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Old 9th April 2021, 20:10   #11
Dorchester2
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Quote:
Originally Posted by COLVERT View Post
It's the piston seals inside that are worn.---
The cap at the end unscrews and has the valve remover on it.--There are no counter weights and nor are they needed. It's just the air pressure that moves the sliding section.---The tiny hole at the business is calibrated to let a certain amount of air flow through the gauge.---

Thank you for that but in that case I'm puzzled to learn why my tester is failing while indicating the highest pressure whatever tyre & pressure I'm testing...
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Old 9th April 2021, 20:30   #12
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It looks like there is a bit missing from your gauge. The end that presses on the tyre valve should have a round gasket which seals against the valve stem, and a pin which then presses against the valve, allowing a sample of air to be released, which ejects the gauge to showing the relevant pressure.
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Old 9th April 2021, 23:01   #13
COLVERT
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Quote:
Originally Posted by Dorchester2 View Post
Thank you for that but in that case I'm puzzled to learn why my tester is failing while indicating the highest pressure whatever tyre & pressure I'm testing...
The air from the tyre and the calibrated friction balance one against the other to give you a reading.-- No friction from the seal means the sliding section can go to the maximum distance which is what is giving you the reading you are getting.
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Old 10th April 2021, 07:07   #14
Dorchester2
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Here is my tester from another angle and how it looks like.

Obviously if anybody possessing the same may take a pic of his it would help me a lot to understand the difference, i.e. the shape of seal and pin we were talking about above.

Thanks.



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Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp
  • This vehicle was the 7,517th 75 to run off the production line, out of 112,381
  • This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214
  • This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s
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Old 10th April 2021, 15:55   #15
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Have a look at this, just a pic I found online. I have an old pencil gauge but not sure where it is.

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Old 10th April 2021, 15:59   #16
Dorchester2
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Thank you Steve. Hence does it look like I only need the right seal?
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Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp
  • This vehicle was the 7,517th 75 to run off the production line, out of 112,381
  • This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214
  • This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s
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Old 10th April 2021, 18:05   #17
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I think its more than just the rubber gasket. Bit of internet digging revealed this old Rover tyre pressure gauge. As well as the gasket there's a brass screw type thing in the centre.

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Old 10th April 2021, 19:17   #18
COLVERT
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Quote:
Originally Posted by stevestrat View Post
I think its more than just the rubber gasket. Bit of internet digging revealed this old Rover tyre pressure gauge. As well as the gasket there's a brass screw type thing in the centre.

That screw out bit is the very carefully calibrated hole that lets the air into the gauge.


If you look up Air Gauging on the internet you will find lots of info on how air flowing through a hole can be be used to very accurately gauge the diameters of holes. Also the thickness of sheet materials down to 0.00005 of an inch.
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Old 11th April 2021, 12:57   #19
Dorset Bob
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It looks like you need a new seal washer.

Could be worth contacting Gordon Edwards of Vintage Pumps, as he is a specialist on this kind of thing.

https://vintagepumps.co.uk/tyre%20pr...%20gauges.html
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Old 11th April 2021, 16:47   #20
COLVERT
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Quote:
Originally Posted by Dorset Bob View Post
It looks like you need a new seal washer.

Could be worth contacting Gordon Edwards of Vintage Pumps, as he is a specialist on this kind of thing.

https://vintagepumps.co.uk/tyre%20pr...%20gauges.html
Nothing special about the washer and very easy to make one.---
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