The Stovebolt Site Forums The Shop Area Engine Shop Oil pressure is OK on 1954 235. Whew!

I Posted a new thread, in case there are issues unique to the 235. I was very concerned, because the pressure gauge said I had about 30 lb. while running down the road, but it dropped to ZERO while idling.

I did an oil change and put in straight 30W. No difference. So I went to AA parts and bought an inexpensive mechanical gauge. It sais I have almost 30lb. at idle, and maybe 35-40 on the road. Whew! So, what could cause that difference? Before I replace the original gauge, which at least functions, what else can I do? Could the old tube be the problem? Blow it out? Hook up the new plastic tube temporarily to see if it matters? Any ideas? I don't want to buy a new gauge if I don't have to, but I do want accurate readings. Thanks.

Sounds like you know what to do. Could be some crud in the line causing erroneous readings. That's what I would look at first. Remove the line completely and clean it out really good, then see what happens. 1954 as a long time ago.

The original type gauge is a very delicate device which is easily damaged or if you're lucky there's just a bit of air in there. Reaching up there to change a dash bulb can be enough to destroy calibration. Anyone have experience with repop gauge accuracy?

Thanks, Curt, but I don't air is the problem. After installing it, I noticed that the translucent tubing on the new gauge was 2/3 air, but worked fine. I think the column of oil pressure pushes the air into the gauge, maybe compresses it a bit, but the gauge indicates the pressure of the oil (air). After all, you don't prime the tube, so you have to start with the air which is captive in the tube? But I admit that I could be 100% wrong about this.

Deve, you were spot on! After I cleaned out the line, the original gauge was fine. Found that the red plastic tube from a can of WD40 would fit the ID of 1/8 line great, so first filled it and let it soak, then used air. Biggest headache was working under the dash. Other option was to remove the whole cluster, but I had just enough room to wiggle the wrench so I did it that way. Going back, the old fittings were stiff and hard to get started by hand. So I learned a trick: chucked up the nut in my cordless drill, careful not to touch the threads (they go around anyway inside the chuck) and let 'er rip for a minute or so. Just like new. Thanks for your help.'

Harry

Glad to hear it worked out for you. You haven't lived until you are upside down inside a UH-1N Bell Helicopter, or an HC130 Airplane, or even a Cessna 172 or Piper Cherokee. The wiring and gauges are so insanely tight, usually it takes another person to help pull you out of the area you are stuck inside. So, if you are upside down, with your butt resting sorta on the seat and your head deep inside the under-dash area of a pickup, you can fully relate to the HATRED and total animosity technicians have for engineers who absolutely and without any reservation had their head totally up their asses when designing these machinations without ever considering what would happen when something went wrong. I hated engineers so much I became one so this madness would never happen again. I totally lost.

Although these trucks were engineered pretty well, there are still things today that completely zoomed right over their heads. Its just not cost effective to care about the technician. Good job on fixing your truck! You are among the short few who attempt to do it right! Most people would just purchase new gauges.