redstinger

Engine only has 30 hrs on it. 454 stroked to 489 on a Chaparral 2550SX. Verifired oil pressure with a mech gauge fyi, it is dead on the same as the elec gauge. 50 psi cold at 3500rpm, then pull back throttles to 3200 rpm to cruise, you can watch the oil press come down slowly to 25-30 psi range. Cruise for 5 minutes. Back down to idle, pressure barely above 0, Take off again 3500 rpm, back up to 40, but then after 1-2 minutes back down to around 20 psi.

The dipstick is just above the full mark, right on the word "FULL". Using Valvoline straight 50w. Using stock merc oil cooler with a tall AC delco filter (extra qt capacity). Is the extra stroke hitting causing the crank to hit the oil and churn it up to cause the thinining of the oil.

MILD THUNDER

iTrader: (3)

Sounds to me like you have bearing issues.

Let me guess, the oil psi was ok the first couple hours, then started dropping. Did you use a eagle crank??

redstinger

Yes, Eagle crank.

MILD THUNDER

iTrader: (3)

I'll bet you a six pack of beer that the eagle crank clearances were not within spec of what they should have been. The engine was assembled and clearances were never checked.

Eagle cranks are notorious for being all over the place tolerance wise. What happened more than likely is your bearing clearances were way too tight, and now you've worn the bearings into the copper. Now, your clearances are way to big, and your oil pressure is sucking.

No easy fixes here. Time to pull the engine before you do any more damage. Its not the stroke, weight of oil, brand of oil, filter size, etc. You can just for giggles, cut open your oil filter. Look for copper colored flakes in the filter media.

mike tkach

iTrader: (3)

i agree with mild thunder,but i question the use of 50 weight oil,unless the bearing clearances are .0035 or more,the oil is to thick when cold,and bearings just wont get prpoerly lubricated.i have seen guys make that mistake in my drag racing days.

MILD THUNDER

iTrader: (3)

Mike, I bet he had low oil pressure symptoms, and went to a 50w thinking it would solve the issues. Just a guess

redstinger

I ran 10w30 oil for breakin first 10 hrs, then changed again at 20 hrs to the valvoline 50w racing oil. Obviously pulling the motor again is not what I want to hear. I called my engine builder and reported the behavior and he said not to worry, he installed a HV pump with a low pressure spring. This is not a high performance race boat and 99% of my boating consists of cruising around at 35 mph or less. I'm changing the oil tomorrow to castrol 20w50 and a k&N filter for the hell of it.

I was referred to this builder by my local Fountain/Formula dealer, as he does all their machine work, so I guess I have to have faith he knew what he was doing.

MILD THUNDER

iTrader: (3)

Not trying to sound like a jerk, but I would NOT continue to run a engine that has almost 0 oil pressure at hot idle. I don't care if it was a 4 cylinder in a 16ft boat.

I've read some of your older posts, and in my honest opinion, find yourself a new engine builder. Low psi spring in a HV pump, so 20psi at 3500RPM is ok???

DO NOT, I REPEAT, DO NOT listen to this hack of a so called engine builder. I dont care if he builds engines for the nasa space shuttles. Any engine builder that told me 0 oil psi at idle, and 20psi at cruise is just fine, I'd run, not walk away from him. I've seen stuff like this a million times, and in the end, YOU are the one thats gonna be out the money when you throw a rod thru the block, destroy your crank and rods if they aren't already.

BTW, a bearing or journal doesnt know if its in a race engine or a cruiser engine. All it knows is that it needs the proper clearance, and a film of oil to ride on. Race engine, car engine, motorcycle or snowmobile, if its wrong its just gonna let go sooner or later.

JRider

iTrader: (1)

In that case save your old filter and cut it apart to see what kind of particulate you have in there! Then decide if you need to pull the motor.

MASCH

I would think if it had a clearence problem to begin with it would have shown up long before 30 hours. Cut the filter apart, look at it and go from there. 5 psi at an idle sounds pretty low as does 20 psi @ 3500. Volume is far more important than pressure, unfortunately no easy way to gauge volume.