Oil Pressure

Doc

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You could also use a smaller oil filter if you could find one that fits the stock location, maybe one from a celica? You loose some surface/filtration area, but if you're regular about oil changes you'd be OK.
 

60wag

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Worn bearings have a larger than desired gap in them allowing too much oil to flow through them. Thicker oil can help if they aren't too worn out. A new pump might help a bit. I can't see how changing the oil filter would do anything.
 
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Oil pressure drop is almost never caused by the pump or the filter. Increase will almost never be achieved by changing either.

The largest factor in your oil pressure is the clearances in the bearings which determine how much oil can pass through them. The oil "stacking up" against this resistence to free passage is what allows the pressure to build. The regulator in the pump (or on the side of the block in the case of the F engines) is what determines the maxoil pressure.

Low pressure is almost always the result of worn bearings, and the asnwer is almost always to replace them with new.

A worn pump (rare) can contribute. Worn out or overly low viscosity oil can too. A clogged filter (again, rare) can, and a failed pressure regulator spring (once again, a rare occurance) can also.

Bet on worn bearings.


Mark...
 
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Read my thread about how great mine is running......I switched to 20W-50 and my oil pressure is much higher. Put on a K&N oil filter....its pretty big.

This picture is idling, its moves just a tad bit higher at highway speed, and running great.
press.JPG
 

Cruiserdrew

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Mark W said:
The largest factor in your oil pressure is the clearances in the bearings which determine how much oil can pass through them. The oil "stacking up" against this resistence to free passage is what allows the pressure to build. The regulator in the pump (or on the side of the block in the case of the F engines) is what determines the maxoil pressure.

Low pressure is almost always the result of worn bearings, and the asnwer is almost always to replace them with new.


Bet on worn bearings.


Mark...
Mark-Maybe you could comment on this oddity that has bothered me for 5 years on my 76 2F motor. I notice a slight drop in high RPM oil pressure. When warmed up, it's 45 psi at 2000 RPM and 40 at 3000 RPM. THis used to worry me, however, the truck still runs well and doesn't knock. I have changed the oil pump with no effect, and I also changed the rod bearings also with no effect. Is this a symptom of worn main bearings? My buddy's truck with a fresh 2F does not do this. This motor has 180k miles, and unknown maintanence before 1990. I run 20w-50 motor oil.
 
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3puttcop said:
Read my thread about how great mine is running......I switched to 20W-50 and my oil pressure is much higher. Put on a K&N oil filter....its pretty big.

This picture is idling, its moves just a tad bit higher at highway speed, and running great.
My stock guage doesn't work, so I have an analog, manual guage hooked up. I'm running a mix right now (due to the oil loss issue I have) of 20-50 and 15-40 - don't know what the ratio is. I get about 25psi at idle and 50psi above 1500 rpm or so. If it's 15-40 without the 20-50 in the summer months (85 degress ambient and above) my pressure is 20psi at idle, and 45-50 psi above 1500 rpm. Not a big difference.

I'm just looking at the reliability issues still - oil pump was on the list of "maybes" - I was reading in the Haynes or FSM - can't remember - that the idle pressure for the 2F was 4.3psi at idle, and 35psi (or above) at 1600rpm. That seems a little crazy to me.
 
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My oil pressure in my rebuilt 82 2f when cold is hovering around 50psi. When warmed up it will idle around 30psi and cruiseing down the highway while warm it will sit at 50 - 55psi
 
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Can you drop the oil pan and change the bearings? These the bearings on the camshaft which means you have to pull the engine to pull the cam out the front?

Also where is the oil pressure read? To read pressure you have an enclosed volume (the crankcase)?
 
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Swank60,
I changed the oil in my truck about a year ago and when after adding the new oil and filter I started the truck and no oil pressure. It was at the low mark prior to the change. I was blown away and didn't know what to do. I talked to a redneck buddy of mine who has experience with big truck engines and he thought that maybe "dat oeel pum aint got no pawer ta prime itself". Sure enough he was right. I put an OEM pump and cleaned out the pan thoroughly and my oil pressure with half synthetic 10W40 is dead steady at the high mark (not the max mark). IMHO, there is no mod or trick for increasing oil pressure other than a new pump. FYI I use the NAPA gold filters (Wix). If you have leaky vavles, bad distributor, or other engines discontinuties then that's another issue.
 

Tapage

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I search a lots of info about this theme. The oil press in my 2H and 2F engines are about 62psi at 2400 rpm at opertaive temp ( 82ºC )
 
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Cruiserdrew said:
Mark-Maybe you could comment on this oddity that has bothered me for 5 years on my 76 2F motor. I notice a slight drop in high RPM oil pressure. When warmed up, it's 45 psi at 2000 RPM and 40 at 3000 RPM. THis used to worry me, however, the truck still runs well and doesn't knock. I have changed the oil pump with no effect, and I also changed the rod bearings also with no effect. Is this a symptom of worn main bearings? My buddy's truck with a fresh 2F does not do this. This motor has 180k miles, and unknown maintanence before 1990. I run 20w-50 motor oil.

