15B2 lower unit frozen

[FDS]

Hi: I am a new member and this is my first thread.<br /> I have owned my 89 15B2 Tohatsu for two years now, so decided to replace the impeller. Following the service manual, I removed the four nuts and washers that hold the lower gearcase on the drive shaft housing, then removed the upper spring pin from the shift rod joint. The manual states that the lower gear case should drop off. But it would not come apart. I tried to separate it by pounding on the lower unit with the butt end of a two foot long piece of 2"X6" wood, but it still would not come apart. So, after removing the engine cover, I turned the OB upside down and sprayed WD40 onto the gear case bolts and tapped on them with a brass ballet. I also used a razor blade and cut thru the paint where the unit is supposed to come apart, then sprayed that area also. I then removed the lower swivel mount bracket which then allowed me to see into the drive shaft housing where I could see the drive shaft. Thru that hole I sprayed more WD40 so it would run down the drive shaft and onto the drive shaft splines. I let the parts soak in WD40 for two days, then started pound on the lower unit again. It still would not come apart.<br />I'm at my witts end. I still don't know where the problem is. At the drive shaft splines, or the area where to two sections mate together. If anyone has any suggestions, I would appreciate any help given.<br />Thanks, Frank

 

[TOHATSU GURU]

Re: 15B2 lower unit frozen

It could be either one or both. You can try pulling the powerhead. Usually that will pull the crank and drive shaft apart if they are stuck.

 

[DanDVM]

Re: 15B2 lower unit frozen

Hi Frank, <br /> Having recently dealt with a similar problem on my 5 hp Nissan thought I'd throw in my 2 cents worth. Make absolutely sure all the bolts holding the lower unit have been removed. My manual shows 5 bolts(on the 15 hp), not 4 holding it in place, one in the front coming from the top that might be easily missed.(The Clymer manual shows several models and can be misleading however). If all the bolts have indeed been removed use care in how much you bang on it. I can attest to the fact you can mess up the shift rod and the lower unit by forcing it. As Elvin said, removing the powerhead is not too hard and will tell you at least if the problem is at the upper end of the driveshaft.<br /> Good luck!

 

[granpafish]

Re: 15B2 lower unit frozen

Dan is right on. Be absolutely sure that there is not a 5th bolt. You wouldn't be the first to be fooled on that issue. Also don't count on WD 40 being too good at corrosion relief. It is actually just a water displacement product. Get some good Liquid Wrench type product. I personally think that "Kroil" is terrific. Can be hard to find. Let it soak for couple of days. Good luck Granpa

 

[TOHATSU GURU]

Re: 15B2 lower unit frozen

5 hp's only have two bolts holding the lower unit on

 

[FDS]

Re: 15B2 lower unit frozen

Oops, Sent a blank reply.<br /><br />Elvin: Thanks, but I'll hold off and pull the powerhead when other options fail.<br /><br />Dan5: I can't find another bolt. Although there are two other bolts below and to the rear of the subject joint. one holds the screen for the emergency water inlet. The other mounts an anti corrosion zinc anode. But it sure seems logical that there is a bolt holding it together because I couldn't even get it apart enough to break the paint at the joint.<br /><br />Grandpafish: Good Idea> I'll try to get something better than WD40 (that's what I had available).<br /><br />I can't get back on the OB for a few days. First I got to replace the water pump and timing belt in my truck (that's what pulls the Boat). But thanks alot for all the info. I'll keep you informed.<br /><br />By the way, my service ;manual was printed by NISSON Co. LTD, however, no printing date. <br /><br />Frank

 

[FDS]

Re: 15B2 lower unit frozen

Well I'm back working on the Tohatsu. The lower unit still will not release from the drive shaft housing. I again tipped it upside down, removed the lower swivel mount, but this time I took Grandpafish's advice and got something better than WD40. I sprayed the driveshaft with PB Blaster. Also the bolts and the junction where it supposed to come apart. Again I tapped and pounded on it but it still woull not release. I'll let it soak overnight, then do the same thing tomorrow. I still don't know if there is another bolt holding this thing together. I keep hoping someone out there in iboat land who has the same outboard and had the experience of removing the lower unit. Although I'm following the service manual, I still have the fear that I'll "break it" apart and find out that anouther bolt was holding it together.<br /><br />Salmon are starting to come up the Columbia, and I'm still farting around with this problem.<br />Frank

