17 replies to this topic

[Lukie-J]

Non-mini but thought someone might have an idea of how I might be able to fix this.
After fitting new thermostat to my Polo 6n I stripped the thread on the thermostat housing.
The thermostat housing is plastic and has a thick screw (not a bolt) with a 10mm head.
Is there any way of fixing this, even if it's temporarily so that I can securely screw the thermostat cover back onto it?
Not sure how much water pressure there would be around that point too so whether spending £40 on a new housing is the only way to go.
Thanks in advance!
Lukie-J

[Ethel]

Depends on the type of plastic, is it thick enough to make up a threaded bush?

[Pigeonto]

I have helicoiled plastic.But I did put superglue on the insert before winding it in

[Lukie-J]

Not sure what a threaded bush is! It's in the thermostat housing
http://www.ebay.co.u...g-/160858178688

It's the top screw in this picture, with the 10mm head.

EDIT: link was broken!

Edited by Lukie-J, 24 November 2012 - 05:52 PM.

[Ethel]

Link's still no good, that looks like an octopus porn site!

A bush is just a something that fits around, or in, one component to fit it to another, in this case it'd be a tube threaded on the inside (as per the original thread), and outside(to fit a bigger one cut in the stripped hole).

Is there room for a nut on the other side? 10mm spanner suggest it's M6 thread.

[Lukie-J]

There isn't space for a nut the other side unless I drill through the whole thermostat housing.
How would I go about making up a threaded bush then?
Thanks for the replies

[mike.]

I'd try a fat self tapping screw, give it a tap in to get it started then wind it in. If you get one thats slightly bigger than the hole it should cut its own way in.

Just try and get one with a bolt head on it so you can get some force onto it.

[dklawson]

There is no reason you cannot use a HeliCoil in plastic. I would consider a HeliCoil to be the preferred repair method.

You said the hex head is 10mm. I assume that means that the threads on the bolt are 6mm. Is that right? IF that is correct, you could temporarily insert a 1/4 UNF fastener until you get the HeliCoil kit to fix the threads permanently. The 1/4" fastener will be a little bigger in diameter and will probably roll its own threads into the plastic when you screw it in. Just go light with the torque so you don't strip it as well. When you tap for the HeliCoil the residual threads from the 1/4 UNF bolt will be removed so no harm done.

[Ethel]

A self tapper (self driller) is an idea, but be careful not to force it and crack the plastic, some have notches in the end to help cut the thread.

Another idea, I must be bored,

glue in some threaded rod or a cut down screw and use a nut instead.

[Wise Old Elf]

If it is not under a huge amount of pressure I would be tempted to fill the hole with an epoxy (something like JB Weld), let it harden and then drill and re-tap the thread.

J

[Tamworthbay]

A trick I have used a few times that has worked well- put some araldite in the hole, get the bolt you will use and coat end in mould release, at worst wax polish will do. Then squeeze and rotate bolt into the hole. When the glue goes off you can unscrew and clean the bolt. I actually use DP410 structural adhesive as I have access to it, but araldite will work just as well. It takes as much pressure as the original thread in my experience, but you MUST use a mould release/wax of you will do as much damage getting a stuck bolt out.

[Cooperman]

A Heli-Coil is the correct repair and works fine.

[graemedench]

How about a rivnut?

[Cooperman]

How about a rivnut?

No, in a hard plastic a Heli-Coil is the correct & professional way to repair it.

[oliver122]

wouldnt he be able to just retap to 8mm thread as long as he has got the material to tap into ? or if you have no luck mate found one brand new on ebay £30 quid http://www.ebay.co.u...7c0cb96a&_uhb=1