What does a lowered PSI guage reading mean?

ziekman@cox.net

ziekman@cox.net

Active Member
Jun 23, 2009
1,242
Old Saybrook, CT
Boat Info
2012 45 Yacht
Engines
D6 Volvo Penta IPS
My two engines were always running around 50 - but after a 4 hour run from Montauk to Saybrook yesterday I noticed they were both around 29 - what does that mean, is it something I need to address?
 
I have the same engines. Its odd that they both would have the same below normal readings. One of my engines dropped like that a few months ago. It was an overused oil filter causing the problem. I would change yours asap if you
haven't already. When was the last time you changed your oil?
Don't run those engines unless you get the oil pressure fixed. They absolutely need at least 50PSI to avoid trouble.
Get a good mechanic involved right away.
 
Thats a beautiful boat. Congrats. I see you are running in salt water like me. Are you doing anything to rinse-out the engines after each trip?
 
Thanks - we are having a great time with it! As for the salt water, we keep the boat in fresh water, so everything gets wash out on the way home. As for the engines, I believe they are a closed system, so there is no need to manually rinse them out.
 
Just so you have "all" the details on your 8.1s engines.....
They have both a closed cooling system for the block and head just like a car BUT they also have sea water cooling on the exhaust manifolds, heat exchanger and Kool Fuel system.
I know for sure - just spent $7,000 changing out all four exhaust manifolds, rebuilding one of the heads and replacing all the gaskets on everything. I have just modified the intakes to allow me to rinse out the system with fresh water after every trip to prevent any corrosion.
 
I was probably running around 2500 - 3000 RPM, but I didn't notice the drop until we were at the end of the 4 hour run - it was a very rough ride the whole way, and to be honest with you, I usually monitor continually, but was distracted with the seas. I was watching the temperature gauges, but I really wasn't keeping me eyes on the PSI's.

I did contact my dealer earlier today and he said the oil runs very hot during a long run like that, to check my fluid levels (which I'm going to do tonight), and that I'm probably in the range of oil and filter service so I'm going to do that early next week. He didn't seem to overly concerned. He said that as the oil cools down, the pressure should rise.

My plan is to do the above and then watch for the PSI on a short run this coming Sunday.
 
29psi at 3k plus it a bit low....BUT hot won out oil will drop psi's.

Usually when the pressure drops it is because the rod bearings are worn.
 
I don't know the spec for your engines, but for most engines the minimum spec is about 10psi. Did the psi come back up at idle? How about once the engines had cooled down? I wouldn't be too worried about it - it's likely just due to the oil getting nice and warm... especially since both engines did the same thing. It's been pretty hot, lately.
 
Lazy Daze said:
I don't know the spec for your engines, but for most engines the minimum spec is about 10psi. Did the psi come back up at idle? How about once the engines had cooled down? I wouldn't be too worried about it - it's likely just due to the oil getting nice and warm... especially since both engines did the same thing. It's been pretty hot, lately.
Click to expand...

Thanks - I do think there is a warning at 10 for these engines. I wish I knew better and watched the PSI after coming back up at idle, but I didn't. New oil and filters this week, then we will see what it does. But thanks for your confidence, I'm not getting too worried at this point.
 
My boat runs about 50 PSI at speed. I agree with other post that 29 psi is not so low as to be a concern. See what it is at idle hot. Should be >10psi or you have an issue. Are you using 25W40 oil or something else where the viscosity would be more sensitive to temperature?
 
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