Is liguid/gel gasket any good for some parts?

I want to paint my clutch, alternator and crank cover on my bike and the genuine gaskets are quite expensive for what they are. If possible I'd like to use some liquid or gel type sealant. How good are they and has anyone got any recommendations?

Thanks.

[G]

I used to use the red gasket sealer from halfords as an addition to factory gaskets.

I wouldnt like to trust it on it own to be honest.

How much are the standard gaskets?

[embee]

It's like most things, it will work well if it is good quality stuff and the joint is designed to be sealed using it.

This unfortunately is where it usually falls down, most cheaply available stuff isn't particularly good, and joints designed for gaskets usually don't work well with sealants.

Best RTV stuff is for example Loctite 5900, but it costs a fortune and is available mainly from industrial type suppliers. "Blue Hylomar" is often reasonably successful.

Joints for sealants are designed with a chamfer or recess of some sort where the sealant can form a bead (a bit like a formed-in-situ O-ring if you like). You can sometimes modify a gasketed joint face to give this feature, file a 1mm x 45deg chamfer on the inside edge for example. Properly designed it will work, very many car engine cover or sump joints are done in this manner nowadays.

One traditional (old-fashioned) successful method of replacing a thin gasket is to use "Wellseal", which is a bit like a non-drying sticky varnish, looks a bit like runny Marmite, and lay a piece of thread (strong cotton button thread is ideal) around the centreline of the joint face. I have used this very successfully on old bike gearboxes etc (a trick I learnt when I worked at Rolls Royce from the "old-timers"). It is very time consuming though. Wellseal smells wonderful too if you like that sort of thing!

It is worth a try if you want, all it will cost you is a few quid and some time. If it doesn't work, get replacement gaskets.

The main thing to watch for is if there is anything in the assembly which is sensitive to the gasket thickness (clearances, endfloat etc).

I used a liquid gasket sealent from Halfords when I put the VTR back together... not had any problems either. However I only used it on the RHS engine cover join to the main body of the engine.
I can't remember what it was called but I think it was about ?8 - ?12. It was black and really difficult to get out of the tube... and a little messy to apply.

[yorkie_chris]

+1 about being careful with endfloat.

Translation

Use it on side covers and such, but not on crank halves, base gaskets unless you intentionally want to change compression ratio. Definately not cylinder head gaskets (They leak fine without any help )

Thanks guys. If I show you what I want to paint can you tell me whether you'd do it or if I should just cough up? I don't think there are any extreme pressures or liquids in there waiting to spew out.

(Ignore the different bikes, same engine)






Here's the microfiche pic:

[timwilky]

Mate bought a "restored" Matchless 500 single G80 a few years ago. It ceased up despite careful running on the way home. when we stripped it, the oil ways were bunged full of red hermitite.


Using sealants is all well and good. But apply sensibly and appropriately.

[Sid Squid]

In your first pic is the generator cover, the second at the front is the timing cover and the rear one is the clutch.

Go buy the right gaskets, sealants various can work fine, but those areas aren't intended for such sealing means.
Carefully taken apart there's a chance you can reuse them with a bit of goo on them, but I wouldn't miss the gaskets out.

He he. I know nothing. I'm from Barthelona.

Will do then Squid. Goo? Oil so the gaskets don't go on dry? It'd be good if I can get the covers off without breaking them.

[Sid Squid]

Goo -noun

General term for a number of liquids, gels, pastes or sealants.

In this case the addition of a sealant to a previously used gasket, in case it's second time around performance may be in doubt.