It's a cool way of doing it.

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philthehill
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Re: Fitting an oil gauge.

Postby philthehill » Sat Jun 27, 2020 7:44 pm

The threads in the block are 1/8" BSP x 28 TPI (parallel). The threads on the oil pressure switch are 1/8" x 28 TPI BSP (taper).

It is possible to use NPT taper threads in BSP parallel threads.


jaekl
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Re: Fitting an oil gauge.

Postby jaekl » Sun Aug 30, 2020 12:05 am

Phil, what made you to change your mind? Someone referenced this post on another messageboard. Earlier this year I confirmed the sender and the gauge tubing adapter are 1/8 NPI, but this post had some strong opinions that it should be BSP. I also know that the original style senders have a Whitworth sized hex, so I went and checked again and checked a couple of blocks. A NPT pipe threads all the way in very smoothly. A 27 TPI thread gauge falls into the grooves very easily. The 28 TPI left little gaps. With the 3/8 inch length, there's not much to see. I forgot to check if it's tapered but I think it is feeling the way the pipe tightened up.

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philthehill
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Re: Fitting an oil gauge.

Postby philthehill » Sun Aug 30, 2020 9:42 am

In my 5th September 2013 post I stated that the oil pressure switch threads in the block as 1/8" NPT x 27 TPI. In light of my post above (which I cannot edit as it has been timed out) and the query raised I have revisited the oil pressure switch threads thread and this morning also made physical checks on the oil pressure switch threads in two blocks.

You are correct in that the 1/8" x 27 TPI NPT tap will go into the female threads in the block as you say smoothly. But so does a 1/8" x 28 TPI BSP but certainly not as smoothly as the NPT tap. So I will revise the above and state that the threads in the block are 1/8" NPT x 27 TPI.
The real problem lies with the oil pressure switches and block adapters which have both 1/8" BSP and 1/8" NPT threads and again come in both taper and parallel threads. One adapter I have has male 1/8" NPT taper threads and 1/8" BSP parallel threads.

To sum up - the block adapters which ever taper thread is used will fit into the block but the other male and female threads in the adapter should be checked for correctness.
The photo below has a 1/8" NPT tap screwed into the block adapter.
img278 (2).jpg
img278 (2).jpg (208.29 KiB) Viewed 258 times
In the photo below the oil pipe adapter screwed into the block adapter has a 1/8" NPT taper thread and a 1/8" BSP parallel male thread for attaching the oil pipe.
img279 (2).jpg
img279 (2).jpg (112.96 KiB) Viewed 258 times


jaekl
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Re: Fitting an oil gauge.

Postby jaekl » Sun Aug 30, 2020 12:47 pm

So that's confirmation that the Series A engine is completely UNF (well except for the studs, UNC). We don't have to worry about coming across a BSP fitting over here, but I'm glad the threads will match what we have. I can see that brass and maybe even steel can accommodate the slight discrepancy in the threads when using BSP. Pipe threading involves a bit of interference to seal.

I just remembered, I think the drain and fill plug in the gearbox is not NPT, so no the A Series is not completely Americanized. That what I just have stated above rather than UNC, but it's still wrong.

oliver90owner
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Re: Fitting an oil gauge.

Postby oliver90owner » Sun Aug 30, 2020 1:37 pm

It should be quite easy to check those threads with a set of thread gauges (or with a travelling microscope, if you have access to one).

pgp001
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Re: Fitting an oil gauge.

Postby pgp001 » Sun Aug 30, 2020 2:01 pm

In the ideal world BSP and NPT threads should not be directly mixed, but I generally use a bit of PTFE tape when assembling them and have had no bother so far on the smaller sizes such as 1/8".

Phil P

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Re: Fitting an oil gauge.

Postby ampwhu » Mon Aug 31, 2020 6:51 pm

pgp001 wrote:
Sun Aug 30, 2020 2:01 pm
In the ideal world BSP and NPT threads should not be directly mixed, but I generally use a bit of PTFE tape when assembling them and have had no bother so far on the smaller sizes such as 1/8".

Phil P
i've never been a fan of PTFE. having been in the plumbing game for more years than i care to remember, i use a liquid equivalent that's suitable. once this has dried, it is almost impossible to undo. its made by Cimberio in Italy. (about the only thing they got right). It's fine to use on thread you don't want to undo again.

pgp001
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Re: Fitting an oil gauge.

Postby pgp001 » Mon Aug 31, 2020 8:12 pm

Yes I do use thread seal as well depending what I am doing, PTFE is good for air fittings, but you dont want bits of it coming loose and getting stuck in oil ways.

Probably best to use the liquid variety in this instance. I quite like Wellseal.

Phil

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Re: Fitting an oil gauge.

Postby oliver90owner » Mon Aug 31, 2020 9:28 pm

It's fine to use on thread you don't want to undo again.

But don't a lot of threaded fixings eventually need to come apart on a vehicle?

An appropriate loctite (or similar) product would surely be better than risking breakage later?

Wellseal is for sealing joints to prevent fluid leakage, not primarily for preventing fixings from undoing. I’ve used it, in the past, as a sealant between metal-to-metal joints where no gasket is employed (crankcase halves on engines, as an example).

If the application includes a tapered thread a sealant, such as Wellseal, may be adequate, but a filler type would be preferable in my book - the item is never likely to unscrew with a tapered thread. I would use it to prevent leakage on parallel threads where no great hydrostatic pressure is involved - otherwise an appropriate gasket/O-ring/washer would be employed.

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Re: Fitting an oil gauge.

Postby ampwhu » Mon Aug 31, 2020 9:38 pm

No not really. In the case of the oil pressure adapter being screwed into the banjo bolt, I'm never going to unscrew it for any reason in the future. If I wanted to remove the pressure gauge adapter, I'd just fit another banjo bolt without a hole down the middle.

In the case of using the liquid sealant I use on pipe fittings, your not going to want to remove it further down the line. If its thought out from the start, the glue is permanent. It's never ever leaked in the years we've used it. Therefore we use nothing else.


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