Okay.
I have a 1994 Mercury 150hp Black Max.
Serial Number: OGO77269 or 0G077269 can't really tell if they are zeros or Os.
Bought the boat about a month ago. First sea experience showed that the motor was having trouble keeping cool.
Replaced water pump / impeller (which had a gasket out of order and a impeller that needed to be replaced) as well as the two thermostats (very corroded). The engine stays pretty cool now; I feel like that problem is fixed.
The one piece of bad news that I do get is that the mechanic thinks he see's a slight 'wobble' in the flywheel, but nothing he thinks justifying keeping off the water. He says he'll keep an eye out for one for me. While at his shop, his coworker mechanic says he thought he heard a bearing noise, when he was walking by and my guy was working on it. My mechanic says he sees a slight wobble but doesn't hear any bearing problem noise.
Two weeks ago we made about a 10 mile run offshore (southern California) and did some trolling around looking for kelp paddies. On the way home running after running at about 3500rpms for 20 minutes I noticed that the voltage gauge was pretty much pinned at 16 volts and then got an alarm from the Lowrance (sonar/gps) unit, signalling a High Voltage Alarm of 18 volts I think.
We turn the alarm off, we are almost home anyways. At the time didn't really know what too much voltage could harm anyways. At least it's not a low voltage alarm, I remember thinking. After getting back on shore and doing some research it seems that this high voltage problem is really nothing to take lightly.
Today the mechanic comes by and we do some tests.
1. He checks the voltage regulators and says that they both ohm test fine according to the book. (I think I remember reading somewhere on this site that you need to test these with a amptest or ammtest not an ohm test, but who am I to question the mechanic)...
Also, the tachometer is reading high I think. At idle the tach is reading like 1500rpms and when we throttle up to somewhere that should be ballpark 1500 the tach is reading like 3000rpms. A sign that I think the voltage regulator is failing? After testing both tachometer leads (one on each voltage regulator) they are both reading higher rpms than the boat is really running at.
Note: These are the clear (yellow) potted voltage regulators not the black ones that are OEM replacements and not CDI's.
2. A larger red wire, that goes to the trim solenoids, and the 4 red wires from the 2 voltage regulators are all on one post on the starting solenoid. While the engine is running a multimeter at the positive on the starting solenoid and grounded to the engine shows it bouncing back and forth from 13.5-14 volts down to 3, 4, 6 volts just for a instant at a time. At the same time if I put the multimeter at the battery terminals it shows a rock steady voltage usually in the high 13's.
The mechanic suspects the way the dual batterys are hooked up and thinks that maybe there is some arcing or something is loose on the negative battery cables. So I grab a set of jumper cables out of the car and directly hook up one battery to the (+) starting solenoid and the (-) to a good ground on the engine. The same results are made with the fluctuating voltage when tested at the starting solenoid and rock steady when tested at the battery terminals.
The mechanic now goes into the cuddy and thinks that because the purple wire from the ignition switch is powering all of the engine gauges that this somehow would be causing this. I cannot wrap my head around how this could be. To eliminate this as a cause of the fluctuating voltage we start the engine, disconnect the wiring harness and turn the perko switch to off. So now the engine is a stand alone entity. right? Same results. Reconnect the wiring harness and turn the motor off. stumped.
So I come back to the posts here and read...
The stator has 2 sets of windings on it. One feeds the voltage regulator. The other feeds the ignition system. They should be totally independent of each other. You should be able to totally short out the voltage regulator and not kill the engine.
Check for continuity between either of the yellow wires and all the other wires from the stator. There should be none except to the other yellow wire. If there is any, the stator is bad.
If that's good, check the stator output to the ignition with a DVA. I would bet it drops drastically when you connect the voltage regulator. It shouldn't. If it does, pull the flywheel and take a look for loose magnets, or contact between the flywheel and the stator. Thought is a bad flex plate or upper main bearing allowing the flywheel to contact the stator when a little pressure is put on it by loading the alternator coil, causing a magnetic short.
The 2v AC output to ground from each yellow wire is of no significance. It would just indicate you have a sensitive meter. The voltage between them should be about 15V at idle, up to 90V at WOT. It does indicate that there is probably no electrical interconnection between the coils. (as it should be) as one would expect the readings to ground to be different, and at least one significantly higher if there were an internal short.
In any case, the trouble is under the flywheel.
hope it helps
John
from post http://forums.iboats.com/showthread.php?t=432446&highlight=Mercury+black+max,+voltage+regulator
j_Martin seems to be the expert in this field. Any comments would this flywheel theory be the reason for the fluctuating voltage and the pegged high voltage at high rpms? Or any other ideas or comments? I'd probably rather the problem not be something like upper or lower bearings...
Thank you very much.
