Question: Oil Pressure Gauge Question

[rusteze]

I am a new member to your site and need help with 1969 C3 oil gauge.
Your site is very informative and well done so my question is:
Can air get trapped in oil line that go to cabin oil pressure gauge if
so can that be giving me the fluctuating readings on gauge and how
do I bleed it out? Thanks Rusteze,

 

[bill81vette]

I believe the gauge is electronic
Perhaps your sending unit is going bad..

Sent from my DROID RAZR using Tapatalk 2

 

[Vettehead Mikey]

The stock gauge on a '69 is mechanical. It doesn't matter whether air is trapped in the line or not- pressure is pressure. Air might actually help dampen any fluctuations.

When do you get these fluctuations and how large are they?

 

[rusteze]

Thanks Bill81Vette, Glad I found you guys, need to do better research in my Service Manual. Rusteze

 

[TimAT]

69 gauge is mechanical. Having air in the line is no deal at all. If you're seeing big jumps in the reading one possibility is the bypass at the oil filter mount is having a problem. Opening and then closing.

 

[rusteze]

Oil Pressure

Thanks Guys, would never of found these kinds of solutions in the manual will look in to all of them. Rusteze

 

[rusteze]

Oil by-pass

Thanks for all the input guys, Looks like there is no sending unit on this one, there is however a fitting just above the spin on filter a 1/16th tube [ a Bourdon] as it called goes directly to the gauge. The first time I start it 35 to 40 psi then after it warms up it starts. So TimAT can you tell me more about the oil by-pass or any one this looks like the issue. Rusteze

 

[Vettehead Mikey]

The first time I start it 35 to 40 psi then after it warms up it starts.

35-40 psi on a cold engine sounds low to me and marginal on a hot engine. When you say 'after it warms up it starts' what's 'it'?

 

[TimAT]

Thanks for all the input guys, Looks like there is no sending unit on this one, there is however a fitting just above the spin on filter a 1/16th tube [ a Bourdon] as it called goes directly to the gauge. The first time I start it 35 to 40 psi then after it warms up it starts. So TimAT can you tell me more about the oil by-pass or any one this looks like the issue. Rusteze

Correct- that little tube above the filter goes to the gauge. Technically speaking, the "Bourdon" tube is internal to the gauge. You might take a close look at that tube- from the engine all the way to the gauge. If it's got a spot that's starting to seep or even if it shows a little sign of rubbing on something a failure might be in the near future.
The oil filter bypass is attached to the block- the oil filter mounts on it.
I might think about installing a temporary gauge and seeing if it follows the factory gauge.

The way I read the above, the gauge reads steady until after the engine and oil warm up, and then starts fluctuating. IS that correct?

 

[rusteze]

"Whats It"

Sorry, After warm up or running a while the gauge [oil]reads like the tachometer drops down below to 25psi at 2000rpm and up to 50psi+ when past 3500rpm then holds.What is the safe operating reading if the gauge is working properly? Rusteze

 

[Vettehead Mikey]

Sorry, After warm up or running a while the gauge [oil]reads like the tachometer drops down below to 25psi at 2000rpm and up to 50psi+ when past 3500rpm then holds.What is the safe operating reading if the gauge is working properly? Rusteze

That sounds perfectly normal to me. Oil pressure rises with engine speed, up to the point where the pressure relief valve opens.

 

[TimAT]

I agree with Mikey-- I don't see a problem.

Cold, I get nearly 80 PSI- once it gets hot, it runs around 65 PSI. With the oil pump I have, that's about right on for my engine. (it's NOT stock).