The Stovebolt Site Forums The Shop Area General Truck Talk Oil gauge question

I just rebuilt the 292 in my 63 3/4 ton and with a new oil pump I'm getting 80# of pressure. The factory oil gauge only goes to 60#. I'm wondering if anybody has had the oil gauge go bad with too much pressure.

Larry

I run my '37 with a 30 lb gauge all the time. At idle when its hot, it shows 25, above idle, who knows? When the 250 was new and had heavy oil, it was in the 60 psi range, but with the
5w30 oil, its not that bad.

I heard the gauges can go bad and blow oil everywhere, but have never seen it happen.

Joe

Larry,

That's some ferocious pressure! If the gauge did rupture, it would probably take out half the dash.


Stuart

Sounds as though your oil pressure relief valve is stuck. Blowing out the gauge would be the least of the problems; a blown oil filter would take longer to detect and could spell finis to your engine.

What's the pressure at a hot idle? 80 lbs. from a cold engine isn't terrible, but it will put a strain on the pump drive and distributor gear. If you're getting 80 lbs. hot, you need to reduce the spring tension on the pressure relief valve and pump some of that oil back into the pan.
Jerry

Thanks for the responses!

I know about the stuck relief valve. This block was supposedly rebuilt, with about 10k on it, when I got it. One of cylinder was scored real bad, but the piston looked perfect considering 10k. Anyway had it bored, put it back together used same oil pump. Primed the oil till I felt the drill start to really work. I have a mechanical oil gauge I keep in the tool box for when I first start a motor that's all the use it gets. I always put it on a motor when I first start it. The oil gauge read 80# plus on the prime, OK the drill turns fast. When I started it blew the oil filter gasket, OK maybe I didn't tighten it enough. I put another filter on same thing. (Think I posted that here.) I bought another pump standard replacement made by Mellings. This time when I primed it, it went to 80# and held.

I hooked up the oil gauge the previous owner installed it goes to 80# and is mechanical also, today. I get a different reading a bit over 40#. Maybe I blew more than the oil filter gaskets. I'll have to check the gauge in tool box and see if it reads good, now.

Larry

Most of these small mechanical gauges are the Bourdon type. If you go too far past the upper range there's a couple small gears inside that can get out of calibration when one of them moves past the end of it's teeth. Depending on what the needle does when it moves past the end determines how much it's off when normal pressure is restored. It's possible to reposition the gearset and check it against a known good gauge but don't use any sharp tools on the tube or bend it too far.

Harold, Would the gauge still read zero with no pressure?

Larry

You can't always depend on the zero reading at O pressure. If your gauge has a little pin sticking out of the face of the gauge at the zero pont it prevents the needle from going below zero if the calibration is off. If the needle is pressed against the pin at zero pressure you need to check at another pressure to see if it's calibration is OK.

If there's no pin and it reads zero at 0 pressure it's probably OK.

If it reads above zero at 0 pressure it needs repair or calibration or replacement

Many of these if you exceed the upper pressure by a small margin (maybe 20% or so) are repairable but way too much pressure can straighten the tube and make them useless. But some are pretty delicate almost like repairing an old mechanical watch.

Great information, Thank you so much.

I've had a few old gauges apart out of curiosity and they are worse than a mechanical watch. Some mechanisms seem to be finely balanced, and you just CAN'T tweak correctly.

Larry

I know you are talking later model here but as info I had my 37 guage redone and calibrated for 60lbs back in 2000. Still works fine......
Just last Friday I took the guage for my 52 Panel over to the "guage man" and he calibrated it for 60 lbs in about 10 minutes. I had put a 60 lb decal/reface on it and he said it should be fine! Just info....

Achipmunk, Thanks for the info. The gauge that is bad now is he one I keep in my tool box. I wonder if there is a "Gauge man" in my neighborhood.

Larry