I looked in the AMM, Continental O/H manual,Cont. Manual M-0 and Cont. Operator's Manual and can't find anything - for the oil pressure relief valve with the external screw, does screwing it in (towards the engine) increase pressure? And, how many turns equals approx. how many psi?

First question I’d ask is : Why do you feel you need to adjust oil pressure? Has oil pressure changed significantly recently? If so, I’d really want to figure out what caused that change, before I started chasing oil pressure. It could be a symptom as opposed to the disease.

MTV

Turning it in should increase pressure.

Turning it in increases pressure on the spring which in turn increases oil pressure. I'm not sure there's a hard fast rule to number of turns equals pressure increase?

Like MTV is alluding to it's pretty unusual to ever adjust oil pressure on these engines, certainly in my experience anyways. It's worth some time to take it all apart make sure the seat of the valve doesn't have some crud on it. Also good to double check one's gauge if it's a mechanical one...

mtv wrote:First question I’d ask is : Why do you feel you need to adjust oil pressure?
MTV

Because I want to know. I have noticed you have done this before - some guy asks a question and your response is 'why do you want to do that'. Not very useful.

Like has been said; check the plunger and seat for contamination before making any adjustments. A speck of carbon can make you lose a fair bit of oil pressure.

To answer your question: screwing the screw further into the engine does increase the oil pressure. There is a rule of thumb for turns/psi but it’s not coming to me at the moment. Regardless, adjust 1/4 turn at a time then check pressure.

The springs can go soft and the plungers do go bad so there are reasons you might lose pressure besides bad bearings or something like that. I’ve have springs go soft on two different Conti engines, one shortly after overhaul with new springs installed. Also had the plunger fail, maybe from weak springs?

Good luck.

C180_guy wrote:

mtv wrote:First question I’d ask is : Why do you feel you need to adjust oil pressure?
MTV

Because I want to know. I have noticed you have done this before - some guy asks a question and your response is 'why do you want to do that'. Not very useful.

Probably because all of us were thinking "I wonder why he needs to adjust oil pressure?"

C180_guy wrote:

mtv wrote:First question I’d ask is : Why do you feel you need to adjust oil pressure?
MTV

Because I want to know. I have noticed you have done this before - some guy asks a question and your response is 'why do you want to do that'. Not very useful.

Adjusting oil pressure is a very serious thing. If oil pressure has decreased, and you can’t explain it, that is a serious maintenance issue. And I’ve never met a mechanic who would just adjust the pressure without understanding the reason oil pressure has decreased.

Now, if you are truly “just wanting to know” how to increase oil pressure, it suggests you MAY be about to do something dumb. Please forgive me for feeling empathy for your engine.

MTV

C180_guy wrote:I looked in the AMM, Continental O/H manual,Cont. Manual M-0 and Cont.

It’s in the M-0 manual. Section 6-4.10.1. The whole procedure, with diagrams.

Chris

C180_guy wrote:

mtv wrote:First question I’d ask is : Why do you feel you need to adjust oil pressure?
MTV

Because I want to know. I have noticed you have done this before - some guy asks a question and your response is 'why do you want to do that'. Not very useful.

I am grateful for this website and for these dialogues (both sides) because there are probably more folks like me out there who aren't interested in getting snubbed for asking the "stupid question" and consequently are able to enjoy multiple thought processes.

Take care, Rob

Reference Avweb.com article, accident probe: maintenance matters. Root cause oil suction screen obstructed. Hadn’t been checked in 13 years.

redbird wrote:Reference Avweb.com article, accident probe: maintenance matters. Root cause oil suction screen obstructed. Hadn’t been checked in 13 years.

The engine in that article was a Lycoming TIO-540, different animal than our Continental O-470s.

Ross

airChris wrote:

C180_guy wrote:I looked in the AMM, Continental O/H manual,Cont. Manual M-0 and Cont.

It’s in the M-0 manual. Section 6-4.10.1. The whole procedure, with diagrams.

Chris

Interestingly, my old 470 overhaul/maintenance manual sez the oil pressure relief valve is non adjustable--
not the first thing I've found in it that is incorrect or outdated.
However, the much newer "O-M Manual" has the scoop, as Chris said.
Here it is: