New 6HP Tohatsu burning oil

[MattFL]

I'm looking for guidance on what to do next. I just bought a new 6HP Tohatsu, almost 13 hours on it now, and when I slow down from cruising speed (3/4 to full throttle) I smell the distinct smell of burning 4-stroke oil. It starts easy and runs great. At slower speeds and idle I don't smell anything. Before the first start-up I added an hour meter / tachometer, filled with the recommended oil and followed the 10-hour break-in procedure religiously, but I'm afraid I was too nice to it. After a couple of hours you're allowed to give it 1/2 throttle, then after a couple more you're allowed 3/4 throttle, etc... But for the first 9 hours it was 99% idle or just above idle as we trolled for fish in the local lake. Was I too nice to it during break it? What should I do next?

 

[TOHATSU GURU]

Re: New 6HP Tohatsu burning oil

Too nice. The rings haven't seated. Your probably running 10w-40 too. Drain the oil, switch to 10w-30, only fill it to slightly above the lower hash mark and run it WOT for at least an hour.

 

[MattFL]

Re: New 6HP Tohatsu burning oil

Yes, 10-40 is what the manual recommended for my climate so that's what I put in. I will switch to 10-30 and try to run it harder for a while and see if that helps. the motor has really loosened up during break in, so I hope there is still enough roughness in the cylinder to wear the rings in. Thanks!

 

[MattFL]

Re: New 6HP Tohatsu burning oil

Have you seen this often, and does it typically clear up with a little hard running?

 

[pvanv]

Re: New 6HP Tohatsu burning oil

See it all the time. The oil sump on all 4-stroke OB's run a bit on the cool side, so break-in is slower. Run the lowest viscosity that the weather will allow (10w-30). Make sure it's rated FC-W for corrosion resistance. Fill to 3/4 on the dipstick -- not even a drop above full, and have at the throttle. After warm-up, "Drive it like you stole it" for about 10 more hours, and you should be OK.

 

[Sea Rider]

Re: New 6HP Tohatsu burning oil

If you installed an hour meter and tach and read manual regarding break in period, why didn't you followed manual's break in period sequence ?

Happy Boating

 

[MattFL]

Re: New 6HP Tohatsu burning oil

If you installed an hour meter and tach and read manual regarding break in period, why didn't you followed manual's break in period sequence ?

Happy Boating

I did follow the procedure, perfectly. Please note that the procedure indicates maximum allowed throttle openings, but says nothing about minimums. I spent the time fishing with my son, and since the manual said nothing about minimums, I did not expect any problems.

 

[pvanv]

Re: New 6HP Tohatsu burning oil

Still not a problem. Just finish the break-in. Run it hard.

 

[MattFL]

Re: New 6HP Tohatsu burning oil

Thank you much for the replies, I will take your advice and run it hard as much as I can. Second question; my 7 yr old son loves to fish, which means slow running with the motor. If I continue to put slow running hours on it, with the occasional couple minutes of hard running here and there, will this prevent the motor from ever breaking in properly? Or will this just result in it taking longer to complete the break-in?

 

[pvanv]

Re: New 6HP Tohatsu burning oil

Likely just a longer break-in, as long as the rings don't get carboned-up and refuse to seat. Unlikely on a 4-stroke.

 

[TOHATSU GURU]

Re: New 6HP Tohatsu burning oil

Four-strokes defy the intuitive logic of being gentle on machinery. Run them hard, RPM is your friend with these things.

 

[pvanv]

Re: New 6HP Tohatsu burning oil

Four-strokes defy the intuitive logic of being gentle on machinery. Run them hard, RPM is your friend with these things.

Yep. Run it like you stole it.

 

[MattFL]

Re: New 6HP Tohatsu burning oil

I guess that makes sense.. you figure they expect most little outboards to spend a significant amount of time at wide open, and I'm sure they take that into account at design time.

 

[MattFL]

Re: New 6HP Tohatsu burning oil

I just wanted to follow up with a conclusion. I've got almost 20 hours on it now. After posting here I ran almost a full internal tank through it at cruising speed (3/4 throttle, somewhere between 5000 and 6000 RPM), then after that just started using it like normal, which means probably 60% trolling at just above idle, and the rest cruising at 3/4 to full throttle. I'm very happy to say that I don't see any more smoke or smell any more burning oil, so you guys were right! I've had several new 4-strokes; boats, motorcycles, cars, yard tools, generators, etc.. and this is the first one that has ever burned enough oil during during break-in to cause visible smoke and smell. There was also oil on the spark plug when I took it out (during break-in). But I'm glad to see that it seems to have broken in nicely. Thanks everyone!

 

[pvanv]

Re: New 6HP Tohatsu burning oil

4-stroke outboard oil sumps are too cool -- at least cooler than ideal, because they are splashed with sea water all the time. Hence the arduous break-in.

Glad it worked out for you...