Tohatsu 3.5hp - No tell tale

[Polarsailor]

Hello there

I have an about 15 year old Tohatsu 3.5hp 2-stroke outboard. The tell tale has stopped working. I have checked the pipe and nipple where the pipe attaches to the block and they are clear. You can blow through the engine (with the gearbox off) but it does feel a bit restricted. I have dropped the gearbox off and changed the impeller which was intact but quite deformed. Still no tell tale. Before I completely strip the engine and attempt to clean the waterways which I presume are blocked with salt/corrosion has anyone got any suggestions?

I have no idea where the waterways run so a workshop manual, or schematic would be very useful if anyone has one. I presume the water ways are primarily in the block.

Any advice gratefully received!

 

[jamie N]

Umhh? I'd the same issue with mine, and did take the engine head off and clean the block which was completely congested with all sorts of shite. It only took a few minutes, and was quite easy and satisfying. The whole operation was less than an hour, and worked. Of course yours might be a different problem but it wasn't a big deal to do.
Good luck.

 

[Bobc]

When mine stopped, I would stick an airline up it. Always seemed to clear it.

 

[jamie N]

OP says "I have checked the pipe and nipple where the pipe attaches to the block and they are clear. You can blow through the engine (with the gearbox off)".
I agree though, that was my 1st thought through experience also!

 

[BobnLesley]

I submit this proposal as you advise it's a 15 year old Tohatsu 3.5hp 2-stroke outboard and we cured (without damage) a 14 year old Mercury suffering from the same problem; I probably wouldn't offer it up for a relatively new/valuable engine. Ours had been providing a poor flow for a couple of years and finally given up completely, so:
We stood the engine in a bucket filled with a strong muriatic/hydrochloric acid solution and ran it for 10/12 minutes, by when the tell tale was once more flowing freely, then into another bucket for a ten minute fresh water flush. We'd been warned of the untold damage this would do to the engine's aluminium castings and gaskets, but as we'd bought a new motor anyway and I didn't have the time/inclination to strip it down, I felt we'd nothing much to lose - I suspected that I'd shear just one or more bolts if I tried.
We did that back in 2017 and continued using the engine as a spare and occasionally paired with the replacement Nissan for another three years until we passed it on to someone whose need was greater than ours; the last I heard (Aug 23) that Mercury is still running happily.

 

[QBhoy]

Check the seal at the water pipe from impeller up to head. The one I had, had the same issues. Also had crap blocking the intakes to the pump too.

 

[onesea]

When mine stopped, I would stick an airline up it. Always seemed to clear it.

I used a large syringe on mine then flushed with plenty of fresh water been fine since.

 

[QBhoy]

Vinegar and turning upside down can help. Just don’t leave it in there too long

 

[Grumpydev]

Did you get this sorted? I have recently bought one and have the same issue, nothing/hardly anything coming out of the tell tail, but can pump air through it fine.

Changing the impeller on these looks like a bit of a faff (putting the leg back together anyway) so was hoping to start with easy potential fixes first

 

[Refueler]

Fernox or Rydlyme ... they do Alloy safe versions ......

Or any of the domestic boiler cleaner fluids... (alloy safe version).

 

[Grumpydev]

Fernox or Rydlyme ... they do Alloy safe versions ......

Or any of the domestic boiler cleaner fluids... (alloy safe version).

That's probably what I'd do in the future if it starts to slow, but it's currently picking up barely anything so not sure there will be enough flow for it to really work.

 

[Polarsailor]

Did you get this sorted? I have recently bought one and have the same issue, nothing/hardly anything coming out of the tell tail, but can pump air through it fine.

Changing the impeller on these looks like a bit of a faff (putting the leg back together anyway) so was hoping to start with easy potential fixes first

Hi There

Yes I did. Took the head off and no obvious blocked waterways. Then took leg off and changed the impeller and that sorted it. The impeller was obviously quite distorted with age. Changing it was OK but very fiddly and make sure you don't lose the small stainless pin that locates the impeller on the shaft. Mine is fine now.

 

[Grumpydev]

Hi There

Yes I did. Took the head off and no obvious blocked waterways. Then took leg off and changed the impeller and that sorted it. The impeller was obviously quite distorted with age. Changing it was OK but very fiddly and make sure you don't lose the small stainless pin that locates the impeller on the shaft. Mine is fine now.

Thanks - do you have the service manual or did you just wing it?

Looks like there's two varieties of this 2 stroke engine, one with the impellor behind the prop, the other one (which is the one I have I think) needs dropping the whole bottom leg off by the looks of it.

 

[Polarsailor]

Thanks - do you have the service manual or did you just wing it?

Looks like there's two varieties of this 2 stroke engine, one with the impellor behind the prop, the other one (which is the one I have I think) needs dropping the whole bottom leg off by the looks of it.

Thanks - do you have the service manual or did you just wing it?

Looks like there's two varieties of this 2 stroke engine, one with the impellor behind the prop, the other one (which is the one I have I think) needs dropping the whole bottom leg off by the looks of it.

Just winged it take some pics. My impeller was internally on top of the gearbox so you have to take the leg off. The diff bit is getting the gear linkage, driveshaft and water pipe reconnected. A stiff bit of wire and patience helps….

 

[Grumpydev]

Just winged it take some pics. My impeller was internally on top of the gearbox so you have to take the leg off. The diff bit is getting the gear linkage, driveshaft and water pipe reconnected. A stiff bit of wire and patience helps….

I have one of those things at least..

I've ordered the parts, will change the gear oil while I'm at it - thanks for the info

 

[C08]

Mine gets blocked from time to time and a length of wire usually does the trick. You need to take off the rubber tell tale tube and the wire will go 2 -3" inside the head to clear it. Brilliant engine only spoiled by having to take the cover apart to take off the cowel.

 

[Grumpydev]

Mine was slightly more involved.. the impeller had seen better days, but there was no pin in it (definitely missing, didn't fall out) so wouldn't have been doing anything anyway, the water pipe was disconnected at the bottom, and the rubber grommet at the top was fitted upside-down

Put it all back together this morning and fired it up and we now have a pee stream any fella would be proud of

If anyone is struggling putting them back together it's a piece of cake once you've taken the head off because you can get to both ends and the drive shaft sticks up when you're putting the head back on, and as long as you don't have any liquid gasket causing havoc you will probably be fine reusing the gasket

 

[Grumpydev]

Well that didn't last.. after about 5 minutes use it went from a constant stream of water, to vapour/exhaust gasses to absolutely nothing

Nothing appears to be blocked, I can pump air through the telltale outlet and its not blocked, I can flush it through with the flushing attachment, but nothing appears to go up or down the copper pipe inside the leg, even though its not blocked.