F-134 Oil pressure sender

The old sending unit was seeping a little oil, so I ordered a replacement. The replacement sender fit fine and appears to work normally. It did have a different connector for the wire so I cut off a length of 10-32 brass machine screw and soldered it to the connector, and now it hooks up to the wiring harness just like the old one.

My question is, the old sender has this brass fitting that screwed into the engine, that has a metered orifice. The new sender just has a 1/4" pipe fitting and no orifice. The metered fitting will not come off the old sender, and I don't want to destroy it trying, because if the new one fails at least the old one will plug the hole....the light now goes out almost immediately when the engine starts...it used to take a couple of seconds..I'm just wondering if I'm getting an accurate indication without the little orifice.....I know a gauge would be best, and maybe that will be next.....

Also the old sender had a "55" stamped on one flat of the fitting, and a "6" on one of the others....any meaning that anyone knows of?





Thanks,

Randy

 

Thanks Howard...I've been looking at capillary tube gauges, but I will not drill a hole no matter what.....so maybe just a test gauge one day in the pressure port just to see what's going on in there....

 

A very small orifice may act as a damper. Also it might serve to restrict oil loss in case of some kind of damage to the sending unit. But the ultimate pressure reading reaching the sender would be the same with either fitting.

 

Good point about the possible oil loss.....I thought maybe it was there to keep the full force() of the oil pump from acting directly on the sender's diaphragm or whatever is in there....I guess that would be a damper as you said....

Stewart-Warner offers a nice looking gauge, and they also have braided capillary lines...but I'd probably have to drill a hole..

Some of the other early CJ's had electric sending units that would drive a regular gauge...then all I'd need was a wire that could be fished through the grommet where the wiring harness goes.....

 

Mine is in a guage set hung under the dash at center. Mechanical capillary type. Copper line. Goes through the same hole and grommet as the wiring harness.

 

Do you remember what make it is or where you got it? I think that if i were to use a 10 or 12" flex line from the engine, support it on the firewall, and then connect it to a copper capillary line there should be less danger of the copper work hardening and breaking.....

 

"if i were to use a 10 or 12" flex line"

Sure. In the old days they would make a couple extra loops of tubing into a coll to absorb movement and reduce vibration/fatigue.

 

The thing about a flex line is you can route it away from the brake pedal etc. Using a 90 degree fitting it can follow the head oil line. I went out and looked at the area and there is a clip fastened to the back of the block that holds the oil line to the top of the head. There is an additional loop on that clip that would hold a flex line just fine. From there to a clip fastened to an extra long floor panel bolt....should work fine. I have a 59 MG that has a flex line/capillary tube arrangement..has been trouble free..of course the MG is more modern....

 

"of course the MG is more modern...."

Please, stop... it hurts when I laugh...

 

Oh but it is!! Built four years later and using technology from 20 years earlier!

Went to O'reilly's today, didn't expect much but I was surprised to find a whole display of various gauges....and they also had copper capillary tube kits.....so when and if I find one of my spare/leftover modern Smiths (MGA) oil pressure gauges I'll just see if i can make it work.

And the coil means of isolating the engine movement/vibration seems like the simplest way to go....simple is good...

 

OK. Oil pressure gauge is finally installed. Used a 1/8" steel "run tee" T fitting from the engine, added the sender for the light, routed the copper capillary tube through the wiring harness firewall grommet, and then to the gauge...

Warm it indicated about 40 psi when cruising at 35mph, idle is about one needle width off the stop, and the light is out....