High oil pressure reading

Chamil1204

Recruit
Joined
Jun 12, 2020
Messages
3
Hi. Looking for advice on what may be causing the oil gauge to read high on Mercruiser 3.0 LX. The gauge jumps up to 80 and stays pinned at max even when the boat is not started but just battery on with key on accessory. I would be grateful for Any help. Thx
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Faulty gauge, faulty sender, damaged (grounded) wire...

Chris.........
 

Chamil1204

Recruit
Joined
Jun 12, 2020
Messages
3
Okay, I’ll check/replace those. I’m new to boating so this is all a learning experience. Many thx
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Don't just replace all those, do some diagnostics and just replace/fix what needs fixing.

1. Find the oil pressure sender. Pretty sure it's a light blue wire,I think on the starboard side of those engines. Remove the wire from the sender. Gauge reads zero (with the key on). Replace sender. Gauge still reads high, step 2. (Refit wire to sender)

2. Disconnect light blue wire from the back of the gauge. Gauge reads high, replace gauge. Gauge low, step 3.

3. Find pinched/grounded wire.

Just had a thought. I'll check on my boat in the morning (it's night here at the moment).. a missing gauge ground might do it to. Let me check... In the morning...

Chris...
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
51,357
agreed, proper diagnosing costs $0 and saves you thousands.

never ever just throw parts at a problem.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
...Just had a thought. I'll check on my boat in the morning (it's night here at the moment).. a missing gauge ground might do it to. Let me check... In the morning...

Chris...

Just pulled the ground wire off my oil pressure gauge, and ..... it pegs high... So that is also something to check. Ground wire on the gauge (test light to the purple)...

Chris..
 

Chamil1204

Recruit
Joined
Jun 12, 2020
Messages
3
That was it! The ground wire was loose.... I jiggled the wires in back and wella! Gauge reads normal now. Words cannot express my sincere gratitude. It was very nice of you to take the time to check on your boat.... thx again.
 
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