[Healeys] Ethanol effects on rubber

Tim Davis BN7 tld6008 at mchsi.com
Fri Jun 22 18:41:37 MDT 2018

What material is the Toms diaphragm made of? That's what you need to know.

Tim Davis BN7

----- Original Message -----
From: Bob Spidell <bspidell at comcast.net>
To: Healeys <healeys at autox.team.net>
Sent: Fri, 22 Jun 2018 15:19:17 -0400 (EDT)
Subject: [Healeys] Ethanol effects on rubber

Just when you thought you'd heard the last on this ...

Having bragged about my scientific creds, I decided I needed to do some 
'scientific' experimenting.  I bought a new HD8 diaphragm jet from Tom's 
and put it in a jar submerged in denatured alcohol.  If you're not 
familiar with denatured alcohol, it's ethanol--i.e. booze--with one or 
more denaturing chemicals to make it unpalatable to drink.  When I first 
did this thought experiment, I thought DA was mostly ethanol, but the 
quart I bought at a hardware store claims to be 45-50% ethanol and the 
remainder methanol (and probably some water as both alcohols are 
hygroscopic).  Though this mixture doesn't represent the 10% or so of 
ethanol in gasahol, IIRC from my college chemistry and lab technician 
days that methanol is even more corrosive than ethanol.  So, this should 
be a good test of the rubber part of the jet's resistance to these 
solvents (and the brass part too, I suppose).  I put new jets in my 
BJ8's HD8s two years/12K miles ago, and should have done this then in 
case the results were scary, but maybe this will tell us something.  
I'll check the jet periodically for degradation and, if anybody's 
interested let you know.



More information about the Healeys mailing list