Sealants

Author
Discussion

kenmorton

Original Poster:

271 posts

257 months

Friday 18th June 2004
quotequote all
what is the difference between silicone engine gasket sealant (RTV ? whatever that stands for ) and ordinary building silicone ?

Thinking of gearbox joint and engine sump joint in particular.

>>> Edited by kenmorton on Friday 18th June 00:02

Pigeon

18,535 posts

253 months

Friday 18th June 2004
quotequote all
By "ordinary building silicone" you mean the stuff you get at B&Q?

The engine version will be capable of withstanding higher temperatures and more resistant to degradation by oil/fuel.

Personally though I wouldn't use silicone round an engine because it has a tendency to squeeze lumps out when you tighten the bolts and the lumps can block oilways and cause mayhem. If "gasket goo" is required I use Hylomar and only put on a very thin smear.

deltaf

6,806 posts

260 months

Friday 18th June 2004
quotequote all
Silicon RTV is oil resistant, ordinary silicon sealer ISNT.
The downside to buying RTV (loctite etc) is its price, around 30 squids for a mastic sized tube, however it IS the very best you can get.
Dont be tempted to uses sealer on sump gaskets or cam cover gaskets as itll allow the gasket to be squeezed out when tightening it. RTV is primarily used for metal to metal gasket manufacture, such as on cast alloy sumps and gearbox casings and then only a smear in the form of a continuous bead needs to be applied.

hth.

warmfuzzies

4,114 posts

260 months

Saturday 26th June 2004
quotequote all
RTV means room temperature vulcanising, means it goes off to a rubber like at room temperature, should be good for oils etc, but not too good for higher pressures.

kevin

stevieturbo

17,520 posts

254 months

Sunday 27th June 2004
quotequote all
£30 sounds a bit expensive for RTV ??

Aside from that, Ive used normal building ( double glazing silicone actually ) on quite a few engines, and never had any problems. I can usually get it for nothing as I work on construction sites, so why not use it ??
Do not use silicone of any kind where it may come into contact with fuel.

While many like Hylomar, I hate the stuff. It may do its job, but its very messy.

warmfuzzies

4,114 posts

260 months

Sunday 27th June 2004
quotequote all
Hylomar is great, but only if the mating surfaces are perfectly flat/square, I used to used it a lot. But if there's any hint of a non flat surface it leaks like a sieve.

kevin