lower unit removal

[matth121]

Hi guy's, I'm about to remove my lower unit but before i do, i wanted some clarification.
its an 81-82 merc 25HP, lower unit type is C according to the Seloc manual i have. There's a notation in the removal section that says this" older units- remove the shift lever coupler located in the bottom cowling behind the carburator." My question is this- do they mean remove the linkage rod that moves the shift lever or remove the actual ball that the rod connects to to shift the gears. 2nd question would be, once i lower the unit from the drive shaft housing- does the shift shaft come out with the lower unit or will it remain in the driveshaft housing. Im not a big fan of this manual, would be nice if it had better pics i guess. Thanks for any help

edit- I'm also wondering if I really need to pull the prop and drain the oil since I'm only taking the lower unit off to inspect my exhaust tube/ tuning pipe.

 

[Laddies]

Re: lower unit removal

No you don't. remove the coupler that is on the top of the shift rod item #35 - http://www.ishopmarine.com/ishop/js...cCatFilter=MM&eCatSupFldr=supplier-050-025-MM
the long shift shaft will come with the unit, in some cases the reverse lock actuater on the shift rod must be removed use care not to turn the shift rod as turning it we change it's length for shift purposes later, then remove the 4 bolts and drop the unit down.

 

[matth121]

Re: lower unit removal

ok, now heres where the problem with my motor comes into play. one of the previous owners modified my linkage to work with an evinrude control box. I was able to replace both cables, but they're aftermarket cables with locking barrels on one end and a link kit required for the bare wire on the motor side. got that all to work with what was there, but it's a bit different than the original setup. the rod shown in the pic, #30, mines different, the hook that goes into the plate, #23 shift lever, is there but the rest of the rod is straight with a plastic socket threaded onto it, this snaps onto a ball thats connected to what i believe is similar to #35, but somehow different. in any case, this is what has to be moved to shift gears....is this what needs to be removed? i'm pretty sure that it is, as this is the only thing i can see enabling the shift rod to shift gears. thanks for your help

 

[Laddies]

Re: lower unit removal

All the lever #34 with the disconnect pin #35 i it is for is to convert the back and forth movement of the upper shift linkage to up and down movemet to shift the unit, some of the disconnect pins are held with a screw instead of a clip as shown just remove the little connecter pin and the shift shaft is free to drop down. None of the other shift linkage has anythng to do with dropping the unit

 

[matth121]

Re: lower unit removal

ok, my fault, was looking at it from the wrong side of the motor...so lower unit off, big piece of twisted metal poking out from the 1" to maybe 1.5" hole. I even went and bought a pair of needle nose big enough to try and remove it but with no luck. It could be a 2" piece or it could be the whole pipe, cant tell. I can tell that what ever it is is free moving, i can push it back up the hole and spin it, just can't get it out. About to pull the powerhead since i'm guessing i shouldnt even bother trying to put it back together at this point. Should i buy a new adapter plate, or should i have an exhaust shop weld a new pipe onto the existing plate? The ishopmarine.com listings dont show an adapter plate for a long shaft- it is different right?? longer tuning pipe? appreciate anyones thoughts on my new project here. Thanks,
matt

 

[Laddies]

Re: lower unit removal

The is only 1 length pipe for both a long or short shaft engine. Pull the powerhead and remove the broken tube look at it and see if it would be possable to make a new pipe to replace the broken tube and put it in the powerhead adapter or find a donor engine that's a lot of money for a piece of pipe 13 1/4" long.

 

[matth121]

Re: lower unit removal

i agree, way to much money. Six bolts holding my powerhead on, gonna wait till tomorrow to pull it off. so 13 1/4" long is my length, any idea on diameter? just copy the old one i guess. I'll keep you posted, thanks

started a new thread- powerhead removal -help, but i think i'm good now

 

[Laddies]

Re: lower unit removal

13 1/4 long it's about 2" diameter and the bottom has been squared out to fit into the socket in the driveshaft housing

 

[matth121]

Re: lower unit removal

i'll see what i can do, but i dont see it being a problem to make up something like that. About the powerhead- theres no need to remove the starter, carb and flywheel before pulling it is there? my seloc manual, which im starting to think is junk, has all that stuff coming off 1st, also, this link to a manual shows the same thing...
http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/826883r2/4.pdf

but i removed the lower cowl, linkage and wired in kill switch and tach and it looks like those 6 bolts are all thats holding the whole thing in, so i should be able to remove it as a unit and reinstall the same way right?

