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Author Topic:   Mecury 225 EFI Over Heats

toolman posted 11-14-2010 08:24 PM ET (US)
I had a intermediate warning light and horn that was coming on from time to time. I check a few things thinking it was a low oil alarm because my Mercury 225 EFI doesn't have a motion sensor on the pump. I thought [the cause of the alarm] has to be the low oil sensor on the engine tank. After eliminating that I found the overheat sensor was the problem. The ECM was sending a warning that the sensor was bad. When I took the sensor out the plastic sleeve around the sensor was melted. Now I am concerned that the plastic oil pump gear may be melted too. I have no warning on pump rotation. Last year when I bought the boat it had a new lower unit put on by a Mercury repair shop. After a lot of checking, they had put the wrong collar on the lower unit, letting water leak out when idling. [The Mercury 225-HP EFI engine] was getting hot when idling. I fixed that, but want your advice if I should take the oil injection off, in case the oil pump gear is melted. THANKS
Chuck Tribolet posted 11-15-2010 06:41 AM ET (US)
If it got hot enough to melt the temperature sensor, I'd be
worried about more than just the oil pump gear.

Chuck
jimh posted 11-15-2010 08:30 AM ET (US)
Your narrative demonstrates one of the weaknesses of the alarm system on the Mercury 225-HP EFI engine: the alarm system does not seem to clearly indicate what is causing the alarm to sound. The operator has to investigate and deduce what might be causing the alarm. This can lead to mistakes in diagnosis of the true cause.
If your alarm system does not have a motion sensor for the rotation of the pump shaft, you must have an older engine. I believe that Mercury added the shaft motion sensor to their alarm system on newer models.
Cf.: http://continuouswave.com/whaler/reference/OMCvMERC.html
See section under sub-heading Alarm Sensors and System
If you have worries about the integrity of the automatic oil system, you should immediately begin to pre-mix oil with your gasoline in a 50:1 ratio. This will insure that the engine is being properly lubricated while you continue to operate the engine and perform further testing.
To assess the function of the oil mixing pump, monitor the oil level in the two oil reservoirs. If the pump is operating, the oil level in the two reservoirs will begin to decrease as oil is used. If there is no change in oil level, or if the rate of oil consumption is not appropriate to the rate of fuel consumption, you may have a problem with the automatic oil mixing pump. There are test procedures described in another REFERENCE article. See
http://continuouswave.com/whaler/reference/mercuryOilInjection.html
You may also wish to partially disassemble the mixing pump and withdraw the steel drive shaft to inspect the end which meshes with the plastic gear. You may be able to draw an inference about the condition of the plastic gear by examination of the condition of the steel gear. If there is a lot of plastic debris on the steel gear, it may be a sign that the plastic gear has deteriorated.
As you probably already know, repair and replacement of the plastic gear that drives the metal shaft of the oil mixing pump is difficult and expensive. It requires a substantial teardown of the power head. My local Mercury dealer--with 50 years in the business of selling and servicing Mercury outboards--could not recall a single instance in which a customer elected to have the plastic gear replaced. Whenever it had failed, the customers just switched to using pre-mixed oil and gasoline as a fuel.
If you discover the automatic oil mixing pump on your Mercury outboard is no longer functioning due to the plastic gear failing, you can re-fit an after-market replacement pump which operates electrically. Because of the high cost of repair of a failure of the plastic drive gear in the Mercury oil injection system, an alternative after-market solution has been developed. It replaces the OEM oil mixing pump with an electrically operated pump.
The cost of a gear replacement is estimated at $1,200. The cost of retrofitting an electrically operated pump is estimated at $575.
For more information on this solution, see:
Marine Solutions (Wisconsin)
http://www.marinesolutionswi.com/
They have retrofit kits available for Mercury V6 outboards:
--135 to 200-HP, 1989 through 1999
--200 to 225-HP, 1995 through 2001 3-liter
The manufacturer of this retrofit comes with some credentials. Robert Kachelek, president of Marine Solutions, was formerly the director of Outboard Service for Mercury Marine.
toolman posted 11-16-2010 12:28 PM ET (US)
The motor has been run hot in the past but this year has been running fine until this warning horn that was caused by the faulty temperature sensor. I have check the oil level and it is using oil my even to much. But I am concerned about the gear being damaged to the point I might just take the whole system off and premix my oil..
jimh posted 11-18-2010 08:59 AM ET (US)
If you happen to own a fancy digital multi-meter which includes a frequency meter function, you could try testing the signal from the shaft rotation sensor by monitoring its frequency as the engine runs at a steady speed. If the frequency of the output signal from the sensor is erratic while the engine speed is constant, this can be interpreted as a sign that there is a problem. The problem is either the input shaft is not being turned at a proper speed, or the sensor is defective.
toolman posted 11-18-2010 07:54 PM ET (US)
That is a concern I have because my Merucry 225 EfI 1996 model doesnt have a oil pump motion detector sensor. Im afraid the only sign i will get is a blown motor when the pump stops turning.

