1996 Mariner - Voltage regulator replacement

[Hez]

1996 Mariner 2.5L - OG360900

I noticed last weekend while on the water, that my motor was not outputting proper voltage. While running, I was showing 12.8v on the graph. After verifying the battery was good, and doing some good ol' bbc research ( http://www.bbcboards.net/showthread.php?t=654404 ),

I found this:












Based on the above evidence, would you guys agree that a bad voltage regulator is the correct diagnosis?

I also inspected the stator wires (underneath the stator), all seemed good there - is there anywhere else I should be checking?

As far as replacing these - is it as simple as removing the coil plate, swapping out and reconnecting regulators and reassembling the coil plate?
Can anyone offer any input or tips for that job? I do have a service manual from European Marine to aid with the job.

Parts: I'm finding regulators ranging from $30 to $200 a piece. OEM is what I plan on doing, but I figured I would also address this topic here...is OEM the right call? Is there a cheaper alternative that is acceptable?

Additionally, I'm running an AGM cranking battery (I am now aware of the recommendations to run wet cell), but with the new style of regulators with the inline circuit (PN 8M0084173), does that mitigate the issues the stator motors have with the AGM style batteries?

Any help and input is appreciated.

[Casslaw]

I’m curious about the wet cell vs agm battery issue myself. Since the new style 8M0084173 regulators are fused, does that fuse stop the regulators from being fried due to a voltage spike coming from the battery side?

The replacement doesn’t look hard, looks as you described above Hez, hope you’re right!

[CatFan]

The voltage reading on the graph can be very misleading. You can’t accurately measure battery voltage at a remote point without a second set of measurement wires. Measure on the battery posts with a meter.

[Hez]

The voltage reading on the graph can be very misleading. You can’t accurately measure battery voltage at a remote point without a second set of measurement wires. Measure on the battery posts with a meter.

I did perform tests on battery posts with a meter after I noticed the voltage on the graph. That is how I know the battery is good. After bringing the battery to a full charge, I disconnected it for 24 hours and checked the battery, which had the following readings:

12 hrs: 12.73 v
24 hrs: 12.72 v

That is how I came to the conclusion that the battery was good. The voltage reading on the graph is what clued me to start digging deeper. For what it's worth - I remember the prior voltage readings near 14.0v on the graph

[CatFan]

I did perform tests on battery posts with a meter after I noticed the voltage on the graph. That is how I know the battery is good. After bringing the battery to a full charge, I disconnected it for 24 hours and checked the battery then, which had the following readings:
I
12 hrs: 12.73 v
24 hrs: 12.72 v

That is how I came to the conclusion that the battery was good. The voltage reading on the graph is what clued me to start digging deeper. For what it's worth - I remember the prior voltage readings near 14.0v on the graph

Those voltages really aren’t very good for an AGM. 12.8V is the lowest full charge OCV for an AGM that I’m aware of.

[Hez]

Those voltages really aren’t very good for an AGM. 12.8V is the lowest full charge OCV for an AGM that I’m aware of.

I really don't think the battery being bad is the issue here. I fish every weekend...all day both days...and the battery runs 2 graphs...livewells...poles...and starts the motor...and has not "failed" me yet....even with the situation with the regulators.

Not to mention it is one of the highly touted Duracell AGMs that Sams Club offers that is less than 2 years old

[Casslaw]

My wet cells measure 12.83-12.85 after sitting for 24 hours. My Noco charges to 14.4 before shutting off and going into maintenance mode.

Would his battery being .03 volts “low” cause the regulators to blow? It appears by the color of the connections (and a search of regulators on this board) that he has at least one regulator that has popped.

[JOE54]

tests for reg are in serv manuals

[CatFan]

I really don't think the battery being bad is the issue here. I fish every weekend...all day both days...and the battery runs 2 graphs...livewells...poles...and starts the motor...and has not "failed" me yet....even with the situation with the regulators.

Not to mention it is one of the highly touted Duracell AGMs that Sams Club offers that is less than 2 years old

I don’t think your main problem is batteries either, but being that low does indicate they are not fully charged. Maybe battery, maybe charger or could be the parasitic load from the boat draining it.

[Kzehr75]

Just did this to my 1998 200 merc efi. Mine was doing the exact same thing. Voltage wouldn’t increase when running and battery was tested on multiple testers and showed good. I replaced both and now when running, I’m getting 14.3 volts. Changing them is pretty easy. The new regulators will come with the bullet connectors attached so make sure you pay close attention to what connectors are on the which wires so you can attach the right connectors to the right wires. Some will have the female ends and others will have male ends. After that just put the plate back on. Not hard, just watch which connectors goes where. I went ahead and replaced my battery as well. Don’t forget to change out the fuses. They come with a 25 I believe and they will need to be changed to the 30. Pm me if you have any questions and I can send pics or whatever.

