Mercruiser 470 Only Showing 10 volts

[Long2757]

Haven't had my boat (1988 Wellcraft 192 cuddy) out since last summer. Started it up the other day and it was spraying water from the heat exchanger. Luckily it was just the end cap had pushed out, guess it wasn't fully drained before winter and I forgot to leave the drain open. I was able to flatten the end cap with a 5 lb hammer and get it to seal up.

Went to run the boat on the muffs today before we headed to the lake and I noticed it was only showing between 10-12V+ on the gauge in the dash. Hooked up a multimeter to the battery while it was running and only got 12.2V+ so it's not charging.

Not sure if it's a bad regulator or the stator coils are bad. Started reading on the forum and searching online and decided it was much cheaper to just order the alternator conversion from Breezeworks that I had seen mentioned. Amazon has a Sierra kit for $750 but I paid $363 with tax and shipping for the Breezeworks kit.

Hopefully it comes with instructions on how to wire it up. I assume the new alternator has a built in regulator so I can unhook the stator and bypass the regulator and be done with that ancient charging system and hopefully be able to enjoy my boat before the season ends. Just put new wheels and tires on the trailer, new LED lights on the trailer, and new seats in the boat.

 

[ROY WILLIAMS]

my wellcraft MCM470 conversion the AC generator ...the MCM470 regulator had a lot of failures AC generator works over 15yrs ... then I drain the sea water plug under the heat exchanger ....drain it out .. also the drain plug is a zinc and the heat exchanger is not with no corrosion ..
I changed the distributor points with the Pertronix 1146 ...uses lower gasoline and the HP is higher on the boat..

 

[Eric 3.7LX Alpha 1]

Here's the wiring diagram to add in a belt driven alt. Power it off the purple wire to the choke, not the wire between the choke and (+) terminal on the coil. That wire is a resistance wire and you won't get full 12 volts to power the alternator.

You're pretty lucky on the exchanger, I had two early frost nights that damaged my previous exchanger over the years. Usually it will split one of the tubes that run in the exchanger and you will drain your coolant out the drive seawater pick up. You can solder off 2 or 3 tubes on the 4" exchanger and still cool okay, don't recall exactly how many but it's in the service manual.

 

[Long2757]

Thank you for the diagram. Once my kit arrives I'll post an update and a pic or two.

 

[Long2757]

Got the kit from Breezeworks and installed it. Took the boat out yesterday. Was nice to have it charging the battery. Fairly simple to install and wire up.

 

[Bluedaffy]

Got the kit from Breezeworks and installed it. Took the boat out yesterday. Was nice to have it charging the battery. Fairly simple to install and wire up.

Nice. Feels good to check something off the fix list. I just got my first boat this past spring. It's a 1989 3.7LX Mercruiser, so probably very similar--if not the same--as your stock charging setup. I too went with breezeworks and had no issues. Great kit!

If you wouldn't mind humoring my curiosity: how many volts are you at now while running? And does your dash still show a bit different than at the battery posts? Mine shows 14.6V at the battery all day, and 14.0 on the dash. Just asking for the sake of comparison.

 

[ROY WILLIAMS]

Got the kit from Breezeworks and installed it. Took the boat out yesterday. Was nice to have it charging the battery. Fairly simple to install and wire up.

the voltage on the dash gauge is 13.75-14 volts ..

 

[ddrieck]

I had the same issue with my 470 not charging and it ended up being the voltage regulator. Rather than replace it I ordered the same kit you have. But when I went to install there wasn't enough room so I went ahead and made my own brackets and installed an alternator I got off Amazon. Haven't had a no charge issue going on 2 seasons.
I returned my kit for a refund with no issues from Breezeworks, company was great to work with.
(everyone, please do not contact me for measurements on my brackets)

 

[ROY WILLIAMS]

I had the same issue with my 470 not charging and it ended up being the voltage regulator. Rather than replace it I ordered the same kit you have. But when I went to install there wasn't enough room so I went ahead and made my own brackets and installed an alternator I got off Amazon. Haven't had a no charge issue going on 2 seasons.
I returned my kit for a refund with no issues from Breezeworks, company was great to work with.
(everyone, please do not contact me for measurements on my brackets)

my mcm470 1978,,,,,,,, then put it ""down"" the alternator 1990 , next to the oil filter ,,, when the antifreeze bottle plastic is on top ,,,, MCM470 .mercrusier changed it,,, a few years later dropped the plastic bottle down ..
I bought the regulator in the 1988 and it was dead in 1990 ..then adapt it to update the alternator ..over 30yrs ..