Model Engine Maker

Help! => Specific Engine Help => Topic started by: Gas_mantle on March 18, 2019, 01:53:40 PM

Title: Gaskets / steam tight seals etc.
Post by: Gas_mantle on March 18, 2019, 01:53:40 PM
I've just given my vertical engine a run on the hot stuff for a while after disassembly and painting thankfully it runs fine but has an annoying leak  at the valve chest cover. The leak is small but annoying and I think tightening the studs any further is risky so leaves me looking at the gasket.

At the moment I have 0.35mm Flexoid gasket paper smeared in steam oil as the seal, does that sound too thick? Should I add any other compound such as Bosswhite etc?

Any help gratefully appreciated  :)
Title: Re: Gaskets / steam tight seals etc.
Post by: AOG on March 18, 2019, 02:22:15 PM
I’ve used this stuff for years on aircraft and it seems to work well with steam.

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-aviation-form-a-gasket-no-3-sealant-liquid-3/ (https://www.permatex.com/products/gasketing/gasket-sealants/permatex-aviation-form-a-gasket-no-3-sealant-liquid-3/)

Tony
Title: Re: Gaskets / steam tight seals etc.
Post by: derekwarner on March 18, 2019, 02:31:06 PM
For low pressure steam ...say <~~150 PSI]..coarse [thick] grained celluloid paper [approx 0.005 to 0.007"] soaked in oil should be suitable......I say this as modern plasticized papers have virtually ZERO porosity so the adsorption of oil into the paper does not occur

Naturally poor alignment will not be rectified by over tightening M2 [or equivalent] brass bolts & nuts

Sorry to mix Metric and Imperial units.........however if your model was 1:24 scale, using a 0.35 mm thick gasket represents an 8.4 mm thick gasket in real life

Home made gaskets are simple to make........just need an old paper envelope  :facepalm:

Derek

Title: Re: Gaskets / steam tight seals etc.
Post by: Gas_mantle on March 18, 2019, 02:38:15 PM
Thanks guys, I've ordered some thinner paper as that seems to be the best place to start.

My engine isn't a scale model of a real engine but it uses a Stuart no4 cylinder and valve chest so it is 1.5" bore x 1.25" stroke.
Title: Re: Gaskets / steam tight seals etc.
Post by: Tennessee Whiskey on March 18, 2019, 05:03:11 PM
Just a suggestion: lightly rub an oil stone across both surfaces to insure you don’t have a “hidden burr or bulge”   A shiny spot will tell the tale.

Whiskey
Title: Re: Gaskets / steam tight seals etc.
Post by: Zephyrin on March 18, 2019, 05:11:32 PM
0.35 mm is too thick IMHO, and if it is a soft material, a regular tightening may be difficult to keep valve chest and valve rod parallel to the cylinder axis.
a simple oily paper will do it or a smear with thick oil based paint.
Be careful with paint or silicon compound to not over do it, blobs of product inside steam chest may hinder valve movements.

but before the suggestion above by Whiskey is mandatory...
Title: Re: Gaskets / steam tight seals etc.
Post by: kvom on March 19, 2019, 12:10:45 AM
US $1 notes make good gaskets. 

I used the Permatext on one of my engines; it works but was a bit messy.