1984 Mercruiser 120R outdrive self destructed.

[sjoefl01]

1. 10 minutes out in the bay we get a horrible noise coming from the outdrive. The motor starts choking down.
2. I turn the motor off and look in the engine compartment. All guages had been normal nothing hot plenty of oil pressure.
3. Motor will not turn over but the starter torques the flywheel. We sit about 10 minutes and it reluctantly starts to turn and crank but sounds terrible.
4. I look over the back and the top of the outdrive has steam. The noise starts again and we turn it off.
5. I get it home and hook up a water hose. Of course the noise is even worse out of the water. It is a metal on metal coming from the top of the outdrive.

The problem is somewhere between the output of the engine and whatever get disengaged in neuteral. The noise is there and the engine wont turn when the outdrive is hot no matter if it is in gear or not. I have watched the prop and it seem to shift out in neuteral like it should.
I need a starting point. I looked at diagrams and I am having a hard time finding a drawing of what is in the top part of the outdrive. I can see pieces and parts taht are scattered across some pages but I'm havin a hard time figuring out what is in there. I see a shaft with a couple of U joints. That looks suspicious. Whatever happened was quick. It was running fine before this happened. I think something broke or came apart. There seems to be some heat and friction involved now.
The real bummer is this is the first time I had the boat in the water. I contacted the seller and he offered his condolences but nothing else. Please help me if you can.

 

[Don S]

Re: 1984 Mercruiser 120R outdrive self destructed.

Remove the drive and see if the engine starts ok.

Try to turn the ujoint shaft by hand, that will tell you if you have a drive problem or not, also drain the gear lube and check for metal in the oil and on the magnets.

 

[Bt Doctur]

Re: 1984 Mercruiser 120R outdrive self destructed.

check to see if there is any oil in the drive too.low or lack of oil will quickly destroy a drive.

 

[Bondo]

Re: 1984 Mercruiser 120R outdrive self destructed.

1. 10 minutes out in the bay we get a horrible noise coming from the outdrive. The motor starts choking down.
2. I turn the motor off and look in the engine compartment. All guages had been normal nothing hot plenty of oil pressure.
3. Motor will not turn over but the starter torques the flywheel. We sit about 10 minutes and it reluctantly starts to turn and crank but sounds terrible.
4. I look over the back and the top of the outdrive has steam. The noise starts again and we turn it off.
5. I get it home and hook up a water hose. Of course the noise is even worse out of the water. It is a metal on metal coming from the top of the outdrive.

The problem is somewhere between the output of the engine and whatever get disengaged in neuteral. The noise is there and the engine wont turn when the outdrive is hot no matter if it is in gear or not. I have watched the prop and it seem to shift out in neuteral like it should.
I need a starting point. I looked at diagrams and I am having a hard time finding a drawing of what is in the top part of the outdrive. I can see pieces and parts taht are scattered across some pages but I'm havin a hard time figuring out what is in there. I see a shaft with a couple of U joints. That looks suspicious. Whatever happened was quick. It was running fine before this happened. I think something broke or came apart. There seems to be some heat and friction involved now.
The real bummer is this is the first time I had the boat in the water. I contacted the seller and he offered his condolences but nothing else. Please help me if you can.

Ayuh,... Welcome Aboard,.... Is there any oil in the outdrive,..?? I suspect, Not...

You probably tore up the gears in the upper unit, 'n destroyed the lower unit in the process..

 

[achris]

Re: 1984 Mercruiser 120R outdrive self destructed.

Remove the drive. Check that the engine turns over and runs nicely without the drive (Just stuff a hose into the water inlet on the bell-housing). If that's all ok, toss the old drive in the trash and buy a new SEI drive.

Removing an Alpha drive.

 

[elkhunter338]

Re: 1984 Mercruiser 120R outdrive self destructed.

Probably time for a SEI upper/lower unit. That what I did when my upper started making noise, nothing as quick as yours, my upper bearings/gears stated to rust pit and make noise that was not normal.
Been running the SEI unit for 3+ yrs. and about 300 hrs. Still a ok. They stood behind a upper warranty that was not their fault. Some how I got a slit in the u-joint bellows and rusted the u-joints and wiped out the upper seal and the outdrive needed a new input shaft and upper seal. SEI rebuilt the upper unit no cost except shipping one way. Can't say anything bad about SEI. Their units are noisy until they get 20-40 hrs of break in but that is it. Change drive oil after 10hrs and break it in as instructed

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

I went fishing in my little 14 ft standby today so I didn't get a chance to dump the oil. Having said that; I am intersted in this SEI outdrive. This boat is in really nice shape to be so old. The engine looks really good. Does anybody have a source for this SEI drive? I would like to study up on it. Even if the problem is something different I would loike to know about this.

