blue thunder

I agree Reed. An auto engine would do the same thing under the same condition. But if that was the case, I would run higher viscosity oil in the auto engine as well. I certainly don't agree with the straight 50 wgt oil your engines had. Way too thick for pumping when cold. I do like the 15-50 synthetics though. It will flow comparable to the 10w-40 you mentioned and is what I run since producing the bearing in the picture above.

Dave

ursus

My guess to, stick to the basics 1st before trying to find some exotic problem/solution, get an oil temp guage and put the sender on the oil fliter block where merc does it is qucik and easy and temp will not be dif by more than a couple degrees if any than what you measure in the pan and you can't see that on a guage when running at WOT anyways . It will tell you if your at 240 or less or 250 or more which is what you need to know.

The 300hp 454 oil cooler is like 2x 7", the 385hp 454mag 10", the 415hp 502 mag 13"
if you increased your HP signifigantly you need to increase your cooling to match.

rmbuilder

Because you are capable of sustaining 60 lb pressure @ reduced engine speed, and that pressure drops off at elevated rpm’s, leads me to believe that you may have a supply/delivery problem (aeration). Excessive bearing clearance would typically depress pressure across the board, rather than vary pressure by demand, although clearance and/or windage are a distinct possibility.
I have seen instances where the pick-up being located to close to the pan resulted in a similar situation to yours. The pick-up draws its oil supply from beneath; being to close to the pan severely restricts the volume (creating a low pressure area beneath the pick-up) of oil available to the pump. As rpm’s increase, demand does also. When that supply is restricted the oil becomes aerated due to cavitation, the oil becomes a vapor, heats, and at this point the volume the pump is capable of handling is diminished resulting in lower pressure and incomplete lubrication. As you reduce the rpm, demand decreases, supply stabilizes, aeration bleeds out, and pressure returns.
I would suggest you check:
The clearance from pan to pick-up
Did the pan distort or warp during welding?
Is the pick up screen clogged?
Is the pick-up securely attached to the pump?
Bypass spring
Is the oil pump is properly torqued to the rear main?
Hope this helps,
Bob

Washed Away

Hey guys. Great ideas here. Haven't thought about the oil temp. Sounds like a gauge is in order this spring. I'll try to answer some of the questions. Bearing clerances ran .002 on the rods, .002-.0025 an the mains, can't remember rod side clearance but it doesnt stick out in my mind as a worry. I am running mobile 1 after a breakin with regular 10-40 oil. No "death flakes" after second oil change ( still regular oil, this is when I switch to synthetic). Boat is in storage so I'll be very careful when checking filter in the spring rollout. Engine is based off a 365 Mag setup. It is this oil cooler that I have. Oil pan did have some warpage after welding, so I spent some time with clay on my pan to pickup clearences (.25"). The pickup was also welded to new pump (spring removed during welding). The hole in the gallery plug was smaller than 1/16". The distributer is factory stock. The pressure also only drop at idle ( not during run) after longer runs, then slowly rises.

The engine was built for a reliable 500 or so hp @ 5000-5200. I never oil pressure or temp problems with the 365. The block had 200 hours before the tear down, and now has 10-15 hrs on the new build. I have probably added 130-150 hp to the motor. The oil temp problem may be the place to start. I thought the stock cooler would have given me enough protection.

Did I read that a temp gauge can be plumbed at the oil filter housing inlet? (this is where the mech oil psi gauge is)

Reed Jensen

There is a big difference between the little sparkly bits (almost microscopic) and "flakes of death". Flakes of death are very visible bearing material and are actually small flakes @ 1/32 of an inch across. Good luck!

ursus

Oil temp sensor can be placed in the remote oil filter block ( where the oil filter is there is an extra hole there just remove the brass plug)

Merc uses a 2" longer oil cooler on the 415hp 502 mag than on the 365hp 454. The hp500 cooler is like 17" long

jhnrckr

I had the same problem and it turned out my high volume oil pump was sucking the pan dry. I went with a standard volume/pressure pump and it cured the problem.

Gary Anderson

jhnrckr may be on to something.
I ran into this on a Ford FE motor. High volume pump sucked the 10 qt pan dry, flooded the top end with oil. And that was at 3000 rpm.
Worth checking out.
Gary

Reed Jensen

I can't imagine an engine with 10 qts of oil up in the valve cover area. Were the return holes plugged? The valve covers would have been filled up totally. I think the oil was just getting aerated and with the bubbles it becomes compressible and the pump couldn't handle it.

Gary Anderson

Reed Jensen
I wouldn't have believed it either if I had not seen it. I think part of it is lack of adequate return volume, and some may be pickup/pan design as well on those engines. Inadequate pump/pan clearace could result in aeration with the higher volume pump
BTW, I'm not the only one who had encountered this on FEs, see:
http://groups.yahoo.com/group/cccommander/message/13735