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Tohatsu / Nissan 9.8 water pump replacement

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Initially Posted - 09/01/2012 : 23:59:59

There are instructions several posts below if you're looking to replace your impeller.

I replaced the impeller on the Tohatsu this evening with the help of a friend. No problems getting the drive leg separated, and replacing the various bits & pieces for the impeller, cup, etc. However, try as we might, we could not get the drive shaft back into the leg. We could get it as far as about 2" apart, but there's a solid clunk if we try to get it any further. I think the problem lies in the shifter cam rod. The prop is in reverse (I can turn it in reverse and the shaft spins, if I turn it forward, the shaft seems to ratchet and doesn't spin). If I have the shifter (on the drive head) in forward, I can get the assemblies about 1" apart from mating up, and if it's in reverse, about 2" apart. I think the propeller needs to be in forward, but I have no idea how to shift it there manually. I could also be totally wrong, but we worked at this for well over two hours before admitting defeat.

Two things to consider, we were working with the engine tilted all the way up (which meant we spilled a bunch of gear oil that I'll have to replace). I don't know if that makes any difference or not. And the OB was in reverse when we started, or at least it's in reverse now.

Anyone who's done this, please chime in and tell me how to get the drive shaft mated back up with the power head.

I've searched Youtube for videos on it and haven't found one, I can't find a repair manual online, I'm sure it's something simple, but we couldn't figure it out this evening and we'd really like to go crabbing/sailing tomorrow.

Thanks for any help you can offer!

David
C-250 Mainsheet Editor

Sirius Lepak
1997 C-250 WK TR #271 --Seattle area Port Captain --

Edited by - delliottg on 09/02/2012 22:10:56

islander
Master Marine Consultant

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Response Posted - 09/02/2012 : 05:58:14

Dave, With out seeing what you are doing I can only guess as to the problem but when you get to that clunk part sometimes you need to rotate the drive shaft some by turning the prop in order for the splines on the shaft to slide into the base of the engine. You also have to make sure the water tube is lined up so it will slide in. You can shift the lower unit by pulling up or down on the shift rod assuming that you disconnected the shift rod at the barrel bolt.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/02/2012 : 07:42:28

Thanks, but there's only an inch or so of spline, and I don't think it's quite to the point of engagement. Does the shifter rod have to be disconnected for the leg to go back together? We didn't have any drifts or punches so we couldn't have separated it anyway.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/02/2012 : 10:48:29

So my specific question is, does the lower shifter rod need to be disconnected from the upper one. Here's a link to the diagrams: [url="http://tohatsu-nissan-parts.com/Parts%20Catalogs/TOHATSU/4-Stroke%20&%20TLDI/Parts%20Catalog%20MFS8A3-9.8A3%20(2006)%20-%20(00221051-2).pdf"]Tohatsu/Nissan 9.8 parts listing[/url] and my question is (all references are on ppgs 41-42), does part 16-19 (shift rod) have to be disconnected from part 16-3 (cam rod) via parts 16-20 & 21 (shift rod joint & pins)? If so, that'll make it a lot easier to get the cam back into the gear case (I think), but more difficult to thread all the pieces back up through the drive leg (shift rod, drive shaft, and water tube).

Does anyone have a copy of the shop manual they'd be willing to scan the pertinent page(s) from & send to me?

Reading about this online led me to believe it was a 15-20 minute job but we've already got close to 5 man hours into it and the gear case & propeller are sitting in the cabin of the boat right now with a trash bag wrapped around the drive leg. Very frustrating.

Edit: So at least according to [url="http://www.youtube.com/watch?v=n68sb7w-3Hw&feature=player_embedded"]this video from Jamestown Distributors[/url], you do disconnect the shifter rod, but that's for a Yamaha 25 HP OB, but most everything looks similar.

Edited by - delliottg on 09/02/2012 11:23:28

DaveR
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2015 Posts

Response Posted - 09/02/2012 : 15:55:07

Here's a good [url="http://www.tohatsuoutboardparts.com/Parts-Catalogs/Parts%20Catalog%20M8B-9.8B%20%20%282003%29%20-%20%2800221030-5%29.pdf"]parts diagram[/url] that might help you out.

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delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/02/2012 : 19:25:38

Got it fixed! What a relief! I'll write up the whole procedure when I'm not typing on a tiny screen, but I think the whole thing could be easily done in half an hour now that I know how.

