G80CS Pushrod Tube Sealing

General purpose topics/chat goes in here
User avatar
Pharisee
Member
Posts: 1126
Joined: Tue Mar 15, 2016 8:51 pm
Location: Lincolnshire UK
Contact:

Re: G80CS Pushrod Tube Sealing

Post by Pharisee »

arty wrote:Been following this thread as my 55 G3LCS has the same problem even after fitting new rubber seals and steel washers, would be interested in how many O rings it takes to seal and if its successful.
Cheers Arty
Not a CS, but my '54 G3/LS and my '55 M18S both use 4 "O" rings in the head, between the dished and flat washers. The bottom "O" ring seal compresses nicely and there's no sign of any leakage.
I should perhaps add, that both machines have later heads and use the shorter pushrod tubes.
Last edited by Pharisee on Mon Jun 22, 2020 6:11 pm, edited 1 time in total.
I'm from the Fens.... Gimme six.
User avatar
dave16mct
Member
Posts: 3234
Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: G80CS Pushrod Tube Sealing

Post by dave16mct »

The last single I built used 4 O rings. I gave some to a friend and that also used 4. I used the standard O ring at the bottom from the gasket set, but I'll invest in some Nitrile ones in future.
Dave.
User avatar
Iron Head
Member
Posts: 277
Joined: Sun Jan 24, 2016 7:19 pm
Location: BERKSHIRE UK

Re: G80CS Pushrod Tube Sealing

Post by Iron Head »

Well I followed everything by the book and now have what were a very nice original pair of pushrod tubes both split at the bottom! It didn't feel good tightening down, there was just too much resistance from 4 O rings. Perhaps the Viton was against me but they are only 75 Shore hardness against 70 for Nitrile. Tubes were located nicely in the top washers. I'm sure there is a secret to this but I'm going back to original seals, or 3 O rings?!

Iron Head
Yak
Member
Posts: 134
Joined: Mon Jan 13, 2014 12:00 am
Location: SOUTH AUSTRALIA AUSTRALIA

Re: G80CS Pushrod Tube Sealing

Post by Yak »

Only three o rings on my push rod tubes. No leaks. I do not fit the dished washer, the tubes are quite a snug fit in the iron head and the seals show no sign of slipping down. The seals that come in the gasket sets are crap material.
Ray.
User avatar
Iron Head
Member
Posts: 277
Joined: Sun Jan 24, 2016 7:19 pm
Location: BERKSHIRE UK

Re: G80CS Pushrod Tube Sealing

Post by Iron Head »

Thought I'd give an update on what has revealed itself to be a more complex process than it perhaps need be. After several ‘dry fits' and measurements, it appears that there is no exact science to how many O rings to fit!

This is partially due to original vs pattern pushrod tubes. When fitting conical washers, measurement reveals that the washer seats 2.5mm higher on pattern tubes vs originals. Ray was correct (in my humble opinion) that when running original tubes 3 of the 3.5mm thick (in my case Viton) O rings would be about right. However with my pattern tubes 2 O rings, plus of course the washers, seems to have pulled down just right. With the conical washer riding higher and having the effect of extending the fitted length of the tube I'm pretty sure 3 O rings would have split the pattern tubes.

Iron Head
Locked