Gasket cement?

[alanp]

Rusty, your comment about using nail polish remover to get rid of Silicone had me rushing to get one of my pairs of trousers and the wife's remover. I had accidentally (absent mindedly) wiped some silicone on my trousers, virtually ruining them. I'm now a happy bunny since it worked!
Thanks mate.
Alan

[Rusty nuts]

 

[groily]

Ah, Alan, ruined trousers ('pants') . . .  Every time She goes to a place (like the USA or the UK) which sells big sizes she buys me new ones in the vain hope I might look half decent for a bit. And within days, sadly, they are 'ruined' but more comfortable. There's no hope for a man with a shed, no fashion sense and who's past trying to pull the opposite sex with antiseptic displays of domestication.
It's good to know there are products out there though!

[JohnH]

Phew! - You guys really are helpful - Many thanks.
Some responses from me:
I personally wouldn't use gasket cement of any kind on a solid copper head gasket. I would however, use grease, just to facilitate a bit of movement between the four mating surfaces (as mentioned by several posters). I really wanted to confirm that my technology was still valid. I'm less sure about a composite (copper/asbestos .... do they really still contain asbestos?). The gaskets can rarely be re-used so I might use a good quality sealant such as Blue Hylomar. That view seems to be supported by Rusty Nuts and others
     John from Solihull - I live in Cranleigh in Surrey - near to Guildford. My son and his family live in Moseley so I spend a fair bit of time there too!
     Very intersting to hear all the thoughts about silicone sealant - and it's removal - strewth - that will be useful. I'll keep the use of silicone in mind for my primary chaincase although I shall try to get by with a seal with grease alone as John (A101960) suggests is possible - although my experience with a 16MS AJS were pretty miserable!
     I'm very interested in those rocker box gaskets (again John A101960). I can remember using gaskets that were pink on one side and green on the other - slightly furry at the edges as I recall - possibly because they were a bit thicker?
     Finally, I would be very interested to know where in the UK the sheet gasket material can be obtained - as mentioned by Groily.
Thanks for all the very willingly delivered help - I like the humour too!

John

[a101960]

I just thought that it might be worth mentioning that silicone sealant has corrosive properties on aluminium due to the acetic acid content. I am a retired avionics technician and silicone sealants were a big no no on aircraft applications. Amongst the many and varied items that I worked on in particular the pressure relief units incorporated two rubber diaphragm housings that could prove to be troublesome to seal. we used grease to effect a good seal on these. Silicone sealer would have been an easier option but it was not permitted because of potential corrosion problems. This was on military aircraft.

John

[brackenfel]

John mentioned Dowty washers a while back...
These are really good - a friend gave me 3 for the rocker feed oil pipes on my Velo about 10 years ago & they haven't leaked since.. I want to get some for the A10..
Are the sizes measured across the metal part or the rubber insert?  Anyone know what size I'd need for the 2 rocker feeds and the oil pipe feed/return outlets on the crankcases please?

Thanks,
Adrian

[Lannis]

I went back to read the thread and was surprised to see that a couple of techniques that have worked very well for me are not mentioned:

1) Anaerobic gasket maker such as Loctite 515 or 518.  This has a big advantage in that, unless it is squished tight into the joint, it does not set up or harden and form stringers or bits that can get into oilways.   For the cylinder base gasket on my A10, for example, I used a thin layer of 515 with NO gasket, and the joint is as tight as Dick's hatband, no oil leaks at all.   My primary case with a paper gasket (Permatex on one side and grease on the other) was leaking after a short time - I replaced it with a thin skim of 515 and now no leaks.   Same on the A65 - the paper cylinder base gasket stayed soggy with oil all the time, and would weep a little - with a layer of 515 on clean metal surfaces, no leaky.

2) Copper head gaskets for A10 or A65 - I always use an annealed copper gasket with a thin spray coat of "Copper-Cote" sealer on each side.   Never any leaks, problems, or blown gaskets.   WORST thing I've ever done is used one of those sandwich-layered "composite" head gaskets - I've tried it on two different bikes - modern technology is bound to be better, right?   Both times I had to continually tighten the head bolts down and ended up blowing the gasket.

So that's my data point ....

Lannis

[bsa- bill]

Anaerobic

Thanks Lannis that is the word I was looking for, good stuff goes on thin and brings piece of mind as you know it is not going to set anywhere it's not supposed to be

[groily]

John,
My last stock of Flexoid gasket paper in rolls came from Netley Marsh via a mate (so source unknown), but in this case e-bay is as good as anywhere if you just google 'gasket paper'.
Or go to www.auto-connect.co.uk/Autoconnect_Gasket_Paper_3100.html
There are several thicknesses out there in 1 metre sheets, plus loads of A4 sheets, and there are also sets of tubular cutters for making holes of various sizes. Also some good Klinger-stuff for tricky joints, but usually 'non-asbestos' these days. I still use some gaskets I made years ago in Klingerite for one engine's rocker boxes - they seem indestructible.
Re the 16MS . . . I've never managed to seal AMC pressed-steel chaincases for very long myself . . . It is supposed to be possible with neoprene seals etc etc, and I've managed for a while from time to time, but I gave up on permanent leak-free status long ago and just tolerate small drips, which the real experts wouldn't. (The alloy chaincases do seal well though, just as well as on a BSA, so no excuses there for any of us.)

