Aluminum piston in cast iron cyinder

[mu38&Bg#]

Hydrofluoric acid sure is nasty stuff. Google for burns caused by it only if you have a strong stomach. I couldn't find references to how much acid caused these burns. It seems like most cases people where handling a large amount, rather than traces. Viton O-rings are used in many exhaust sealing applications, however. Wouldn't any hydroflouric acid created react with the metals in the area first? Temperature has to exceed 315°C before decomposition occurs.

Greg

 

[cheepo45]

I have sucessfully used head gaskets made out of heavy duty aluminum foil. Maybe it would work for you.
cheepo45

 

[deverett]

I have sucessfully used head gaskets made out of heavy duty aluminum foil. Maybe it would work for you.
cheepo45

As in beer cans? (about 5 thou thick)

Dave
The Emerald Isle

 

[kuhncw]

I've had very good luck with sheet Teflon for head gaskets in my hit & miss engines.

Chuck

 

[wildun]

You have a Viton ring in an internal combustion engine? - I wouldn't have thought this possible but then my experience with this type of engine is zilch and sometimes a bit of a long shot works, at least on a temporary basis!
However have you checked the condition of the 'o' ring after running. I know that viton rings can stand high temperatures, oil etc. but in this case it is being used in a situation (ie. quite high reciprocating motion) which 'o' rings are not really designed for. If there is lots of side clearence in the groove then the ring will 'roll' with the change of direction, if it is snug in the groove, it will tend to deform. Normally they are used for static seals or sometimes as rotating seals (slow rotation) and normally requires side clearence. I cant' see it standing up to the high speed reciprocating action for very long!
As I said though, my experience with these model engines is zero really and any experience with these matters is based on my commercial workshop experience over the years.
I'd say stick with the CI rings till you have got their manufacture down to a fine art and make sure you find the correct piston/bore clearence -
Hope you can get it sorted

PS. Having (later) read the post by NESENG I agree with him about 'o' rings, and none of them, (whatever type of rubber) are suitable for an application such as this.

 

[cheepo45]

I used the heavy duty aluminum foil, but I bet a beer can would also work . I am emptying one right now (for testing purposes)
cheepo45

 

[enfieldbullet]

the viton o'ring probably doesn't get much hotter than the oil in the engine, it must have a fine layer of lubricant over it during it's working time.

the HF could react with the metals on its way out or not so much, it is a fairly low-dissociation acid, which means it is slow to react (slow doesn't mean weak). however increased temperatures should help to make it more reactive. only true way to know is to test the engine's emissions.

i wouldn't use it in the combustion chamber but that's because i'm oldschool like that. if needed i would cover it in rawhide and lard.( read about 'packing' by the old timers, really funny stuff, they would use anything)

 

[Hopper]

... i'm oldschool like that. if needed i would cover it in rawhide and lard.( read about 'packing' by the old timers, really funny stuff, they would use anything)

True dat. When I were a spotty-faced apprentice in the boilerhouse at car factory, an old bloke who had been a stoker on reciprocating-engined steam ships transporting troops in WW2 showed me how to use one of the strings from the boilerroom floor mop as packing in a leaking steam valve stem.
"Boy," he said, " I don't show these things to all the boys but your old man was at sea so I don't mind showing you."

A few other things I learned from him included how to jack the turbine feed pump governer open with an old Brasso tin so it would not trip the overspeed when firing up from cold boilers. And how to use a plate glass and emery paper to "recondition" air compressor valve channels (on compressors standing 10- foot tall.) instead of 'wasting" company money on new valve channels.

Oops, but he never taught me not to hijack threads. Hope you got your IC engine sorted.