250 LeMons Engine: Endless Rear Main Leaks

chad":8ze93lbx said:
my local ford dealer has no rear main seal (rope or neoprene).
Can I usea hunka rope? Need special kind (w/asbestoses?).

Best Gasket bestgasket.com makes a good graphite rope seal. Nothing else supplied now is any good.

So it’s either NOS asbestos rope seal.... or Best Gasket graphite rope (which works) Best doesn’t list a kit for the 250, but I’m sure one of the kits would work. They are trim to fit anyway.
 
humphf !?!..."Best Gasket graphite rope seal". I'll B darned.
Thnx bro~

Only rubber over there:
https://bestgasket.com/vintage-engine-gaskets/

I guess I could lookit some retailer?
It's not the stuff I seal my wood stove door w/every few yrs (offa bundle, spool type thing?).
 
chad":2jgjms1r said:
humphf !?!..."Best Gasket graphite rope seal". I'll B darned.
Thnx bro~

Only rubber over there:
https://bestgasket.com/vintage-engine-gaskets/

I guess I could lookit some retailer?
It's not the stuff I seal my wood stove door w/every few yrs (offa bundle, spool type thing?).

This rope: https://bestgasket.com/rear-main-seals/

They don’t list a specific kit for a small six, but you just need the dia of rope, a longer piece is fine, because you trim it to fit.
 
Are not the rear main seals on the 250 the same as the 302? RockAuto lists them with the same number on a 1980 Ford Granada with either engine. Maybe that is why they don't fit so well?

See Ya,
Mike
 
hafta go 2 the companies direct?
Fel-pro
Victor
etc ?
 
Max_Effort":zn4cx5hq said:
chad":zn4cx5hq said:
humphf !?!..."Best Gasket graphite rope seal". I'll B darned.
Thnx bro~

Only rubber over there:
https://bestgasket.com/vintage-engine-gaskets/

I guess I could lookit some retailer?
It's not the stuff I seal my wood stove door w/every few yrs (offa bundle, spool type thing?).

This rope: https://bestgasket.com/rear-main-seals/

They don’t list a specific kit for a small six, but you just need the dia of rope, a longer piece is fine, because you trim it to fit.

That stuff looks an awful lot like graphite shaft packing for boats. I wonder if it's the same stuff. It's available in sizes from 1/8" to 5/8" in 1/16" increments.

https://www.fisheriessupply.com/western-pacific-trading-gtu-graphtex-ultra-shaft-packing
 
Xctasy hinted at the other problem in post #17 above with are old tech small six's and I agree, what happens when the newer oils are being used in these engines that were designed to use the old straight crude 30 weight oils. They were built with much less precision plus they also have higher bearing clearances to start with compared to the newer engines of today then factor in wear over time, with the synthetic oils being so much thinner and super slick your going to get more leaks. Good luck (y) :nod:
 
Econoline":1xr7dvvs said:
Max_Effort":1xr7dvvs said:
chad":1xr7dvvs said:
humphf !?!..."Best Gasket graphite rope seal". I'll B darned.
Thnx bro~

Only rubber over there:
https://bestgasket.com/vintage-engine-gaskets/

I guess I could lookit some retailer?
It's not the stuff I seal my wood stove door w/every few yrs (offa bundle, spool type thing?).

This rope: https://bestgasket.com/rear-main-seals/

They don’t list a specific kit for a small six, but you just need the dia of rope, a longer piece is fine, because you trim it to fit.

That stuff looks an awful lot like graphite shaft packing for boats. I wonder if it's the same stuff. It's available in sizes from 1/8" to 5/8" in 1/16" increments.

https://www.fisheriessupply.com/western-pacific-trading-gtu-graphtex-ultra-shaft-packing

It does look the same! A “rope rear main seal” is just “shaft packing”
 
Traditional shaft packing is waxed flax, then there is the newer telfon stuff, then the "ultimate" is that graphite stuff.

I see what happens to shafts after many years, the packing wears away the shaft where it is in contact. It can be pretty significant. I can't help but wonder if those that have persistent leaks from the rear main is b/c the old rope seal has worn the crank out of spec. Maybe not that there is any problem with the seals available. Like stated the 250 seal is the same as for 302's of that era and always has been.
 
Econoline that may be a posablity that the seal surface might wear. I can say that my 77 Maverick only had approximately 12,500 orginal miles when I tore it down for a look (had been sitting a few years) the short block was beautiful condition inside and everything still looked factory fresh. Even though it didn't need it I did put a set of fresh Molly Rings, Celevite 77 Bearings, freeze plugs, and a Felpro gasket set it came with the neoprine rear main seal just like the original seal. Never had any external oil leaks I used a straight 30 weight Valvoline oil also. The head did need some repair work though. (y) :nod:
 
Back
Top