The Stovebolt Site Forums The Shop Area Engine Shop oil pressure gauge for testing?

where do I put a mechanical oil pressure gauge on a 235? I'm new to 235's and want to fire up the engine, but it has been sitting for I don't know how long. I was going to prime the system first to see if there was oil getting to the top side.

Hy vintage_car, the port for the gauge is near the back of the block on the left side, a couple of inches above the oil pan mounting surface. Depending on the year you may not get a lot of pressure on the gauge, the older engines with babbitted rod bearings, only put out around 15 p.s.i., hope that helps.

mine is a 1954 235...not sure if that is good or not.

1954 should be higher pressure 235 - 30 psi oil pressure would be nice in that engine.

I have a 1957 235 and was wondering about the oil pressure also. cold I have about 30 but after about a 10 mile trip it drops to around 10 at idle and 25 at speed. Is trouble coming?

No, your OK with that. My guess is that your engine has a lot of crud build up that is restricting the flow but 25 is fine to run. If it drops to 15 then start to think overhaul. Also the gauge may not be correct. How many miles is on your engine
59chevy36?

I have no idea of the milage. I have had it about 10 years. I put in a aftermarket speedo and it has about 1000 miles. Inside the engine looks clean . I change oil and filter about once a yearand used 10w40 lastime. someone said that a 30 hd may be better,it has a elect guage plumbed like it shows in shop manual.engine runs around 180 when driving.block id says its a 57 . i found a tag on the motor mount that said it was rebuilt and bored 40 over but no date.

Hey guys.

I, too, like 59chevy36, have a 1957 235. I put HD 30W in the Blue Funk at the last oil change. Seems to me that it takes a little longer after startup for the guage to go up to 30 (original guage). It'll also sometimes drop down to about 15 when idling. I kinda wondered if things had truly changed or if it was just my perception.

Build-up debris in passages increases pressure, except for the rocker oil line.
The usual cause is loose bearings.

Okay- I get the part where debris will increase the oil pressure, for example, in the oil sump pump. But, what are you saying otherwise? Crud in the rocker oil line will decrease the pressure? Low oil pressure is the result of loose bearings?

Hey! Is anybody out there?! Is this thing on?!

Blockage in the rocker line is unfortunately common, but it only restricts flow to the rockers. Your gauge probably won't show anything.
Low pressure is:
1. reduced output (excessive end play in the pump, very (very!) small leak in the pick-up
2. oil too thin (10, 5W20)
3. bad relief valve spring (relief opens too soon)
4. loose bearing clearance

Using straight 30 isn't a good idea unless the air temperature is always high, takes too long to get to the bearings.
If you have 10-15 at idle, and 30 or more cruising with 20 or 10W30 you're probably safe for now, but don't beat on it.

Thanks for all the info, panic!