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David Brown 990 oil drainback

9

990guy

New User
It takes 30 seconds for oil pressure to show when cranking and the level is over the full mark before cranking. Running oil pressure is 50 to 55 psi and the oil level is lower after it is running. Looks like the oil filter housing is draining back to the sump when the engine is off. Is there a check valve to prevent that? Or it it just draining back through the oil pump? I wouldn't expect that since it has good oil pressure when running. Any ideas? 15-40 oil. Not a show tractor, used on the farm a lot!
 

Could just be the line is full of older, nasty oil and it takes some time for the pressure to overcome the oil. How long has the line been there?
 
Oil is good, it has progressivly getting longer to get the pressure gauge to move. It is about a quart over full before starting and then it drops to normal level after starting because it has filled the oil filter housing.
 
the filter is designed to drain back. a 10-15 second wait for pressure to register is normal. have you actually timed it?
 
(quoted from post at 14:33:47 02/03/20) the filter is designed to drain back. a 10-15 second wait for pressure to register is normal. have you actually timed it?
Click to expand...

Yes 30 seconds. One one thousand, two one thousand. Then it jumps up quickly. Not sure why anyone would design in drain back. No oil during startup and wrong (too high) dipstick reading when checking before starting. Large engines can have pre-oil pumps or pressurized tanks that supply oil prior to starting.
 
(quoted from post at 15:04:10 02/03/20) Oil is good, it has progressivly getting longer to get the pressure gauge to move. It is about a quart over full before starting and then it drops to normal level after starting because it has filled the oil filter housing.
Click to expand...


Is the line fairly new? Is it full of oil or air or both? Are you certain the gauge is on good shape?
 
(quoted from post at 06:30:26 02/04/20)
(quoted from post at 15:04:10 02/03/20) Oil is good, it has progressivly getting longer to get the pressure gauge to move. It is about a quart over full before starting and then it drops to normal level after starting because it has filled the oil filter housing.
Click to expand...


Is the line fairly new? Is it full of oil or air or both? Are you certain the gauge is on good shape?
Click to expand...

The gauge jumps up to 60 when cold, runs at 55 and drops rapidly when shut off. The level on the dipstick drops by a quart after the gauge moves up. After sitting the dipstick is up by a quart.
 
(quoted from post at 14:52:35 02/04/20)
(quoted from post at 06:30:26 02/04/20)
(quoted from post at 15:04:10 02/03/20) Oil is good, it has progressivly getting longer to get the pressure gauge to move. It is about a quart over full before starting and then it drops to normal level after starting because it has filled the oil filter housing.
Click to expand...


Is the line fairly new? Is it full of oil or air or both? Are you certain the gauge is on good shape?
Click to expand...

The gauge jumps up to 60 when cold, runs at 55 and drops rapidly when shut off. The level on the dipstick drops by a quart after the gauge moves up. After sitting the dipstick is up by a quart.
Click to expand...

You pull the dipstick with the engine running and it's a quart low? How can you tell? The dip stick of a running engine is normally covered in oil way past the markings.
 
(quoted from post at 06:17:20 02/05/20)
(quoted from post at 14:52:35 02/04/20)
(quoted from post at 06:30:26 02/04/20)
(quoted from post at 15:04:10 02/03/20) Oil is good, it has progressivly getting longer to get the pressure gauge to move. It is about a quart over full before starting and then it drops to normal level after starting because it has filled the oil filter housing.
Click to expand...


Is the line fairly new? Is it full of oil or air or both? Are you certain the gauge is on good shape?
Click to expand...

The gauge jumps up to 60 when cold, runs at 55 and drops rapidly when shut off. The level on the dipstick drops by a quart after the gauge moves up. After sitting the dipstick is up by a quart.
Click to expand...

You pull the dipstick with the engine running and it's a quart low? How can you tell? The dip stick of a running engine is normally covered in oil way past the markings.
Click to expand...

I stop the engine, pull and wipe the dipstick and then check. after 1/2 hour it is back to a quart over full. I pulled the valve cover, there is no storage of oil up there or blocked drainback passages.
 
(quoted from post at 15:09:19 02/05/20)
(quoted from post at 06:17:20 02/05/20)
(quoted from post at 14:52:35 02/04/20)
(quoted from post at 06:30:26 02/04/20)
(quoted from post at 15:04:10 02/03/20) Oil is good, it has progressivly getting longer to get the pressure gauge to move. It is about a quart over full before starting and then it drops to normal level after starting because it has filled the oil filter housing.
Click to expand...


Is the line fairly new? Is it full of oil or air or both? Are you certain the gauge is on good shape?
Click to expand...

The gauge jumps up to 60 when cold, runs at 55 and drops rapidly when shut off. The level on the dipstick drops by a quart after the gauge moves up. After sitting the dipstick is up by a quart.
Click to expand...

You pull the dipstick with the engine running and it's a quart low? How can you tell? The dip stick of a running engine is normally covered in oil way past the markings.
Click to expand...

I stop the engine, pull and wipe the dipstick and then check. after 1/2 hour it is back to a quart over full. I pulled the valve cover, there is no storage of oil up there or blocked drainback passages.
Click to expand...

Ah, ok, that makes more sense. Like Rich (RG Martin) said, it's designed to drain back. If he says it,I believe it. Mine takes some time to come up too.
 
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