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Old 05-28-2013, 08:20 AM
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355 old pressure question

This concerns me a little but I'm hoping its nothing. I have noticed if I am rolling on the highway around 3500rpm I have about 55psi. But if I hit the throttle hard to accelerate the pressure will drop to 25-35 and then jump back up to 50-70psi when I stay in it and fluctuate at that range.

Once off the highway the pressure is 30psi at idle.

I have a 7qt Hamburger pan and a Milodon HV pump.

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Old 05-28-2013, 08:32 AM
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Quote:
Originally Posted by TylerS10 View Post
This concerns me a little but I'm hoping its nothing. I have noticed if I am rolling on the highway around 3500rpm I have about 55psi. But if I hit the throttle hard to accelerate the pressure will drop to 25-35 and then jump back up to 50-70psi when I stay in it and fluctuate at that range.

Once off the highway the pressure is 30psi at idle.

I have a 7qt Hamburger pan and a Milodon HV pump.
Do you know how close the pick up is to the bottom of the pan? The oil pressure should be a linear gain with RPM without a drop. High on my suspects list would be the pick up is not close enough to the bottom of the pan (1/4 to 3/8 inch) so that vehicle movement is either allowing it to become exposed as oil moves around with G force or the pick up is so close to the oil surface level that it is forming a vortex that draws air in with the oil.

A quick and dirty test would be to overfill by a quart or two to see if that stabilizes the situation.

I will also say that for a high volume pump it strikes me that 3500 RPM an 55 psi appears to be a bit low. This migh be just where the Milodon relief valve is set too, but typically these pumps are into about 65-70 pounds before the relief valve opens.

Bogie
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Old 05-28-2013, 08:46 AM
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I have no idea where the Oil pickup is but the machine shop said they measured it and is correct.

That's what sucks about a S10 only way to remove the pan is by removing the engine.
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