.46 Muffler Gasket?

[tizdaz]

Hi guys, as per title, I'm trying to find a gasket for my Leo .46 Glow engine muffler (its basically same as the os .46 engine in terms of fitment).

 

Only ones i can find are genuine OS gaskets (£15 for a pack of 3! ...no thanks!) ..surely there's cheaper ones around!? Anyone know of any UK retailer that sell them 🙂 ?

 

Or could i use something like this instead: https://www.eurocarparts.com/p/carplan-instant-gasket-38gm-549773891?gclid=CjwKCAjw0dKXBhBPEiwA2bmObeJKnCqN6JPa8V_WqQFWd2bG3TgAjmAXZDiYJqY1KTh1-iylymVXZRoCBXgQAvD_BwE ?

 

Cheers!

Edited August 11, 2022 by tizdaz

[Zflyer]

I have used stiff card with a coat of varnish. 

[Paul De Tourtoulon]

Sorry but nothing will last, use a piece of wet and dry 240 grit to resurface the cylinder and silencer then a thin smear of locktite over the joint.

[Don Fry]

High temperature gasket paper is cheap enough. E bay.

[Kevin Fairgrieve]

Make your own.

Plenty of good video`s on the tube.

Gasket

[Nigel R]

I'm with Paul on this one. Pack the exhaust port to stop debris getting in, lap the face on the joint, wash out and clean up carefully. Repeat on silencer. Tiny smear of slow cure epoxy when reassembling.

 

Most anywhere else on an engine, if needed, I'd make a real high tech one from oil soaked newspaper.

[ken anderson.]

hello tizdaz,have a go with clear silicone,if the mating surfaces are ok,you'll get a good seal...or try brown parcel paper gasket as well as the silicone...

 

ken anderson....ne..1....silicone dept.

[Engine Doctor]

I would go for the epoxy method. It seals properly, doesn't come loose in flight, and lasts as long as you want it to. No special prep required. Wipe engine and silencer faces clean with meths or thinners. Make sure the screws are clean and oil the threads lightly inc the threads in the silencer. Spead a thin coat of epoxy on one surface and screw together. Wipe off any excess. 

When you want to remove silencer just remove the screws (hence the oiled threads) and give the silencer a sharp tap. 

Paper or gasket material silencer always compress and come loose resulting in a very messy ( metallic grey oil) model or fall off in the scrub and are lost forever.

Good luck and keep IC going 👍

[Peter Christy]

I'm with Engine Doctor on this one! Nothing beats a smear of 5-minute epoxy. Gaskets always end up coming loose, epoxy doesn't. Just make sure both surfaces are oil-free before joining.

[kevin b]

2 hours ago, Peter Christy said:

I'm with Engine Doctor on this one! Nothing beats a smear of 5-minute epoxy. Gaskets always end up coming loose, epoxy doesn't. Just make sure both surfaces are oil-free before joining.

Gaskets don't "come loose". They are not mechanical components, Though they can leak or perish with age and use.

If the exhaust "comes loose" then the problem is with the fixings. Usually a combination heat expansion, worn nuts and screws, or incorrect fitting.

How many people have serviced / overhauled an engine and not replaced the cylinder head, or exhaust bolts ?

Or even the prop nut ?

Full size engine manufacturers always recommend bolt replacement on their engines.

I wonder what Jon would say about anybody sealing an engine with epoxy !

Normal epoxy is not heat resistant. If it was any good they would use it on racing engines, wouldn't they ?     

 

There again, if you have already stripped the threads on your carburettor mounting and glued that in what does it matter ?  😉

 

kevin b       Billy bodger dept

Edited August 12, 2022 by kevin b

[Ace]

For small 2*s I use a strip of PTFE tape (white stretchy stuff ) which just fits width wise. Remember to put a slot in for the exhaust gasses and screw holes. I have found it comes in two thicknesses, thinner for water compression joints and a slightly thicker (preferred) one for gas threads. Thin so no compression loosening screws over time but thick enough to take up any irregularities, plus heat proof for glows.

Edited August 12, 2022 by Ace
Additional info

[PatMc]

I've also used PTFE tape but let the screws make there own holes as they're inserted & only cut a token lengthwise slit. First time the engine fires it burns the unsupported tape away. IIRC Brian Winch mentioned this method in one of his columns way back - probably last century. 

[Graham Bowers]

All I can add to this is a bit more detail on how a bolted (screwed) joint works to help you decide from what is above.

 

The tension in the screws pulls the joint together, and places the silencer, silencer to engine interface and the engine casting that accepts the screw into compression. If the engine to silencer interface is metal to metal, the lumps and bumps on the mating faces will bed in and that'll reduce the screw tension. If there's a gasket in there, it'll bed in and reduce screw tension.

 

Either way, the designer has to make sure there's enough stretch in the screw for the joint to stay tight when the bedding in happens.

 

If we owners modify the interface with a gasket material that beds in more than the screw stretch can accommodate, it'll loosen.

 

So in my opinion, if you must have a gasket, pick a gasket material that's thin and sturdy, and keep checking the screws until the joint has bedded in.

 

 

 

Edited August 13, 2022 by Graham Bowers

[Engine Doctor]

Over the years there must be many silencers laying in fields surrounding most flying clubs waiting for next generation time teams to dig them up ; this has happened mainly due to the use of silencer gaskets , often supplied with engine compressing , going soft due to the deluge of oily exhaust and heat then releasing tension on mounting  bolts and vibrating loose. 

That doesn't count the ones that have nearly fallen off. 

Using epoxy that's easily removable for an exhaust seal is not a bodge but a practical way to effect a seal that lasts and proven to work on glow engines. No good for petrol engines as temp is too high and proper metal exhaust gaskets work best.

Please don't compare with car practice .We are talking of model glow engines exhaust that generally have very small surface areas with a lot of leverage on the joint due to poor design . Any thing that can compress will eventually and allow the joint to become loose. 

Don't forget many engines are basically updates of old designers and silencers we're an afterthought or in many cases simply a means to squirt the exhsust away from the model.

Of course you can keep tightening the mounting bolts and risk stripping or distorting the faces , which I have had to correct many times and when the damage is done you might have some sort of a seal.

So a simple smear of epoxy works well, lasts until you need to undo the joint, is easily removed and cleaned off5

[Andy Stephenson]

Epoxy seems to be the best material to use. Silicone has been suggested but if any exudes into the exhaust passage it will remain there causing a partial blockage, whereas epoxy will soften and break off leaving during the first run leaving it clear of obstructions.

[Peter Christy]

I switched to epoxy decades ago, and have never had a silencer come loose or leak using it. Before then, I was constantly tightening bolts, and my models always had streaks of black/grey aluminium dust in the exhaust residue.

 

Epoxy just works! Trust me!

 

--

Pete

 

[kevin b]

ED.

I quite agree, but the point I was making was that a "bodge" is no excuse for proper maintenance.

My understanding of a "smear" of epoxy is probably the same as yours, but I doubt that a lot of modellers would understand.

The only exhausts I have had coming loose have been on second hand engines.

Replacing the screws and making sure the silencer threads are good (Helicoil if necessary) seems to cure the problem.

If I see that the screw heads are mangled I change them before I start.

 

It's amazing how many "knackered" engines I have obtained that once serviced and rebuilt properly run really well.

[Martin Harris - Moderator]

An additional point to check is that the thread hasn’t pulled the face of the machined face outward preventing a gas tight seal. A small counterbore would ensure the best clamping force on the joint.