***Alternator mesurements for 3.7 Mercruiser mod**Not much room in engine bay**

[Lukelona]

Does anyone have 3.7 Mercuiser with the alternator modification done to it?
Mine has power steering and is all stock.
Looking to do alternator modification as preventive maintenance, but I don't have much room in the engine bay.
My motor sits down in the bay where deck is about at the top of stator, with 6-10" maybe on the side.

It seems like the pics I've seen of alternator mod the alternator stocks out to the side quite a bit, which I won't have the room for.
I'm gonna make my own brackets regardless, and just buy alternator separate.

Can someone measure how many inches from furthest point of alternator to the widest point of engine for me?
Probably the cooling hose far starboard side to edge of alternator?
Trying to see if I'll have enough room or if I'm stuck with this stator setup.

Also, I've heard of adding a different voltage regulator like a automotive style but I'm not sure which one would work, or if it would be safe (explosion etc)

Thanks in advance

 

[Lukelona]

 

[alldodge]

I try to stay away from 3.7 questions but since others have not replied maybe this will help

In order to get my new motor (502 MPI) in my engine bay I had to remove the alternator and sea water pump to give me enough room to install it. It was one of those words ***** to get the ALT back on. This was the only way I had to do it

 

[Lukelona]

Thanks Alldodge ....
I don't know how I can fit a alternator in this darn thing.
Any ideas would be great if anyone wants to chime in
Thanks

 

[bruceb58]

It looks like you already have 5 lbs of "you know what" in your 5 lb bag.

The reference to "you know what" was on purpose

 

[alldodge]

Thanks Alldodge ....
I don't know how I can fit a alternator in this darn thing.
Any ideas would be great if anyone wants to chime in
Thanks

Out side of cutting into the opening and then reseal I don't have a clue.


Do you have any room to cut?

 

[Lukelona]

It looks like you already have 5 lbs of "you know what" in your 5 lb bag.

The reference to "you know what" was on purpose

Meaning....? Lol
The motor takes up every inch of engine bay? Lol

 

[Lukelona]

Out side of cutting into the opening and then reseal I don't have a clue.


Do you have any room to cut?

I've seen people do this, and I'd try it, but my starboard side has a stringer right at edge of deck. Of course the port side has room to cut lol.

In my head I'm thinking of a way to add a "external" alternator lol

 

[Lukelona]

Mine has Voltage gauge on dash, but doesn't display in numbers. It shows like a car gas gauge with 4 lines (I.e 1/4) and starts with 10 ends with 16v.
(maybe 18, can't remember off hand)

But what has me nervous about this charging system is I have a remote floodlight on bow and when I have radio on and click the light on the radio cuts out like voltage drops below 12v?

Maybe it's the dreaded regulator is getting weak?
Is it possible to add a new regulator that's not the water cooled one?
I've heard the stator is very reliable, it's the regulator that gives problems.

 

[stonyloam]

OK first off it is not that the regulator is unreliable, there are a lot of 30 year old regulators out there that are working just fine. The problem is that they are expensive, if they were 50 bucks I would still have one. Looks like that will be a difficult instillation, so you need to find out exactly what is going wrong. I would get a good digital voltmeter and measure the regulator output when the engine is running. If you are getting about 14 volts your regulator is OK. For 12 v or above 16 volts then you probably need a regulator. A good used one on e bay is 100-125 dollars. I would instal a better voltage gauge in the boat and have my battery checked. Check and clean all of your connections, especially the spotlight and radio. Couple of questions: did this problem just start? How old is your battery? Another thing to try is monitor the battery voltage on the battery when you turn the light on. If you do not get a large voltage drop when you turn it on, look for a poor connection on the radio. Good luck.

 

[wrestling coach]

If this helps here is a photo of my alternator conversion. Low mount non power steering. It came as a kit.

 

[Lukelona]

? I would get a good digital voltmeter and measure the regulator output when the engine is running. If you are getting about 14 volts your regulator is OK. For 12 v or above 16 volts then you probably need a regulator. A good used one on e bay is 100-125 dollars. I would instal a better voltage gauge in the boat and have my battery checked. Check and clean all of your connections, especially the spotlight and radio. Couple of questions: did this problem just start? How old is your battery? Another thing to try is monitor the battery voltage on the battery when you turn the light on. If you do not get a large voltage drop when you turn it on, look for a poor connection on the radio. Good luck.