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delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/02/2012 : 22:09:12

OK, back home waiting to grill some rib eyes in celebration. I still think this whole job could be done in less than 45 minutes. All parts references below refer to this link: [url="http://tohatsu-nissan-parts.com/Parts%20Catalogs/TOHATSU/4-Stroke%20&%20TLDI/Parts%20Catalog%20MFS8A3-9.8A3%20(2006)%20-%20(00221051-2).pdf"]Tohatsu Parts Listing[/url].

Here's what you'll need:
Rebuild kit for your water pump
Grease (we used anti sieze compound)
A set of drift pins or punches
Mallet
10mm box end wrench (or as my Brit helper called it, a "ring spanner").
A 10mm ratchet, extension & wobble joint would be helpful, but not necessary.
Needle nosed vise grips
Regular vise grips
Screw driver or steel spatula/scraper (to open the gap between the drive leg and to scrape gaskets)
Duct tape or zip ties

Procedure:
This is probably best done with the engine tilted down, but we did it with it completely tilted up, which actually made some things easier.

Break the shift rod / cam rod joint (parts 16-19 & 16-3 respectively). For this you'll need the mallet, a drift or punch to drive the roll pin out of the connector (parts 16-20 & 21 respectively), and a pair of vise grips to hold it on the other side when you're driving the pin out (and then again when you're driving it in). Clamp the vise grips on the side of the cam rod away from where you'll be driving the pin out, and have a holder steady the cam rod with them. Before driving the pin out, tape or zip tie the shifter rod (part 16-19) to the upper drive leg. If you don't do this, it's free to drop out of the shifter linkage up inside the cowling. Don't ask me how I know. Drive the lower pin (closest to the propeller) out being careful not to lose it, and put it in a safe place, you're going to need it when you reassemble everything. We didn't realize you had to do this, so instead we unscrewed the keeper for the cam rod from the top of the gear housing (part 15-34). Don't do this, you'll have a mess on your hands as the gear oil is now free to pour out when you try to remove the drive shaft / gear assembly & prop. Trust me.

Break the bolts (parts 14-2) for the lower unit gear case (part 14-1). There are four of them handily labeled 1-4 which is their tightening sequence. Loosen and remove three of the four leaving the forth loose, but still attached so the housing doesn't drop to the ground in the next step. Use the mallet to gently break the seal. Use the screw driver or scraper to work them apart if necessary. These are the four lowest bolts on the shaft, not the four that are in indentations on the 5" extension piece (if you've got an XLS). Once it comes apart, have your helper support the leg while you remove the last bolt, and then slide the entire assembly out. The drive shaft is longer than 2' so expect to have to draw it out quite a way before it's free.

Remove the impeller housing (part 15-20): Remove the four bolts holding down the impeller housing (part 15-25 & 26), and slide it and the impeller (part 15-18) all the way up the shaft. There is a cylindrical key between the impeller and the shaft, make sure you get that as well (part 15-19). There's a replacement key in the kit in case you lose the original. There will be two gaskets, and a wear plate that you'll be replacing along with the impeller (parts 15-22, 23, & 24). Clean the old gaskets off of the housing and the gear housing. Remove the old cup (part 15-21) from the impeller housing along with the old impeller and any bits that might be impacted in the water tube passages (we didn't find any, but YMMV). Insert the new cup into the housing and make sure it's seated as close to flush as you can get it. Mine stood proud by about 1/64 or so, but the two gaskets & wear plate made up for that. Slide the gaskets & wear plate down the shaft making sure they go on in the right order (gasket with gallery cut outs (15-24), wear plate (15-22), gasket with water pump cut outs (15-23)). Put a little grease on the flat where the key sits, and stick the key to it, then slide the new impeller down the shaft. Line up the key way in the impeller (it's opposite one of the vanes, so pretty easy to do), then slide it over the key and seat it all the way down. Now slide the housing down to the top of the impeller. The drive shaft always rotates clockwise, so you need to get the impeller vanes bent in the right direction. I put a little bit of gear oil inside the cup to make it easier to slide the housing on. Slowly rotate the drive shaft clockwise as you slide the cup over the impeller. It should go on pretty easily, at least in my experience. Once down & seated, tighten up the four retaining screws for the housing and you're done with changing the pump.

