K-Series Mechanical Oil Sender Install

[Logan_Se7en]

Hi everyone,

 

My electronic sender has become unreliable and I am refitting a Stack mechanical gauge. After research I saw it should have a M12 size fitting to the oil filter area. I went to install the new kit and the threads seem to be different. I also noticed some thread shavings came out with the old sender. Does this mean it has been retapped at some point? The old sender seems to be a 1/8 NPT. What would your recommendation be for continuing the install? I have some photos of the old sender along with the shaving that came out. Thanks!

 

Logan

Edited April 5, 2024 by Logan_Se7en
typo

[MV8]

The K series is likely bspt, not npt. Should be m10x1.0 for the new gauge but it looks like it may be 1/8 bspt above the m10 fitting. You could remove the m10 fitting from the end to check. If it is 1/4 bspt instead of 1/8 bspt, there are adapters or a 1/8 bspt compression fitting could be used if sized to match what is probably a metric sized capillary tube. (FWIW, bspt and npt are not interchangeable (slightly different thread count). They will seem to fit each other but will leak a little even if using sealing tape.)

The bspt top thread damage should not be a problem.

[Logan_Se7en]

1 hour ago, MV8 said:

The K series is likely bspt, not npt. Should be m10x1.0 for the new gauge but it looks like it may be 1/8 bspt above the m10 fitting. You could remove the m10 fitting from the end to check. If it is 1/4 bspt instead of 1/8 bspt, there are adapters or a 1/8 bspt compression fitting could be used if sized to match what is probably a metric sized capillary tube. (FWIW, bspt and npt are not interchangeable (slightly different thread count). They will seem to fit each other but will leak a little even if using sealing tape.)

 

The bspt top thread damage should not be a problem.

 

Thanks. The suspected 1/8 fitting above the M10 in the photo does appear to thread into the housing on the car (not 100% certain if it is a bspt or npt) so I will plan on installing that directly and check for leaks. I found on an Elise parts website where the K Series oil sender can be 1/8 NPT or M12x1.5 so that is making believe it may be NPT. Haven't seen anyone else talking about this size on the Caterham forums so curious why it is non standard.

 

reference: https://www.eliseparts.com/shop/engine-management-sensors/k-series-oil-pressure-switch/

[MV8]

Online stores can be wrong too. The only practical way to know if it is bspt or npt is to use an sae thread pitch gauge on the old sender. Thread pitch gauges are included with tap and die sets. Sae gauge is used to show threads per inch even though bspt is not sae. There is usually a one thread per inch difference so npt and bspt don't actually mesh evenly. Metric and bspt "go together like peas and carrots", so I expect it will fit.

Edited April 5, 2024 by MV8

[Logan_Se7en]

Solution was to clean the interior threads and I was able to install the M10 adaptor. Not sure why it was not threading initially but after the install there seems to be no leaks after an hour of driving.

[slowdude]

57 minutes ago, Logan_Se7en said:

Solution was to clean the interior threads and I was able to install the M10 adaptor. Not sure why it was not threading initially but after the install there seems to be no leaks after an hour of driving.

My sender went toast too. I've got all of the parts except for the adapter. Do you have the link for the m10 adapter?

[Logan_Se7en]

8 minutes ago, slowdude said:

My sender went toast too. I've got all of the parts except for the adapter. Do you have the link for the m10 adapter?

The adaptor came with the Stack kit. Depending on what you already have you will just need an M10 to 1/8 NPT fitting.

[slowdude]

21 minutes ago, Logan_Se7en said:

The adaptor came with the Stack kit. Depending on what you already have you will just need an M10 to 1/8 NPT fitting.

Goated. Thank you!

[MV8]

On 4/8/2024 at 6:08 PM, Logan_Se7en said:

Solution was to clean the interior threads and I was able to install the M10 adaptor. Not sure why it was not threading initially but after the install there seems to be no leaks after an hour of driving.

I suggest never trying to remove it (fittings don't make good taps and the filter is usually before the fitting port so the shavings would not be caught by the filter). The rover oil filter brackets are available new just in case or it can be machined.

Edited April 10, 2024 by MV8

[slowdude]

52 minutes ago, MV8 said:

I suggest never trying to remove it (fittings don't make good taps and the filter is usually before the fitting port so the shavings would not be caught by the filter). The rover oil filter brackets are available new just in case or it can be machined.

Wait so I shouldn't install a mechanical or I shouldn't re-tap it?

[MV8]

Both are fine but retap is not necessary with the right fitting, which may be included.

 

The threads of the sender or mechanical gauge fitting should be the same as the port in the bolt-on filter manifold. Your manifold may be 1/8 bspt, 1/8 npt, or M12.

 

The picture above shows a compression fitting screwed into the M10 fitting and clamping the tube. The male threads of the compression fitting maybe 1/8 bspt or npt where it goes into the female end of the M10 fitting. I expect this to fit the filter manifold directly without tapping but I don't know for sure.

 

Another option is if you want M10 and the manifold surface is flat enough to seal against with the washer, the manifold can be removed and tapped for M10 (or m12 if you want to use that size), cleaned of shavings, and reinstalled. The m10 and m12 do not seal at the threads. They both rely on the washer to seal.