1989 Sea Ray (Mercury) 100hp lower unit removal

[ethan169]

Ok so I have a 1989 Sea Ray (rebadged Mercury form what I understand) 100Hp outboard. I bought the boat/motor/trailer without know much about the condition of anything. It was a great deal even for just scrap metal.... So i guess i had to. Anyway I was told the that motor ran. The whole setup had been sitting for some time. The deck on the boat is all rotted out and the latest registration sticker on it is 2007. Although the seller mentioned they had the motor running this spring (I doubt it but who knows) I checked a few things here and there replaced a few oil injection lines and a fuel line (all cracked) and tried starting it up just to see where my starting point was. I turned it over by hand first and it seemed ok. So i connected a battery and tried starting.

After some messing with the started and quite a few cranks I got it to fire up. I only had it running for maybe 5-10 seconds then I **** it down. I didnt see any water coming out the pisser on it so i figured the impeller is bad. Nor surprised as im sure its been sitting dry for some time. So I went to remove the lower unit. Which shouldn't be that difficult.

I removed the 4 nuts and washer on the sides and the additional nut and washer up by the zinc. The lower unit doesnt really budge too much. I can rock it side to side just a tiny bit and see that its moving a little. But it wont really come down. I tried tapping with a rubber mallet lightly on the cavitaiton plates but that didn't do much and I don't want to break any of them.

Any suggestions on removing it? I was dark and cold so i decided to call it a night. I do have the forward gear selected by the way. Is there something else that holds it on? It almost feels like there is another fastener holding it.

Thanks for the help!

EDIT: Serial number is C171764

 

[carholme]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

What is the s/n of the engine?

Gerry

 

[ethan169]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

What is the s/n of the engine?

Gerry

Sorry I should have included that.

The serial number is C191764

 

[carholme]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

That s/n comes up as:

SEA RAY - (100 H.P. (1989M ))
Serial No: 0C191764 Model No: 91004129D

Parts List for model 91004129D:

(4 CYLINDER) - Mercury, Mercruiser, Force, etc. Parts Lookup

You seem to have everything undone and it may be corrosion at the top of the driveshaft splines holding it in. Do not bang on the anti-cavitation plate as you stand a good chance of breaking it. Get some hardwood or metal wedges and with them installed between the top of the LU and the bottom of the driveshaft housing, start tapping them inwards. Try and have the wedges located on structure rather than open areas if you can. If it doesn't pop with some good force on the wedges, you may have to shoot some penetrating oil in there to try and free up the splines.

I have a manual for the engine but unfortunately, I do not have the Powerhead section for the four cylinder which I believe yours is. Everything else is the same and I can send it to you if you PM me with and email address.

There is a chap on here by the name of Fun Times and he may have the four cylinder section 4B.

Gerry

 

[ethan169]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

That s/n comes up as:

SEA RAY - (100 H.P. (1989M ))
Serial No: 0C191764 Model No: 91004129D

Parts List for model 91004129D:

(4 CYLINDER) - Mercury, Mercruiser, Force, etc. Parts Lookup

You seem to have everything undone and it may be corrosion at the top of the driveshaft splines holding it in. Do not bang on the anti-cavitation plate as you stand a good chance of breaking it. Get some hardwood or metal wedges and with them installed between the top of the LU and the bottom of the driveshaft housing, start tapping them inwards. Try and have the wedges located on structure rather than open areas if you can. If it doesn't pop with some good force on the wedges, you may have to shoot some penetrating oil in there to try and free up the splines.

I have a manual for the engine but unfortunately, I do not have the Powerhead section for the four cylinder which I believe yours is. Everything else is the same and I can send it to you if you PM me with and email address.

There is a chap on here by the name of Fun Times and he may have the four cylinder section 4B.

Gerry

I was avoiding using anything to pry between the two cases. But I wasnt thinking of a wood wedge. Or maybe a plastic wedge made from delryn or something. Ill see what I have kicking around the shop.

The manual would be great even if its just the lower sections! You are correct btw it is a 4cyl version. Did they make the 100 in a 6? or was that the 115hp model?

Im sending my info in a PM now.

Thank you!

 

[carholme]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

Manual is on the way. The other 100 is a three cylinder and there are some older six cylinders.


Gerry

 

[James R]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

There is a steel locating dowel in the lower unit at the rear where it bolts up to the exhaust housing. This sometimes corrodes especially if the motor has been in salt water. You may have to apply heat to free it. Wedges are the usual way to go.

 

[ethan169]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

So i had a little time last night to try this again. I made some wedges out of wood but i think the wood is too soft. All I had was some "hard" pine or Fir 2x4's. I have some hard wood peices somewhere I just have to find them. Anyway the wedges didnt do much. I dont even really have much of a gap to even start them in. I did use a light rubber mallet to tap above the anode to try and seperate just enough to get something in their. I was able to get that side to open up about 0.020 or 0.030" just enough to get a little wedge in their or the tip anyway.

I did see in the rear of the lower unit (opposite of the prop) there is a shaft that appears to go into the upper. Im used to my alpha I on my other boat so I assume this is the shift shaft? I do have the throttle in the forward position. Is there anything else that needs to be loosed up there? Its almost like it doesn't budge at all on that end by the shift shaft. Ive got a healthy supply of PB blaster and some amazing stuff called "S'ok" but that one isnt in an aerosol. can I use penetrating oil with out damaging anything?

Where exactly are you applying heat? I have torches I just dont want to damage anything since we are dealing with aluminum and rubber seals or plastic parts etc. I can use a propane torch for lower heat but its still more then enough to cause damage.

Thanks for the help!

 

[James R]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

Apply heat to the rear end of the lower unit where it joins the exhaust housing. It usually takes quite a bit of heat as aluminum dissipates heat very quickly.

 

[carholme]

Re: 1989 Sea Ray (Mercury) 100hp lower unit removal

Yes, that is probably the shift shaft you are looking at on the front end. Directly behind the shift shaft is the engine driveshaft. See items 18/36 in this link from the parts listing:

Mercury, Mercruiser, Force, etc. - Gear Housing(Drive Shaft) - (4 CYLINDER)

Therefore, if the driveshaft splines are corroded where it enters the crankshaft, you won't get much movement on the front end.

Gerry