Oil pressure drops when manifold pressure increases - normal?
09-30-2006, 01:48 PM
#1
Oil pressure drops when manifold pressure increases - normal?
When I'm coasting at like 1500 RPM with 0% throttle, my oil pressure is around 45 psi or so. As soon as I roll into the throttle a little and bring the vac from -18 inches to like -10 or -5, my oil pressure will drop to just below 40 psi. Is this normal?
09-30-2006, 08:47 PM
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When deaccelerating, basically using the engine as a brake your oil pressure will rise...maybe the oil pump has less resistance when the engine is basically being turned by the weight of the vehicle?? I have noticed this in other vehicles
Dave
Dave
10-01-2006, 02:51 AM
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I have also noticed this, even on my stock Hoe.
I belive the reason for this is:
When coasting, the crankshaft will align itself in the centre of the main bearing.
This will give the same bearing clearance around the crankshaft/bearing.
As soon as you get on the throttle, the crankshaft will be pushed towards the sump by the combined force of the working pistons. Remember that something must take up the down force fom the piston /rod during the work stroke.
When the crank is pushed down, the bearing clearance will be greater where the oil enters the bearing resulting in more flow and lower pressure.
Br//
I belive the reason for this is:
When coasting, the crankshaft will align itself in the centre of the main bearing.
This will give the same bearing clearance around the crankshaft/bearing.
As soon as you get on the throttle, the crankshaft will be pushed towards the sump by the combined force of the working pistons. Remember that something must take up the down force fom the piston /rod during the work stroke.
When the crank is pushed down, the bearing clearance will be greater where the oil enters the bearing resulting in more flow and lower pressure.
Br//
10-01-2006, 06:08 PM
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Originally Posted by tahoe
I have also noticed this, even on my stock Hoe.
I belive the reason for this is:
When coasting, the crankshaft will align itself in the centre of the main bearing.
This will give the same bearing clearance around the crankshaft/bearing.
As soon as you get on the throttle, the crankshaft will be pushed towards the sump by the combined force of the working pistons. Remember that something must take up the down force fom the piston /rod during the work stroke.
When the crank is pushed down, the bearing clearance will be greater where the oil enters the bearing resulting in more flow and lower pressure.
Br//
I belive the reason for this is:
When coasting, the crankshaft will align itself in the centre of the main bearing.
This will give the same bearing clearance around the crankshaft/bearing.
As soon as you get on the throttle, the crankshaft will be pushed towards the sump by the combined force of the working pistons. Remember that something must take up the down force fom the piston /rod during the work stroke.
When the crank is pushed down, the bearing clearance will be greater where the oil enters the bearing resulting in more flow and lower pressure.
Br//
That's kind of what I was thinking/trying to say but I didn't do as well as you
Dave
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