Merc 175XRi Low Oil Warning

[jbasser]

I have a 1992 Mercury 175XRi. When I was out fishing the other day the Low Oil warning started beeping while running down lake at about 60mph. I backed off and it stopped. Thinking it was low on oil in the oil reservoir in the bilge I filled it to 3/4's; it was down to about a 1/4 tank. I ran it again and the beeping started again and then stopped when I backed off to about 35mph. By the time I got back to the launch it was beeping constantly. Now it beeps constantly when it's idling. At no time while I was running it back to the launch did the motor overheat. I have a temp gauge and the temp was in the normal range (Needle on the left). I checked the reservoir on the engine and it was full; the tank in the bilge was still 3/4's full. When I got the boat home I checked the continuity of the sensor on the cap to the engine reservoir and it checked out okay (float up no continuity, float down continuity). I then replaced the sensor mounted behind the oil pump and the Low Oil warning still beeps when the engine is at idle. My next step will be to replace the oil pump, a high ticket item (about $185). I heard that the ignition switch could also cause a false warning. Is this true and how would I go about checking that out? I'm afraid to run it until I get this cured. Any help you can give would be deeply appreciated.<br />Thanks.<br />JBear

 

[orca]

Re: Merc 175XRi Low Oil Warning

G,Day<br />First put some oil in the fuel tank and run with 50:1 until the problem is found.<br />The small oil tank on the motor must be full at all times, undo the cap and top up the tank, if the alarm stops then the problem is probably an air leak in the lower tank, make sure that the caps are sealed properly.<br />The oil pump would be the last thing to change, the pump drive may have failed or the alarm system may need attention. It can also be a switchbox failure.

 

[KCLOST]

Re: Merc 175XRi Low Oil Warning

Pull the pump and inspect the gears... Look for fragments of plastic indicating damage to the plastic gear....

 

[wilde1j]

Re: Merc 175XRi Low Oil Warning

If the oil pump drive has failed, you have 3 choices:<br />1) replace the failed gear [very expwensive since the PH must be torn down]<br />2) use premix, or<br />3) install an aftermarket electronic oil pump drive system<br />The least likely cause of the alarm is an alarm failure.

 

[jbasser]

Re: Merc 175XRi Low Oil Warning

Well I finally found the problem with some help from my brother. After checking the pump and both the cap sensor and motion sensor, and fully bleeding the oil pump system, we found a disconnected ground wire on the back of the motor. Didn't notice it at first because it was still paritally in the connector sleeve. Can't believe I took the motor cover over a half a dozen times before the wire finally come loose and hung down so I could see it. Just goes to show there is more to these electronic marvels of invention than what the manuals tell you. I guess the disconected wire was dirupting the voltages enough that it affected the oil warning system, but not enough to affect how the motor ran. At any rate I learned a lot about the oil injection system, probably more than I wanted to know.<br />JBear

 

[LubeDude]

Re: Merc 175XRi Low Oil Warning

Thanks for letting us know what the problem was, so often we never hear.