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Author	Topic: Mecury 225 EFI Over Heats
toolman	posted 11-14-2010 08:24 PM ET (US) I had a intermediate warning light and horn that was coming on from time to time. I check a few things thinking it was a low oil alarm because my Mercury 225 EFI doesn't have a motion sensor on the pump. I thought [the cause of the alarm] has to be the low oil sensor on the engine tank. After eliminating that I found the overheat sensor was the problem. The ECM was sending a warning that the sensor was bad. When I took the sensor out the plastic sleeve around the sensor was melted. Now I am concerned that the plastic oil pump gear may be melted too. I have no warning on pump rotation. Last year when I bought the boat it had a new lower unit put on by a Mercury repair shop. After a lot of checking, they had put the wrong collar on the lower unit, letting water leak out when idling. [The Mercury 225-HP EFI engine] was getting hot when idling. I fixed that, but want your advice if I should take the oil injection off, in case the oil pump gear is melted. THANKS
Chuck Tribolet	posted 11-15-2010 06:41 AM ET (US) If it got hot enough to melt the temperature sensor, I'd be worried about more than just the oil pump gear. Chuck
jimh	posted 11-15-2010 08:30 AM ET (US) Your narrative demonstrates one of the weaknesses of the alarm system on the Mercury 225-HP EFI engine: the alarm system does not seem to clearly indicate what is causing the alarm to sound. The operator has to investigate and deduce what might be causing the alarm. This can lead to mistakes in diagnosis of the true cause. If your alarm system does not have a motion sensor for the rotation of the pump shaft, you must have an older engine. I believe that Mercury added the shaft motion sensor to their alarm system on newer models. Cf.: http://continuouswave.com/whaler/reference/OMCvMERC.html See section under sub-heading Alarm Sensors and System If you have worries about the integrity of the automatic oil system, you should immediately begin to pre-mix oil with your gasoline in a 50:1 ratio. This will insure that the engine is being properly lubricated while you continue to operate the engine and perform further testing. To assess the function of the oil mixing pump, monitor the oil level in the two oil reservoirs. If the pump is operating, the oil level in the two reservoirs will begin to decrease as oil is used. If there is no change in oil level, or if the rate of oil consumption is not appropriate to the rate of fuel consumption, you may have a problem with the automatic oil mixing pump. There are test procedures described in another REFERENCE article. See http://continuouswave.com/whaler/reference/mercuryOilInjection.html You may also wish to partially disassemble the mixing pump and withdraw the steel drive shaft to inspect the end which meshes with the plastic gear. You may be able to draw an inference about the condition of the plastic gear by examination of the condition of the steel gear. If there is a lot of plastic debris on the steel gear, it may be a sign that the plastic gear has deteriorated. As you probably already know, repair and replacement of the plastic gear that drives the metal shaft of the oil mixing pump is difficult and expensive. It requires a substantial teardown of the power head. My local Mercury dealer--with 50 years in the business of selling and servicing Mercury outboards--could not recall a single instance in which a customer elected to have the plastic gear replaced. Whenever it had failed, the customers just switched to using pre-mixed oil and gasoline as a fuel. If you discover the automatic oil mixing pump on your Mercury outboard is no longer functioning due to the plastic gear failing, you can re-fit an after-market replacement pump which operates electrically. Because of the high cost of repair of a failure of the plastic drive gear in the Mercury oil injection system, an alternative after-market solution has been developed. It replaces the OEM oil mixing pump with an electrically operated pump. The cost of a gear replacement is estimated at $1,200. The cost of retrofitting an electrically operated pump is estimated at $575. For more information on this solution, see: Marine Solutions (Wisconsin) http://www.marinesolutionswi.com/ They have retrofit kits available for Mercury V6 outboards: --135 to 200-HP, 1989 through 1999 --200 to 225-HP, 1995 through 2001 3-liter The manufacturer of this retrofit comes with some credentials. Robert Kachelek, president of Marine Solutions, was formerly the director of Outboard Service for Mercury Marine.
toolman	posted 11-16-2010 12:28 PM ET (US) The motor has been run hot in the past but this year has been running fine until this warning horn that was caused by the faulty temperature sensor. I have check the oil level and it is using oil my even to much. But I am concerned about the gear being damaged to the point I might just take the whole system off and premix my oil..
jimh	posted 11-18-2010 08:59 AM ET (US) If you happen to own a fancy digital multi-meter which includes a frequency meter function, you could try testing the signal from the shaft rotation sensor by monitoring its frequency as the engine runs at a steady speed. If the frequency of the output signal from the sensor is erratic while the engine speed is constant, this can be interpreted as a sign that there is a problem. The problem is either the input shaft is not being turned at a proper speed, or the sensor is defective.
toolman	posted 11-18-2010 07:54 PM ET (US) That is a concern I have because my Merucry 225 EfI 1996 model doesnt have a oil pump motion detector sensor. Im afraid the only sign i will get is a blown motor when the pump stops turning.