After engine bath problem
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Senior User
Joined: Mar 2007
Posts: 271
Likes: 1
From: arkadelphia, ar
After engine bath problem
Any one ever had a problem with the sender for the oil pressure after washing the engine?
Yesterday I took my truck to the local car wash to get some of the oil off the engine, (leaky valve cover gasket.........go figure!) and after the bath, the oil pressure light stays on, unless I unplug the wire from the sender!
I have a manual pressure guage so I know there is pressure, about 40 at anything but an idle (then it's about 18), but I would like for the light to work also. Think it's the sender or maybe something else wet that is causing a short?
Yesterday I took my truck to the local car wash to get some of the oil off the engine, (leaky valve cover gasket.........go figure!) and after the bath, the oil pressure light stays on, unless I unplug the wire from the sender!
I have a manual pressure guage so I know there is pressure, about 40 at anything but an idle (then it's about 18), but I would like for the light to work also. Think it's the sender or maybe something else wet that is causing a short?
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The sending unit is basically a spring with a metal contact plate. When there's oil pressure, the contact plate is pushed away from the sending unit body, and the light stays off. When pressure drops, the contact plate is allowed to push back and ground out, causing the light to come on. If water gets in the sending unit, it will short out and cause the light to come on. The sending unit is cheap and simple to replace.
By the way, unless you're using a T-fitting, you shouldn't be having this issue, because you should always install a mechanical gauge in the same location as the original factory sending unit (thereby replacing it). Installing a mechanical guage anywhere else in the block will be upstream of the sending unit, providing a false reading (too high). If you have both your sending unit and mechanical gauge sourcing from the same tap using a T-fitting, then you're okay. Otherwise, you may not be.
By the way, unless you're using a T-fitting, you shouldn't be having this issue, because you should always install a mechanical gauge in the same location as the original factory sending unit (thereby replacing it). Installing a mechanical guage anywhere else in the block will be upstream of the sending unit, providing a false reading (too high). If you have both your sending unit and mechanical gauge sourcing from the same tap using a T-fitting, then you're okay. Otherwise, you may not be.
Senior User
Joined: Mar 2004
Posts: 448
Likes: 0
yea just water shorting it. it'll dry out and start working
later models had a white plastic cap to shield the top of the switch
by design it is open to atmosphere where the brass terminal is attached to the black insulator
later models had a white plastic cap to shield the top of the switch
by design it is open to atmosphere where the brass terminal is attached to the black insulator
