Opinions on Oil Pressure & Gauges

I have a newly rebuilt engine in my '72 S3. Ran the engine on the test stand with 40-60 psi (depending on engine temp) using the stock electrical gauge/sender. After installing the engine and wiring everything in, the gauge would build to 60 psi then slowly drop to zero. I installed a cheap mechanical gauge in place of the sending unit. Gauge reads a solid 70 psi at 800 rpm, cold. Pressure is a little high but I am not concerned about that on a new rebuild. My question: should I install a new gauge that reads 0-100? or just get a new sending unit for my existing gauge? Probably a $200 difference between these options. Will the higher pressure damage my stock 0-60 psi gauge?

What I did was install a mechanical gauge from a TR6 – no reliance on an electric sender:

Close to looking original though it goes to 100 psi.

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Only the very knowledgeable would notice and only a judge would care. Looks good to me.

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The gauge either works or it doesn’t. The sender, OTOH, can do all kinds of flaky stuff. Your problem is surely the sender, NOT the gauge.

Regards,
Ray L.

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Where did you route the tubing for the mechanic gauge?

Braided cable… under the intake manifold:

Through the same hole/grommet as used for the reverse lamp wires:

Then into the instrument area with enough slack to open it fully:

I now know that a right angle connection is available for the gauge - that would be a good idea.

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Thank you! I am going to go with the same set up you are showing. Not being able to trust an oil pressure gauge after a rebuild is nerve wracking. The mechanical gauge will provide some assurance.

i have a mechanical oil gauge in the engine compartment as a back-up check. I like the look of the smith’s (which seem to work) in the dash…

where did you acquire the Gauge and Braided line ?

SNGB sells one, 0-100 psi

To expedite other’s searching for the same:

https://www.sngbarratt.com/us/#!/English/parts/6f5f99ad-15cd-43d6-900f-7e691794d67b

$234 for the kit.
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Barratt’s lists it as applicable for the Series I but (and I stand to be corrected) that is only because the bezel matches the other gauge on the Series I dash. For non-Series I applications, either accept the minor discord in appearance or transplant an appropriate bezel.

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The current generation of Smiths gauges are junk. I recently bought one of the iconic dual-gauges used in so many Brit cars, and BOTH the capillary water temp and mechanical oil pressure side were flaky as hell. The oil pressure side was off by 10 psi in the 40-60 psi range.

I just so happened to be going by my local gauge shop, and he said “don’t send it back, I can fix it”…he ended up spending 4 hours monkeying around with it. He only charged me for an hours labor, but I would have been ahead of the game having an original restored.

When I picked it up, his comment was “that’s the first time I’ve seen the inside of a ‘new’ gauge in 20 years…they look like cheap replicas if the old gauges”.

Which is why I’m converting mine to modern stepper motor movements…

Regards,
Ray L.

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The gauge was from a TR6 - bought on eBay for $30.

The braided line was from 7 Enterprises:

The fitting I used was from Mini Mania:

https://www.minimania.com/part/OA/Oil-Pressure-Gauge-Adapter-For-Fitting-Into-Block

A 90° fitting I probably should have also used:

https://www.minimania.com/part/OAA/Classic-Mini-Angled-Oil-Pipe-Adapter

If you are okay with a plastic line (the one in my TR is 55 years old) then Mini Mania has that too:

https://www.minimania.com/part/A-PL04/Classic-Mini-Hose-Kit-Oil-Pipe-5-Oil-Pressure-Line-Kit--Sprite-And-Mg-Midget

Having said all that (and looking for that right-angle connection) it appears these blokes have everything and for much less. Shipping seems to be reasonable too. Mostly because of the pound/dollar rate and no VAT.

http://minispares.com/

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Ditto on the 0-100 gauges being junk. I had one that was wildly inaccurate…in fact it wouldn’t read above 30 PSI when I tested it with compressed air. An original Smiths gauge from a Lotus Europa reads 0-60…if you can find one. I believe the Sunbeam Tiger also read 0-60.

By the way, there are many old threads on this subject in the archives…part numbers, hose routing, the whole enchilada.

Yes, the Europa gauge is probably the closest to an identical 0-60 psi E-type gauge, with mechanical guts.

I have to believe those gauges must have also come in some other (more common) car. Lotus never had anything like that made special for their cars…they were masters of raiding Triumph, Ford, and BMC parts bins. As an example, the rear bumper on a Europa is front bumper from a Mk1 Cortina, while the front bumper on a Europa is a 105E Ford Anglia front bumper, just turned upside down!

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That’s how they got the “Europa” name: IIRC, part of the deal was to use components from all EU(ropean) members.

Interesting…is that how the early ones ended up with Renault engines? :face_vomiting:

I’m glad they corrected THAT mistake later on.

I like my new “Smiths” oil pressure gauge. At startup and with decent revs it reads 50 lbs and then decreases as the engine heats up. It makes me feel good compared to the original gauge and the replacement sender that would suddenly drop to zero for no known reason and then jump up past 60. Only a few hundred miles on it so far. Will see how it handles 5000 miles this September.