 

[John_S]

Re: 15B2 lower unit frozen

The Clymers manual shows five bolts for the 8-40hp 2 cyl 2 strokes. Four, plus one in the front above the other 4. My 18E actually has four, and my 40C has 6. They are all very evident. <br /><br />While I've didn't have any seperation problems on either of the nissans, I have had issues with other small outboards. I have put a piece of 2x4 against the top of the anti-cavitation plate and used a hammer against the 2x4 for additional encouragement.<br /><br />You stated that the shift rod roll pin was completly removed, so that can't be it. I have been known to leave it partially in, and not clear of the rod. <br /><br />Was there allot of corrosion around the 4 bolts? Was this a saltwater engine?

 

[DanDVM]

Re: 15B2 lower unit frozen

Clymer manual mentions the use of heat at the joint if all else fails. I've never tried it. In the case of my frozen on lower unit, the problem turned out to be corrosion on the driveshaft splines, necessitating powerhead removal. In that case,however, even though the lower unit could not be removed, you could see the joint open up just a little when bolts were removed and could wiggle the lower unit slightly. That also would be the case, I think, if the shift rod were stuck. Sounds like the lower unit may be heavily corroded in place.

 

[FDS]

Re: 15B2 lower unit frozen

JohnS: There is a bolt in front in the gearcase, but my service manual shows it (the head of it) in front of the water pump, after the lower is seperated foom the driveshaft housing. I don't know what the blot is used for/holds together. The shift rod roll pin is completly removed and the shift rod is free of it's upper section. Turthfully, I haven't even tried to see if I could even put a socket on it's head. The four bolts/studs that are protruding from the driveshaft housing,thru the gearcase flange do seem to have corrosion on them where they come out of the metal. I have been trying to pick around their threads with the point of an Exacto knife with hopes that the PB Blaster will be able to seep in.<br /><br />Don 5: I think I'll hold off on using heat on the joint. I don't want to ruin the seals and paint.(the troubles I have with stuck parts, and I'm worried about a little paint ?).<br /><br />Well I sprayed, tapped and pounded today, so I'll let it soak in for another day. There's always tomorrow.<br /><br />Thanks everyone

 

[John_S]

Re: 15B2 lower unit frozen

SDF,<br /><br />If you are referring to the front bolt, just ahead of the shift rod, in this picture: <br />

<br />It is not holding the unit.<br /><br />If you are refering to an external bolt, near the shift rod, then it is probably holding the unit on. I thought the 18 had the same lower unit as 10 and 15hp. From the next picture, you see, I only have four bolts. (well, you see 2 of 4)<br />

<br /><br />Well, after cropping and downsizing, the detail is getting lost! <br /><br />PS: While, I instictly think torch, with appling heat, try a hair dryer or heat gun. Maybe a couple heating/cooling cycles will be enough. <br /><br />While I agree with the post above, that I would expect to get a small seperation of the lower unit, even if drive shaft stuck in powerhead, it might still be the issue.<br /><br />Picture of waiting too long to replace pump:<br />

<br /><br />That was a hold you hand on the power head, and idle all the way home day!

 

[FDS]

Re: 15B2 lower unit frozen

JOHN S: Your pictures are worth a thousand words, they are great. Picture #1 refers to the bolt that I was talking about yesterday. I should not have to remove that one.<br />The two (2) bolts in picture #2 secure the lower mount bracket. It was this bracket that I removed so I could peek into the driveshaft housing and spray PB Blaster onto the driveshaft. I just hope that there isn't a seal on the bottom of the driveshaft guard pipe.<br />These pictures give me the confidance that there are no more bolts holding the gearcase to the driveshaft housing. Now all I have to worry about is corrosion that may be in one of two areas. If it was seized only at the driveshaft splines, I would think that there would be a little play at the gearcase flange. Meanwhile, today I'm going to spray and tap and spray and tap. I've got more patience than gearcase housings.<br />Thanks for the pictures. That sure looks like my gearcase.

