Can't get lower unit off!

[drmarke]

I have a 1988 40 HP 2-stroke 3 cylinder Yamaha.
It was running rough yesterday, quit peeing water but didn't burn up.
Checked lower unit oil today (Ugly white).
Tried to remove lower unit (sheared off 4/5 bolts and broke part of lower unit ?trim plate, tryng to seperate the lower unit from the mid-section. Used heat, wood block, chisel... sections are galvanized together!
Have given up hope of salvaging lower unit, but would like to get it off and replace with a used lower unit or rebuilt.
PS: I think maybe the shaft is stuck up in the spline?
How can I get it to break lose? (I don't want to screw up the mid-section too)
Thanks in advance.

[kahoona]

I do not know it this will help or not but I had the same problem when replacing my lower unit last month. I was even going so far as to cut around the joint with a hacksaw blade. I was using a Clymer manual. I found one more bolt that was not mentioned in the book. After I took that out it was easy. I have a different model but still???

[Ken]

kahoona - yeah, that bolt that is hidden under the trim tab stumps a lot of owners the first time they try to drop down the lower unit.
But drmarke has five lower unit bolts on his 40 horse Yammie - and he has "sheared off 4/5".
So, I assume, he has found the five in addition to the trim tab bolt.

drmarke - See above. I was hoping someone with more experience than me on lower unit removal would chime in here. But this may help.
My trusted marine mechanic (the one I go to when I am in over my head) told me about a lower unit he had that sounded as bad as yours. He had to cut a hole in the side of the upper casing to expose the drive shaft so that he could heat it with a blow torch - the splines of the drive shaft had corroded with the splines of the end of the crank (probably what has happened to yours).
If you can get any space at all between the lower unit and the upper case, try wedging small pieces of tapered wood all around the perimeter and just keep on tapping them in hopes the driveshaft will break loose.
If that fails, then you might want to take your outboard to my mechanic [img]smile.gif[/img] ,
Good luck,
Ken K

[drmarke]

Thanks Guys,
Here is the story: I was able to hammer around the lower unit with a chisel, and opened up a 1/8" crack. The bolt under the trim tab (which was sheared off) was still holding fine despite torch / hammer / screaming and cussing. I took a saw-szaw and cut the bolt and the lower unit released nicely. That particular bolt would still not come out with a punch and hammer! (drilled it out) Other bolts were removed with lots of heat and bolt extractor for one and had to drill other two out (was able to save threads) and re-tapped.
Next to the bearing carrier in the prop shaft housing!
Manufactured a puller with galvanized steel and wouldn't budge and 5/16" metal bent. Not to be outdone, I went and manurfactured a stainless steel puller. Heated with torch, sprayed liquid wrench and turned 1/2 turn nightly. Came out on third day! (Removed prop shaft assembly).
Now looking for a splined socket to hold drive shaft in order to remove drive shaft. It has a pinion nut on the end of the shaft which holds it in place!

This is not a job for the weak!
Mark

[Hamfisted]

You should be able to wrap a shop towel around a non-critical area of the driveshaft and grip it with a suitable pipe-wrench on the towel, good enough to loosen the pinion nut. Use a long box wrench on the pinion nut.


Mike

[drmarke]

Mike,
Thanks.. I put a Pipe wrench on it and got it right off. All these seals are burned up from heating the bearing carrier.
Question? All the gears, bearings look good. Are the only things I have to replace the: O-rings, oil seals on the prop side and the water pump on the shaft side? I was getting water in the lower unit initially, hense the repair.
P.S. The top of the aluminum housing for the water pumpp looks like it has a hair-line crack at the top on the exhaust side (but above wear the water pump housing seats. Is this something to concern myself with?

[Hamfisted]

You can seal up the hairline crack with some JB Weld epoxy before it gets any worse.
The driveshaft seal under the waterpump is responsible for 80% of the water intrusion leaks in the lower unit. There is a radius tension spring on the shaft lip of the seal that likes to break and let water from the waterpump travel down the shaft.


Mike

[drmarke]

Thanks for your help. I ended up scraping the lower unit due to the lower unit housing being in too bad of disrepair. The welder said that the seating for the water pump was cracked in two places and he couldn't weld that and there was some deep pitting in the front of the foot (cancer) that was not repairable. (I had broken the cavitation plate LOL)
Found a rebuilt foot for $400 and will put it on Friday. I did manage to get every removeable piece out of the Lower Unit though and learned tons. Plus several new tools: Impact driver, bolt extracters and I manufactured a bearing puller!
Mark

[Hamfisted]

Yeah it was almost 20 years old anyway. This sounds like the way to go.


Mike