Inspection and Maintenance on Tohatsu M3.5B2

[daveson]

Hello,
i have a second question about my Tohatsu M3.5B2 engine.
I bought it 6 years ago and use it on my sailboat only very few times. I'd say 15-30 hours per year. But the engine is always at the transom of the boat, from april till october, but tilted up and not touching the water.
During winter it is stored in a shed, dry but cold. When using the motor for the last time each year i'm using it until there is no more gas in it in order to empty the tank. Then i put some engine oil through the spark plug hole and change the gear oil. But thats all i do. Nothing else.

In the manual it says one has to do a lot more maintenance and inspection, some examples:

Every 10 hours or each month: check and clean fuel filter (i don't even know where it is), clean fuel tank (how?), check the spark gap (works fine since 5 years)...

Every 100 hours or 6 months: strip, clean and adjust carburetor (has to be done by the dealer), check water pump (also by dealer), check pipes for damage

Do i have to do these things really? Do i risk damaging the engine when not doing them? Or is this overkill? Which of these tasks are really important? Should i give it to a dealer for maintenance and inspection now after 5-6 years?

Thanks for your help,
daveson

 

[Sea Rider]

Re: Inspection and Maintenance on Tohatsu M3.5B2

If possible flush with plain water after each use, those engines have very small diameter water passages that can be clogged with salt very easily specially in the pee area. Clean small filter located at fuel ****, regap spark plug to 1.0 mm, add some drops of thick oil on the shift lever(where it plays) every 50 hours constant use or at least once a year before winterizing. You should perform these simple maintenances in order for the engine to start well and run as expected.

Other issues like checking impeller or stripping down the carb will be subject to yout tech mechanical skills, if not, buy a service & parts manual or send to a reputed dealer.

Happy Boating

 

[daveson]

Re: Inspection and Maintenance on Tohatsu M3.5B2

Ok, so if i don't want to do the impeller and carburetor check by myself would you recommend giving it to a dealer for inspection now after five years? Or is there no need for it as long as the engine works well?

Thanks
daveson

 

[daveson]

Re: Inspection and Maintenance on Tohatsu M3.5B2

Just spoke to my Tohatsu Dealer. I live in Berlin, Germany, thats why the prices are in Euro. He wants 75 Euro for inspection and replacement (if needed), the costs for the needed parts NOT included. I would end up paying more than 100 Euro for a changed impeller then, which is 140 USD. Thats really too much for that little engine i think.
The repair kit for the water pump costs 32 euro which is 45 USD. I think i will try to change the impeller by myself. Do you think it is possible to do it without the service manual, perhaps with help from this forum and instructions from the internet?

Thanks
daveson

 

[pvanv]

Re: Inspection and Maintenance on Tohatsu M3.5B2

The factory recommends impeller inspection/replacement annually; that is for a worst-case situation in salt and silt. In the Great Lakes, we often get 3 years. But 6 years is definitely pushing it. They dry out over time, even if not used. The kit you want is Part # 3F0873220M $34.75 USD.

The fuel filter is integral with the fuel shutoff valve. If you run really clean gas, keep debris out of the tank, and run it dry before storage, you can get many seasons of service. If clogged too badly, you would replace the entire valve: 309700110M FUEL **** $17.37 USD.

FWIW, shop labor rates vary from location to location. Ours is $75.00 USD per hour, and I might expect an hour to do the full maintenance, including wp kit, fuel ****, carb needle, and general lube. Since a new motor costs about $1,000 USD, that doesn't seem out of line.

If you have basic mechanical skills and some good tools, you can do the wp yourself. The first time will take longer than usual, because of the learning curve. Figure over an hour the first time. After that, it goes pretty quickly. Regardless, it is a good idea to get a copy of the Factory service manual from your dealer, as it explains details that you might otherwise miss. This is especially true if you need to do more than replace the needle in that slide-valve carburetor.

 

[daveson]

Re: Inspection and Maintenance on Tohatsu M3.5B2

Ok, i think i'll try it by myself. Will try to get this service manual.
But quite a difference in costs, my dealer wants 140 USD for this full maintenance you mentioned, without the parts...

 

[old-gubbins]

Re: Inspection and Maintenance on Tohatsu M3.5B2

here is a link to a parts manual, which shows how the outboard is assembled.

http://www.tohatsuargentina.com.ar/t.despiece/2t/2003.2.5hp.3.5Ahp.3.5Bhp.pdf

I don't think you will find a Tohatsu shop manual on line, but most small Mercs are - I think - Tohatsu, so you might find a Merc manual ( I did for a 6.0 hp 4 stroke).

Here is a link, but I don't see your model there, sorry.

http://1manual.com/Mercury manuals/Service_Manual_Index.html

Hope this helps,

O-G

 

[isaksp00]

Re: Inspection and Maintenance on Tohatsu M3.5B2

I changed the pump impeller on my 15 yr old Honda 8HP myself, and I'm not a mechanic - I am fairly practical with tools, though. Get the service manual (one time using it instead of a service shop pays for itself). You have to know what items to disconnect so you can properly remove (or pull down somewhat) the lower unit. Removing the water pump cover and replacing the rubber impeller was straightforward.

 

[pvanv]

Re: Inspection and Maintenance on Tohatsu M3.5B2

The Tohatsu Factory Service Manual is copyrighted, so can't be copied and distributed for free. Be sure to get the Factory manual, as many aftermarket manuals are useless. Maybe the German mechanics get paid more than the US wrenches; either way, should only take an hour or so for a trained tech to do the job. If you do it yourself, it will take longer the first time, but it will give you a level of appreciation and confidence that you can't get by paying a mechanic -- and you will have the manual for any future use.

 

[isaksp00]

Re: Inspection and Maintenance on Tohatsu M3.5B2

Forgot to mention... I also cleaned my carb myself, and cleared some clogged jets. I have no idea what the Tohatsu 3.5 HP carb is like, but I gotta believe they're pretty similar in these small, 4 cycle motors. With the official Honda shop manual, I didn't find it too hard (there are not many parts to these), and the engine did run stably after I put it all back together. If you are somewhat handy, I'd consider it as doable. Same for the fuel pump, if it is a simple diaphragm type, for that matter.

I figure I likely saved myself a few hundred dollars by doing the impeller, the new diaphragm and the carb cleaning myself, even if it likely took me about 4 times as long as a pro.
Peter

 

[Sea Rider]

Re: Inspection and Maintenance on Tohatsu M3.5B2

International Labor Prices :

Europe
USA
South America :

Happy Boating

 

[pvanv]

Re: Inspection and Maintenance on Tohatsu M3.5B2

Forgot to mention... I also cleaned my carb myself, and cleared some clogged jets. I have no idea what the Tohatsu 3.5 HP carb is like, but I gotta believe they're pretty similar in these small, 4 cycle motors. With the official Honda shop manual, I didn't find it too hard (there are not many parts to these), and the engine did run stably after I put it all back together. If you are somewhat handy, I'd consider it as doable. Same for the fuel pump, if it is a simple diaphragm type, for that matter.

I figure I likely saved myself a few hundred dollars by doing the impeller, the new diaphragm and the carb cleaning myself, even if it likely took me about 4 times as long as a pro.
Peter

No fuel pump on that model. Just good ol' gravity.