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oil sending line for gauges


Angie

Angie

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Has anyone plumbed into this spot for the oil pressure sending line for the gauge? I am thinking of taking the (after filter side) and reducing this size down to the 1/8th line into the cab gauge. any comments?

thanks
 

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RonD

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Oil pressure is the oil the engine can not use, it is the back pressure in main oil passage going out from oil filter to bearings and valve train.

So thats where you need to tap into the pressure, the main passage between oil filter and bearings, this will give a true pressure, i.e. if pump or filter clogs up you would see it here first

It is just a pressure reading so you can "T" off existing Sender/switch location, doesn't hurt anything or reduce pressure reading for either.

Oil pump pumps more oil than system can use, by design, so when passages are flowing as much oil as possible then the oil backs up and oil pressure goes up.
Higher RPMs don't make bearings or valve train openings any bigger, but oil pump does pump more oil since it is RPM based, so back pressure goes up with RPMs.
Back pressure above 6psi keeps valve train well oiled, high spot of engine, around 4psi is when you would hear ticking begin to start.
Over 60psi back pressure can cause "washing" at the bearings, actually "dries" them out causing early failure

General rule of thumb for oil pressure is 1psi per 100rpm, up to about 40psi, 4,000rpm
All oil pumps do have a high pressure ball and spring, spring pressure can be adjusted on some, if back pressure exceeds, say 60psi at the pump, ball would be pushed open against spring pressure allowing pump to bleed off excess back pressure to the oil pan
 
Last edited:
Jbrown1238

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Angie said:
Has anyone plumbed into this spot for the oil pressure sending line for the gauge? I am thinking of taking the (after filter side) and reducing this size down to the 1/8th line into the cab gauge. any comments?

thanks
Click to expand...
I have plumbed off that same spot on the remote adapter. It has worked perfect for 150,000 miles. I use a remote filter adapter with 26 inches of main hose in both directions, as well as a smaller diameter hose to feed the oil pressure gauge. The oil pressure hose is six feet long. The oil pressure is proportionately the same through the entire rpm range as when I tested it with the normal length and diameter plastic tube supplied by Autometer. I also use the remaining port on the adapter to measure oil temp.
 
Angie

Angie

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Ron, thanks for that informative write up... as I figured, tap into post oil filter port.

jbrown, thanks for the reassurance knowing it can be done there in a safe manner and will work. Looked over this spot and thought to my self... why not place it here... asked a friend about that spot and he said he can't see why it wouldn't work, that is why i asked if anyone has done it.

cheers, thanks
 
Jbrown1238

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Angie said:
Ron, thanks for that informative write up... as I figured, tap into post oil filter port.

jbrown, thanks for the reassurance knowing it can be done there in a safe manner and will work. Looked over this spot and thought to my self... why not place it here... asked a friend about that spot and he said he can't see why it wouldn't work, that is why i asked if anyone has done it.

cheers, thanks
Click to expand...
I had concerns at first and thought it might give me a false pressure reading. I am no expert but after a few test I concluded that fluid pressure shouldn't drop over extended length hose like air pressure will. Fluid won't/shouldn't compress under pressure. In theory it should maintain the same pressure over that little bit of distance.

I had the same concerns with oil temp using the remote adapter as a location for the electric sensor. I thought the remote location might give the oil a chance to cool slightly before being measured by the gauge. I used a laser thermometer to check the temp of freshly drained oil from the pan compared to the temp reading on my gauge. The temp was within two degrees.
 
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