 

[granpafish]

Re: 15B2 lower unit frozen

Frank, You certainly have the patience to get this done without destroying the lower unit. I'll bet that most of us (that includes me) would probably have moved on to the "get a bigger hammer" solution by now. Do you know if that lower unit has ever been removed? I know of a number of engines that old that have never had the impeller changed. If that be the case, then the corrosion would probably be such that "tap and spray" is the only way to do it on your own without doing damage. I also agree that it is time to add the heat to the equation. Keep us posted. Granpa

 

[FDS]

Re: 15B2 lower unit frozen

Grandpafish: No, I'm not ready to put the torch to it. I'm still worried about burning the seals.<br />Well, after five days of having the OB upside-down,spraying PB Blaster down the driveshaft and onto the flange area, today I laid it on it's side and let the PB Blaster run down to the inside edges of the flange. Then turned it over to wet the other side. Later, I mounted the OB right side up and pounded down on the rear of the (skeg?). FINALLY, I noticed a slight gap (not quite enough to slid in a box cutter blade, but definitely and opening) in the last 3-4 inches of the flange area. Now my problem is I don't have anything to pound down at the front of the flange. Tomorrow I'll start to cut two pieces of 2"X4" About 20 inches long and cut sections out of them so them conform to the sides of the gearcase, just below the flange. then I'll bolt them together tightly so they will have a grip on the metal. that way I'll have something to pound on at the front of the gearcase. Wish me luck

 

[granpafish]

Re: 15B2 lower unit frozen

Frank, We're about to enter our 3rd week of this intrigue. It's better than a Tom Clancy novel. I'm ready for the next chapter. Can't sleep. Of course, I have no life. Granpa

 

[FDS]

Re: 15B2 lower unit frozen

I didn't get anything done Saturday because my fishing buddy dragged me off to fish salmon on the Columbia River couldn't refuse him. No fish. but we tried. <br />I trimmed two 2"X4"s and bolted them on the sides of the gearcase nice and tight. With the motor mounted on the boat and a 2"X6" set under the motor mount to ground (to keep the boat trailer tires from absorbing the shock of the blows), I pounded on the front end of the 2"X4"s and nothing happened. I pounded on the back end and it opened about enough to slide in a boxcutter blade. I didn't dare pound on the back end any more for fear of breaking it. So I got my 200 LB fishing buddy to stand on the back part while I pounded of the front end. No luck. One problem is, because of the mount, there is less than a foot of vertical space to pound down onto the front end.<br />Now don't anyone tell me to use a bigger hammer because I am using an 8 LB sledgehammer. <br />I don't know what to do next. Tip it upside-down and spray again, then pound some more? It's got a tube that covers the top half of the driveshaft so I can't apply heat to the splines where goes into the crankshaft.<br />Does anyone have any new ideas?

 

[TOHATSU GURU]

Re: 15B2 lower unit frozen

When you have done everything that has been suggested let me know.

 

[fishon71]

Re: 15B2 lower unit frozen

Heat the studs till they are red, then wack it again!

 

[FDS]

Re: 15B2 lower unit frozen

Well, I finally got it off. It was frozen on the studs just like Fishon71's Nissan. It wasn't frozen on the driveshaft splines. And if I would have taken Alvin's advice and pulled the engine, I would found that out weeks ago, which would have pointed me to the studs.<br />I didn't think my butane torch would be big enough to do the job with all that aluminum to absorb the heat, but that and a whole lot of pounding on the wooden brace that I made (see picture) finally did the job. <br />I wish to thank everyone that for all the advice that they gave me and I'm sorry for not using some of it sooner. Perhaps, someone out there with the same problem will also benefit from this thread. <br />