Dustin
I have a 1994 Mercury 150hp Black Max.
Serial Number: OGO77269 or 0G077269 can't really tell if they are zeros or Os.
Bought the boat about a month ago. First sea experience showed that the motor was having trouble keeping cool.
Replaced water pump / impeller (which had a gasket out of order and a impeller that needed to be replaced) as well as the two thermostats (very corroded). The engine stays pretty cool now; I feel like that problem is fixed.
The one piece of bad news that I do get is that the mechanic thinks he see's a slight 'wobble' in the flywheel, but nothing he thinks justifying keeping off the water. He says he'll keep an eye out for one for me. While at his shop, his coworker mechanic says he thought he heard a bearing noise, when he was walking by and my guy was working on it. My mechanic says he sees a slight wobble but doesn't hear any bearing problem noise.
Two weeks ago we made about a 10 mile run offshore (southern California) and did some trolling around looking for kelp paddies. On the way home running after running at about 3500rpms for 20 minutes I noticed that the voltage gauge was pretty much pinned at 16 volts and then got an alarm from the Lowrance (sonar/gps) unit, signalling a High Voltage Alarm of 18 volts I think.
We turn the alarm off, we are almost home anyways. At the time didn't really know what too much voltage could harm anyways. At least it's not a low voltage alarm, I remember thinking. After getting back on shore and doing some research it seems that this high voltage problem is really nothing to take lightly.
Today the mechanic comes by and we do some tests.
1. He checks the voltage regulators and says that they both ohm test fine according to the book. (I think I remember reading somewhere on this site that you need to test these with a amptest or ammtest not an ohm test, but who am I to question the mechanic)...
Also, the tachometer is reading high I think. At idle the tach is reading like 1500rpms and when we throttle up to somewhere that should be ballpark 1500 the tach is reading like 3000rpms. A sign that I think the voltage regulator is failing? After testing both tachometer leads (one on each voltage regulator) they are both reading higher rpms than the boat is really running at.
Note: These are the clear (yellow) potted voltage regulators not the black ones that are OEM replacements and not CDI's.
2. A larger red wire, that goes to the trim solenoids, and the 4 red wires from the 2 voltage regulators are all on one post on the starting solenoid. While the engine is running a multimeter at the positive on the starting solenoid and grounded to the engine shows it bouncing back and forth from 13.5-14 volts down to 3, 4, 6 volts just for a instant at a time. At the same time if I put the multimeter at the battery terminals it shows a rock steady voltage usually in the high 13's.
The mechanic suspects the way the dual batterys are hooked up and thinks that maybe there is some arcing or something is loose on the negative battery cables. So I grab a set of jumper cables out of the car and directly hook up one battery to the (+) starting solenoid and the (-) to a good ground on the engine. The same results are made with the fluctuating voltage when tested at the starting solenoid and rock steady when tested at the battery terminals.
The mechanic now goes into the cuddy and thinks that because the purple wire from the ignition switch is powering all of the engine gauges that this somehow would be causing this. I cannot wrap my head around how this could be. To eliminate this as a cause of the fluctuating voltage we start the engine, disconnect the wiring harness and turn the perko switch to off. So now the engine is a stand alone entity. right? Same results. Reconnect the wiring harness and turn the motor off. stumped.
So I come back to the posts here and read...
The stator has 2 sets of windings on it. One feeds the voltage regulator. The other feeds the ignition system. They should be totally independent of each other. You should be able to totally short out the voltage regulator and not kill the engine.
Check for continuity between either of the yellow wires and all the other wires from the stator. There should be none except to the other yellow wire. If there is any, the stator is bad.
If that's good, check the stator output to the ignition with a DVA. I would bet it drops drastically when you connect the voltage regulator. It shouldn't. If it does, pull the flywheel and take a look for loose magnets, or contact between the flywheel and the stator. Thought is a bad flex plate or upper main bearing allowing the flywheel to contact the stator when a little pressure is put on it by loading the alternator coil, causing a magnetic short.
The 2v AC output to ground from each yellow wire is of no significance. It would just indicate you have a sensitive meter. The voltage between them should be about 15V at idle, up to 90V at WOT. It does indicate that there is probably no electrical interconnection between the coils. (as it should be) as one would expect the readings to ground to be different, and at least one significantly higher if there were an internal short.
In any case, the trouble is under the flywheel.
hope it helps
John
from post http://forums.iboats.com/showthread.php?t=432446&highlight=Mercury+black+max,+voltage+regulator
j_Martin seems to be the expert in this field. Any comments would this flywheel theory be the reason for the fluctuating voltage and the pegged high voltage at high rpms? Or any other ideas or comments? I'd probably rather the problem not be something like upper or lower bearings...
Thank you very much.
Dustin
