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77' IT175 Carburetor Won't Stop Leaking

13 Feb 2020 08:21
Songpool5
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77' IT175 Carburetor Won't Stop Leaking #1
Hi Experts!

I'm continuing to work on this great IT175 that I got earlier this winter, but I'm having a continuing problem that I was hoping for some advice on.

I've adjusted the float switch to the factory spec., replaced the fuel valve + needle, and the corresponding gaskets, but no mater my tinkering, fuel continues to slowly drip out of the overflow drain on the bottom of the carb.

Can anyone confirm if the floats are supposed to be oriented so that the brass tabs are down towards the bottom of the carb? Any other ideas why it might be slowly dripping?

Thank you!

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13 Feb 2020 13:52 13 Feb 2020 13:52 by RT325.
RT325
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77' IT175 Carburetor Won't Stop Leaking #2
I wonder if you attach a clear hose to the pipe & bring it up the side of the carb. Then have a cuppa tea--then see if it's risen up in the tube to the level of the top of the tube so you can verify its going over the top & out--or if its broken neat the base of the tube. Might have to rethink that plan as might not work [would it?]. Or sit carb upside down with bowl off but hooked up to the tank & see how much finger pressure it takes on the float arms to stop the flow. Can be a pain sometimes when things like that happen for no obvious reason.
Welcome by the way.
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13 Feb 2020 14:36
MarkT
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77' IT175 Carburetor Won't Stop Leaking #3
My guess is maybe the manual you have has the wrong specs? Is the float arm parallel to the carb body with the needle/seat closed?

Where did you get the new float needle and seat? Some aftermarket stuff isn't too good.

Is the carb body corroded? Rarely I've seen a pinhole in the casting bypass the needle and seat.

If you have the carb off the engine, float bowl removed, you can attach low pressure air (<3psi) to pressurize the fuel inlet and hold the float arm closed with your finger and look for leaks with soapy water...

Finally, a couple of times I've seen the brass stand pipe in the float bowl get a hairline crack in it. With float bowl off, fill it with thin liquid (water is safer than gas) to a point just below the top of the stand pipe and see if you get the drip out of the fitting. at the bottom. Stand pipe should almost be as tall the gasket surface in the bowl.

Pictures would help too...

1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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16 Feb 2020 12:08
Songpool5
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77' IT175 Carburetor Won't Stop Leaking #4
Gosh dang it Mark, you really have seen it all haven't you?

Sure enough, a hairline crack down the overflow tube... Any advice on how to patch? I sanded and cleaned with mineral spirits and was thinking of some jb weld unless anyone has a reason not to.
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16 Feb 2020 13:38
MarkT
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77' IT175 Carburetor Won't Stop Leaking #5
Standard JB Weld will eventually dissolve in gas...

The specialized JB "gas tank weld" epoxy should hold up... most auto parts stores carry it. I remember finding a brass tube at the hobby shop that was slightly larger and soldering it over the original. I don't remember how well it worked... I remember it not being easy to solder. I do remember just replacing a couple of float bowls with used ones and throwing the bad ones away.

I'd probably try the JB fuel-proof epoxy if I did one today... that sounds like a good idea. :likey

1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

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16 Feb 2020 19:21
Bobv07662
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77' IT175 Carburetor Won't Stop Leaking #6
I have had success by pulling the split tube out and replacing it with a similar sized piece of brass tube from the hobby shop.
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