[Hez]

Thank you guys for the replies.

I don’t think your main problem is batteries either, but being that low does indicate they are not fully charged. Maybe battery, maybe charger or could be the parasitic load from the boat draining it.

Understood, thanks for taking the time to explain.

Just did this to my 1998 200 merc efi. Mine was doing the exact same thing. Voltage wouldn’t increase when running and battery was tested on multiple testers and showed good. I replaced both and now when running, I’m getting 14.3 volts. Changing them is pretty easy. The new regulators will come with the bullet connectors attached so make sure you pay close attention to what connectors are on the which wires so you can attach the right connectors to the right wires. Some will have the female ends and others will have male ends. After that just put the plate back on. Not hard, just watch which connectors goes where. I went ahead and replaced my battery as well. Don’t forget to change out the fuses. They come with a 25 I believe and they will need to be changed to the 30. Pm me if you have any questions and I can send pics or whatever.

Thanks for the reply! I will shoot you a PM

[leonreno]

I would definitely stick with OEM regulators. Looking at some of the aftermarket ones makes me wonder, also have heard of people
installing aftermarket ones and they are bad out of the box.

[Hez]

I would definitely stick with OEM regulators. Looking at some of the aftermarket ones makes me wonder, also have heard of people
installing aftermarket ones and they are bad out of the box.

Yes sir, only OEM for me on stuff like this.

[Casslaw]

I too believe the regulators are bad, or at least one but of course change both!

My question is what made those wires burn like that? I’d hate to see Hez change the regulators only to have this happen again.

So, what causes regulators to go bad?

[CatFan]

I too believe the regulators are bad, or at least one but of course change both!

My question is what made those wires burn like that? I’d hate to see Hez change the regulators only to have this happen again.

So, what causes regulators to go bad?

The stator engines were designed to recharge the battery after cranking the engine, run a pump or two and nav lights. When they are used to keep up with the bigger electrical load you see in modern bass boats, the regulators run hot.

[Casslaw]

The stator engines were designed to recharge the battery after cranking the engine, run a pump or two and nav lights. When they are used to keep up with the bigger electrical load you see in modern bass boats, the regulators run hot.

So it’s basically age and being bolted to the coil plate where it’s incredibly HOT? That does make sense, I just hate replacing parts without knowing why they went bad. What you’re saying makes sense though. Thanks

[EuropeanAM]

So it’s basically age and being bolted to the coil plate where it’s incredibly HOT? That does make sense, I just hate replacing parts without knowing why they went bad. What you’re saying makes sense though. Thanks

Recommendations:

-Replace BOTH Regulators using only the latest OEM Mercury/Quicksilver Regulator

-Replace ALL browned, blackened or burnt Bullet Connectors

-Install a WET CELL, Traditional Cranking Battery with at least 800 CCA Capacity. DON'T use maintenance free, AGM, Lithium, Gel, etc.

-Make sure connections are CLEAN, engine-cables FIRST, remaining lugs Largest to Smallest, and finish off the connection with a Stainless Locknut. DO NOT use wing-nuts.

Improper Battery Type, Bad or Heavily Discharged Battery, and Poor Connections are the leading causes of Voltage Regulator Failures. Pay very close attention to the above recommendations- as failures can potentially result in something that "Smokey the Bear did NOT refer to as a "minor thermal event"".

[Hez]

Recommendations:

-Replace BOTH Regulators using only the latest OEM Mercury/Quicksilver Regulator

-Replace ALL browned, blackened or burnt Bullet Connectors

-Install a WET CELL, Traditional Cranking Battery with at least 800 CCA Capacity. DON'T use maintenance free, AGM, Lithium, Gel, etc.

-Make sure connections are CLEAN, engine-cables FIRST, remaining lugs Largest to Smallest, and finish off the connection with a Stainless Locknut. DO NOT use wing-nuts.

Improper Battery Type, Bad or Heavily Discharged Battery, and Poor Connections are the leading causes of Voltage Regulator Failures. Pay very close attention to the above recommendations- as failures can potentially result in something that "Smokey the Bear did NOT refer to as a "minor thermal event"".

Thank you sir.

[Hez]

Where is the best place to source the bullet connectors?? Anyone have any recommendations?

[leonreno]

That’s a good question, I do think the regulator comes with the bullet connectors already attached, you will have to buy the other side. Might be that Mercury sales them, check with who sells your regulator to you.