Oil pressure sensor

[Drummer72]

I have a leaking oil pressure sensor on my '71. The fitting that is screwed into the manifold and holds that little hose is the culprit.
It seems to be leaking where the hose comes out of the plug.
Two questions: Does anyone have any suggestions how to cure this leaking?
Second, what kind of thread does this plug come with. I assume it's UNF 3/8" but I could use confirmation before ordering any taps or replacement parts.

Jeroen

 

[Jack]

I have a leaking oil pressure sensor on my '71. The fitting that is screwed into the manifold and holds that little hose is the culprit.
It seems to be leaking where the hose comes out of the plug.
Two questions: Does anyone have any suggestions how to cure this leaking?
Second, what kind of thread does this plug come with. I assume it's UNF 3/8" but I could use confirmation before ordering any taps or replacement parts.

Jeroen

1/8" NPT ... aka pipe thread ... it is a tapered thread ... commonly used throughout USA & elsewhere. I know it seems much larger than 1/8" but that is what it is ... 1/8" NPT.

It is NOT UNF 3/8" ... it is 1/8" NPT.

The plastic tube gets brittle with age & will crack. Also, on my 71, the brass part that screws into block failed ... it had a very tiny integral ferrule that slipped inside the ID of plastic tube .. the ferrule broke off allowing tube to come loose ... all oil left engine VERY quickly ... engine did not survive. Suggest replace tubing from engine to gage ... inspect all fittings for stress/cracking ... replace if any are questionable.
JACK:gap

 

[Jack]

clarification

I have a leaking oil pressure sensor on my '71. The fitting that is screwed into the manifold and holds that little hose is the culprit. It seems to be leaking where the hose comes out of the plug. Jeroen

I apologize, I should have described more clearly. The brass fitting & plastic hose/tube I refer to are common to both 71 & 72. It supplies oil pressure through tube to mechanical oil pressure gage. Neither 71 nor 72 had "oil pressure sending unit" as used in later C3s with electrical op gage. The 71 & 72 brass fitting screws into top-rear of block, very near the back of intake manifold, near distributor base ... that brass fitting and its hole in block are both 1/8" NPT.
JACK:gap

 

[Drummer72]

Thanks Jack for the info. It does indeed seem to be bigger than 1/8". Replacing at least the tube is probably the only way to take care of this problem properly.

Jeroen