1971 mercruiser 165 will not spin prop when engaged.

[bigguy6f4]

Ok guys here is my proplem as well described as i know how to say.

1971 Mercruiser 165 with the 250 4.1L Gm inline 6 cyl.

We were wakeboarding last night and while towing my big butt the boat just suddenly stoped but the engine rpms kept high.

My buddy shut her down and yelled that he thought we spun the prop bushing.

However its a brand new prop with less than 6 hours on it. I was doubt full.

My fears where correct when we tried to go forward again and a light gear rubbing noise sounds when you engage frontwards or backwards.

We took the top inspection cap that houses the top bearing assembly off the outdrive and the oil was grey and frothy with lots of white bubbles. looked like water in the oil to me. after lots of cussing we went agaid and took the whole outdrive off and discovered the bellow that houses the ujoints was full of water. upon inspection all my ujoints are very greasy and very very smooth. looked just fine by me. maybe its suppose to have water in there???

any ways before we took the outdrive off but still had the inspection top plate off i had my buddy start the boat and engauge it for a bit. and all the gears were spinning on the top side. so ive isolated it to the lower half of the unit.

after we took the outdrive off the linkage to select forward and reverse was in good shape and was operating correctly. so that seals the deal that its in the lower unit. i can grap the prop and spin it with my buddy turning the gear selector shaft with plyers and you hear a gear slippin sound and the gears on the top of the outdrive will not move.

Any suggestions? i have an old lower unit that has a cracked lower unit. however i might could swap a part or too. help!

thanks so much! Drew

 

[ziggy]

Re: 1971 mercruiser 165 will not spin prop when engaged.

did ya overheat?
there isn't supposed to be any water in the bellows.
sounds like yer gear lub is contaminated with water. perhaps from the bellows being full of water. the ft. seal of the drive only keeps lub in, not water out.
since yer bellows was full of water. ya need to replace the gimble brg, ujoints, and at the very least, go look at the drive gear yoke for rust at the seal area.
ya will need to replace whatever caused the water in the bellows, the bellows themselfs maybe. while yer there replaceing the bellows, ya should do yer water hose, and shift cable too.....

if ya over heated. and since ya had the top cap off seeing the gears turn. that leaves the drive shaft in the lower which can snap at the oring groove, or if ya didn't overheat. a spun prop......

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

im sure its not the prop. as far as overheating i have no idea. how do i check for a broke downshaft at the oring? do i need to remove the lower unit from the upperunit at this point?

 

[Don S]

Re: 1971 mercruiser 165 will not spin prop when engaged.

how do i check for a broke downshaft at the oring? do i need to remove the lower unit from the upperunit at this point?

Yes, you have to seperate them.
You really need a manual for your drive so you don't mess things up. You could have had a real mess running the engine with the cap off the drive. It has the upper bearing race in it that supports the vertical shaft.
Anyway, here is a link to an Alpha service manual. It's newer than yours, but the info on taking apart and putting back together is basically the same.
http://www.boatfix.com/merc/Servmanl/6/6covr3.pdf

Just scroll down to the outline and click on the LETTER of the section you want to view.

 

[JustJason]

Re: 1971 mercruiser 165 will not spin prop when engaged.

i can grap the prop and spin it with my buddy turning the gear selector shaft with plyers and you hear a gear slippin sound and the gears on the top of the outdrive will not move.

If your facing the back of the prop, and the drive unit is in front if you... and you try to spin the prop clockwise while the unit is in forward gear... the prop will spin freely and you will hear a ratcheting sound from the clutch dog and spring inside of the lower unit.

However its a brand new prop with less than 6 hours on it. I was doubt full.

Is it a rubber hub or a plastic hub? A plastic hub, once they are broken they will spin. With the rubber hubs... sometimes they will stick enough that they appear to grab by hand, but not stick enough when they are trying to push the boat.

Sounds like you have multiple problems going on. You need a reseal on the drive for sure. You need to replace your bellows. You need to check your outer transom plate for rot If there was water un the bellows you need to change your u joints. While you have your u joints apart, stick the input shaft into the coupler and try to spin it. You also need a gimbal bearing, and you might as well replace your lower shift cable while your in there.

As far as why its not shifting, well... you need to take apart the drive to reseal it anyways. you'll get it. Just make sure you get the correct manual. And make sure you buy the special tools to pull the drive apart correctly

 

[Bt Doctur]

Re: 1971 mercruiser 165 will not spin prop when engaged.

what about the coupler. friction would spin the shaft no-load.
pull the drive and see what comes out. aluminum slivers with the yoke shaft .

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

Just a thought. There are several Afpha 1 Units for sale in my area and was curious if the whole upper and lower unit would bolt up to my current transom hookup thangy. (excuse the crude terms as i know know what to call it.)

here is a unit still hooked on a boat that is fairly new on a rebuild with papers from the shop to prove it. the boats motor is junk so they guy is just parting it out. he is asking 300 bucks for the whole thing. and i could prolly get some bellows from it too if it would fit on my current transome plate thingy.

any thoughts?

 

[Haut Medoc]

Re: 1971 mercruiser 165 will not spin prop when engaged.

