Recently bought a boat from my best friend. I am fairly familiar with the history of the boat. It's Mercury 175 has never had any issues at all. The last couple of times my buddy took it out the oil horn went off. He said the cap on the oil reservoir under the cowling was cracked. If he opened the cowl and filled the reservoir the issue went away. As for the cracked cap, he "bubba'd" it and glued it. However, the horn would still go off sometimes.

I recently had some work done on the boat and had that person replace the cap on the reservoir under the cowling. Took it out this weekend for my initial trip. Ran the boat for 30 minutes without issue....visited a friend on the lake at his dock for 1 hour or so. Headed back up lake to the boat ramp...about half way back the alarm went off. Turned engine off for a few minutes and fired her back up...went off again. This time I opened the cowl and filled the reservoir under it. Since I was only about a 10 minute idle from the ramp I just idled back without any additional oil horns. BTW, the motor did not seem hot.

Any chance there is some sort of vacuum issue that is restricting normal oil flow to the engine (ie- a bad hose or fitting)?

Not opposed to having a tech troubleshoot it. Normally with this year Merc I would go to Gunter Marine with full confidence. However, I remember seeing a post a few months back that mentioned that he was in poor health and might be out of the motor business.

Any ideas on fixing the issue or any ideas of a good mechanic for older Mercs somewhere in Ft Worth or surrounding area?

Thanks,
Mark

I started in this business back in 83 with Gunter he is doing better talked to him about a month ago he is back at it but only works 2 or 3 days a week. Your problem is the upper tank has not been bled properly or the pickup screen in the boat tank is gelled up and is restricting oil flow.....OPTI

Opti, thanks for the info. Don't know Marc personally but great to hear he is back at it. I am going to try to give him the business, but if he is too backed up I will be looking you up.

Thanks again,
Mark

OPTI,
I have the same problem with a 2005 carbureted Yamaha 150. Would bleeding the upper tank apply to Yamahas as well as Mercs? If so, what is the process for properly bleeding the reservoir?

Thanks in advance for any help.

jfe