Thanks for great response, I recently bought the boat from a friend. It had been sitting for few years until I brought it back to life lol
I've put new starter, rebuilt carburetor, impeller and the radio.
Runs perfect. I haven't checked with multimeter yet, but I will tomorrow. Also I'll clean all connections as you said.
The one battery is older (unknown age) it was in it when I got it and still had charge. Probably not very good anymore. The other battery is almost new automotive battery I had laying around.
I know it should have marine battery and cranking battery just haven't made it that far yet.

But just the one newer battery should supply more then enough for one spotlight right?
And yea I'm not a fan of the gauges in this thing. I'll end up replacing voltage gauge and temp gauge at least.
I don't want to buy another regulator like this especially used. It'd be an expensive time bomb lol
Imho.

 

[Lukelona]

If this helps here is a photo of my alternator conversion. Low mount non power steering. It came as a kit.

I wish my motor sat that far up out of the bilge. Lol
Mine is sunk down there half way.
Could you tell be how many inches the setup goes past the starboard cooling hose?

 

[wrestling coach]

I wish my motor sat that far up out of the bilge. Lol
Mine is sunk down there half way.
Could you tell be how many inches the setup goes past the starboard cooling hose?[/QUOTE
Sorry I can't measure at this time. The boat is in winter storage 300 miles away.​

 

[alldodge]

This should help, ALT is 5.6 inch wide, so I will guess it's 3.5 to 4 inch away

 

[Lukelona]

I have roughly 3" to the starboard side of that hose. I'm stuck. I can't be the only one with this issue? Lol
Anyone seen a high mount with power steering? That doesn't require the extra pulley on crank?
Cuz i cannot fit the extra pulley on front either..smh.

 

[Pocket Change]

I put an alternator kit from Wagner electric on my 3.7. Comes with all the brackets. The alternator goes where the cooling system overflow tank is. I relocated it on the transom. I have power steering so I had to install another pulley on the front of the motor. To me it's much easier to buy the complete kit than try to fabricate it.

 

[stonyloam]

The one battery is older (unknown age) it was in it when I got it and still had charge. Probably not very good anymore. The other battery is almost new automotive battery I had laying around.
I know it should have marine battery and cranking battery just haven't made it that far yet.

But just the one newer battery should supply more then enough for one spotlight right?
And yea I'm not a fan of the gauges in this thing. I'll end up replacing voltage gauge and temp gauge at least.
I don't want to buy another regulator like this especially used. It'd be an expensive time bomb lol
Imho.

It all depends on how things are wired. Does the alternator charge both batteries? Lots of times the accessories are run off of the second battery, so the starting battery does not get drained. If it has a battery isolator, than if the older battery is in poor shape, it could very well be that the spotlight drops the voltage enough to turn off the radio. One bad cell would drop the voltage to about 10 v, and turning on the spotlight would drop it even more. You should be able to use a single belt to run the ps and alt, besides it does not look like you have much room in front of the engine. In any case, once you get a good voltage reading on the regulator output that will tell you a lot. If it is putting out 14 v or so your regulator should be OK, And that gives you plenty of time to figure things out. Oh by the way, welcome to the 470 Club !

 

[stonyloam]

Just took another look at your photo. What is under that deck panel in front of the engine? It must open up to allow access to the front of the engine (eg front motor mount) If it does and the bilge is open on the sides of the engine, a low mount alternator should work. It will just be under the deck.

 

[Lukelona]

It all depends on how things are wired. Does the alternator charge both batteries? Lots of times the accessories are run off of the second battery, so the starting battery does not get drained. If it has a battery isolator, than if the older battery is in poor shape, it could very well be that the spotlight drops the voltage enough to turn off the radio. One bad cell would drop the voltage to about 10 v, and turning on the spotlight would drop it even more. You should be able to use a single belt to run the ps and alt, besides it does not look like you have much room in front of the engine. In any case, once you get a good voltage reading on the regulator output that will tell you a lot. If it is putting out 14 v or so your regulator should be OK, And that gives you plenty of time to figure things out. Oh by the way, welcome to the 470 Club !

I'm not sure how it's wired exactly because I didn't set it up. But it has a battery switch labeled
"off, 1, all & 2".
That would make sense if the spotlight runs Off only the crappy battery. Maybe I could try it with switch set to only the "good" battery to see if that helps?
The deck panel is access to the fuel tank.
I recently pulled motor without removing it so I think it's just for fuel tank.