Reassembly: Smear a little grease on the splines at the top of the driveshaft (15-1), careful not to get any on the top of the shaft itself. I'm not sure why, but everything I read said not to do it, so, don't. Also smear a little on the shaft about five inches up from the impeller housing where there's a guide bearing (you'll see the wear marks). Now line up the shaft with the hole in the drive leg and slide it in past the guide bearing. You'll have to fiddle with the cam shaft rod a bit, but it's pretty easy to get it through it's hole on the front side of the drive leg, then continue to slide it up. The water tube should just slip right onto the pump housing and the leg should mate right up. Famous last words, this is what hung us up for so long last night, but it was because we hadn't broken the shifter rod joint. Get the four bolts in and snug but not torqued yet. Reconnect the shifter rod with the cam rod. This may take a little fiddling, but not too much. Again, be careful with the shifter rod, it's just hanging on by a "L" inside the engine and it's kind of a pain to get back together if it falls out (trust me). Reverse the procedure for driving the pins out and your linkage should be ready to go. Make sure you can shift properly. Now go back and tighten up the four bolts using the sequence embossed in the drive leg for 1-4.

You're done!

I also removed my prop and put anti-sieze grease on the spline. There was a bit of galvanic corrosion going on so getting some grease on there seemed like a good idea. I also checked the bolts holding the gear housing together.

This might be a good time to drain & refill your gear case. I simply topped mine off since I'd lost some through the cam rod hole by stupidly removing the seal & retaining plug. Don't do that.

Hope this helps a future Tohatsu / Nissan 9.8 owner.

Edited by - delliottg on 09/28/2012 10:05:37

islander
Master Marine Consultant

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Response Posted - 09/03/2012 : 06:09:25

Congrats on gettin er done! I didn't follow up on my earlier advise because I never worked on a Tahatsu before and obviously the shift rod comes apart differently than most engines. Not knowing this I didn't want to add to the confusion. The reason for not putting grease on the top of the spline is that when you slide the spline into the bottom of the engine (It's cup shaped), The grease won't squish out preventing the spline from fully seating, Sorta like a Hydro-lock.

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delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/03/2012 : 15:52:24

Thanks, I appreciated the help.

And here's the end result:

It took it a second to prime the pump and water was piddling out like before, then all of a sudden it started going great!

I meant to take pictures of the whole process, but kinda needed both hands for what I was doing, plus Rita's help, and didn't really want to pick up the phone with greasy hands, so you'll have to live with my descriptions.

Edited by - delliottg on 09/03/2012 15:53:26

britinusa
Web Editor

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Response Posted - 09/28/2012 : 20:21:49

David, did you install the remote controls for the engine or were they part of the original purchase?

paul

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delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/28/2012 : 22:06:36

I installed them myself, it wasn't too difficult.

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britinusa
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Response Posted - 09/28/2012 : 22:15:46

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg
 I installed them myself, it wasn't too difficult.
<hr height="1" noshade id="quote"></blockquote id="quote">

Mo Pics! The riskiest time when docking is when the helm has to lean over to change OB fwd/rev/neutral. Do the controls really make a difference?
(new thread?)
Paul

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delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 09/29/2012 : 15:11:55

Agreed, I'd hate to have to lean over the stern to adjust my gear & throttle while coming into my slip. With mine mounted directly on my tiller it's easy to adjust on the fly as I come in or go out. I probably make a dozen or more gear changes on the way in depending on the current, tide & wind. If I'm lucky, it's an incoming tide with a NWly wind, then I'm golden, easy to get in. Worst seems to be a Nly wind on an outgoing tide. The tide's pushing me downstream while the wind's pushing me almost exactly opposite. Makes it really-really interesting when I make my turn to starboard into (hopefully) my slip. I've blown my turn twice this season. Neither were disastrous, but both made for rapid heart rate & high blood pressure while sorting it out (and being carried sideways or backwards downriver toward the closed end of the fairway).

Have you watched Rick (TakeFive's) video of his wife & him working the wheel, throttle & gears in concert while crabbing into their slip? She's kneeled down over the top of the OB while they back into their slip, making all the gear, throttle and tiller changes while he drives. Pretty impressive to watch.

I'll take more pictures when I get down to the boat next (maybe tomorrow afternoon after the game). I know you have a wheel so it's not going to directly apply to your boat, but running & attaching the Morse cables really wasn't that hard, it's all snap in stuff, had to replace the standard choke knob with one provided by the kit, as well as the thick rubber gasket it goes through with the cables. Then remove the external shifter & replace it with the provided connector to the shifter assembly, same with throttle. Probably less than an hour to do if I remember correctly. Actually one of the easier mods I've made to the boat. It seems like I wrote it up, but I couldn't find any photos on my old Shutterfly account, so maybe not. I'll look shortly.

Found it: [urlhttp://www.catalina-capri-25s.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=17890&SearchTerms=power,tiller]Here's the thread[/url].

Edited by - delliottg on 09/29/2012 15:16:56

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