Oil Pressure
 

I have a fairly new engine,melin pro 604 cid.When i first started it
the oil pressure was at 75 psi according to electric guage at idle and buried the guage when i reved it.I have taken the boat out about 6 times,everything find.Started up the engine last week and oil pressure was at 60 psi cold and 45 warm but reved up to 60 psi.I put a mechanical guage on this week,now the electric guage reads 30 psi and the mechanical guage reads 20 at idle and drops to 15 when you rev it.Any suggestions before i pull the motor.

Pull the oil filter, cut it open and look inside. I suspect there will be bearing metal because I think you have a bearing-probably a main-going south. But that is a good easy first step.

soudns like what happene to me. I still haven't checked the bearings. Check your oil level thoigh. Mine was SUPER low (thank my ex-mechanic for that one, he said he "topped it off" before he have it back to me)

good luck.

I drained the oil,nothing on the magnetic plug.Installed new oil,
pressure still bad,pressure drops when revved,like sucking air.Motor only has 10 hours on it and never past 3500.Motor is all
new,lunati 4340 crank,oliver billet rods.Suspect problem with pump but don't know what effects filter bypass might have on pressure.There were 6 qts of oil in pan at time,never low.Don't know what the difference is with the merlin blocks and there priority oiling system.

Bearing metal is non-magnetic-look in the filter.

I removed filter and cut open,nothing in filter.Any ideas now2

If it drops when revved and there is no metal then there must be a restriction somewhere in the oiling system or the pickup tube has come loose and you are drawing air. Was the pickup stock or aftermarket, welded? You might try a new filter first to see if that may have been doing it. Greg P from this board had a similar problem and it turned out that moisture was blocking the filters on his engine. I am not familiar with the bypass set up on your engine so hopefully someone else might chime in on that part of it. The good news is no metal in the filter.

Have you tried to overfill the oil, just to see if the pressure increases???
Just try it at the dock.

As said earlier. The pickup can come out or become loose.
Is it welded???

If you still have low pressure, pull it. You don't have enough pressure to run it. All you're going to do is more damage.

My first test also would be to add a couple of extra qts. of oil. That way if the pressure does come up, it is because the extra oil will keep the pump supplied if the pickup did come off. But wouldn't run it long with extra oil, just enough to diagnose.

The pump came with the Steff's pan and the pickup is welded on.
I will try a new filter and more oil and see if there is a change.At
least it did not happen on the water and the presure has not dropped below 20 psi.

Excalibur;

I have a fresh Pro 632 Merlin with similar parts, its fresh due to similar probs you are experiencing...you have likely lost you pick-up as I did. (I thought my electric gaffrig had a bad sender because of the erratic readings I was getting) Here are my current oil pressures at various times, (mechanical gaffrig) Start-up 75, running 50-55, idle with Hot Oil 20-25, sometimes see 15 @ very low rpm (650). As others suggest I would add a couple of quarts to see if that helps, if so your pickup is laying in the pan. IF this is the problem, RE-BEARING your motor, mains and rods. Its very cheap insurance to avoid larger problems later. ( I didn't insist this from my builder when I lost my pick-up and it cost me $4500.00 and 8 weeks last summer.) Keep us posted.

Ok guys,tell me what happened.I bought a new wix filter this time and installed it,normal oil level and pressure is back to normal.The oil filter bypass was removed at one time and i think the filter failed.Pressure is back to 75 at idle and reves to 90 cold.
60 warm to 75 when revved.The oil did have a little gas smell but i noticed when i removed the filter it was like nothing was going through it,same old used oil as in the block originally.thinking of buying factory oil filter housing and installin filter bypass like block was originally intended to have.if filter fails then pressure will still be there.

Wow! That is great news. I never get that lucky. I have a slightly suspicious pressure on my port engine and will change the filter and hope for the best. Good luck to you,

BT :cool:

Go here:

http://www.offshoreonly.com/forum/sh...threadid=18759

Your scenario sounds just the same as Greg's.
Maybe you could get him involved in this thread.

If you have a remote oil filter be sure that the flow is in the proper direction, meaning that it is plumbed correctly. It is easy to mix up the lines going to the filter if it was off during the rebuild. The oil is supposed to enter the filter from the outside and return through the center hole. If it is plumbed incorrectly the filter will fail quickly as yours did, some act as a check valve and flow is severly restricted.
Hope this helps.

No, i am not using a remote system as of yet.Stock location is
still being retained.Thanks though.