Which adhesive for (polypropelene?) 2-stroke fuel tank?

Advice please... I need to stick a plastic fuel tap into the hole in the bottom of a plastic 2-stroke fuel tank (the tank looks like polypropelene) on an outboard motor. The fuel tap was originally a screw-in job but a previous owner stripped the threads. I used Araldite last time, but it didn't hold very well.

What adhesive should I try next? Superglue? I also have some Golden Hermatite. Perhaps that would work...

Thank you.

Al Deveron

Reply to
Al Deveron
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no adhesive will work*, find another way to do it.

  • unless youre willing to remove, empty, steam clean the tank, then flame the area to create a suitable surface for bonding.

NT

Reply to
meow2222

Personally, as such a safety critical item, I would be looking for a new replacement for the entire tank.

Christian.

Reply to
Christian McArdle

Aha, yes! Bonding with a soldering iron might work... Could be a mess if it fails though...

Thanks,

Al D

Reply to
Al Deveron

Unfortunately, that could take some time, since parts for this obsolete motor are hard to find. I'm just looking for a quick fix that's quick, cheap and reasonably secure.

Al D

Reply to
Al Deveron

You might be able to find a generic tank and tap a new hole into it (or with a correctly formed outlet already there). Is the tank some weird and wonderful shape, or would any old unit do?

Christian.

Reply to
Christian McArdle

You might be able to reinstate the thread using one of those whatnots... a metal spiral, forget the name. Or maybe make a ring that screws in, and the tap screws into that. Etc.

One thing you dont want is fuel pouring out, so I'd make it tough and secure.

NT

Reply to
meow2222

The tank is a rather specific shape. It has to fit inside the outboard motor's upper alloy casing, and the cap has to coincide with a hole in the alloy casing.

But thank you for the suggestion.

Realistically, I'm just looking for the best way to use the current tank. Surely some kind of goo or adhesive will form a leakproof joint between the stripped petcock and the stripped hole in the tank...

Al D

Reply to
Al Deveron

Thanks; that might be the ideal solution, but it's more tricky and time-consuming than I want to get involved with.

Yes, within reason. I did use Araldite previously. It got me out of trouble, but, of course, there was no real adhesion there, so it was only hanging in there on a wing and a prayer.

I figure there must be something more suitable than Araldite...

Al D

Reply to
Al Deveron

I would try a large diameter, short brass nut, washers and bolt into a tight fitting hole with a "suitable-for-fuel rubber" washer each side - then drill and tap the brass bolt and screw in the (or a new) petrol tap. This assumes you can get a nut into the right position and it will self hold whilst tightening up ( use loctite ).

If not, and this assumes the plastic is thick enough, drill and tap a larger hole and either fit a petrol tap in direct, or a bolt which you can then drill and tap perhaps with a washer on the outside to strain relieve a bit.

Or as the others suggest - get a new or s/hand one but then thats not D-I-Y...

Also depends on "what if it leaks" - a lawn mower/ outboard motor I wouldn't worry so much, but if it leaks somewhere where vapours could collect, go the new route.

Nick

Reply to
Nick

============================ 'Helicoil' - I'm not sure if they work in plastic but worth asking from a stockist.

Cic.

Reply to
Cicero

============================ 'Helicoil' - I'm not sure if they work in plastic but worth asking from a stockist.

Cic.

Reply to
Cicero

======================= This might be a possible starting point:

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depends on what access there is through the filler cap.

Cic.

Reply to
Cicero

Unfortunately, the thread is stripped off the plastic petrol tap too. But tapping new threads is more trouble than it's worth. Thanks for the suggestion, though. I really just need a quick fix until such time as I can obtain a second, identical motor to butcher for spares.

It wouldn't be the end of the world if it started to leak a drop or two every 30 minutes ro so, since it is an outboard motor hanging off the back of a boat.

However, I reckon it should be possible to jerry-rig it so that it doesn't leak at all. Last time, I fixed it in with Araldite. It didn't leak at all - but it wasn't very strong either. The tap pulled out too easily. I reckon there must be some adhesive - or other goo - that will give some adhesion and be impervious to 2-stroke mix. Red Hermatite? Golden Hermatite? Superglue? Uhu? The fit is still pretty snug despite the lack of threads.

BTW, I'm not at all sure what kind of plastics the tank and petcock are. They may well be something other than polypropylene. Nylon, possibly. One thing's for sure: they look like the sort of plastic that's not easy to stick together!

Al D

Reply to
Al Deveron

Update: I just tried sticking it in with Superglue. It formed an incredibly strong joint (much stronger than Araldite did). I just hope that the

2-stroke fuel won't weaken it.

Al D

Reply to
Al Deveron

The message from Al Deveron contains these words:

I've a feeling they're polyethelene, but neither is amenable to gluing. You can weld them with hot air and a filler but it's not easy.

Reply to
Guy King

Al Deveron was thinking very hard :

None will be effective I fancy.

You said late that the threads were damaged on both items. Could you not take the tap along to a machinists shop and ask them to clean the threads on the tap up or even tap it down to a slightly smaller thread size?

Then ask them to make up a brass fitting - like a threaded nut with a large flat shoulder on it. Cut out the treaded portion in the tank then fit the above with a soft washer impervious to fuel. In other words trap the tank firmly between the two parts.

Reply to
Harry Bloomfield

Helicoil?

Reply to
Harry Bloomfield

HOt glue might work. Almost nothing sticks to polyolefins.

Reply to
The Natural Philosopher

I figure you dont want to hear it. You could save yourself a lot of wasted time experimenting.

NT

Reply to
meow2222

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