OMC115 V4 no oil alarm, possible malfunction

[stuartkinner]

Hi folks - I have a 1995 OMC 115hp V4, just bought it secondhand and had it serviced, but I am still getting an (apparently) intermittent problem with the 'no oil' horn sounding at low revs.<br />PROBLEM DESCRIPTION: I launch the boat in a canal and motor at 6 knots for about 10 minutes to get into open water, but after about 5-7 minutes of low speed motoring the horn sounds (beeps every half second or so). Last time this happened I switched the engine off, shook the oil resorvoir around in case there was an air bubble somewhere, re-primed the oil bulb, and then went off at higher speed. Had no further problems all day, including 10 minutes of low speed motoring on the way home.<br />OTHER INFORMATION: There's plenty of oil in the resorvoir, and the service guys said that oil was flowing fine when they serviced it, so I am guessing that it might be (a) sensor in oil resorvoir playing up, (b) sensor on VRO playing up, or (c) VRO malfunctioning. Given that everything was fine for the rest of the day, and that there's no apparent leakage or spattering of oil or fuel inside cowling, I am guessing that it's not a problem with the VRO.<br />Can anyone advise? I've been told that I can bypass the problem by just pre-mixing all the time, and forgetting about the separate oil resorvoir, but I'd like to avoid this if I can.

 

[Walker]

Re: OMC115 V4 no oil alarm, possible malfunction

The reservoir tank "low oil" alarm is one beep every 40 seconds I think. <br />Your alarm sounds like its coming from the VRO pump.

 

[stuartkinner]

Re: OMC115 V4 no oil alarm, possible malfunction

Thanks Walker. Does anyone know how I can figure out whether the sensor is just faulty, or whether I need to replace the VRO? The bulb on the oil hose is always firm, which to me indicates that there is plenty of oil getting to the VRO...

 

[Walker]

Re: OMC115 V4 no oil alarm, possible malfunction

Do this. Premix gas/oil 50:1 in your fuel tank. Disconnect the wiring to the VRO and see if the alarm stops. Mark the oil level in the reservoir and run your engine on the premix and see if the oil level goes down.

 

[R.Johnson]

Re: OMC115 V4 no oil alarm, possible malfunction

Most times that I have run into this problem, it was the sender in the oil box. Can you get your hands on another box to try?

 

[marinemech]

Re: OMC115 V4 no oil alarm, possible malfunction

2 things come to mind<br />1 check filter in oil tank may be restriced<br />2 if air\oil temperature is around freezing oil may be to thick to pump

 

[seahorse5]

Re: OMC115 V4 no oil alarm, possible malfunction

When you get that on and off beeping sound, squeeze the oil bulb hard for a few seconds. If the horn quits, then you either have a weak VRO pump or an air leak in the line somewhere. A common problem area is where the oil lines clamp to the amber plastic tube in the front of the motor, port side.<br /><br />If you have the smooth vinyl oil hose that is now brittle, replace it with the factory "rubber" oil hose.

 

[stuartkinner]

Re: OMC115 V4 no oil alarm, possible malfunction

Thanks to all for the advice - I won't be able to work on the boat until the weekend, but I really appreciate the help, and will post an outcome this weekend.

 

[seahorse5]

Re: OMC115 V4 no oil alarm, possible malfunction

Here is the link for more info on the "VRO" pump and the urban legends that surround it.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000028

 

[stuartkinner]

Re: OMC115 V4 no oil alarm, possible malfunction

Problem seems to have resolved itself - apparently an air bubble in the oil hose, which has now gone. I've run the engine multiple times at low speed, with no problems. My mechanic just replaced the oil tank filter and hose, so they were not the problem, and the oil level is dropping, so that is not the problem. Thanks to all for the advice - just goes to show that, as seahorse has pointed out, the VRO isn't always the culprit!