1985 MerCruiser 190

the dragon

Recruit
Joined
Feb 11, 2024
Messages
4
Good morning guys, I have a 1985 MerCruiser 190 i/o in a 17 ft Baretta boat. I ran the boat last year and i noticed that the voltage gauge was only showing 11.5 charging volts at any speed. My guess it is the alternator. but there are no videos that show a step by step replacement of it. I have to put the charger on the battery the night before I take it to the lake. any help would be greatly appreciated. Dave
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,099
A manual is better than a video

Take a picture with your phone of the battery and alternator wiring (this will help you put it back)
Disconnect the battery wiring and remove the battery.
Take it in to have load tested
Remove the alternator wiring, then unbolt the alternator
Take it in to have tested

Replace/repair as needed

Replacement is reverse of removal
 

Dubed

Petty Officer 1st Class
Joined
Sep 3, 2021
Messages
285
This is a 3.7 190?
There is no alternator unless someone upgraded. If you have the original system, time to upgrade
 

stresspoint

Master Chief Petty Officer
Joined
Sep 19, 2022
Messages
871
Good morning guys, I have a 1985 MerCruiser 190 i/o in a 17 ft Baretta boat. I ran the boat last year and i noticed that the voltage gauge was only showing 11.5 charging volts at any speed. My guess it is the alternator. but there are no videos that show a step by step replacement of it. I have to put the charger on the battery the night before I take it to the lake. any help would be greatly appreciated. Dave
Oh no , the worlds gone back in time too the 80s , nothing step by step on how to get an alternator off and back on again,

step 1, get a manual > google search.

step 2 , locate alternator section and use manual to test , remove and replace alternator if found to be faulty.
 

the dragon

Recruit
Joined
Feb 11, 2024
Messages
4
This is a 3.7 190?
There is no alternator unless someone upgraded. If you have the original system, time to upgrade
yes it is a 3.7 190, if there is no alternator then how does it recharge the battery, also what upgrade do I need
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,099
yes it is a 3.7 190, if there is no alternator then how does it recharge the battery, also what upgrade do I need
there is a stator assembly under the front damper pulley. there is a really really expensive water cooled voltage regulator at the back of the block near the head. if you overheated it, you will most likely have taken out the voltage regulator.

the normal fix for the 470 motor was an alternator conversion. If yours has the original regulator, it lasted 20 years longer than most.
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,679
This is what the alternator would look like if yours has been converted.
It's the silver object on the left. It might be higher than that.
Picture from breezeworks site.
1707750399437.png
 

ROY WILLIAMS

Petty Officer 1st Class
Joined
Aug 8, 2022
Messages
333
yes it is a 3.7 190, if there is no alternator then how does it recharge the battery, also what upgrade do I need
I was the MCM470 Mercrusier 1978 engine 3.7L ....... the regulator of the damaged it ...30 years ago ..... then the alternator updated it 1990.... did the video >>>>
 

the dragon

Recruit
Joined
Feb 11, 2024
Messages
4
I was the MCM470 Mercrusier 1978 engine 3.7L ....... the regulator of the damaged it ...30 years ago ..... then the alternator updated it 1990.... did the video >>>>
okay here is a dumb question, if the stator is still good and the regulator is bad can I just change out the regulator and how do you test to see if the stator is good
 

Scott06

Vice Admiral
Joined
Apr 20, 2014
Messages
5,428
okay here is a dumb question, if the stator is still good and the regulator is bad can I just change out the regulator and how do you test to see if the stator is good
Don't know how you can test it but yes you can change out the regulator if you can find one. In addition to being trouble prone, I believe they are NLA hence the alternator that most folks do.

1708013097573.png
 

Dubed

Petty Officer 1st Class
Joined
Sep 3, 2021
Messages
285
okay here is a dumb question, if the stator is still good and the regulator is bad can I just change out the regulator and how do you test to see if the stator is good
The cheapest way out is to replace with an alterator kit. If you can find a regulator, they are big money. Plus, the stator probably wont be too far behind. Breeeworks has a conversion kit delivered, under $400. Plus Kevin is great to deal with, and he has other parts in stock you will be needing for that 3.7.
 

the dragon

Recruit
Joined
Feb 11, 2024
Messages
4
The cheapest way out is to replace with an alterator kit. If you can find a regulator, they are big money. Plus, the stator probably wont be too far behind. Breeeworks has a conversion kit delivered, under $400. Plus Kevin is great to deal with, and he has other parts in stock you will be needing for that 3.7.
do you have Kevins phone #
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,099
There are test procedures in the manual

If I owned a 470, I would be tempted to take a $30 40 amp gas powered welder regulator and mount it to a water cooling plate to replace the NLA water cooled regulator
 

ROY WILLIAMS

Petty Officer 1st Class
Joined
Aug 8, 2022
Messages
333
okay here is a dumb question, if the stator is still good and the regulator is bad can I just change out the regulator and how do you test to see if the stator is good
the stator/and regulator semi conductors a damaged MCM470 of my 1978.

1708037056720.png


now my MCM470 of that updated it alternator ///...year 1990 ....
damaged is stator/regulator ...
 

ROY WILLIAMS

Petty Officer 1st Class
Joined
Aug 8, 2022
Messages
333
okay here is a dumb question, if the stator is still good and the regulator is bad can I just change out the regulator and how do you test to see if the stator is good
my regulator 1987 is the cost 130 dollars ...3 years damaged it .... then the alternator ....1990..
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,075
the stator supplies about 40 volts AC to the regulator ,its there its rectified to DC voltage and regulated
 
Top