Fuel sight glass question.

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Model T Ford Forum: Forum 2012: Fuel sight glass question.
Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Pletcher on Monday, August 06, 2012 - 01:50 pm:

I have an aftermarket sight glass to show gas level in the tank of my '26 T. It is mounted just inside the passenger side door. When the gas level is low the sight glass doesn't leak, but Saturday after filling the tank, I noticed that the bottom of the sight glass is leaking. It seems to be coming from the joint where the glass tube is attached to the copper base. I'm taking it off the car this afternoon and want to repair it. Any suggestions for sealing the glass tube to the base?

Regards,
Larry Pletcher

'26 T roadster
'25 DB bus sedan
'31 A tudor


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Monday, August 06, 2012 - 02:55 pm:

The original was probably leather but a washer or o-ring made of Nitrile (aka: Buna-N) is your best bet. Next would be Nylon or Acetal but these are plastics and would need a higher compressive force to seal. As a last resort, replace it with leather.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Monday, August 06, 2012 - 06:33 pm:

Larry:

More likely the gas is leaking above that joint and running down. For a site glass to work the top of it MUST be open to air which means that you need to mount it so there is no chance that the fuel can overflow and come out of the top vent hole. The problem is a bit like a gas cap leaking when you have a full tank and the gas cap simply has a hole in it rather than a couple of offset holes to prevent the liquid from squirting out through the vent hole when the fuel sloshes around. If the leak is the vent hole itself then you need to figure out how to mount it higher or to baffle the vent in some fashion.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jay - In Northern California on Monday, August 06, 2012 - 09:01 pm:

Larry, A picture of your gauge would help here.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Pletcher on Monday, August 06, 2012 - 10:21 pm:

Thanks for your replies. I spent most of this afternoon working on it and the photos that follow show a sight glass that does not leak anymore. Before I drained it I verified that the leak was at the bottom and that the small hole in the cap was open.

I let the tube drain and then removed it. I took off the cap and saw that there was a leather pad that appeared to put pressure on the glass tubing as it was tightened. I experimented with the cap and found that when the cap was tightened and I covered the hole in it, I could not blow air through the inlet at the bottom. When the cap was loosened, air would escape. At this point I assumed that I could have stopped the leak by simply tightening the cap.

I cleaned the sight glass and re-installed it. I made sure the top cap was tight, and the leaking was over.

Again thank you for your comments. I hope these photos work. It has been a long time since I tried to upload pics to the forum.
Regards,
Larry Pletchergas sight glass 1gas sight glass 2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nick Miller on Saturday, August 11, 2012 - 08:53 am:

Larry,
I too have a gas gauge that needed work. I broke off part of the glass tube when removing it. Filing and grinding evened the top of the glass tube and a rubber gas line filled the gap like a longer seal. New paper behind the glass, cleaning and reassembly worked without a leak. The top vent never seems to leak ether. Great conversation piece and practical time saver.
Nick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown on Saturday, August 11, 2012 - 09:45 pm:

Hi Larry: I had one of these and it worked well. I put a shut off valve at the gauge. If the glass cracks it will empty the tank in your floor. You can keep the valve closed for safty, and turn it on when you want to use the gauge. There are valves that fit right at the gauge and gas line and look like they belong there.


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