MEP 701a/Gasket Material

[FarmingSmallKubota]

I have been working on this Mep 701a it only has 106 hours but being as old as it is it needed some things. It came dry so fluids and filters, 24v battery was dead so i converted it to 2 12v batteries and replaced the 2 prong nato plug with the current plug because the wiring was so stiff. also ran new cables to the starter. i got carried away and replaced all the external hardware to modern stainless hexhead hardware because i was dealing with all the straight and phillips head screws that were rusted and stripped. Also got a chance to break out the Rivnut setter to replace several that stripped. now comes the meat of this post. the gasket between the fuel tank and the screwed in shround that accepts the fuel cap was leaking. I could not find a replacement and I hate cutting cork gaskets so i used material I have here mil-prf-900f. My question is will this rubber hold up to fuel. the military spec just says its rubber but not what kind. i also need to make a gasket for the fuel fill area of an H140 heater and that currently has rubber as well. Or should i buy a butyl or Neoprene sheet of Gasket.. BTW i have 30 sheets of this 900f from a GP buy so its readily available. I also cut the rubber sheets into strips for the surround for the instrument panel and used liquid nails to attach it.

 

[Coug]

Quick read through the specs doesn't list anything about oil/fuel resistance in it's requirements.

Not to say your rubber doesn't have that resistance; just it isn't part of the spec.

 

[2Pbfeet]

@Coug thanks for the specification. Actually, I think that the specification goes further in 6.1; "Material covered by this specification is intended for use in gaskets for watertight and airtight closures. It is not intended for use in equipment dor food service or containers for potable water." To me, the focus of the specification seems to be water, temperature, and ozone resistance

In searching around, I see that some MIL-PRF-90PF products that are EPDM rubber which is great for water and terrible for diesel. I don't know if all MIL-PRF-90PF is EPDM, but I was unable to find products that weren't EPDM rubber.

@FarmingSmallKubota If it were me, I would use a different gasket material as it seems to me that the odds of your current material being successful do not look that great to me.

All the best,

2Pbfeet