Jointing/sealing compounds

Is there a sealing compound for plastic parts? I was given a vax carpet cleaner with issues and found the motor shaft was rusty indicating a possible leak from one of the water tanks. Perhaps a defective o-ring seal? Anyway I wondered if anyone new of a jointing compound which might make a better seal with the old ring. I have no idea where to source a replacement o-ring seal and from past experience with oem dealers they can be very expensive for a what should be a penny part. Hence suggestions with sealing/jointing compounds...

CT1 ! Not cheap but has a long shelf life EVEN AFTER being opened ! less flrxible/stronger than silicon and has 101 uses! Noel.

It's unlikely to be a non standard o ring. You can get standard rings from a variety of sources, I use simply bearings in leigh.

As long as the solvent (Methyl Chloride ) doesn't affect the plastic, Hylomar will provide a non setting seal, if you can't find a replacement for the O ring..

Wellseal used to be good, but required Trichlorethylene as a solvent, so definitely non preferred!

Howard

Easy enough to make your own O ring, just buy a larger diameter ring of the same cross section, cut it down to the right length and a drop of superglue will join the ends it'll save messing with a sealant. It's a none critical use so any difference in hardness shouldn't affect the outcome. Done it plenty of times using larger rings and/or proper O ring nitrile "cord".

Our experience at work with Hylomar was that the solvent would affect the O rings causing them at first to swell then, as the solvent dissipated, they would shrink to a smaller than original diameter and leak. You can try letting the solvent evaporate, but it is a bit of a hit and miss method. Mostly miss in my view and probably best avoided.

A new O ring without any sealing compound is really the way I would go. The old O ring has most likely taken on a permanent set over the years and so has lost all of its nip. I would measure the O ring groove to try and determine what the original size was rather than the old O ring.

Neil

With Hylomar, it does no harm to allow the solvent to evaporate before closing the joint. Maybe not so good if you're on the clock, but that's how it was meant to be used.

I've never used Hylomar on o rings but it definitely works better on the few gaskets I have tried it on if it is allowed to dry out before assembly. Then it works very well on usually problematic gaskets.

.

Predictably enough, Vac appears not to list spares down to o-ring level, but I was curious to know what their pricing might be like … and was reasonably impressed:

**LINK**

https://www.vax.co.uk/spares-and-solutions?product_list_dir=asc&product_list_order=price

MichaelG.

I would use silicone grease on O rings involved in water sealing especialy if difficult access to replace.

David

I agree with David on the use of silicone grease. We always used it on the seals of underwater cameras with great success, but there is one proviso. More is definitely not better. A little on the fingers and run the o ring through to just 'wet' the entire surface and then install. Too much and leaks occur. I am not entirely sure why but in the case of underwater use I think it has something to do with the changes in pressure forcing the excess silicone out of the joint leading to voids and very expensive leaks.

Pero

Vaseline is perfectly adequate for O-rings where their function is sealing due to their rubbery property. In fact most rubber seals benefit from appropriate liquid or grease application. For example a car oil filter rubber gasket is not a reliable seal if puton nice and clean and dry and the pressurised oil will somehow target one point and push through. However slight wetting of all the sealing faces with oil makes it seal

O-rings seal by squashing into a supportive groove, the shape, size and finish of which is important. I guess the grease, being mobile, provides a seal at low-pressure before the O-ring is fully squeezed into place by the camera going deep, especially if the groove is imperfectly machined or is worn. I believe a wipe of Silicone oil also helps keep O-ring rubber supple. However, I think too much grease in the groove stops the O-ring from deforming correctly under high pressure.

Dave

I’ve used LS-X on leaks before. Sold at plumbers merchants.

Do a search for the size o-ring you need on ebay. That has not let me down.

Russell

+1 for ebay.