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MG MGB Technical - Carb Float Repair (HIF4)

I checked the archives, and was surprised not to be able to find anything on this issue.

This weekend I found one of my HIF4 carb floats full of fuel. It looks like it has a tiny crack perpendicular to the seam. It's very small - I couldn't shake any fuel back out of it. I'm guessing that when the carb cools, the air inside the float contracts and draws in fuel.

Anyway, I'll order a replacement float today, but with the holidays I'm afraid it'll be a week or more before it arrives. Providing I can get the fuel out of the float, has anyone got a good temporary fix - something I can smear over the crack to keep the car running just for the next week or so? Of course, a big concern is that whatever I use doesn't wash off and gum up the works.

Thanks much.

Matt K.
Matt Kulka

Matt,

I'm not familiar with the float material, but can it be soldered?

Cheers, Doug
Doug Keene

Matt,

Could try soldering -- if float is brass
glg

Be careful applying heat to a closed container filled with gas fumes. Your could end up with some nasty shrapnel embedded in you. Think JB weld.
R. L Carleen

The floats on original HIF4s are a yellow/orange colored plastic.
willie L.

Thanks for so many quick replies. The float is indeed yellow plastic.

I haven't used high tack in years, but still have a can on the shelf. It hasn't hardened, and the can says it won't dry, nor will it dissolve in gasoline. It's just such gooey stuff, I'm afraid of it getting into the passages and clogging something.

I was tempted to break out some epoxy I found under my workbench, but didn't know if that was so caustic it would deform the rest of the plastic. I have some JB Weld down there too. I know it adheres to metal, but didn't know if it worked on plastic. I didn't read the tube, will it withstand gasoline?

Again, thanks in advance.

Matt
Matt Kulka

Matt,
I believe the non metallic floats are nylon, and if so, you ought use a solvent that will actually cause the nylon to melt and flow into itself. Or, as previously suggested, for a temporary fix, just fill and cover with JB Weld. I used JB Weld plus an metal mesh sheet to repair a gash in a gas tank and that repair lasted for the life of the truck (about 5 years until my ex wrecked it). If the material it is bonding to is cleaned thoroughly (NO trace of oil or other contamination) and roughed up with sandpaper, JB Weld does an exceptional job bonding and resisting all sorts of chemicals.
Bob Muenchausen

Matt

package instructions from JB Weld:

"Fixes, fill and bonds to any surface...plastics"
"Not affected by oil, water, petrol, chemicals"

"Surface for application must be clean, dry and free from dirt, grease, oil, etc...For best weld, roughen surfaces to be welded with file or coarse sandpaper."

"Allow 4 to six hours to dry to touch. Let cure 15 hours at above 50 F. After 6 hour cure, heat lamp or light bulb near weld will speed drying time."

Paul
Paul Hanley

Matt - To get the gas out of the float try this trick. Place the float in a pan of water and then heat the water until the bubbles stop issuing from the float. Remove the float from the water and let it cool. Keep repeating this until all the gas is expelled. I have serious doubts that JB weld will adhere well enough to the plastic material of the float to stay put while imersed in gas - regardless of what the instructions say, most adhesives won't. You could try carefully running a hot soldering iron along the seam where the crack is in an attempt to melt the plastic and close the crack, then roughen the surface with sandpaper, clean well with solvent and then smear a bit of JB weld over the repaired section. This "might" work as an interem fix.
Good luck - Dave
David DuBois

Doug -- just two minutes apart thinking the same.

No wonder they put warnings not to use a hair dryer in the shower and fiddling with gasoline while smoking.

Matt -- You've probably got fixed by now, but just another thought on a nylon float:
of course, shake out the gas --

then attach a hose to the inlet hole then submerge the float in a tub of water; blow gently into the hose to determine exatly where the leak is --

take note or mark it then with a hot piece of metal - like heated with a propane torch, gently swab the leak area to fuse the crack.

Good to see all the replys -- hope you're up and running soon.
glg

Expel the gas by alternate warming and cooling to pump it out of the crack.

Then just reinstall it - it won't fill up again before the new float arrives....
Chris at Octarine Services

Had the same, tried heating and cooling like Chris suggests but couldn't find any dampness appearing on the outside, despite it being 3/4 full of fuel. Tried drilling a pin-hole to drain the fuel then sealing it up as a temporary measure while the new float arrived but it failed again within a few miles. I wouldn't try a repair for long term use, if it fails during a long journey you'll be pouring fuel out under the car as well as maybe run out unexpectedly. Tip: mine failed I cross-connected the overdrive switch to the fuel pump and manually ran the pump for a few seconds every couple of minutes and proceeded merrily on my way without leaking.
Paul Hunt

Just another thought - how about drilling a hole to drain out the fuel and then screw in a small self tapping screw??
Chris at Octarine Services

I had the same problem with a float in a ZS carb; filling with fuel. I drilled a very small hole to get rid of the fuel and then used a sealant over the hole and around the float seams. I can't remeber the name of the sealant but it was in a yellow squeeze tub and I picked it up at a NAPA store. It stated that it was impervious to gasoline. Well, within a couple of days the float was full of fuel again. From my experience I wouldn't bother trying to seal the float; just wait for a new one to arrive.
Mark Jones

I had to get to work, so what I ended up doing happened to be both of Chris' replies. I thought about heating/cooling the float to get the gas out, but it was about 3/4 full, and the crack was so small I figured the new float would arrive before I got it drained.

I drilled a small hole in the top of the float to drain it. I put a tiny dollop of high-tack on the inside of the hole, and plugged it with a tiny brass screw. Accounting that the screw is heavier than the nylon I drilled out, I set the float height on the small end of the tolerance range.

I'm hoping that the screw being above the fuel level will keep it from leaking in much fluid. And since the crack itself is so small, I figured I could go a week or so without it taking on too much fuel. Even if it does, it only takes about an hour to remove the carbs, open the one float bowl, drain the float and reassemble. And you really can tell the difference in the car's idle, so I'll know when it sinks again.

And with the in-laws coming for Thanksgiving, it's not such a bad thing to have to retire to the garage for a little while.

All in all, I like the idea of melting the nylon with a touch of solvent. But the question remains what solvent to use? The soldering iron is also a great idea. When the new float arrives, I'll probably repair this one just that way and keep it with the spares - drain hole and all.

Many thanks for all of the replies. If I learn anything new I'll be sure to add it.

If I don't get back here before then, Happy Thanksgiving to all my American buddies. (Do the Brits stop to give thanks that the Puritans found somewhere else to go?)

Matt
Matt Kulka

Absolutely!!

I stop and give thanks on a regular basis 8-)

Chris at Octarine Services

Chris - Kind of like giving thanks when a precosious teenager (and one that can't spell) leaves home?
Cheers - Dave
David DuBois

This thread was discussed between 24/11/2003 and 25/11/2003

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