SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: vintage240zracer on June 23, 2014, 10:17:00 AM

Title: Oil Pressure fluctuating
Post by: vintage240zracer on June 23, 2014, 10:17:00 AM
Hey all-
So got the my new boat and ran well my first time out. Though I noticed oil pressure was all over from 20-45. Nothing I would normally see I figure if all was perfect. Seems like if I let off the oil would go up, cruzing (3500 rpm) and it would lower to 25, but creep up and then down. Not a lot of chop.
Checked the oil once we got back on land and looked like it was low on oil, nothing on dip stick,  my bad I should have checked before we launched, but new boat was just serviced. Yet checked again in the morning and only 1/2 qt low. Previous owner was saying 6 1/2 qt. to change oil.  Now I think most BB Chevy take 7 qt with filter?  I am assuming that it was low, but seems like it is not draining back? or it was just low and the dipstick is not accurate. This is all stock from what I can tell. Oil was very clean, no lifter tapping from low oil pressure as I have seen and heard before! Assuming it is a Hyd cam.  My plan next time out is to put a mechanical gauge to verify, change oil and put 7qts.
Anyone see this before?
Also I will be getting a little heat in the motor, as the gauge never moved and there is nothing regulating the water as I have read some folks doing here. So will start reading a lot of those threads.
Overall very Happy with the purchase even if if I have to put a fresh bullet in it over the winter!


thanks-

JW
Title: Re: Oil Pressure fluctuating
Post by: Your Mom on June 23, 2014, 12:07:50 PM
Switch to a 10qt pan... and your oil pressure will fluctuate with water/engine temps...during a cruise to an idle. I would recommend a valve of some sort right off your pump to get your engine temps to 140-160 especially in a BBC or BBO.
Title: Re: Oil Pressure fluctuating
Post by: mobboss on June 23, 2014, 12:15:27 PM
usually oil pressure fluctuation indicates low oil . its from starving the pump.   
Title: Re: Oil Pressure fluctuating
Post by: GT Jets on June 23, 2014, 01:07:12 PM
Do you have any idea what the oil temperatures were running?

It almost sounds like you were foaming the crap out of the oil because of a viscosity issue.

Also sounds like you have a stock truck pan. No bueno imho.

Try it again with the proper oil levels, if it continues, consider pulling the pan and checking the pickup height. A concave pan and a close pick up will do exactly what you describe.

Good luck.


GT

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Title: Re: Oil Pressure fluctuating
Post by: GoinBrokeBahner on June 23, 2014, 01:32:21 PM

Do you have any idea what the oil temperatures were running?

It almost sounds like you were foaming the crap out of the oil because of a viscosity issue.

Also sounds like you have a stock truck pan. No bueno imho.

Try it again with the proper oil levels, if it continues, consider pulling the pan and checking the pickup height. A concave pan and a close pick up will do exactly what you describe.

Good luck.


GT

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Definitely check pickup clearance!!!
😖🔫

I've heard of worn oil pumps allowing oil to circulate right back into pan as psi rises thru a spring loaded bypass door(circular plate in side of oil pump)??


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Title: Re: Oil Pressure fluctuating
Post by: jamiemwedmore1234 on June 23, 2014, 01:53:49 PM
I had a oil pick up come loose and was loosing oil  pressure that way who ever built the motor Pryor to me owning it didn't tackle weld the pick up to the pump     


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Title: Re: Oil Pressure fluctuating
Post by: vintage240zracer on June 23, 2014, 07:00:00 PM
Do you have any idea what the oil temperatures were running?

It almost sounds like you were foaming the crap out of the oil because of a viscosity issue.

Also sounds like you have a stock truck pan. No bueno imho.

Try it again with the proper oil levels, if it continues, consider pulling the pan and checking the pickup height. A concave pan and a close pick up will do exactly what you describe.

Good luck.


GT

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You are 100% correct on all accounts - Stock - Stock - Stock
Thanks for the input- Yeah I had a similar problem with one of my "Z" motors. Those pickups crack at the block mount and sucking air in at block height-

JW
Title: Re: Oil Pressure fluctuating
Post by: vintage240zracer on June 23, 2014, 07:05:58 PM
I had a oil pick up come loose and was loosing oil  pressure that way who ever built the motor Pryor to me owning it didn't tackle weld the pick up to the pump     


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Been there done that on a Small block! I always tack the pick up, or at min use oil grade red loctite if no welder available-

JW
Title: Re: Oil Pressure fluctuating
Post by: mash on it on June 24, 2014, 08:31:30 AM

Also sounds like you have a stock truck pan. No bueno imho.



A stock "truck" pan will not fit with a Berkeley intake, more likely a "Chevelle" pan, and when set up properly, work fine in a cruiser.
Mine sits at 70+ psi at speed, and ~50 at idle, warm (6 Qt. system)

I have yet to see a BBC that doesn't use some oil with hard use. Mine's a qt. per 25 gallons.

Dan'l
Title: Re: Oil Pressure fluctuating
Post by: jamiemwedmore1234 on June 24, 2014, 12:02:53 PM

Been there done that on a Small block! I always tack the pick up, or at min use oil grade red loctite if no welder available-

JW
when I noticed the oil pressure drop I was 6 miles down river  quik fix was added 3 mor qrts over filled it got me back to the trailer  motor was still shot tho


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Title: Oil Pressure fluctuating
Post by: GoinBrokeBahner on June 24, 2014, 12:28:54 PM
when I noticed the oil pressure drop I was 6 miles down river  quik fix was added 3 mor qrts over filled it got me back to the trailer  motor was still shot tho


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Getting my new one welded up tonight and should be on Elsinore Sunday! Can you believe my motor is still good, bearings and all, I couldn't!!!!
(Did replace pan though...)


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Title: Re: Oil Pressure fluctuating
Post by: jamiemwedmore1234 on June 24, 2014, 12:33:44 PM

Getting my new one welded up tonight and should be on Elsinore Sunday! Can you believe my motor is still good, bearings and all, I couldn't!!!!
(Did replace pan though...)


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straight luck. I would go put some numbers dwn on the ca lotto


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