Would You Buy Another Tohatsu??

[Chotu]

My 5 year old Tohatsu MFs 8 outboard has been just awful to me.

It was overheating because the thermostat went. Finally got that squared away and running well, now a month later, there is water in the oil!!

Today, I couldn’t get the pull start going. Seemed seized.

I rotated it by turning the prop by hand and then it started being able to be pulled by the pull start.

Pulled it hundreds of times since it sometimes requires that after sitting in the davits.

Some hydrocarbon droplets were seen in the water, but I figured it might have been a carb overflow from tipping the motor.

After getting too tired from pulling and having it only attempt to start a couple times out of the hundred or so pulls, I decided to check the oil.

The oil spurted out the dipstick hole and overflowed. It was not normal color. Not super milky but a bit milky. Like caramel.

I had been running with no thermostat waiting for one to come in. I have it now and it’s on my to do list. But, now water is getting into the oil.

What the heck is going on with this thing???

Should I cut my losses and get a new outboard? Get it professionally repaired?

Would you buy another tohatsu after this?

[Orion Jim]

I had a 3.5 for my dinghy. Worst engine ever. I bought a Honda and it runs just as reliably as the old Mercs and Elgines I had as kickers since the early sixties. They can blame the new fuel but some manufacturers have managed to design reliable engines which burn this stuff, and some haven’t.

[Dockhead]

Originally Posted by Orion Jim

I had a 3.5 for my dinghy. Worst engine ever. I bought a Honda and it runs just as reliably as the old Mercs and Elgines I had as kickers since the early sixties. They can blame the new fuel but some manufacturers have managed to design reliable engines which burn this stuff, and some haven’t.

I have the 3.5 (branded Mercury). It stopped running due to deteriorated gasohol fuel. But I'm not sure why these would be more vulnerable to that than any other small 4 stroke. I have switched to naphtha based "engineered" fuel and so far no further problems.



It's a cheaply made engine but it was cheap to buy. I haven't yet concluded that it's not a decent engine, but we'll see.

[dwedeking2]

Originally Posted by Dockhead

I have the 3.5 (branded Mercury). It stopped running due to deteriorated gasohol fuel. But I'm not sure why these would be more vulnerable to that than any other small 4 stroke. I have switched to naphtha based "engineered" fuel and so far no further problems.



It's a cheaply made engine but it was cheap to buy. I haven't yet concluded that it's not a decent engine, but we'll see.

My theory is that the smaller jets in the carb clogged up faster with fuel issues. I've upgraded to the 6 hp and don't seem to have nearly the problems I had with the 3.5.

[rslifkin]

Yes, smaller carbs are more sensitive to junk getting in them. And smaller engines tend to be cheaper, which often leads to them having poorly designed, cheaply made carbs as well.

[Dockhead]

Originally Posted by dwedeking2

My theory is that the smaller jets in the carb clogged up faster with fuel issues. I've upgraded to the 6 hp and don't seem to have nearly the problems I had with the 3.5.

That sounds logical. So I'm using "engineered fuel" in the small motor.


I like the 3.5 not only because it's cheaper, but especially because it is just about the heaviest outboard I can easily manhandle all over and around the yacht. 6hp would still not be enough power to make my 3.1m RIB plane, but is much heavier, and I would need to handle it with tackle from the boom, like I used to handle my old 8hp Selva, which is a PITA.

[Lake-Effect]

Aren't Tohatsu the makers of small outboards for many 'major' brands?

I've heard horror stories about just about every brand of 4-stroke outboard, including Honda's, so it's maybe just the case that they're all fussy. It's also possible that the OP just ended up with a lemon.

We have a 1983 Suzuki 5 hp 2-stroke that is still first-pull reliable, but it still took me a couple of years to learn its quirks, and to baby it with fresh ethanol-free gas.

[Dockhead]

Originally Posted by Lake-Effect

. . I've heard horror stories about just about every brand of 4-stroke outboard, including Honda's, so it's maybe just the case that they're all fussy. It's also possible that the OP just ended up with a lemon.. .

Yeah, I've heard the same.

AFAIK, all 4 strokes under 5 or 6hp are extremely vulnerable to jet clogging.

That doesn't prove that the Tohatsu 3.5 is a good engine! It may not be. But jet clogging alone doesn't prove that it's a bad engine, at least based on what I know about the phenomenon.

I had the same issue exactly with a 1kW Honda suitcase generator, which I think is universally respected as a good unit.

[thomm225]

Originally Posted by dwedeking2

My theory is that the smaller jets in the carb clogged up faster with fuel issues. I've upgraded to the 6 hp and don't seem to have nearly the problems I had with the 3.5.

The 4, 5, 6 HP 4 strokes seem to do better than the smaller engines because of the above info I believe.

I bought my Mercury (Tohatsu) 5 hp 4 stroke new in 2011. I have used nothing but 10% Ethanol in it.

I treat the fuel with Stabil in October each Fall and then burn off the left over fuel/gas over the Winter and the following Spring.