Just a thought. There are several Afpha 1 Units for sale in my area and was curious if the whole upper and lower unit would bolt up to my current transom hookup thangy. (excuse the crude terms as i know know what to call it.)

here is a unit still hooked on a boat that is fairly new on a rebuild with papers from the shop to prove it. the boats motor is junk so they guy is just parting it out. he is asking 300 bucks for the whole thing. and i could prolly get some bellows from it too if it would fit on my current transome plate thingy.

any thoughts?

It will bolt right on if it is a Gen 1.....
However, you will need the correct drive ratio, in this case is it a 1.65 :1......
Forget using old bellows, you can get new ones for like 50 bucks.....

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

you have to excuse my lack of knowledge in this area.. but.. is a alpha 1 a gen 1? what do i have? and what would bolt up? thanks. and if the gearing is different then id need a different prop right? thats no big deal if thats all it comes too.

 

[JustJason]

Re: 1971 mercruiser 165 will not spin prop when engaged.

anything up to and including an alpha 1 gen 1 will bolt up to the housing. You probably have a #1 drive with an eyelet in the top cap.
however.... it doesn't do ya any good to buy a drive unless its pressure tested first.
And it NEEDS to be the same gear ratio... changing the prop won't fix it. I have a feeling that there is nothing wrong with your drive except that it leaks. If you seal it up it should be ok. I think your shifting woes are coming from someplace else. Is this a saltwater boat?

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

no its a freshwater boat.

I currently have the upper and lower outdrive set up on my work bench. i can get a buddy to use pliers and turn the gear selector on the upper section and the propeller will ingage. howeve its very hard to turn one direction and clicks and makes the pliers jiggle when i turn the prop the other directions. which is normal i believe. when i turn the gear selector the other direction the effects are reversed. so i think the gear selector is working fine.. however when i turn the output shaft with the forward or reverse gear selected it will not spin the gears in the top cover.

 

[Don S]

Re: 1971 mercruiser 165 will not spin prop when engaged.

i can get a buddy to use pliers and turn the gear selector on the upper section and the propeller will ingage.

Assuming you are referring to the shift shaft in the top/front of the lower unit, it should move easily with 2 fingers. If it takes pliars to move it, you have a problem. Either bent shift shaft, or worse, internal problems in the shift mechanism.
The lower needs checked out. If you don't have the special tools, you can create a lot of problems for yourself just trying to get it apart.

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

no it turns with fingers easily.. however if you turn the prop the wrong way it will center itself and you cant hold it with fingers. pliers was just a easier way to turn it freely.

 

[Don S]

Re: 1971 mercruiser 165 will not spin prop when engaged.

Turn the vertical shaft clockwise. While turning the shaft, turn (By Hand) the shift straight forward. the prop shaft should turn CW. Continue turning the vertical shaft and turn the shift shaft counter clockwise (by hand) and the shaft should turn CCW

If you have been doing all of your testing by turning the prop the wrong direction, then it will ratchet. Even if you use pliars.
If turning the prop to see if it goes in gear, you need to turn it the opposite direction of the above instructions.

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

Ok, ive made up my mind to just get a new lower unit at the least and maybe a new upper if i can find a combo for a good price. alpha 1 gen 1.

my current lower unit is so old that it uses a really really old outdated thrust washer that is not beveled. the output shaft that attatches the prop has no beveled area to hold the correct thrust washer to use a newer prop. It just has a straight cut washer and a lip on the output shaft.

AND,,, the fin on the bottom most part of the lower unit is either ground down,, or 1.5 inches shorter than the spare lower unit i have. so im always banging up my prop becasue it offers no protection.

AND,,, now something inside the old piece of junk is broke. Id rather just spend a few extra coin and get the correct lower unit and if im luck just get the whole upper and lower unit intact to just bolt on.

SO... How do i tell a gen 1 from a gen 2?

 

[Don S]

Re: 1971 mercruiser 165 will not spin prop when engaged.

Ok, ive made up my mind to just get a new lower unit at the least and maybe a new upper if i can find a combo for a good price. alpha 1 gen 1.

First of all, it's a 71, it IS NOT an Alpha I Gen I. You probably have what is known as a "One" drive. It's the model before the R, and MR, which were before the Alpha I that came out in 87.
You don't have a Gen II unless it has been repowered with new drive, engine and transom shield manufactured after 1991 or 1992.

 

[BAYLINER185]

Re: 1971 mercruiser 165 will not spin prop when engaged.

And to add to the madness the SKEG fin that you say is ground down 1 1/2" isnt for protection to your prop. You keep banging up your prop because of other reasons. And these other reasons may be the result of why your drive suddenly doesnt want to work any more.

Replace the drive as you say you are going to do and be more carfull.300.00 bucks is a steal for a complete drive. Id buy and run as fast as you can.

 

[JustJason]

Re: 1971 mercruiser 165 will not spin prop when engaged.

have you split the case yet?

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

http://dallas.craigslist.org/boa/632227903.html

is there a way to tell if this is a gen 1 or gen 2?

and yes,,, i only hit my prop when i try to load the boat. its a bear. even if i trim up all the way i still hit something past the boat ramp. a big rock or broke piece of concrete or a 1000 pound catfish. unsure what. im in the process of fixing my trailer so its better suited to load the boat.

 

[bigguy6f4]

Re: 1971 mercruiser 165 will not spin prop when engaged.

and no i havent torn it in half yet.