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Discussion Starter #1
i just built a new motor for my truck. i have 400/400 injectors in. when ever i open it up my oil pressure gauge drops way low and throws the light any ideas??
 

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Demon Dually
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If by open it up you mean WOT and that is when the light comes on I would guess that your HPOP isn't keeping up with the injectors. Which oil pressure gauge by the way? The low pressure or do you have a high pressure gauge hooked up? If you are referring to low side pressure then you could have a bad pickup tube or a faulty lpop. You could even have a bearing that isn't seated correctly.
 

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Discussion Starter #3
i mean the low pressure oil, i didnt notice this before, but today i took the line that feeds my gen 3 and ran threw a stock tranny cooler because my oil was getting to hot. im wondering if the oil just cant flow threw the cooler fast enough. but the hpop is also fed threw the front cover so it should be enough??
 

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<<< THE GAUGE WHORE...
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Factory oil pressure gauge is an idiot light... I would bet thats what your looking at? When you get on it your HPO system (what ever one that is) is sucking more out of the res then your LPOP can supply...

You may have a weak LPOP, a drain down issue or a super HPO system...
 

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Demon Dually
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Get it off the stock tranny cooler for starters. I would imagine that it is restricting flow. I also agree with CSIPSD that you have a low pressure pump issue to look into. If that is the old pump on there you should consider upgrading to a high volume pump. Not high pressure by the way. You need more oil to get to the HPOP faster.
 

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A friend of mine had similar issues with his 97 psd. His truck would run strong and fine, but as soon as the oil thinned out and he hammered down the throttle, the low pressure oil would drop to like 5-10 psi. (on a mechanical gauge) It was the strangest issue that he absolutely couldn't figure out.

Till this day he doesn't know what the issue is, and it has actually kept him from driving the truck for the past few months.

He is running a new lpop, Gen3, 300/80 injectors, s480 turbo, swamps tuning, full fuel system.

Everything on the truck seems 100%, other than the oil pressure issue, which he can't figure out. The truck still ran fine with the low pressure, but obviously it's not good on the engine. I think the motor will get pulled and torn down eventually for inspection.

Anyways, you're not alone with the mystery oil pressure issues. I just hope you figure out your issue better than my friend Dan has been able to.
 

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Discussion Starter #8
I will get a high volume pump tomorrow and give that a try, but i do need to cool my oil, ive been haveing high temps since the block is filled
 

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Demon Dually
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What trans cooler are you using? If it is the regular little cooler grab one from a 6.0 Liter. They have larger tubes and more capacity.
 

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Demon Dually
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PSDfan99, Tell your buddy to check into oil pickup tube issues. They have been known to crack.
 

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Discussion Starter #11
i have a 6.0 cooler for my tranny. and took my factory 7.3 trans cooler and mounted it up top right behind the grill, i took the line that feeds my gen 3 ran that into the cooler and returned it to the gen 3
 

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PSDfan99, Tell your buddy to check into oil pickup tube issues. They have been known to crack.
Ya I think that's probably the next thing he's going to look at.
 

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Not second guessing anybody, but did you check bearing clearances when you built the motor, all of them, not just rod bearings and main bearings.

In my experiance of building motors (no Powerstrokes, but bearings are bearings), with a new oil pump (which if you did not replace on a new motor build, I do get to call you a dumbass), the biggest reason for low oil pressure is excessive bearing clearance.

Not sure if our motors have hydraulic lifters or not, but that is another concern, but just like oil pumps, they should also be brand new.
 

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Not second guessing anybody, but did you check bearing clearances when you built the motor, all of them, not just rod bearings and main bearings.

In my experiance of building motors (no Powerstrokes, but bearings are bearings), with a new oil pump (which if you did not replace on a new motor build, I do get to call you a dumbass), the biggest reason for low oil pressure is excessive bearing clearance.

Not sure if our motors have hydraulic lifters or not, but that is another concern, but just like oil pumps, they should also be brand new.
Yes they're hydraulic lifters.
 

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Discussion Starter #16
yes all the bearing clearances were good, and no did not put a new pump on, since the oil pressure was good before the rebuild. im thinking the prob is the cooler is not letting the oil flow threw fast enough, and the oil pressure sensor is on the gen 3 housing and since the extra supply line is restricted from the cooler the light is thrown cause the hpop is using more oil then supplied now. the light did not come out before the cooler was added. so i just need to find a new way to cool my oil
 

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So you didn't have the issue before the newly added oil cooler? If that's the case, I'd definitely start by taking it off and seeing if it solves the problem.
 

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My Daddy, and my Grandaddy, always taught me. If you ever touch or even look at an oil pump, replace it. I don't care if it has been working good for 3 million miles. If you do not replace it, it WILL lay down on you.
 

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yes all the bearing clearances were good, and no did not put a new pump on, since the oil pressure was good before the rebuild. im thinking the prob is the cooler is not letting the oil flow threw fast enough, and the oil pressure sensor is on the gen 3 housing and since the extra supply line is restricted from the cooler the light is thrown cause the hpop is using more oil then supplied now. the light did not come out before the cooler was added. so i just need to find a new way to cool my oil
Not trying to be an a$$. You know way more than I do about these motors. They are probably right about the cooler. Just passing on what I consider valuable info.
 

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Discussion Starter #20
I think what im going to do is replace the oil pump with a high volume pump and use the ports back by the oil filter to feed the cooler that way it is not tied into hpo system
 
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