Took the boat out yesterday for a short motorized run. I noticed the oil pressure gage would fluctuate between zero and about 40. Then settle down to about 40. Is this from a loose sending unit? Or, what else is going on that I should consider? The motor is a Yanmar 4JH3B, 56hp. Thanks, John Richard s/v Jack's Place
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Potentially, Yes
On my 3GM30 the sending unit is a single wire type so the sender relies on contact with the block for a ground. As you surmized it is possible for this ground to be deficient so if tightening the sender a tad eliminates or reduces the fluctuation that was the problem. Two other potential sources include poor contacts somewhere along the electrical route, typically the bullet connectors, and possibly a bad sending unit. If tightening the sender doesn't improve anything, or even if it does, go through the wiring and disconnect the bullet connectors and put a little silicone dielectric grease on them. If this doesn't work then put in a new sender.
On my 3GM30 the sending unit is a single wire type so the sender relies on contact with the block for a ground. As you surmized it is possible for this ground to be deficient so if tightening the sender a tad eliminates or reduces the fluctuation that was the problem. Two other potential sources include poor contacts somewhere along the electrical route, typically the bullet connectors, and possibly a bad sending unit. If tightening the sender doesn't improve anything, or even if it does, go through the wiring and disconnect the bullet connectors and put a little silicone dielectric grease on them. If this doesn't work then put in a new sender.
Good Point!
Hopefully the oil level would be the first thing one would check, and hopefully before starting the engine. BUT, you're right, the oil should be checked. Also, oil pressure problems have been discussed before and one could check the archives for more good recommend ideas to solve this problem.
Hopefully the oil level would be the first thing one would check, and hopefully before starting the engine. BUT, you're right, the oil should be checked. Also, oil pressure problems have been discussed before and one could check the archives for more good recommend ideas to solve this problem.
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