Mercruiser 170 Alternator Questions

scook

scook

God
Anyone know old Mercruiser 170 electrical???

Engine is a Mercruiser 170, I/O, SN 6916938, in my '85 V-20 with the alternator integrated on the front of the engine. The commutator, holding the magnets is what would normally be the crankshaft pulley. My manuals don't show this configuration - I don't think they used it much.


I pulled the alternator off to get at the coolant circulating pump and have a question about putting the magnets back into the commutator housing. The stator and commutator were really rusted and the magnets were detached from the housing, so I cleaned and treated for rust/corrosion and need to reinstall the magnets. They were adhered with some kind of glue, but I can't tell what it was.

Questions:

1 - Should the magnets be evenly spaced around the commutator housing? They weren't, and it was charging fine, but it seems to me they probably should be???

2 - What adhesive should I use to hold the magnets in?

3 - I checked the resistance of the stator and got .2 Ohms - is that OK?

4 - The windings are corroded, probably 1/3 of the wire in a couple of locations - is that going to generate hot spots? If so, is there a repair I can do, e.g. add some solder, separate & splice the wire . . . (being careful to maintain the insulation)?

The Salmon are running, and I'm pawing the ground to get it back together, but I don't want to screw it up at this point.

The Stator, cleaned up and coils re-varnished

V-20Alternator4-10-10Stator1.jpg



Commutator cleaned up & painted, with magnets placed, but not glued in

V-20Alternator4-10-10Commutator1.jpg


Thanks - Scott

By the way - Thanks to MJ for this great newer site - the pictures are a snap and it really works smoothly compared to the old one.:clap:



Below, if anyone's interested, is a puller I made from an old beam hanger, one Saturday, to get the crank pulley/commutator off. I ended up having to put about 6" of thread on a 3/4" bolt with a chase nut, but it worked.
V-20Alternator4-10-10Puller2.jpg

V-20Alternator4-10-10Puller1.jpg
 
first of all, if any of the magnets are cracked, throw it in the trash, if they are all still in one piece, then you can glue them back in with epoxy, Make spacers out fo wood to evenly space teh magnets. last time I did it was with some JB metal poxy I bought at Lowes, It worked just fine. But before you go any futher, check the stator with an OHM meter. make sure its good, you can go to Rapair electronics.com to get the specs, I would alos recomend one of rapiars regulators as they do a better job than Merc's. If the stator is bad, then repace the system with an external altenator kits, if you just need a balanceer, give me the serial number off the engine, I'll see if I have one
 
Thanks Spare,

The magnets are all good. I thought about JB epoxy - I love advice that includes "the last time I did it" - I'm feeling a lot more confident about this.

Checked the Ohms - got zero with a cheap meter and .2 with my good one. I couldn't figure out how to get the spec off of the Repair electronics.com site. Is this the right link: http://repairelectronics.com/ ??? If so, what do I do when I get there?

Thanks again - Scott
 
its rapiar, not repair, but now its cdi electronics and they don't have it on line any more. I can't remeber the specs, but you should have contnuity thru the yellow wires, but not any from the yellow wires to ground, this is all with the wires disconected from teh regulator. IF you replace the regulator, use the one from CDI, it works much better than the merc
 
Spare - Thanks again for your help. Continuity is good and no short to ground - I think I'm good to put it back together.

Just checked Kendall's site and am delighted to see that she's doing well and back to school. :sun: She's in our prayers!
 
Hey Spare,

I'm posting this so you can show your wife and kids that somebody listens to you and does what you say, even when they don't.

V-20Alternatorcomutator4-25-10.jpg


Used JB Weld epoxy to stick the magnets and clamped them to be sure they were sucked tight to the balancer - didn't want to risk a clearance problem. The JB directions say to wipe down with lacquer thinner or acetone. I thought it was clean enough, but figured what the heck and did it anyway - I couldn't believe how much stuff came off on the rag.

Gettin' ready to put it back together.

Thanks - Scott
 
when you painted it you didn't paint where you glued the magnets did you? if so they will come loose as the paint will release under the glue once the motor heats up.
 
Skools,

Well, I did, but then did a very un-manly thing and read the directions on the JB Weld. I ground all the paint off and did about 5 Acetone treatments (till the rag came up clean) before gluing it together.

I appreciate you keeping an eye on me - Thanks. :nice:
 
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