Too much oil but normal pressure reading?

[PyrPatriot]

What would having too much oil (per the dipstick) but normal oil pressures (31-32) indicate/mean? Wouldnt it be if you added too much oil the system would tell you by having too high of a idling pressure? Or are all the threads of dealerships adding 6qts but the JTs running fine mean there is a healthy margin for error? The owner's manual says that between the bottom of the cross pattern indicator and the top is 1qt of oil measured.

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[foo.c]

Oil pressure wouldn't change unless it was severely overfilled (or under). The pump flows what it is commanded to, so if it is getting normal (not aerated) oil the pressure won't change.

I think you are right there is probably a good margin for error.

 

[ShadowsPapa]

What would having too much oil (per the dipstick) but normal oil pressures (31-32) indicate/mean? Wouldnt it be if you added too much oil the system would tell you by having too high of a idling pressure? Or are all the threads of dealerships adding 6qts but the JTs running fine mean there is a healthy margin for error? The owner's manual says that between the bottom of the cross pattern indicator and the top is 1qt of oil measured.

The oil would have to foam - be whipped by windage or crankshaft throws, etc. for oil pressure to drop.
1 extra quart won't do it.
Yes on the owner manual and the dip stick.

6 quarts is too much but not enough to cause foaming oil.

~30 is normal for lower RPM.
If it was lower, that's a problem. That's because air from foaming can be compressed, lowering oil pressure.

IF it's too high, you have a pressure relief valve problem inside.

 

[PyrPatriot]

Never heard of foaming with oil. Cool!

 

[PyrPatriot]

What if you find your filter floating in oil when you go to remove it pre-draining the pan? Would that be too much oil? Pressure going to such an extent that it pops the filter off? And again, no indicators of high pressure on the system panel.

 

[ShadowsPapa]

What if you find your filter floating in oil when you go to remove it pre-draining the pan? Would that be too much oil? Pressure going to such an extent that it pops the filter off? And again, no indicators of high pressure on the system panel.

Too much oil won't impact how "high" oil pressure is. It's still pumped and there's still pressure relief valves.
You could fill the thing to the crankshaft and it won't make too much pressure. That's not how a pressurized oil system works.
Imagine it this way - if you live where I live and your water comes from a well - will the pressure in your house be higher because the well is full to the top? Will it be lower if the well is down to 1 foot?
No, the pressure will be identical in all cases, all levels, because the pressure is supplied by the pump moving a volume of oil against a restriction. It's what the pump picks up and shoves back out that makes oil pressure. Oil could be coming out the top and the oil pressure would remain the same if the engine could even run.

When you pull the cover off to replace the filter, it opens up drains to allow the oil in that cavity to drain back to the sump. IT would have to be crazy full for that to not drain back due to too much oil- and then foaming would REDUCE pressure. Not increase it.
The only impact over-filling has is foaming - and that's only if it's above a certain point. And the affect of foaming is reduced pressure.

Your oil pressure is read by a sending unit that screws into an oil passage in the block (at least as I remember them). It reads ONLY the pressure in that system as supplied by the pump.
Pressure results from the pump pushing a volume of oil out against a restriction. And the maximum is controlled by pressure relief valves. Even if those valves were under oil, it would still relieve pressure.
In other words, there's no way on earth too much oil can cause oil pressure to be too high.
I may cause oil pressure to be too low due to foaming - air whipped into the oil like egg whites whipped into a froth. Air in the oil is compressible. That may reduce pressure, but can't increase it.

 

[PyrPatriot]

Too much oil won't impact how "high" oil pressure is. It's still pumped and there's still pressure relief valves.
You could fill the thing to the crankshaft and it won't make too much pressure. That's not how a pressurized oil system works.
Imagine it this way - if you live where I live and your water comes from a well - will the pressure in your house be higher because the well is full to the top? Will it be lower if the well is down to 1 foot?
No, the pressure will be identical in all cases, all levels, because the pressure is supplied by the pump moving a volume of oil against a restriction. It's what the pump picks up and shoves back out that makes oil pressure. Oil could be coming out the top and the oil pressure would remain the same if the engine could even run.

When you pull the cover off to replace the filter, it opens up drains to allow the oil in that cavity to drain back to the sump. IT would have to be crazy full for that to not drain back due to too much oil- and then foaming would REDUCE pressure. Not increase it.
The only impact over-filling has is foaming - and that's only if it's above a certain point. And the affect of foaming is reduced pressure.

Your oil pressure is read by a sending unit that screws into an oil passage in the block (at least as I remember them). It reads ONLY the pressure in that system as supplied by the pump.
Pressure results from the pump pushing a volume of oil out against a restriction. And the maximum is controlled by pressure relief valves. Even if those valves were under oil, it would still relieve pressure.
In other words, there's no way on earth too much oil can cause oil pressure to be too high.
I may cause oil pressure to be too low due to foaming - air whipped into the oil like egg whites whipped into a froth. Air in the oil is compressible. That may reduce pressure, but can't increase it.

I think I understand now. Thanks!

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