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CAT D4 oil pressure?

CAT D4 oil pressure?

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tinytec
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The engine oil pressure on my 1947? D-4, serial 6U 2831, reads really low. I bought a new Stewart Warner gage (not yet installed) but it shows only a red and a green zone, with no PSI numbers.

What is the typical pressure on this engine?

Thank you!

Fred
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Wed, Jul 25, 2007 10:43 PM
SJ
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If I remember it was between 30-40 lbs. depending on the oil temp. & condition of the engine. There is so many things that effect the pressure from a stuck relief valve to worn pump & main bearings or another minor thing or a combination of all. In the idle position the pressure can drop quite considerbly even to 15 or 20 lbs.
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Wed, Jul 25, 2007 10:57 PM
Old Magnet
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Reply to SJ:
If I remember it was between 30-40 lbs. depending on the oil temp. & condition of the engine. There is so many things that effect the pressure from a stuck relief valve to worn pump & main bearings or another minor thing or a combination of all. In the idle position the pressure can drop quite considerbly even to 15 or 20 lbs.
Regulated to 30 psi max is what is stated in the manual.
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Wed, Jul 25, 2007 11:06 PM
ttman4
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Reply to Old Magnet:
Regulated to 30 psi max is what is stated in the manual.
If a stuck relief valve is the problem on one of these tractors, will the pressure be hi or lo generally?
Inquiring minds need to know.๐Ÿ˜„
Thanks
~and this too shall pass~
D6 9U6914SP, #46Hyd 1W523, 6A dozer #16C5869
R945B Liebherr Ex. (part owner)
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Thu, Jul 26, 2007 12:30 AM
SJ
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Reply to ttman4:
If a stuck relief valve is the problem on one of these tractors, will the pressure be hi or lo generally?
Inquiring minds need to know.๐Ÿ˜„
Thanks
It can be either way but usually they stick open so then you,d experience lower pressure but it,s fairly rare for them to do it but would more likely be a worn pump or other reasons for low pressure.
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Thu, Jul 26, 2007 12:52 AM
ccjersey
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Reply to SJ:
It can be either way but usually they stick open so then you,d experience lower pressure but it,s fairly rare for them to do it but would more likely be a worn pump or other reasons for low pressure.
I doubt it would make any difference whether you would see high or low oil pressure, but don't these engines have an inlet-throttled oil pressure control system like the D311?

If it has a small external line to the oil pump from an adjacent main bearing cap, that's what it has. Spring pressure pushes the valve open to feed the pump a full stream, and pressure from the main bearing cap pushes it shut to restrict the inlet stream of oil and lower the pressure. So the inlet valve should be wide open when you check the pump.
D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time๐Ÿ˜„
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Thu, Jul 26, 2007 1:38 AM
Old Magnet
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Reply to ccjersey:
I doubt it would make any difference whether you would see high or low oil pressure, but don't these engines have an inlet-throttled oil pressure control system like the D311?

If it has a small external line to the oil pump from an adjacent main bearing cap, that's what it has. Spring pressure pushes the valve open to feed the pump a full stream, and pressure from the main bearing cap pushes it shut to restrict the inlet stream of oil and lower the pressure. So the inlet valve should be wide open when you check the pump.
As wore out as these engines usually are I think it's pretty rare to hit relief pressure (or control pressure) on the oil pump and same goes for the fuel transfer pump.
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Thu, Jul 26, 2007 3:03 AM
ttman4
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Reply to Old Magnet:
As wore out as these engines usually are I think it's pretty rare to hit relief pressure (or control pressure) on the oil pump and same goes for the fuel transfer pump.

Yeah, I was kinda wondering.
But dummy me!!๐Ÿ™„ ๐Ÿ™„ I been running round for last year, thinking I was hot stuff, bragging bout my 9U running 50-55-60# oil press working it. Few months back I got to playing round with my coolant temps, thermostats, flushing things, etc, etc. Finally figured out I was running too cold temps.
After I finally got the working temps on up 180 or so, oil press runs more like everyone else....35-40# And if it worked at hotter temp it would probably run less press than that.
I'm little slow, but finally figured out I ain't nothing special after all๐Ÿ˜„ ๐Ÿ˜„
But I must say, this engine does sound really good to me.....
๐Ÿ˜ฎ (shhhhh....probably lay an egg & blow up in next few days...shhhh)๐Ÿ˜ฎ
~and this too shall pass~
D6 9U6914SP, #46Hyd 1W523, 6A dozer #16C5869
R945B Liebherr Ex. (part owner)
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Thu, Jul 26, 2007 10:52 PM
Old Magnet
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Reply to ttman4:

Yeah, I was kinda wondering.
But dummy me!!๐Ÿ™„ ๐Ÿ™„ I been running round for last year, thinking I was hot stuff, bragging bout my 9U running 50-55-60# oil press working it. Few months back I got to playing round with my coolant temps, thermostats, flushing things, etc, etc. Finally figured out I was running too cold temps.
After I finally got the working temps on up 180 or so, oil press runs more like everyone else....35-40# And if it worked at hotter temp it would probably run less press than that.
I'm little slow, but finally figured out I ain't nothing special after all๐Ÿ˜„ ๐Ÿ˜„
But I must say, this engine does sound really good to me.....
๐Ÿ˜ฎ (shhhhh....probably lay an egg & blow up in next few days...shhhh)๐Ÿ˜ฎ
Hi ttman4,
It's amazing how low the oil pressure can be on these engines and doesn't seem to hurt anything. I think as long as you got flow most parts are happy๐Ÿ˜‰
35-40 lb pressure is still pretty optimum if temps are right. Bearing clearance must be near new spec on your tractor. What do you have at idle?
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Thu, Jul 26, 2007 11:28 PM
Oil Slick
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Reply to Old Magnet:
Hi ttman4,
It's amazing how low the oil pressure can be on these engines and doesn't seem to hurt anything. I think as long as you got flow most parts are happy๐Ÿ˜‰
35-40 lb pressure is still pretty optimum if temps are right. Bearing clearance must be near new spec on your tractor. What do you have at idle?
My D4 seems to run a little less than 20 lbs when the temp gage reads 180. The temp is only 160 in the picture with the oil pressure a little above 20 lbs. Idling fast or slow seems to have little effect on the pressure.
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Fri, Jul 27, 2007 9:43 AM
tinytec
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Reply to Oil Slick:
My D4 seems to run a little less than 20 lbs when the temp gage reads 180. The temp is only 160 in the picture with the oil pressure a little above 20 lbs. Idling fast or slow seems to have little effect on the pressure.
I've been following the discussions here but waited to post until I had information about my new gage. I finally got around to checking it to see what pressures the red and green ranges represent.

The gage points to the center between the two colors when the applied pressure is just a shade over 5 psi. The pointer reaches the maximum travel at 10 psi and stays there as the pressure is increased to 50 psi. When the pressure is removed the needle drops back to zero. I didn't go beyond 50 psi in case the gage might get damaged.

My Cat runs around 5 psi when fully warmed up. That sure makes me nervous as I'm used to seeing engines with much higher oil pressures ๐Ÿ˜ฎ Apparently it's OK with these old engines though.

Fred
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Sat, Jul 28, 2007 6:18 AM
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