Patching plastic so it is watertight

[Lower]

Silicone some patches on.

 

[Deleted member 174758]

Any plastic welding adhesive, which is designed for the particular type of plastic...

Assuming that the plastic isn't a thermoset plastic - in which case a solvent won't work. And thermosets are used a lot for components which need to take heat. Fortunately, all manufactured plastic components are supposed tlo be marked with the plastics type to aid recycling, so the OP should look for a triangle and a plastic type, or a plastic tupe between two arrows, e.g. ">PA8 GF30<" or ">PPE<" (a type of polyamide nylon, PA 8, with a 30% glass fibre filler AND polyphenyl ether - BTW neither of these can be solvent welded, the 1st is found in a lot of power tool casings, whilst the second is used on components in my tumble dryer: full listing on the BPF web site)

I think I'd be inclined to use a hot melt glue stick with a suitably high temperature

 

[Harry Bloomfield]

I think I'd be inclined to use a hot melt glue stick with a suitably high temperature

Good call - hot melt, will to some extent melt and bond itself to the original plastic component.

 

[bullethead123]

Gone with this stuff, suggested by FreddieMercury's twin.

https://www.toolstation.com/big-boy...rn6q3dtRlGTxYHjvjSBoCA8EQAvD_BwE&gclsrc=aw.ds

Did one sheet of fibreglass and resin/hardener and, two hours later, another sheet and resin/hardener. Will leave to cure overnight and test tomorrow.

Wish me luck.