[TR] [EXTERNAL] Re: TR2-3-4 Engine and Rad Taps

Sun May 2 16:45:02 MDT 2021

Hello All,

For what it's worth, I am a pilot and my recreational aircraft is a restored 1948 Taylorcraft with the Continental C85 engine. The wing tank fuel shut off is an original solid brass valve with a leather washer on the stem that helps stop fuel seepage out of the stem, but it is not perfect. That valve used to seep a drop here and there. My av gas is either red or blue depending on the octane. One day during my biannual check ride it seeped several drops onto the brand-new cream colored chino pants my CFI was wearing. He was not pleased. But at least avgas evaporates along with it's dye and it did not leave a permanent stain. But to prevent a recurrence the IA who does my annual inspection disassembled the valve, replaced the leather washer on the valve stem and lapped the valve stem and the valve body together, by hand, with Clover 400 and 800 grit valve lapping compound available at most machine shop supply houses and perhaps AutoZone, reassembled the valve and it no longer seeps even a single drop of avgas. The whole operation took about one hour. The valve has not leaked, or even seeped a single drop since and that was last summer.

Maybe that will work for some of these leaking or seeping fuel valves. There is a difference between a leak and a seep.

Best of luck to all of you that have this dilemma. I have found that the solid brass valves are superior to steel valves.

Randall Reihing
1959 TR3A
1948 Taylorcraft BC12D85
________________________________
From: Triumphs <triumphs-bounces at autox.team.net> on behalf of Kinderlehrer <kinderlehrer at comcast.net>
Sent: Sunday, May 2, 2021 6:26 PM
To: 'Steve Kirby' <sackirby at chinaautogroup.com>; 'Brian Thomas' <thomasb at queensu.ca>; triumphs at autox.team.net <triumphs at autox.team.net>
Subject: [EXTERNAL] Re: [TR] TR2-3-4 Engine and Rad Taps

Well Steve, it solves the mystery but not the problem. What I understand from your explanation is that you manufacture a product that is not going to perform its intended purpose. There is no indication on the Moss online catalogue that these petcocks will not function as petcocks – or that leaking is guaranteed.

I’ve installed 3 of these, 2 radiators and one block, and in each case I took them apart and polished the cone and seat, none of them have leaked. If I can do it, I don’t see why the manufacturer can’t.

Bob

From: Steve Kirby [mailto:sackirby at chinaautogroup.com]
Sent: Sunday, May 02, 2021 2:16 PM
To: Kinderlehrer; 'Brian Thomas'; triumphs at autox.team.net
Subject: RE: [TR] TR2-3-4 Engine and Rad Taps

I can provide the definitive answer to this question because my company makes these aftermarket valves for Moss Motors (who probably resells them to everyone else in the world).

The response “they all leak” is absolutely correct.  In fact, the problem is so pervasive and resistant to all attempts to solve the problem in manufacturing, that Moss no longer sells a functional valve.  What they sell has no internal drillings, it is just a plug.  It is made to look like the original for authenticity purposes, but does not function (and hence does not leak).

If you disassemble one of these, original or repro, you will see that there are no seals.  The “sealing” is accomplished by a tapered metal stem fitted into a similarly tapered metal body.  The two parts are “clamped” together by virtue of the external spring and depend totally on a very tight and concentric fit between the two metal parts.  This valve was designed well before cars had pressurized cooling systems.  And yes, they always leaked.  But back in the day, before people started using distilled water and high quality antifreeze with effective anti-corrosion additives, the valves quickly plugged up with corrosion and, voila, stopped leaking.  When they were opened and reclosed, they leaked again, until the corrosion re-plugged them.

If you are dead set on trying to make one leakproof, get some valve lapping compound, disassemble the valve, and “lap” the two parts together for an hour or so, until the two surfaces are as smooth and concentric as possible.  I have seen this work on occasion.  Basically you are perfecting the seating of the stem in the body.

If you just want to stop the valve from leaking and don’t care about the function, you can remove the valve and plug or solder the inlet port.

Jaguar used this same valve as a block mounted oil drain tap, with a bit more success due to the higher viscosity of oil vs. water.  Several British motorcycle companies and Indian used this valve as a fuel shut off (and you can imagine how that worked!).

Hope that solves the mystery.

Steve Kirby

President

China Auto Group

22831 Avenida Empresa

Rancho Santa Margarita, CA 92688 USA

Direct:  (949) 261-8208

Fax:  (949) 767-5949

Cell:  (949) 903-0957

Skype: steve.kirby29

www.chinaautogroup.com<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.chinaautogroup.com%2F&data=04%7C01%7Crandall.reihing%40utoledo.edu%7C8c22894cd16a47e29d0208d90db96887%7C1d6b1707baa94a3da8f8deabfb3d467b%7C0%7C0%7C637555912535042640%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=800i3%2B6uk9I7RQ1ptgEkQ27PrlCXVHs4ths3eOV0AwQ%3D&reserved=0>

From: Triumphs <triumphs-bounces at autox.team.net<mailto:triumphs-bounces at autox.team.net>> On Behalf Of Kinderlehrer
Sent: Sunday, May 2, 2021 10:40 AM
To: 'Brian Thomas' <thomasb at queensu.ca<mailto:thomasb at queensu.ca>>; triumphs at autox.team.net<mailto:triumphs at autox.team.net>
Subject: Re: [TR] TR2-3-4 Engine and Rad Taps

Hi Brian,

Moss’s response to the leaking issue was “they all do that”. It’s been many years since I had this same issue. I solved it by taking the valve apart and polishing the parts. I don’t remember how I polished them, maybe it was compound or 1500 grit wet/dry sandpaper.  Some PTFE on the threads that go into the block or radiator also helps. Anyway, no drips since.  I had to do this on 2 radiators.

The other alternative is to use a “modern” petcock.

Hope this helps,

Bob

From: Triumphs [mailto:triumphs-bounces at autox.team.net] On Behalf Of Brian Thomas
Sent: Sunday, May 02, 2021 9:11 AM
To: triumphs at autox.team.net<mailto:triumphs at autox.team.net>
Cc: Brad Smith (britspcars at gmail.com<mailto:britspcars at gmail.com>)
Subject: [TR] TR2-3-4 Engine and Rad Taps

Hi,

I’m having great difficulty getting either of the drain taps in the TR2 to stop leaking.  I’ve tried various used taps from my 45+ year “collection” without any success.  The taps leak mostly out the drain hole but some also where screwed into the block/rad.

I recently ordered a pair of new replacements from Rimmer with high hopes but after install, both leak from the side opposite the lever – see pic.  This is with antifreeze in, rad cap off and no pressurization.  I’ve asked Rimmer for comment, but they are closed until Tuesday (bank holiday Monday).

[cid:image001.png at 01D73F67.8B085740]

The pic is shows the engine install with the spring portion “up” – that’s what it tightened to.

Has anyone had success with current offerings from the various vendors?  I see Moss also offers them – others?  TRF doesn’t currently have them.

I’m about to give up and try the Don Elliot solution sealing the taps where they thread into the block/rad.

Appreciate any suggestions.

Stay well and cheers,

Brian

_____________________________________________________

Brian Thomas                            E-Mail:  Brian.Thomas at QueensU.Ca<mailto:Brian.Thomas at QueensU.Ca>

92 Wyona Lane                          Phone:  613-385-1947

Wolfe Island,  Ontario                Toys:  54 TR2,  56 TR3,  67 TR4A,

Canada  K0H 2Y0                                   01 XKR,  75 John Deere 920

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