Dieselfitter
Active member
- 70
- 236
- 33
- Location
- Cody, WY
1969 truck , truck is in good shape but had air leaks evrywhere , built good air but when you shut truck off i could hear leaks. Certain things drive me batty ,leaks are very high on the list .
compression joints arent really the best option for air tite service in a high vibration climate .
changing the truck over to a flare type fitting would be more time and difficulty than its worth looking at where some of those connections are , and the components that need to be connected .
So tighten all the copper compression and re dope NPT joints . All good , except,
the 2 leaks i found under the dash were on the 2 rubber flex hoses that run from a header block on firewall to air gauge in cluster , the other ran to transfer case air shift.
both hoses are 1/4” male NPT at block and a swivel 1/8” type thread on both gauge and shift selector . 1/8” npt looks like the right thread pitch per inch and fits tight but its not tapered.
Does anyone know what connection type that is called ?
I tested this with a 1/8” female npt thread it runs right on and tightens against the taper , i applied a pipe dope that we use in the trade of steamfitting , i didnt over tighten in that i didnt want to stretch the treads on gauge or shifter , making the components useless.
i let the truck build air and no leaks. 1/8” npt is an option i guess but would rather find the perfect match to that fitting .
compression joints arent really the best option for air tite service in a high vibration climate .
changing the truck over to a flare type fitting would be more time and difficulty than its worth looking at where some of those connections are , and the components that need to be connected .
So tighten all the copper compression and re dope NPT joints . All good , except,
the 2 leaks i found under the dash were on the 2 rubber flex hoses that run from a header block on firewall to air gauge in cluster , the other ran to transfer case air shift.
both hoses are 1/4” male NPT at block and a swivel 1/8” type thread on both gauge and shift selector . 1/8” npt looks like the right thread pitch per inch and fits tight but its not tapered.
Does anyone know what connection type that is called ?
I tested this with a 1/8” female npt thread it runs right on and tightens against the taper , i applied a pipe dope that we use in the trade of steamfitting , i didnt over tighten in that i didnt want to stretch the treads on gauge or shifter , making the components useless.
i let the truck build air and no leaks. 1/8” npt is an option i guess but would rather find the perfect match to that fitting .