[JohnH]

Yet more incredibly useful information. Many thanks to all who have responded - especially the more recent posts from Groily and Lannis and the comments from A101960 about the aggressive nature of silicone sealant. I had wondered about the acetic acid content in silicone sealant - that settles it, I'll use the anaerobic sealant when I can and blue Hylomar when i need to use paper. Thanks Groily re gasket paper - do you use a particular thickness most often?

Thanks again,
John

[JohnH]

Just following up on a point that Adrian mentioned in this thread a while ago:

John mentioned Dowty washers a while back...
These are really good - a friend gave me 3 for the rocker feed oil pipes on my Velo about 10 years ago & they haven't leaked since.. I want to get some for the A10..
Are the sizes measured across the metal part or the rubber insert?  Anyone know what size I'd need for the 2 rocker feeds and the oil pipe feed/return outlets on the crankcases please?

Does anyone have any thoughts? I looked at the Dowty web presences and the concept of the Dowty washers look really sound .... but it looks as though it's probably very important to get a good seal to the bolt at the inner annulus to ensure that the seal is comprehensive.

John

[BSA_54A10]

Thanks Groily re gasket paper - do you use a particular thickness most often?

you need a couple of different thickness.
Some places don't matter ( tappet covers for instance) while others the thickness is important ( gearbox inner )

[bsa- bill]

Talking of Dowty washers I'm unsure that we are all talking about the same thing
A Dowty washer as I understand them to be, is a solid steel washer with a rubber section bonded onto the internal circumference of the washer, the rubber section being thicker than the washer makes the seal.
There are also washers that consist of a thickish rubber washer surrounded around it's outer circumference and partly over both side with copper, these I think seal by squishing up the copper ( which the rubber allows )
Both types work fine but I think the first is a "Dowty" washer.

other opinions are available, and no doubt forthcoming 

[JohnH]

Sorry - I tried to post the attachment as a BMP file. Here it is as a JPG.

Apologies,
John

[Goldy]

I think that the clear silicone takes some beating although I dont know about using normal houshold stuff. I use Granville instant gasket which is available from usual sources in the uk.           http://www.granville-oilchem.co.uk/product_info.php?prod_id=44

[JohnH]

I made a right fist of my last post. All I managed to get onto the board was the extract from the PDF File that I should have included the link for. Here's the link for the complete document:

http://potterassoc.com/PDF/o_rings/Bonded%20Seal%20Information%20and%20Sizing%20Chart.pdf

The extract I posted earlier is from it.

From what I've been able to glean, the Dowty seal is made at the inner annulus of the washer around the bolt. So in the case of the banjo feeds to the rockers, a Dowty washer would go on either side of the banjo and the seal would need to be a tight fit to the smooth surface of the bolt that screws into the ends of the rocker shafts. So I would read that the inner diameter of the washer would be pretty important and should be the same as the outer diameter of the rocker shaft (oil-feed) bolts - I have no idea what size they are though Adrian.

Thanks for the link on the sealant you use Goldy.

John

[bsa- bill]

Cheers John - that is what I recognise as a Dowty washer, used in lots of hydraulic joints and withstand thousands of pounds per SQ inch pressure, so petrol under gravity should be no problem or oil at 60 lbs/in.

[brackenfel]

Many thanks for the link John. These are the ones, the rubber is slightly thicker than the washer & forms a seal between the 2 surfaces when tightened up..

The same friend is going to lend me a few to try on the BSA.. He is an ex RR aero engineer & understands all about sizes etc so I'll report back if I find any useful ones..

Cheers,

Adrian.

PS Just to prove wisdom doesn't come with age I've just agreed to buy a B33 that hasn't run for 10 years.....

[groily]

Missed your query re 'most frequently-used thickness' John - sorry. But, except for gearbox gaskets where a bit of thickness is often needed to maintain free play as already mentioned, I always try to go with the thinner stock from my shelf. But must confess to never having miked it. 8 to 10 thou maybe? Thicker doesn't mean better in my experience, in fact rather the opposite provided the surfaces are decent.
Agree 100% re dowty washers btw - excellent things which really do work (if I have the right size when I want one, which ain't always . . .)

[JohnH]

No probs - Thanks Groily. I was intending to get a couple of thicknesses anyway - and several sheets - I know I'll mess some up!

Good luck with the B33 Adrian - that sounds like a labour of love. Do get back to the list if you manage to pin down the Dowty washer spec as I'd be really keen to try them out on my GF .... never did like fibre washers!

John