1995 Evinrude 175HP Rectifier Problem?

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
I just bought this boat from an individual yesterday. We test drove the boat with the owner with no troubles. Other then the tach not working. I brought the boat home and fired it up on the water hose and it ran good. Left it overnight and pulled it to the lake this morning to find a dead battery. Thought maybe I had left something on. Grabbed a trolling motor battery and hooked it up correctly. Looked up and saw smoke coming out of the motor. Disconnected battery and pulled cowling and saw the rectifier melting. My question is this, would the rectifier go out on its own over night like that? Or did something else cause it to short out? Do I need to look at the stator or the power pack? Or just replace the rectifier? Any help would be appreciated.

Thank you,
Robert
 

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: 1995 Evinrude 175HP Rectifier Problem?

Welcome to iboats!

Tach not working is a symptom of bad rectifier - as is dead battery next morning.

I see no reason to suspect anything else at this point.
 

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
Re: 1995 Evinrude 175HP Rectifier Problem?

What should I read (as far as ohms) on the two yellow wires coming from the stator? I am reading .5 ohms. Does this sound correct?

Thanks again,
Robert
 

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
Re: 1995 Evinrude 175HP Rectifier Problem?

I took the battery that smoked the rectifier to be tested this morning. The guy at AutoZone told me the he "thinks" it had 3 bad cells. If the battery truly had 3 bad cells would that fry the rectifier? And then what caused the first battery to go dead over night?
 

Seasport

Chief Petty Officer
Joined
May 2, 2005
Messages
410
Re: 1995 Evinrude 175HP Rectifier Problem?

The resistance between the yellow & yellow/grey wires should be about 0.2 ohms- so you're OK there. Also check that there's no connection between these wires and ground.

The fact that your tach wasn't working suggests a faulty recitifier/regulator. You may have a shorted diode in there which caused the rectifer/regulator to get so hot. A shorted diode could allow the battery to discharge through the rectifier and stator windings and they will get very hot.

What is the voltage reading on that trolling battery? If you had 3 shorted cells it would read about 6V. Probably not your problem. I'd replace the rectifier/regulator.
 

rkersh409

Petty Officer 2nd Class
Joined
Aug 19, 2006
Messages
100
Re: 1995 Evinrude 175HP Rectifier Problem?

Thank you Petty Officer 1st Class. I do not have any reading between the two yellow wires and ground. So I think I am good there.

I know my rectifier is bad cause it was smoking and melting the silicon. I am just trying to figure out what caused the rectifier to go bad. Cause it drained the good battery and smoked with the bad battery. Also trying to figure out if my stator is bad also. The bad battery showed 8V and 300 cranking amps on a 1000 amp battery. Thing is that I never tried to crank it with the bad battery.

I know the rectifier has constant power coming off of the battery. So if it drained the good battery why didn't it smoke the rectifier then. Instead of when I put the bad battery on?

Trying to figure this out before replacing just the rectifier and having it go out within a few months cause of another bad part.
 

Seasport

Chief Petty Officer
Joined
May 2, 2005
Messages
410
Re: 1995 Evinrude 175HP Rectifier Problem?

Maybe it was cooking the rectifer with the other battery connected too but you never noticed - especially if it was near flat anyway.

You can damage the rectifier if you disconnect the battery while the motor is running or if you have poor quality battery connectors (wing nuts - get rid of them).

Your stator windings must have been getting hot too but they measure OK. Is there any physical sign of damage there? Most likely failure there is for them to go open circuit in which case you'll get no voltage out.

I think you'll be OK if you replace the rectifier/regulator.
 

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: 1995 Evinrude 175HP Rectifier Problem?

Rectifiers are like people, even good ones go bad sometimes.

only other way to test it I could think of would be measure AC output to rectifier with the engine running...never heard of anybody doing that...not sure what to expect...I'd replace it, then make sure you're getting charging voltage...
 
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