The Stovebolt Site Forums The Shop Area Engine Shop 235 WTF Oil pressure??

'53 235 Full Pressure,

Fresh overhaul, approx 1 hr. on engine,
Truck has a "216 splasher" Oil Pressure gauge 0-15-30 psi.

First few engine runs, Oil press was most always at 30psi.
I've run it a couple of times more (in the garage) and driven it once (2 miles) to get gas.

Now (idling) oil pressure is +/- 16-17,
when I bring up the RPM, pressure will go to 30,
if I back off the RPM, pressure drops back down.

Oil quantity's full,
New filter,
water temp stays around 180.
Oil ozzes out of holes on top of rockers when idling when pressure was at 30 (should it be more?)
Pump is a Melling M-29 (new)

Any suggestions, How do I trouble-shoot this?
Jim

That seems about right to me. Other more experienced minds will probably be along soon and offer advice.

I have two trucks with "splasher" oil gauge and later high pressure 235s. They both do the same thing and I would say it is normal. No doubt, with higher rpms you are pinning the oil gauge at 30 and the actual pressure is higher. Of course, we are assuming your gauge is accurate as the real pressures could be higher or lower.
Kent

I'd suggest tapping into the side of the block temporarily with a gauge you know to be accurate, possibly one with a 0-50 PSI range or so. Factory original gauges have a tendency to be extremely inaccurate at times. Since "idiot light" switches had a turn-on pressure of 7 PSI, a lot of engines without a gauge that had a pretty severe pressure drop at idle never let it be known. As long as the pressure comes up off-idle, you probably don't have a problem.
Jerry

I have the exact same setup. '53 full pressure engine and a 30# gauge. 10,000 miles since total professional rebuild. The needle stays pegged on 30# until it is thoroughly warmed up. Once it is warmed up it drops to 15-16 at idle. I keep the idle at around 450 RPM. At 600 RPM, it pegs the 30# gauge.
You are fine. Nothing to troubleshoot whatsoever. 15 PSI is twice as much as you need at idle. Oil oozing at the rocker arms at idle verifies this.
Carl

I thought I had an (oil pressure) issue,

Thanks for all the great responses.
Jim

I swear mine never drops below 30, but maybe I'm losing my mind.... I'll confirm next time we run the engine.

56 235 engine in my 53, running mechanical lifters with stock oil pressure gauge. At speed it pegs the needle at 30psi. Warmed up at idle about 10psi.

What is your RPM at idle? What weight oil are you using? You live too close to the Arctic Circle to count.
Carl

I just wanted to add another confirmation . The 235 in my '37 pegs at 30 till it warms up then is about 15 at idle. Very old engine.

1) Low according to my ears, 2) unknown, but likely 15W40 and 3) pfft.

"pfft"? Since I don't speak Canadian, I do not know what that means. I have a feeling that I probably don't want to know.
My Arctic Circle reference was intended to illustrate that colder ambient temperature will have an affect on oil viscosity, resulting in higher oil pressure than what can be expected in a warmer climate.
Carl
Socially awkward Yank.

pfft

exclamation (probably meaning #1 or #3)?

1. used to represent a brief sound such as that made by the passage of a bullet or that of a small, muffled explosion.
"Pfft! Pfft! Pfft! Bullets ricocheted around the room"
2. used to convey the suddenness of a malfunction, disappearance, ending, etc.
"then pffft, that was the last we heard of them"
3. used to express a contemptuous or dismissive attitude.
"pfft, I don't know what all the fuss is about"

(from Google dictionary - presumably similar meaning in Canadianese?)

Haha, nice work! I would say number 3 is accurate...