 

[Laddies]

Re: lower unit removal

Yes, it should lift off as a assembly

 

[matth121]

Re: lower unit removal

powerhead came off fairly easily, now i'm trying to figure out how to remove the adapter plate. Seems like i need to remove whats left from the clamps, kinda was hoping to leave it all attached to the boat, but i'm thinking thats not going to happen. Let me know what you think. I should have some neat pictures of what looks to be 3 different pieces of my exhaust tube if i can get that apart.

 

[matth121]

Re: lower unit removal

I got it, wont bore you with the details, but if you need em, they're in a post called "help with adapter plate". have everything apart, will post photos of whats left of my tube later- appears to be a rolled then crimped piece of tin, came apart at the crimped seams, where it didn't rot that is. Im wondering if the new tube im making needs to be squared off at all.... theres no block that it needs to fit over, seems like a straight round piece of pipe should do it, please let me know what you think

 

[matth121]

Re: lower unit removal

ok, got some pics, the 1st 2 are whats left of my exhaust tube, what fell out of the driveshaft housing when it was removed. the 3rd and 4th are of my adapter plate missing the exhaust tube after i cleaned it up, found what may be a problem. There's a crack in the adapter plate where the exhaust tube joins, starts at the end of the flange and extends about 1/2 an inch. Here's my question, does this matter? i know cracks are never good, but this isn't the engine itself, it's just a plate that joins the motor and the driveshaft housing together. It's aluminum, so would have to be TIGged. Should i fix it, ignore it, or replace it. Any thoughts?

i know the crack is hard to see, but it's there. not very good at standing still to take pics, best i could do

 

[Laddies]

Re: lower unit removal

That's the area that the tube is swaged into to hold it in place and with it cracked could be the reason the tube came out?????

 

[matth121]

Re: lower unit removal

that thought did cross my mind but it's really a very fine crack. still possible i guess. so what do you think about using aluminum instead of tin or steel and tigging it all together, basically guaranteeing it stays together. also- is it 13 1/4" long or do I need to make sure there's that much sticking out from the plate, which would make it around 14" for the pipe considering what goes inside the plate. what do you think is the severity of this crack? is there enough pressure passing through there to possibly make this alot worse, or is there nothing to worry about? I know if it was a cylinder wall, i wouldnt even ask cause thats guaranteed to go boom eventually, but this is just a plate, so it should be ok i'm thinking. thoughts?

 

[Laddies]

Re: lower unit removal

The total length of the tube is 13 1/4" from end to end before it is installed into the adapter plate. The rest I really have no idea, if it were mine I would probably get it welded before installing the pipe.

 

[matth121]

Re: lower unit removal

ok, got the pipe made up, 13 1/4" exactly, attached with a bit of muffler cement inside the joint and suaded in, and JB Welded the outside around the base as well as the crack( muffler shop that put the pipe into the plate didnt think the crack was even anything to worry about. ). Cost me $10 by the way, i'll post the pics of my new tube in a bit, but i have a question. Is there supposed to be any clearance between the tube and the housing or should it be flush with the bottom of the housing? I have a bit of clearance right now and was considering using tech steel(something like mighty putty) to make a seal at the base, just a small rope of it around the tube end to close up the gap when i install it back in the housing? very small gap. But is there supposed to be a small gap, to allow exhaust to come out the upper exhaust vent by bypassing the hole in the bottom of the housing while at idle? I'm thinking my gaskets will be here today as they cleared customs 3 days ago, so I'm getting excited to put it all back together. This is my last question before i can tell you the results of all this work. Thanks for any help you can offer,
Matt

 

[Laddies]

Re: lower unit removal

I think that the dimples on the lower sides of the tube keep it from rattling around so without them on the new pipe its probably a good idea to stabilize the tube with something.

 

[matth121]

Re: lower unit removal

i dont think rattling is an option. this pipe is a piece of aluminized steel exhaust pipe and it's mounted solid, once everything's bolted together, it'll be dead solid in the center of the driveshaft housing. my concern is just the gap. do i need a gap, or should i get rid of the gap? and i'm only talking 1/8" here, not a big gap at all. i'm wondering if the exhaust gas needs to be able to bypass the bottom hole(which forces it out thru the prop) when it's idling and might not have the pressure to force it out the lower exhaust.

 

[matth121]

Re: lower unit removal

here are the pics of my new tube mounted in adapter plate.