Belt size confirmation

[karayj]

I have a 1989 3.7 Mark cruiser now I will say that I have an alternator attached to it from the previous owner. My question to you guys is though what is the bell because I went last week after the belt broke on me to a parts place by the lake and they gave me a belt which seem to be at at least half inch which in my thought process is too big.

I put the belt on correctly. She lasted about nine minutes all sudden smoke from the engine compartment and sure enough I knew what was going on.

So the belt length was, but I think the width was wrong, which is why I got destroyed so quickly. So is it 3/8 which I think it is or half inch the belt that was on there is a Napa 25 7490

 

[karayj]

I have a 1989 3.7 Merccruiser now I will say that I have an alternator attached to it from the previous owner. My question to you guys is the belt width because last week on the lake after the belt broke on me I went to a parts place by the lake and they gave me a belt which seem to be at at least half inch think which in my thought process is too big.

I put the belt on correctly. She lasted about nine minutes all sudden smoke from the engine compartment and sure enough I knew what was going on.

So the belt length was, about 50 inches but I think the width was wrong, which is why I got destroyed so quickly. So is it 3/8 which I think it is or half inch the belt that was on there is a Napa 25 7490. the pulley on the alt is smaller so I guess I have to go with that 1st.

The Power Steering pulleys are 1/2 for sure THIS SUCKS!!! Now I know why it would squeal sometimes .. I need to find a better pulley

 

[Dubed]

The alternator kit is aftermarket and would have come with an appropriate sized belt. There's no way to tell you what that is.
The alternator kit on my 3.7 uses a #15505 belt which I'm pretty sure is 7/16"....
Maybe look up original belt size for your motor and that should give you the width needed (not the length)

 

[karayj]

The alternator kit is aftermarket and would have come with an appropriate sized belt. There's no way to tell you what that is.
The alternator kit on my 3.7 uses a #15505 belt which I'm pretty sure is 7/16"....
Maybe look up original belt size for your motor and that should give you the width needed (not the length)

Well, actually, you’re 100% right I ended up figuring it out. I didn’t see this post but yeah pretty much a 50 or 51 inch belt will work 7/16.
Now there is a little bit of rubbing and I think the old belt was the same scenario. It’ll eventually wear down properly. I don’t think they make a skinnier one. I am looking into a different pulley for the alternator something a little bit wider. Thank you for the post, but I can say now that I’m all set onto the next problem.