Classic cars forum & vehicle restoration.

MartinC · Joined: 27 Jun 2009 Posts: 97

A few years back i used some brown silicon sealer to seal a rocker cover on with. My mate was a double glazing fitter and gave me a tube out of the van. The brown was used for plastic wood effect windows.

It worked perfectly but i didn't keep the car all that long.

Anyone else used DIY silicon to make gaskets with?

I need to seal all round a large Bedford sump and the 'proper' silicon sealer for engines is expensive and in very small tubes.
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1937 Standard Flying Twelve
1942 Bedford OYD
1947 Cadillac Fleetwood Sixty-Special
1954 Hillman Minx
1956 Austin A30
1957 Vauxhall Victor Super
1960 Car Cruiser Carousel caravan
1962 Car Cruiser Carissima caravan

peter scott · Joined: 18 Dec 2007 Posts: 7211 Location: Edinburgh

No pressure on a sump gasket. Should be fine.

Peter
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Ashley · Joined: 02 Jan 2008 Posts: 1426 Location: Near Stroud, Glos

I use Loctite Silicone Grey Flange sealer type 5699 and have done for years, it works better than anything else I've ever tried and million times better than Hylomar or Wellseal, both of which are from WW2 and almost useless IMO.

I've tried other silicones, but Loctite are the best by a margin. Check out their website.

Bitumen Boy · Posted: Wed Jul 31, 2013 11:09 pm Post subject:

Well, I was going to say that I've never come across a good silicone sealant - and I haven't, but that's using them as a normal sealant for baths, showers and so on. Thinking on it though, I reckon you'll get much better results using it as a gasket material, so long as you keep it clean. Applying the stuff to two surfaces designed to mate together and then applying compression is going to be a whole different ballgame to trying to make a neat joint between two (usually) inherently slippery surfaces at funny angles to each other. Give it a go.

JohnDale · Posted: Thu Aug 01, 2013 10:59 am Post subject:

Back in the 50's, when ah were nowt but a lad, building 28hp Bedford engines with new gaskets, sealer was never used,only grease, on both sides of the gasket. Having said that the Loctite grey sealer is excellent for face joints & mandatory on certain points on Cummins engines. Cheers,JD.
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1958 Ford Zephyr Mk2 Convertible
1976 Ford Granada Ghia.

kevin2306 · Posted: Thu Aug 01, 2013 2:02 pm Post subject:

i personally wouldnt use domestic type silicone mastic anywhere near an engine etc. ive rebuild many a motorcycle racing engine that has been trashed by the silicone breaking down and blocking oilways.
much better to use the proper oil resistant rtv sealant.

kev

MartinC · Joined: 27 Jun 2009 Posts: 97

What does RTV stand for?
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1937 Standard Flying Twelve
1942 Bedford OYD
1947 Cadillac Fleetwood Sixty-Special
1954 Hillman Minx
1956 Austin A30
1957 Vauxhall Victor Super
1960 Car Cruiser Carousel caravan
1962 Car Cruiser Carissima caravan

Ashley · Joined: 02 Jan 2008 Posts: 1426 Location: Near Stroud, Glos

I don't know, but I do know there are so many different types of silicone and that it's very difficult to find out exactly what each is intended to do. Therefore I think it's best to stick to ones sold for specific jobs because even then some aren't very good, which bring me back to Loctite.

Yamaha also do a really good one called Yamabond, but it's pricey.

Penman · Joined: 23 Nov 2007 Posts: 4850 Location: Swindon, Wilts.

Hi
I used a silicon type sealer when I had an aluminium/plastic heater matrix start leaking between the tubes and the header/footer tanks.
It was from a plumbers merchant and came in a proper tube not one of those gun applicators, I forced it in between the vanes from both sides and let it cure off and it was still dry 2 yrs later when I traded on.
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Bristols should always come in pairs.

Any 2 from:-
Straight 6
V8 V10

colwyn500 · Joined: 21 Oct 2012 Posts: 1745 Location: Nairn, Scotland

MartinC · Joined: 27 Jun 2009 Posts: 97

Isn't that what all silicon sealer does?

From searching like yourself I discover that RTV is supposed to be two-part. However the tube of fancy RTV super duper special engine sealant I have here is just a tube of sealer.
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1937 Standard Flying Twelve
1942 Bedford OYD
1947 Cadillac Fleetwood Sixty-Special
1954 Hillman Minx
1956 Austin A30
1957 Vauxhall Victor Super
1960 Car Cruiser Carousel caravan
1962 Car Cruiser Carissima caravan

kevin2306 · Posted: Thu Aug 01, 2013 7:15 pm Post subject:

Dobbin · Joined: 15 May 2013 Posts: 67 Location: Central Scotland

Over 25 years ago I used Dow Corning clear silicone sealer to repair sorry, seal a leaking cork gasket on my Opel Ascona after doing the tappets. The sealant was great. However I must have had a small air pocket in it that wasn't visble from the outside. After I took the car for a run to check everything was ok I popped the bonnet to see that everything was sealed, it was but I had a large, approx. 2" diameter silicone bubble with oil in it. Ooops. after it cooled down the bubble disappeared. I ran it for about a week or so until I could get a gasket. That stuff was very flexible. Oh the joys. Haha.

JonV2 · Joined: 02 Jan 2010 Posts: 38 Location: Melbourne Australia

A negative story for Silicone...
About 10 years ago I had a Holden Commodore; this had a 5 litre V8 but from the moment I bought it, it had suffered severe overheating problems. After installing electric thermo fans, running some very expensive coolant etc, I finally had the radiator 'rodded'. The radiator guy said about a third of the tubes were blocked with bits of hardened silicone. I finally worked out that this came from a P.O, who had used window silicone as a waterpump gasket....
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Jon
1950 MkV Jaguar Saloon (On the Road)
1968 MGB
1959 XK150