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-   -   Low oil psi 454 500HP (https://www.offshoreonly.com/forums/general-q/252533-low-oil-psi-454-500hp.html)

picklenjim 05-03-2011 01:24 PM

http://youtu.be/7IpJlYssvkM

Listen close starting at :56

pantera232 05-03-2011 07:46 PM

The pan had a slight dent in it nothing insane, so we tapped it out and the old pickup had touched the dented service, so we fixed pan and adjusted the new one a little higher , measuring to keep it 3/8 of the bottom...

Since the rockers were loose the motor was making a ticking noise, so were going to adjust with motor running to get rid of that problem, the oil is straight 40 weight, used in diesal trucks, we put this in after trying the 15w40 and haveing low psi

BillK 05-03-2011 09:00 PM

Pantera,

You are missing something very simple. I think as much as you dont want to, you need to pull the engine down one more time and triple check ALL of the bearing clearances. If the engine had good oil pressure before, and nothing was done to the crankshaft, then it should have good oil pressure now.

One thing to check first .... are the lifters the same ones that were in the engine before ??? If not, or maybe even if they are, is the oil hole in the lifter either coming up too far or going down too far and getting uncovered during operation ? That will certainly bleed off oil pressure and cause a similar problem. If the cam is ground with a smaller base circle and the lifters are not correct, they can go down too far and uncover the oil hole.

Other than that, you really need to go back to basics and forget about all of the trick issues. It is somthing very simple causing the problem.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Rage 05-04-2011 05:47 AM


Originally Posted by BillK (Post 3393856)
Pantera,

One thing to check first .... are the lifters the same ones that were in the engine before ??? If not, or maybe even if they are, is the oil hole in the lifter either coming up too far or going down too far and getting uncovered during operation ? That will certainly bleed off oil pressure and cause a similar problem. If the cam is ground with a smaller base circle and the lifters are not correct, they can go down too far and uncover the oil hole.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

The symptoms are exactly what I experienced when I replaced the stock shrouded hydraulic roller lifters with unshrouded Crane lifters in a Gen 7 (496HO) engine with non stock cam. At max cam lift the top of the slot in the Crane lifter (that the roller sits in) would breech the bottom edge of the lifter oil gally ~0.030" and release oil past the roller and back into the crankcase. Oil pressure was great before the Cranes and after I put stock lifters back in.

c_deezy 05-04-2011 06:29 AM

These are very good reply's, and sound like the most plausible suspect based on the symptoms (ticking and little oil coming out on the rocker end).



Originally Posted by BillK (Post 3393856)
Pantera,

You are missing something very simple. I think as much as you dont want to, you need to pull the engine down one more time and triple check ALL of the bearing clearances. If the engine had good oil pressure before, and nothing was done to the crankshaft, then it should have good oil pressure now.

One thing to check first .... are the lifters the same ones that were in the engine before ??? If not, or maybe even if they are, is the oil hole in the lifter either coming up too far or going down too far and getting uncovered during operation ? That will certainly bleed off oil pressure and cause a similar problem. If the cam is ground with a smaller base circle and the lifters are not correct, they can go down too far and uncover the oil hole.

Other than that, you really need to go back to basics and forget about all of the trick issues. It is somthing very simple causing the problem.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md


Originally Posted by Rage (Post 3394028)
The symptoms are exactly what I experienced when I replaced the stock shrouded hydraulic roller lifters with unshrouded Crane lifters in a Gen 7 (496HO) engine with non stock cam. At max cam lift the top of the slot in the Crane lifter (that the roller sits in) would breech the bottom edge of the lifter oil gally ~0.030" and release oil past the roller and back into the crankcase. Oil pressure was great before the Cranes and after I put stock lifters back in.


NOPUN 05-04-2011 11:53 AM

You know what?
I took a brand new race engine apart one time because of low oil pressure. turned out to be a faulty oil filter.
I would change the oil filter and try that before I pulled the engine again. Just sayin.!!!!


Thank You FRAM. :(

pantera232 05-04-2011 07:24 PM

I adjusted rockers today no more noise...
the pushrod is sending oil though up to the rocker there is a puddle there, @ 800rpm 20-30psi, but its not filling up enough to go through the next hole which is the front bairing rolling on the valve stem..

the lifters are morel from marine kinetics and so is the cam..
It could be possible that the oil hole isnt lining up... If we modify a distributer cap so the oil will run to the lifter gallery we can see if its leaking..

Maybe i do need to try a set of stock lifters are they the same size?? so i could use my new custom pushrods ? I dont have a morel to measure bc there in the motor..

Do i need to run the 1/6 inch piece of steel that covers cam under intake manifold or it doesnt make a difference.??

Will putting the boat in the water with a load on it maybe change anything? im getting 35psi when rev to 3000rpm on trailer dont think it would hurt for a 20 min low rpm test

picklenjim 05-04-2011 07:47 PM

You should have 80lbs. cold at idle with that pump and 40+ at idle hot. If Bob set you up with that cam and lifters than I doubt that is the problem.

Have no idea what your talking about with modifing a distributer cap.

The 1/6 inch piece of steel under the manifold?

Putting it in the water won't change anything. Don't waste your time and engine.

Are you sure this is a gen 6 block. Is it a carb engine? Does it have the fuel pump on the block or on the waterpump or electric pump?

blue thunder 05-05-2011 06:40 AM

What part number oil pump are you running?

jeffswav 05-05-2011 09:02 AM

I asked this question a long time ago, but did you make sure you do not have the oil lines reversed?


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