Capillary tube fitting leak

[gjz30075]

I have a leak where the capillary tube goes into the adapter in the head. I'm pretty sure it's not the
adapter. When first assembled a few years ago, it was a freshly 'rebuilt' gauge from Mo-ma and
there was no leak. Gauge failed recently so back to Mo-ma it went. I now have a leak at this
fitting location and I'm reading that there should be a gasket on the bulb, where it meets the
adapter (adapter has a gasket where it meets the head). Moma says no gasket it needed.

If there should be a gasket, it looks to be pretty unique with a large i.d. to a not much larger o.d.

So, should there be a gasket at the location in the picture?

[types26/36]

If I remember correctly there should be a small copper washer on that location.

[rgh0]

I believe the original design was no gasket and just a compression fit between the aluminium adapter and brass sensor bulb.

If using a steel or brass adapter or a badly corroded aluminium one you may fail to seal without some form of gasket or sealant. I have used teflon tape on the bulb flange in the past. A soft copper washer or fibre washer may also work.

cheers
Rohan

[gjz30075]

Thanks Brian. I'll start calling our Lotus vendors to see if they have one.

[gjz30075]

Rohan, it's possible my adapter is 'borderline' , going from 'no leak' to now leaking. I'll lightly
dress the mating surface and hopefully it'll make a difference. I'll continue to look for gasket/washer,
or use teflon tape.

Thanks.

[types26/36]

Greg, just checked my spare gauge and it has a copper washer.

[gjz30075]

Thanks Brian!

[pharriso]

Yes, there should be a small copper seal, needs to be soft (ductile) to seal...

[gjz30075]

Just sourced a couple from RD Enterprises so it must be a real thing.
Thanks.

[pharriso]

Just sourced a couple from RD Enterprises so it must be a real thing.
Thanks.

Or an empty envelope...

[RichardHawkins]

Excuse me if I hijack this post, as I am currently working on this general topic of temperature measurement.

I have two gauges, I don’t remember how or why. Both are reasonably correct at 80C, one has a grommet for sealing where it passes through the bulkhead, but the temperature indicating needle is loose and tends to fall off, the other has no grommet, but the needle is secure. Does anyone know if a grommet can be fitted without cutting the capillary or the grommet, or how to secure the needle?

Richard Hawkins

[gjz30075]

You might be able to fit the grommet over the brass nut but I've always simply slit the grommet to fit on
the capillary tube

[pharriso]

I've rebuilt / recharged a number of these dual gauges & sensors...

the other has no grommet...... Does anyone know if a grommet can be fitted without cutting the capillary or the grommet....

Richard Hawkins

You can slit the grommet so the nut passes through, then use Superglue

.... but the temperature indicating needle is loose and tends to fall off.....or how to secure the needle?

Richard Hawkins

Twist the chrome bezel off the gauge, remove glass & seal... heat the sensor to 212 deg F in a saucepan of boiling water & replace the needle with a dot of superglue with the needle at the indicated temperature. It should be a push fit without, but the superglue will may sure the needle stays put.

[Craven]

RichardHawkins wrote:
.... but the temperature indicating needle is loose and tends to fall off.....or how to secure the needle
It’s a very small taper fit, very very light tap will do it.

[RichardHawkins]

Thanks for the suggestions. My travels today took me past Nottingham, so I called at Speedograph Richfield, there I was assured of what I already expected that the grommet won’t pass over the nut. Speedograph secured the needle for me while I waited and supplied a new bezel, which I thought was good value at £10 all in.

Richard Hawkins