Tohatsu 9.8 raw water problem

Hi folks! Hope everyone is doing well. Here is my problem:

Pulled lower unit to replace raw water impeller.

When re attaching lower unit the water tube fell out. I stuck it back up in there, but couldn't tell if it was fit properly. Then I re aligned the shaft, the shift shaft and the water tube, and screwed the lower unit back on. The first one I did, (I have two) the water tube stayed attached to the head when I dropped the lower unit. It runs fine.

When I started it back up, nothing came out the pee hole. This is about normal, since I often have to stick a piece of monofilament or something in there to get it to come out. The pump appeared to be working, since there was water coming out of a few places on the lower unit. This also is normal, but this time there was much more water coming out the forward part of the lower unit a few inches above the waterline. Finally a trickle came out the pee hole, very hot, I put it in gear and throttled up at the dock still not much water and hot. I figured the thermostat should have kicked in by now. There was some steam but not a lot. I went ahead and shut it down.

When I pulled the thermostat cover, the gallery was bone dry.

OK I figure I mis aligned the water tube when I put it back together. My question is did I do any damage to anything else by pushing raw water up there around the head? Is it better to fit the tube to the pump housing first and then stick the shafts back up in there, or better to try and get the tube fitted right up there first and then fit the lower unit?

It is a real pain to do this job on my boat. I have a swim platform to work off of, but you still can't see up in there. plus its freezin *** cold ( about 45 deg F). The only alternative is to take the whole motor off- an even much bigger pain, as I am in a remote location.

I would appreciate any observations suggestions etc. THAnks
Charly

 

Hi Charly,

I'll guess this is about the water tube #31, right ?

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Others do it like you did with the first one, they let the water tube #31 and the top rubber gasket #32 stay attached in its top mounting.

The below vid shows a Tohatsu 8 Hp 2-stroke, but the order of work for the impeller replacement is the same as on your 9.8 Hp 4-stroke.

For the handling of water tube #31 and the lower rubber gasket #33 best check the vid from 17 min 11 sec* and further.

( P.S. * it looks a bit clumsy there, but the guy is partly working with one hand, while the other hand holds the cam every now and then to give us a better view. )

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And below a Nissan 9.8 B, where the order of work for the impeller replacement is also the same as on your motor.

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Best check the handling of the water tube #31 and the lower rubber gasket #33 in this vid from 9 min 33 sec and further.

Don't worry about your engine, since that won't help, just redo the water tube #31, and the top rubber gasket #32, and the bottom rubber gasket #33, and see how it runs then, and act further from there.

Below a related thread, where I've got the exploded view drawing and the first vid from...

Sailboat Owners ---> Tohatsu 9.8 O/B - Impeller change​

Good luck !

 

Its tricky friend. When possible, put the tube up in first and get a feel for it going right. Then do the rest. You probably smashed the upper gasket into the hole. If you don’t hit the hole mighty easy n right; you need to make sure the gasket doesn’t get fouled on the end and close off. It is blind work-not my favorite at all. Then if the tube drops; you need a super light touch or a redo.

Never run over 30 seconds if it isn’t running some water out the sight. My motor will get cottonwood in it or spiny water flea bits, but always pumps a bit even clogged. After a pump change; be smart about fast shutdowns when things aren’t right. The lower gasket is probably okay; otherwise the other poster gave you lots of good tips. If you can get a helper if the tube wants to fall out; it can work better.

 

The upper rubber bushing (32) can get "walleyed" out with heat and time or by simply getting smashed out of alignment for a while, distorting it. The usual repair is to replace both bushings (31, 33) I think 33 is plastic, not rubber and often comes with a complete pump rebuild kit. To prevent this from occurring again, use a thin smear of polyurethane on the upper bushing as you seat the bushing and slide in the water tube, insuring it doesn't ooze over the edge, partly blocking the passage. Let this dry, before reassembly. It'll now stay in place during subsequent leg removal tasks.

 

Yikes. Thanks for the replies. I am going to disassemble again today and try to inspect the thing. Can you see the upper bushing by looking up from the bottom with the lower unit out? This xl shaft. Could I use a coat hanger or something if I have to pull it back down a ways to get a proper seat? Should I put some lubricant on the tube to get it to go in good and nice? What kind of lubricant?

 

If you don’t want to use the poly idea, which I like, but have not done; try spitshine.

 

I googled that and came up with shoe polish or did you mean just to spit on it first lol. The polyurethane Par mentioned. Do you mean caulk? Really feeling like a dumb *** now. I went ahead and ordered a new upper bushing this a.m. If I have to install that, I assume I would fix it to the end of the tube, and poke the whole thing up there, after spitting on it

Oh and how to get the old one out?

 

Yup. Spit is a good lube in the bush. You trying to get me banned?

Cross those bridges when you get there. I think the bushing will fall out.

Or the tube might not have hit the hole even; lots of ifs.

 

That's is a major tip for every test run, no water means no cooling, so that's not good, since a block with no water in it is soon locally overheated.

Check out the water problem first before further testing.

The max 30 seconds test run with no peeing can be repeated if needed, but only after a sufficient cooling down period.

That 7 °C temp might have saved your engine, so winter is your friend here . .

 

The engine isn't in any serious trouble with short no water situations, mostly because aluminum has very good thermal dynamics. It's the impeller that's going to cook in anything more than short duration dry runs. It doesn't take very long for the impeller to heat up the stainless pump chamber, which will "spin" in it's bore, ruining the impeller, chamber liner and the pump body too.

 

Looks like the misalignment was at the pump end. It is running fine now and pumping. Lesson here is to be very careful on re-assembly, making sure shift shaft, water tube and shaft all align perfectly and simultaneously, and that you don't drop any bolts or pins anywhere, especially down into the lower unit housing or you will be Very sorry. I guess the geyser coming out of the pump and splashing up into the bottom of the head didn't get salt anywhere it shouldn't be.