What usually caused dead stators?

[mikeyzx2]

The stator on my '77 Rude V4 has been bad for a while but wasn't too obvious until I couldn't get it to start and run anymore. I noticed a little bit of old black stuff under the flywheel so I talked to OBJ and determined the stator melted down. Well yep I pulled the FW and both charge coils cracked and leaked as well as the nearly all 8 poles had leaked. It's been like that for a while cause it was completely dry, not sticky or fresh looking. <br /><br />To prevent another meltdown, is there anything I need to check out or is it usually an isolated incident? What caused the meltdown? Age, environment, neglect?

 

[MCM]

Re: What usually caused dead stators?

Mike, stator "meltdown" overheating is most often associated with a bad rectifier

 

[mikeyzx2]

Re: What usually caused dead stators?

So I better replace the rectifier. Since obviously the motor's not gonna run right now, the rectifier can be probed, but I won't be able to tell if it's charging right. <br /><br />Will testing it with a meter show if it's bad, or will it be necessary to check it while the motor's running also?

 

[MCM]

Re: What usually caused dead stators?

It can be tested with an ohm meter, the procedure depends on the rectifier,<br /><br />Was the battery charging properly? was the tach working? If the answer to these ???'s is no then there's probably not much need for testing. EDIT:replace it

 

[rodbolt]

Re: What usually caused dead stators?

biggest thing that got them was old age, the potting materiel was kinda pissy. similar to a lot of the rubberized wire insulation of the sixties and 70's. while a bad rectifier can fry the ac lighting portion the ign charge coils are a seperate circuit. but at the same time on the higher output systems in the 35 amp and up range you can generate enough heat with a loose battery cable connection to actually light things on fire. but quite often the older stators just leaked,dripped and quit. usually they quit due to internal corrosion due to the absense of the potting materiel. you would not believe how the old style ign coils craked,I have even taken some NOS ones out of the box and seen cracking due to the plastic type used.<br /> the potting materiel actually helped retain heat accelerating the demise. but it did help keep corrosion down. its why so many high current stators today have open windings with electrical varnish on them and no potting anymore.

 

[MCM]

Re: What usually caused dead stators?

rodbolt, that's interesting, and a good thing to keep in mind.<br /><br />So do you think he should replace the rectifier as a precaution. I think its the three wire but without knowing which motor it is can't say for certain which test procedure would work

 

[rodbolt]

Re: What usually caused dead stators?

if its just a 3 wire system with no regulators or clippers its cheap insurance. I think the 77 model was a 9 amp unregulated but without a trip to the parts breakdown and sometimes actually looking at it it hard to say from memory.<br /> back when all the motor had to do was top off the battery a 9 amp system went for years. with the advent of mega blaster stereos and radars and 3 fishfinders with 6 live well pumps and a beer cooler plugged in it got a bit more complex,expensive and troublesome.<br /> that was before 3 phase charging systems with water cooled regulators and built in battery isolators and all the rest.<br /> but normally the rectifier either works or it dont. 99% of the time a diode opens. if it shorts its only for a brief moment then its open anyway.

 

[mikeyzx2]

Re: What usually caused dead stators?

Alright OBJ told me to checking into the current rectifier just like you said MCM. Okay I'll be a little more descriptive: it's a 1977 Evinrude 85hp, model 85799S. It's likely the 6A alternator, I'm not sure if it would be the 12A. The rectifier is the 3-wire, Y/YG/R colors. Yep rodbolt, the old coils and stuff apparently sucked, 3 of the 4 coils were cracked on it. They would make good fishing weights if I had kept them. I'm gonna replace the rectifier cause I don't wanna be stupid and forget to check it and then throw a new stat on it and torch it too.

 

[Joe Reeves]

Re: What usually caused dead stators?

(Small Rectifier Test)<br />(J. Reeves)<br /><br />Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction. <br /><br />Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other. <br /><br />Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires. <br /><br />Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

 

[MCM]

Re: What usually caused dead stators?

Yep its a 6amp and your right those old coils didn't hold up to time, mine lasted almost 30 yrs. though

 

[mikeyzx2]

Re: What usually caused dead stators?

Ohhh to further add, I hadn't checked if it was charging prior to this. I couldn't get the motor to run right before this so I hadn't thought about it. As far as the tach, it was old and had corrosion inside it, and when the motor did run, on muffs, the RPMs were way up around 3000 or so, at idle, so I wasn't too sure that it worked right. I'm in the hunt for an affordable tach right now anyways to take care of that ordeal.

 

[mikeyzx2]

Re: What usually caused dead stators?

I got the OEM service manual so I'm making sure I'm staying on top of things. <br /><br />JR, knowing how some people don't know how delicate outboards can be when it comes to hooking things up wrong and such, it wouldn't surprise me if it had happened before. <br /><br />I'm enjoying the experiences I've had so far with these motors, good and bad. It's just nice that I'm not alone and you guys are all here to help.