Oil Cooler on 383 ? losing pressure

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HaulinGrass
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Oil Cooler on 383 ? losing pressure

Post by HaulinGrass » Mon Sep 21, 2015 1:51 pm

I have had a problem with my oil possibly breaking down and losing pressure after only a few hours of running with new oil,( Brad Penn Green 20w50 and then tried Amsoil dominator racing oil) motor was recently rebuilt with a bigger cam and victor jr intake, about 525 HP previous motor did not do this. I am told it could need a oil cooler? and also told carb could be too lean and getting the oil too hot , water temp runs 150 all day. my next guess is to send oil sample out to be tested to see whats happening to it after 3 hours. could be getting fuel in it? the first 3 hours of running pressure is 75 PSI, I have changed the oil 3 times in 3 trips out, still does it. Any help would be appreciated.
Last edited by HaulinGrass on Mon Sep 21, 2015 4:56 pm, edited 1 time in total.
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Rich Andrews
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Re: Oil Cooler on 383 ? losing pressure

Post by Rich Andrews » Mon Sep 21, 2015 2:46 pm

Might need another viscosity rating? That new motor build might be just fine with the flow its getting but nobodys ok w low pressure..tuff call hope U get it figured out

What kind of oil pan U running, you have a HV pump?
I'll have my Manatee burger medium please...just say NObama

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HaulinGrass
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Re: Oil Cooler on 383 ? losing pressure

Post by HaulinGrass » Mon Sep 21, 2015 5:29 pm

Its a drop down Pan 8 qts to fill it, HV pump , great pressure for 2-3 hours then starts to fluctuate. it will drop to 20 psi when hard on the gas then rise back up when let off.
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Re: Oil Cooler on 383 ? losing pressure

Post by makinwaves » Mon Sep 21, 2015 5:35 pm

Cheapest thing to try first is the sending unit.

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Re: Oil Cooler on 383 ? losing pressure

Post by Rich Andrews » Mon Sep 21, 2015 5:37 pm

I'm definitely no expert, but sounds like your occasionally getting a lot of oil above the pick up and causing the fluctuations. Mine's real sensitive if I get .5 qt low and will do the same thing.

Are you coming back in w the same amount of oil or loosing it to blow by?
I'll have my Manatee burger medium please...just say NObama

14x8 deckover FELBER 397ci.. HP ???..just stay back!!

LOHA is AHOL backwards

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HaulinGrass
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Re: Oil Cooler on 383 ? losing pressure

Post by HaulinGrass » Mon Sep 21, 2015 5:46 pm

forgot to mention that I installed a second pressure gauge (Mechanical) when I started having this problem. they read within 10psi
it burned about 3/4 of a qt on the days run Saturday, just above the Add mark. I will be glad to add a oil cooler if i can determin this is the problem
but id rather not have it if its not the issue. when I was in Kissimmee 2 weeks ago I added oil when this happen and did not help.
New (Hyper Airboat) 12'x7'6"deckover, 4??ci Water Thunder, 2.7 Ballistic Box, 3 blade whisper tip.. Faster than a Speeding ticket

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Re: Oil Cooler on 383 ? losing pressure

Post by Rich Andrews » Mon Sep 21, 2015 6:13 pm

Can you make the pressure go up or down while driving it? Rocking it side to side? Or does it just stay at a constant?
I'll have my Manatee burger medium please...just say NObama

14x8 deckover FELBER 397ci.. HP ???..just stay back!!

LOHA is AHOL backwards

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skinny99
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Re: Oil Cooler on 383 ? losing pressure

Post by skinny99 » Mon Sep 21, 2015 9:10 pm

Sounds like a cracked pickup.
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HaulinGrass
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Re: Oil Cooler on 383 ? losing pressure

Post by HaulinGrass » Tue Sep 22, 2015 10:01 am

I thought about a possible cracked pick up tube, but I cant understand why it would work for the first 2-3 hours perfect (with new oil) and then start fluctuating..
Im puzzled :banghead:
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glades cat
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Re: Oil Cooler on 383 ? losing pressure

Post by glades cat » Tue Sep 22, 2015 10:38 am

Was the pickup tube welded to the pump?
If so, did they remove the bypass spring before welding?
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Re: Oil Cooler on 383 ? losing pressure

Post by jmpeter9 » Tue Sep 22, 2015 10:55 am

I was having the same issue with my Cadillac motor. I had good oil pressure all day long and then towards the end of the day my pressure started jumping up and down. I thought it was due to losing some oil to blow by. When I dropped my pan to replace my dipstick tube I noticed that the bracket that bolts the pickup tube to the main keep was broken so my tube was just bouncing around inside and once I fixed that I have maintained steady pressure. Hope this helps.
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Rich Andrews
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Re: Oil Cooler on 383 ? losing pressure

Post by Rich Andrews » Tue Sep 22, 2015 11:40 am

as scary and crazy as it sounds, could be a well built motor getting all the flow it needs... but i'd b scared to shit running it
I'll have my Manatee burger medium please...just say NObama

14x8 deckover FELBER 397ci.. HP ???..just stay back!!

LOHA is AHOL backwards

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glades cat
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Re: Oil Cooler on 383 ? losing pressure

Post by glades cat » Tue Sep 22, 2015 1:01 pm

Lack of lubrication/oil pressure will ruin your engine at high RPM.
All you need is 10psi/1000rpm. A stock pump will more than supply it with a tight engine.
If you want to save your engine, find the problem. Sounds like a supply problem.
High volume oil pump with poor drain-back can deplete oil level in the pan at extended high RPM. Was the lifter galley flashing removed?
Some high-end distributors with double o-rings can block the drain-back also.
If in doubt, take the pan off and take a look at the pump and pickup assembly.
"Leave a legacy...Preserve the irreplaceable"
12' x 7' sled built by Scorpion, Cont. O-470-K, 72" Whisper Tip
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HaulinGrass
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Re: Oil Cooler on 383 ? losing pressure

Post by HaulinGrass » Tue Sep 22, 2015 3:35 pm

Thanks for all your help , Im gonna look into some of these suggestions, when I find the problem ill post on here..
New (Hyper Airboat) 12'x7'6"deckover, 4??ci Water Thunder, 2.7 Ballistic Box, 3 blade whisper tip.. Faster than a Speeding ticket

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HaulinGrass
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Re: Oil Cooler on 383 ? losing pressure (

Post by HaulinGrass » Mon Oct 26, 2015 5:38 pm

I think the problem is solved,
I spoke to a very Knowledgeable Motor Builder on here, He suggested I might be running too much oil, ( wrong dip stick) causing the crank to spin in oil and foaming or throwing it places it shouldn't. So I drained the oil and put 6.5 qts in my 7qt pan to start with. Well this weekend was the Third time out running the motor 50+miles each time, No more fluctuation in oil pressure... So Far so good.. Now ill just cut the dip stick tube to match the amount of oil I put in..
New (Hyper Airboat) 12'x7'6"deckover, 4??ci Water Thunder, 2.7 Ballistic Box, 3 blade whisper tip.. Faster than a Speeding ticket

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