 

[Bondo]

Re: 1984 Mercruiser 120R outdrive self destructed.

I went fishing in my little 14 ft standby today so I didn't get a chance to dump the oil. Having said that; I am intersted in this SEI outdrive. This boat is in really nice shape to be so old. The engine looks really good. Does anybody have a source for this SEI drive? I would like to study up on it. Even if the problem is something different I would loike to know about this.

Ayuh,.... Start here, 'n follow the prompts...

 

[SgtRollo61]

Re: 1984 Mercruiser 120R outdrive self destructed.

Sounds like the U-joints exploded! once you remove the outdrive, you should see the problem. If not, like they said the uppers are destroyed.... Sorry.... :grumpy:

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

I put the unit in forward and turned the prop. There was a clonking that happened about once a revolution. I think that is the problem but I have nothing to compare it with. I am draining the oil through a Mr Coffee filter to look for particles or metal parts. There was about a tablespoon of water at the bottom of the unit. The rest of the oil looks kind of okay. I am making a run for the parts house to get a big screwdrived for the vent/fill plug. I don't want to damage it although I think it will need to be replaced anyway.
I saw some magnets mentioned that I am supposed to inspect for metal filings. I don't see anything like that so far. Can somebody help me out? I wanted to inspect what I could before I take the outdrive off.

 

[Don S]

Re: 1984 Mercruiser 120R outdrive self destructed.

You have some water in it already, pull the drive, you will have to do that just to find the drive leak.

The magnet is that little rod sticking out of the drain plug.

The prop will also turn one direction and clunk when in gear, that's normal, it will also not turn the other direction.

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

Okay the drive is laying in my driveway. The U joints don't look that bad. They dont have a lot of play and seem to turn freely. There is a little surface rust but not too much. I am waiting on my wife to get home to crank the boat while I hold a waterhose to the water inlet. There is round opening with an Oring that has water inside. It is about 3/4" and the Oring looks good. That sure seems like a water inlet. Before I took the outdrive off it quit locking in forward. It worked in reverse but when you went forward whatever it is that prevents it from turning backwards was not fully engaging. You could hear it click but it wasn't preventing the prop from turning counterclockwise.

 

[Don S]

Re: 1984 Mercruiser 120R outdrive self destructed.

Just crank the engine over and see if it starts and runs for a few seconds. No water needed for 10 to 15 second run. You just want to see if the engine is still binding.

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

The engine cranked right up. It sounded great. There weren't a lot of shaving in the oil. There were just a few clinging to the fill/vent plug. The racket seemed to be coming from the top of the outdrive. I expected to see the Ujoints all corroded and a water encroachment in the bellows compartment. That is not the case. Now I would like to see what is under that cap. Would that be a normal next step? Should I separate the upper an lower units? This noise was terrible metal to metal friction. I didn't run it much like that but I am expecting to see carnage somewhere. It came on all at once like something breaking.

 

[Don S]

Re: 1984 Mercruiser 120R outdrive self destructed.

Pull the top cap off and look at the gears, there is nothing in the upper to ratchet.

Just a standard ole 12 point socket for the bolts.

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

The bearing at the top is shot. The rollers came apart and it spun in the race. It's getting dark but the gears look like they are okay. It looks like I will need to change the cap and the bearing. I'll also need to find out how the water got in the oil and change the water pump impeller while I am here. Should there be oil on this bearing? The entire gearcase looked dry.

 

[Don S]

Re: 1984 Mercruiser 120R outdrive self destructed.

There should have been between 32 and 36 ounces of gear lube in the drive. Just a hair over a quart. If there wasn't then you know why the bearings went. I would bet all the bearings in the upper are shot. When you do replace the bearings (and seals) you will have to reshim them and reset rolling torque. You need to do some more inspecting. Make sure the surfaces of the gears are smooth without any chips missing in any.
It also takes special tools to do all that work.
Hate to say this, but you better be talking to your wallet and preparing it for some expensive times ahead.

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

Let me check some language There is a sticker that says 3. 0 Litre and it has a big 4. It also has a scribe that says 1.98R. The unit should have been built in 1983 or 84. The serial number is 6845106.

This is an alpha before generation II with a 1.98 ratio?

 

[Don S]

Re: 1984 Mercruiser 120R outdrive self destructed.

It's an R drive, spend some time here looking at the history and ID, and scroll down and look at some pictures.

http://forums.iboats.com/mercruiser...cellaneous-mercruiser-information-329915.html

 

[sjoefl01]

Re: 1984 Mercruiser 120R outdrive self destructed.

That's interesting. The tag says it is an R model but the serial number says it is an MR. I haven't seen anything that tells me what is the difference. I am looking at EBAY to see if I can just find one that is used.