stern drive question?Help???

[adm1476]

I have a 21ft cruiser with a 165 mercruiser in it. Last weekend while using it the drive started grinding and clunking badly. I have a mercruiser drive out of a 470 4cyl. It had 170hp. Can I use this drive on my boat? If so will there be any difference in performance? Oh by the way my boat's drive is a Bravo and the other drive is a Alpha one, does that matter?

 

[Don S]

Re: stern drive question?Help???

You may have to put some years, serial numbers and pictures to this.
The 165 never came with a Bravo drive, not the 6 or 4 cylinder engine.

 

[Bondo]

Re: stern drive question?Help???

Ayuh,... Yer post don't add up...

A 165 Merc, if a 6 cylinder, would be an MC-1 drive...
The 470 will be either an MC-1, or another up to an Alpha 1...
Neither of which is a Bravo...

So,... Yes, the 165, 'n the 470 use the same gear ratio...
The 165, if a 6 cylinder uses a shorter input shaft, but the drives will interchange, if the input shafts are changed as well...

 

[adm1476]

Re: stern drive question?Help???

Yes the 470 drive is an alpha 1 , I always thought that the other was a bravo. But I am not a boat guy, and it is the original drive that came on the boat, so it must be the mc-1. That is good so all I have to do is swap the input shaft, and put new gaskets and seals. I am a car mechanic so I do have engine knowledge. Just in the boat learning curve. Thanks for the info. I'm glad the gear ratio is the same.

 

[Don S]

Re: stern drive question?Help???

You keep forgetting to tell us what type engine it is, 4 or 6 or even a year.

I am a car mechanic so I do have engine knowledge.

If I said my Chevy has a 6 cylinder engine, would you ask what year? or is every Chevy 6 cylinder engine the same?

 

[adm1476]

Re: stern drive question?Help???

It is a 1981 Chevy (Mercruiser inline 6cyl), The drive that I want to use is a 1986 alpha 1 off of a mrecruiser 470 4cyl with 170hp. Also this drive has been sitting in my garage for years, I noticed it is very stiff both while turning the input shaft, and trying to shift it all by hand. Is that normal from sitting? Will it free up after some use? The gear oil is clean,no metal,or water in it.

 

[Don S]

Re: stern drive question?Help???

Along with Bondo's advise on input shaft length, the 470 engines ran a 1.84 gear ratio, while the 6 cyl 165 used a 1.65 gear ratio.

I noticed it is very stiff both while turning the input shaft, and trying to shift it all by hand.

Turning the ujoint shaft could be stiff due to a dry impeller in the raw water pump. (should replace the impeller before using the drive) but the shift shaft should turn very easily. If it doesn't, you will have problems with the engine dieing when shifting.
Turning the input shaft while shifting will make sure the shift dogs engage properly. If it's sitting on the high spots you wouldn't be able to get it into gear.

 

[adm1476]

Re: stern drive question?Help???

So will I be able to use that drive on my boat? Will the different gear ratio cause any problems?

 

[Bondo]

Re: stern drive question?Help???

Will the different gear ratio cause any problems?

Ayuh,... Try it,.. ya might need to go Up in prop pitch...