Reply With QuoteWhat kind of pan and oil pump are you running, and how much oil????
I recently replaced the gauges in my boat. On the first ride out I noticed that I had great oil preassure at idle(60psi)and it increased up to 70-80 as RPMs increased. After I really cranked it up to around 4000-4500 the oil pressure started dropping. It would go down to about 25psi. So I thought it could be the sending unit, I installed a mechanical guage and it is doing the same thing. I pulled the motor and dropped the pan off expecting to find the pickup in the bottom of the pan. Well I cannot find anything that would couse this. I checked the bearings, the pump and anything else I thought would cause it. I have not found anything so I put the motor back together and changed the filter to a Wix. I still have the same problem and I cannot figure it out. I do not know if it was doing it prior to the new gauges because the old gauge was slow to react and I am not sure if it was picking it up.
Any help would be appreciated.
Terry
What kind of pan and oil pump are you running, and how much oil????
Maybe check the by-pass (if you have one) on the filter adapter?
You are most likely sucking the pan dry, foaming up your oil or overheating your oil.
You need to make sure you don't have too much oil which would cause it to foam up by getting whipped up by the crank.
Do you have an oil cooler? If not you can be overheating the oil at higher RPM which would thin it out.
I get the best oil pressure with straight 40 weight and a huge STP Oil filter that looks like it holds about 1.5 quarts. The oil filter alone gave me almost 10 extra PSI.
I am running a 10 Qt milodon marine pan. It has a windage tray and all the baffles. I have 10 qts plus filter oil. I have been running a 30 wt havoline oil.
Terry
I have been running a 30 wt havoline oil.
Terry [/B]
My bet is that 30 wt oil is getting thin after extended RPM runs...try some straight 40 or 50 wt.
My Kendall 40 will drop down some psi after extended RPM's...then it comes back during some idle time.
Some like and use Lucas HD Oil stabilizer.
PS. it's not uncomon for oil temps to rise 100 degrees higher than water temps guring a long hard run.
I am going with Hammer on this one.
I ran a BBF in my old boat 60-75 psi when cold, 20-25psi after 6000 rpm passes. with 50wt.
You are simply warming up the oil.
I would recomend a straight 40wt or even 50wt. You need to consider your main bearing clearances.
Good luck
Another thought would be insufficient clearance between the oil pickup and the bottom of the pan. Good enough for low rpm flow, but not for the higher rpm flow needs.
The above is excellent advice on things to consider. If you're running a Fram Filter by any chance we've had lots of reports of them collapsing and causing pressure drop. That would be the first thing to shitcan if you happen to have one in favor of Baldwin, Wix, or K&N. IMO of course
Sounds like a stock pump, wanna solve the problem, take the pump apart and set the clearance to .0025 and sand the cover flat and smoothe for a good seal against the housing, put a .060 SAE washer in the bypass, you're good to go!..BTW, make sure you have at least 3/8" clearance pan to pickup!...
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