Mercury 150hp XR4 lower unit question

[mark abby]

i have a 1989 Merc 150 XR4.

The input shaft on the lower unit is froze and will not turn. I thought the engine was seized at first because that wouldn't even turn, but, once i dropped the lower unit, it turned freely without the spark plugs. (whew)

So, now my problem is the input shaft on the lower unit. It will not budge one iota. The unit seems to shift OK.

My question is why would this shaft be frozen like that? spun bearing maybe? I noticed it has a special nut below the water pump. If i remove that, will the shaft slide out, or do i have to disassemble every thing? As a retired toolmaker, i don't mind getting into mechanical repairs.

Any help would be greatly appreciated.

 

[mark abby]

Re: Mercury 150hp XR4 lower unit question

ok, so here's where i'm at:

i planned on tearing down the lower unit myself to determine why the drive shaft is seized. got all the manuals for it, but soon realized the tools i need are outrageously priced. i guess they are trying to scare off home mechanics.

so, i'm looking for a used lower unit and i see prices for rebuilt ones almost 1000 bucks. seriously? do they put gold parts in them?

some guy offered me a working used one from a 1979 50 hp mercury, but i find it hard to believe that would work on a 150hp 1989 merc.

would it?

i'm almost at the point where i'll sell the power head and put a 10hp motor on it!!

 

[carholme]

Re: Mercury 150hp XR4 lower unit question

You need to get the cover nut off to remove the bearing carrier and you can make your own tool from a piece of pipe with the slotted tabs for the nut. Just leave the tube long enough so it extends back of the end of the prop shaft so you can drill a hole in it to insert a bar to rotate the tube. Or even weld a plate on it and put a square .5" hole in the centre for a power bar. Once you have the nut out, the carrier is just held in with an O ring around it's circumference.

If you think it is that bad, use a punch to remove the nut, it will only cost $30 to replace if the LU is salvageable.

At least take a look before you spend money.

Gerry

Gerry

 

[Faztbullet]

Re: Mercury 150hp XR4 lower unit question

Just chuck it as the Xr4 small diameter gearcase was bad about chitting pinion bearing especially with a hot foot. JFind a Xr6 unit and swap it over or get a SEI large unit about $900 and swap props.