No problems so far except one over heat issue because I didn't change the impeller for 3 years

This little engine is my main auxiliary on my 6600 lb displacement Bristol 27.

Also I'm pretty good with small engines since my first job at 10-12 years old was cutting grass for $2.00 -$3.00/yard. You learn pretty fast about what it takes to make a small 4 stroke run......

[sailorboy1]

Originally Posted by Chotu

Should I cut my losses and get a new outboard? Get it professionally repaired?

Would you buy another tohatsu after this?

Whether you should fix or replace depends on the cost of the repair. I would find that out first.

My last outboard was a 6 HP Tohatsu and I had it around 6 years. It would run and start fine, except when it wouldn't and one time I torn something in my shoulder trying to get it started. But every problem it had was due to gas problems and I finally figured out that water was getting into the pour spout of the jerry can. After the shoulder problem I took apart (again) the carb and after made sure no water was getting into the jerry can and it never had an issue for a year. Then I decided to get a bigger one, and an electric start one on top so my shoulder got a break, and replace it with a 9.8HP Tohatsu.

So I would and did replace my Tohatsu with another.

[geoleo]

Originally Posted by Chotu

My 5 year old Tohatsu MFs 8 outboard has been just awful to me.

It was overheating because the thermostat went. Finally got that squared away and running well, now a month later, there is water in the oil!!

Today, I couldn’t get the pull start going. Seemed seized.

I rotated it by turning the prop by hand and then it started being able to be pulled by the pull start.

Pulled it hundreds of times since it sometimes requires that after sitting in the davits.

Some hydrocarbon droplets were seen in the water, but I figured it might have been a carb overflow from tipping the motor.

After getting too tired from pulling and having it only attempt to start a couple times out of the hundred or so pulls, I decided to check the oil.

The oil spurted out the dipstick hole and overflowed. It was not normal color. Not super milky but a bit milky. Like caramel.

I had been running with no thermostat waiting for one to come in. I have it now and it’s on my to do list. But, now water is getting into the oil.

What the heck is going on with this thing???

Should I cut my losses and get a new outboard? Get it professionally repaired?

Would you buy another tohatsu after this?

IMHO TOHATSU is the best OB there is.

[Mike OReilly]

Another satisfied 3.5 hp Tohatsu owner here. Been using it on my dinghy for going on seven-eight years. Sees very light use since I'm a 1/2 season cruiser, and tend not to dinghy far. But it's never let me down.

I am careful to run the carb dry when ever I expect it to sit any length of time. At the end of the season I run the tank completely dry. Never a problem (so far).

[ontherocks83]

I have a 2003 6hp Nissan (which is a Tohatsu with a Nissan sticker on it) It runs amazing and has been very reliable. The only thing I do besides regular maintenance, is I put twice the recommended amount of Stabil in at every fill up.

I started doing this years ago with every gas powered thing I own (except cars). I had a chain saw gum up after 2 months with untreated fuel. Now that I treat the fuel I've used almost 2 year old gas in my lawn equipment (2 and 4 stroke) without any issues.

Also since using stabil I never run my carb "dry" since there is always residual fuel left in it anyways. I have never found that I needed to. And as a disclaimer I do not work for stabil I just think it is an amazing product and recommend it to everyone.

[Chotu]

I think I just got a lemon, then.

This thing, though 5 years old, probably has 20-30 hours on it, max.

To have a thermostat go bad, causing the thing to overheat (and seize), now to have seawater getting into the oil is just an awful lot of problems to be having on a brand new (5 years ago) outboard I bought for reliability.

I had an old tohatsu 6hp many years ago that ran flawlessly and went with a boat I sold.

I have had no carb problems or fuel problems with this current outboard. The hard start is only when it’s on the dinghy and on the davits and the dinghy is angled bow up so water doesn’t accumulate in the dinghy.

In that case, it is very hard to start and blows a bunch of oil by when it finally does start.

All in all I’m pretty disappointed in an outboard brand I bought because I’d had good luck with them in the past.

I had an awful time with a Similar size Honda 4 stroke too. That’s why I went tohatsu this time.

The Honda wouldn’t idle from the factory brand new, had lots of trouble starting, etc.

I guess I’ll just fix this tohatsu (again) but I have a lot going on. I tried paying my way into reliability buying a brand new outboard. It didn’t work.

[Chotu]

On a side note:

What are the possible ways water can get into the lube oil?

Just from the cooling galleries, right? Has to be a cracked head?

Is this maybe because I ran with no thermostat?

Theory: Motor starts and runs great. I get to the dock for a 5 minute stop after a 2 mile ride. I shut off the motor at the dock. It sits for 5 mins actually getting hotter than if there was cooling water flowing. I then start the motor and take off, introducing ice cold cooling water into the cooling galleries. This cracks the head somewhere to let cooling water into the oil.

HOWEVER... why was the oil/water in the crankcase so pressurized, it sprayed out at me pulling the dipstick?