There are a couple of things that can cause lower pressure at higher rpms in these motors. It is not at all uncommon. The biggest facotr is the heat of the oil. At higher rpm the oil is under more stress, and is seeing a lot more shear asit goes through the bearings. The higher temp of the oil reduces the viscosity.

Higher rpm also increases the possibility of small bubbles remaining in the oil as it is pulled from the pan and through the pump. Since air compresses the pressure achieved when the oil has tiny bubbles in it is lower than when there are none.
Higher rpm also increases the likelyhood of the spinnging crank whipping the oil and creating froth (more bubbles). An over full condition can actenuate this.


A fresh engine with tight clearances in the bearings will give less indication of these symptoms, because an engine with tight bearing clearnaces is actually running with the reuglator open to a greater or lesser degree at most rpm above idel, bleeding off excess pressure. An engine with more wear and looser clearances will be pushing all of the oil from the pump through the bearings and oly hitting the regualtor pressure at higher rpm.

While the steel of the crank wears slower than the softer material of the bearings, it does wear. It may be that the clearances between the crank and bearings are out of spec, or at least near the limits, even with the new bearings. And the main bearings have a greater impact on the flow of oil and the pressure than the rod bearings do, so if you just replaced the rods...


Mark...
 
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swank60 said:
My stock guage doesn't work, so I have an analog, manual guage hooked up. I'm running a mix right now (due to the oil loss issue I have) of 20-50 and 15-40 - don't know what the ratio is. I get about 25psi at idle and 50psi above 1500 rpm or so. If it's 15-40 without the 20-50 in the summer months (85 degress ambient and above) my pressure is 20psi at idle, and 45-50 psi above 1500 rpm. Not a big difference.

I'm just looking at the reliability issues still - oil pump was on the list of "maybes" - I was reading in the Haynes or FSM - can't remember - that the idle pressure for the 2F was 4.3psi at idle, and 35psi (or above) at 1600rpm. That seems a little crazy to me.

This is acceptable pressure. Not great, but perfectly acceptable.I like to see higher, but that is just beause I'm kinda picky on this issue.

The numbers in the FSM are *minimal* acceptable IIRC. I would not go anywhere near that idle pressure and be happy. 35 at 1600 I could live with, but it would have to climb higher at higher rpm.


Mark...
 
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NocalFJ60 said:
Can you drop the oil pan and change the bearings? These the bearings on the camshaft which means you have to pull the engine to pull the cam out the front?

Also where is the oil pressure read? To read pressure you have an enclosed volume (the crankcase)?

The cam bearings wear very very little and have very little effect on oil pressure anyway.

You do not need to have a closed system to read the oil pressure. The oil pan is not pressurized. The oil pressure is either read from the main feed from the filter to the main oil gallery, or from the cooler, or from the back of the main oil gallery. Just depends on the vintage of the engine. Regardless of which location the sender is in, it is reading the pressure of the oil awaiting passage to and through the main bearings.


Mark...
 
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Fearnofish! said:
IMHO, there is no mod or trick for increasing oil pressure other than a new pump. FYI I use the NAPA gold filters (Wix). If you have leaky vavles, bad distributor, or other engines discontinuties then that's another issue.
Again, oil pumps rarely fail, or even wear to the point that they produce low pressure. Max pressure can be increased by shimming the regulator spring, or simply adjusting it in the case of the external regulator of the F engines. Tight bearing clearances will increase operating pressure (up to the max of the regulator) Higher viscosity oil will produce higher pressure (up to the max of the regulator). Internal mods to the pump (primarily unshrouding and clearancing of the passages) will increase volume out of the pump and will often increase operating pressure (once again... up to the max of the regulator).
Fitting a late model 2F pump to an early model 2F or even an F will increase volume and pressure. (It takes a little bit of modification to put this pump into an F engine).



Mark...
 
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Read my post closer. The external regulator was a feature of the F engine. The 2F pump is internally regulated. It can only be adjusted by replacing the spring or by shimming. Not part of any factory procedure.
The regulator only affects the max pressure that the engine will see. If you engine runs at lower pressure when warm than cold, or at lower rpm, this will not significantly boost pressure under those conditions.

Mark...
 

Mace

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Mark Correct me if I am wrong but wasn't the external regulator on the F motor more for diverting oil to the filter than regulating oil pressure?

So if you increase the psi you increase how much oil goes to the bearings and less goes through the filter

Right?
 
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