Oil pressure Yanmar 4JH5E

[a64pilot]

Originally Posted by Benny737

What would be the normal oil pressure for this engine?

I’d just be guessing if I threw out some numbers, but they should be in the engine’s manual, along with the pressure that the alarm should sound.
Most often the alarm pressure is much lower than an engine will ever see when operating, of course the lowest pressure an engine has is usually at a low idle when hot.

[Tin Tin]

Per manual at rpm 772, psi = 7.3
at rpm 3477, psi = 39-41

[Benny737]

Originally Posted by Tin Tin

Per manual at rpm 772, psi = 7.3
at rpm 3477, psi = 39-41

Than you TinTin
Ii couldn’t find it in the owners manual. Is it in the service manual?

[Tin Tin]

Originally Posted by Benny737

Than you TinTin
Ii couldn’t find it in the owners manual. Is it in the service manual?

Yes, service manual.

[Benny737]

Originally Posted by Tin Tin

Yes, service manual.

Great. Thank you so much.

I believe that owners manual is quite poor in terms of tech info. I will try to find and download the service manual .

Cheers

[Wotname]

Originally Posted by Tin Tin

Per manual at rpm 772, psi = 7.3
at rpm 3477, psi = 39-41

Great info, thanks.

What is the oil pressure relief valve setting (presumably 41+) ????

[a64pilot]

Originally Posted by Wotname

Great info, thanks.

What is the oil pressure relief valve setting (presumably 41+) ????

Maybe, However with a close to healthy engine you’ll find it by going to cruise RPM soon after starting, say within 5 min or so.
Then a strong indicator of a healthy engine is if it maintains close to that pressure when fully warmed up.
Also I believe that 7.3 PSI is a min pressure, I’d expect to see much higher, even when hot and idling.

Proper oil viscosity is of course important to oil pressure as is of course being fuel diluted.
An increasing oil level with a corresponding drop in pressure strongly suggests fuel dilution.
Not saying his is of course, but it’s worth checking after he verifies pressure with a direct reading gauge, if it is in fact low.

[Wotname]

Originally Posted by a64pilot

Maybe, However with a close to healthy engine you’ll find it by going to cruise RPM soon after starting, say within 5 min or so.
Then a strong indicator of a healthy engine is if it maintains close to that pressure when fully warmed up.
Also I believe that 7.3 PSI is a min pressure, I’d expect to see much higher, even when hot and idling.

Proper oil viscosity is of course important to oil pressure as is of course being fuel diluted.
An increasing oil level with a corresponding drop in pressure strongly suggests fuel dilution.
Not saying his is of course, but it’s worth checking after he verifies pressure with a direct reading gauge, if it is in fact low.

Yes, the idle is a min pressure and this is mentioned in the extract from the service manual upthread although not mentioned in the post itself.

No criticism of Tin Tin's post, just a caution that the detail is often found in the service manual itself rather than another's reading of it.

You make a good point about how to determine the actual relief valve setting

[Benny737]

Does anyone knows if the service manual for 4JH5E is anywhere available for a free download?