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Oil sensor warning 2006 25 hp

M

mdugan

New member
2006 Mercury 25 hp 4-stroke. Just starting going off this year. Happens rarely, sometimes when wide open, sometimes at slow speeds. Changed the oil and filter, same thing. Could it be a sensor? Is it possible to hook up an oil pressure gauge to monitor.

Just drive it weekends and only during warmer months.

Any insight would be appreciated.

Thanks
 
Re: Oil sensor warning

I don't have 4 stroke manuals (newer) than 2002, but unless they have changed things there is no tests listed for the oil pump (and the 2006 parts list looks exactly the same as the earlier models).

There is an oil pressure sensor which is probably causing the alarm.

The oil pump itself appears to be a very simple design which would make it prone to blow a seal or two on motors that see very little use.

Alternately, the pressure sensor (which is also a pretty basic design and probably made in China) could be the problem itself - but not worth taking the risk of continued operation just incase it actually is a pump seal that is shot.

Motors that sit most of their lives need far more "preventative" care than ones that run everyday. I rarely see a 10 year old motor that has 1000 hours on it - but I see dozens of 10 year olds that have 200 hours or less - things break quicker if you don't use them, especially if you don't religeously follow maintenance and storage proceedures...


I suggest, if you have some mechanical ability, that you pick up a manual and troubleshoot the oil pump and sensor.

Alternately, a shop will do it for you, but suspect that they would replace both the sensor and the pump. A new pump is about 125 bucks so would cost more in labour to pull apart and rebuild the existing one if that was the issue...
 
Re: Oil sensor warning

Worked on car engines quite a bit but never an outboard motor. Not sure how many hours are on it but I would guess about 50-70 a year.

The alarm went off 4 times this season, both at slow and fast speeds. Shut down motor, inspected, restarted it and seems to work fine. Would you have anymore insight as to whether it is the pump or the sensor from this info?

Thanks very much for the reply, it was very helpful, I will look around the net for a repair manual.
 
Re: Oil sensor warning

My first assumption would be the sensor - it's designed to (close the switch when sends the alarm) if it detects less than 2.25 psi of vaccum.

So it can be tested with a vaccum gauge and an ohm meter.

If the sensor is ok then the pump itself has a cover seal plus 2 or 3 o-rings - any of which could be worn or degraded enough that cause it to occassionally lose pressure.

If you can work on a car this is just the same thing in miniature. Grab a manual (about 35 bucks) and have a go at it.

At worst you will need to replace the pump as a whole unit which would still be cheaper (including the cost of the manual) of having a shop look at it for you...
 
Re: Oil sensor warning

Looked all over the net and cannot seem to find a repair manual for a 2006 mercury 4-stroke 25hp. Does anyone know of any sites where I could find this. Cannot seem to locate one newer than 2004.
 
Re: Oil sensor warning

Yes you can hook up a oil pressure guage to the motor to test. a common problem is the pressure relief valve can get sticky. I will look up the service manual part number for you and post it tomorrow, what is the serial number.
 
Re: Oil sensor warning

My boat is at a different location. I have the purchase receipt which has the serial # on it "OR110375", but I don't think that number is valid as I have tried to enter it on the Mercury site and it always comes back as invalid. Boat is a Mercury 25hp 4-stroke, 3 cylinders, efi. I went to a Mercury boat repair place yesterday and they could not find the part number for the oil sensor unit either. Thanks for the help, getting very discouraged here.
 
Re: Oil sensor warning

No, the "0Rxxxx" is a valid production number. I is used on models built by Tohatsu - which in case you didn't know, your 25 Merc is really a 25 Tohatsu painted up in Merc colours - not a single Merc part on them....
 
Re: Oil sensor warning

Here is a pick of what I think it is #14 in the pic. I cannot get to my Tohatsu books to confirm until Monday. It is the only switch I can find in the Merc Parts diagrams. the part # for it is 87-803538 and lists for 31$. If you can wait until Monday I will confirm it on the Tohatsu side for you.

rgds,

Dave
 

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Re: Oil sensor warning

Hi Dave,

Any luck finding the diagram for the Tohatsu? I am having the same problem as the original person and I don't want to mess around. What would you suggest I do? Replace the whole oil pump? Start with the sensor first?

Also, would you mind if I gave you a call to discuss?

Thank you in advance.

Ben


crankbearing said:
Here is a pick of what I think it is #14 in the pic. I cannot get to my Tohatsu books to confirm until Monday. It is the only switch I can find in the Merc Parts diagrams. the part # for it is 87-803538 and lists for 31$. If you can wait until Monday I will confirm it on the Tohatsu side for you.

rgds,

Dave
Click to expand...
 
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