2006 Tohatsu MFS 8A3 Lots of steam coming out of exhaust relief

[shawnfenwick]

Hello,
I have seen this question before but it was not satisfactorily answered.

I bought a used 2006 4-stroke 8hp longshaft. The motor starts and runs great. The oil is not milky or it's not "making" oil.

When it gets warmed up, in the tank or water, there is quite a bit of steam coming out of the exhaust relief. The telltale stream is really strong, so I don't suspect an impeller.

From the last post that had the same problem, I figured to just change the thermostat, and did that. But the problem still exists.

What this harm the engine?

Thanks to all.

 

[pvanv]

Re: 2006 Tohatsu MFS 8A3 Lots of steam coming out of exhaust relief

Verify the actual temperature with an IR thermometer. You likely didn't have any problem at all. Vapors exiting the idle port is a normal condition, and in cool weather, the exhaust itself will look like "steam".

What is the temperature of the telltale stream? You should be able to hold your finger in the stream. If it's hotter than that, there may be an issue. If the block temperature is above 180, you are overheating. If below, say 150 or 160, you are fine.

 

[dazk14]

Re: 2006 Tohatsu MFS 8A3 Lots of steam coming out of exhaust relief

Shawn,

Got your PM.

I reloaded the original steam machine video prior to repair.

That should now be viewable in my previous thread about a similar situation as you have here,

The mod worked perfectly and the customer is still very happy with the motor.

The 3/32" hole in the fixed portion of the stat was what I used. Head temps stayed in spec.

You could start with a 5/64" if you prefer if you're in very cold waters.

Mike

 

[shawnfenwick]

Re: 2006 Tohatsu MFS 8A3 Lots of steam coming out of exhaust relief

Thank you very much for your answers. For an update to my initial observations: The motor would really steam in bright sunlight. It was like it was steam powered! But the telltale was strong as all get-out.

I took it off the boat and again put it on the stand. I ran it and used my IR laser probe. the cylinders near the plugs at about 2-3000 rpm were max 150deg. All over the motor you could put your hand on it. Maybe 120-130 on the OHC part of the motor. Still steaming.

So I pulled out the thermostat (the new one) and drilled a 3/32 hole in the old one and popped it in. It had much less steam, but I have yet to test it under load.

By the way, when both thermostats were put in a pan of water and it was brought to a boil, they both opened up at the same time. You know, unless mechanically damaged, I don't see what can go bad with them. I sure if the tachion-beam particle-accelerator was aimed at them, it would have some kind of effect, but that particular device is disabled on my outboard as I only got the stripper model.

I must add to this thread: I have another Tohatsu - a 6hp 2012 6hp SailPro Remote with the 24" leg, alternator, etc.

I put it on the stand and after it warmed up (much quicker, I must say) it was steaming as much as the MFS 8A3. (After the mod). So I felt good about the Mod there Mike.

Next time out, I will take my IR Temp Probe and if there is steam, I will take a video of it and take a temperature reading. In retrospect on this, I THOUGHT this was an exhaust idle relief port. When I was on the water on Puget Sound WA, clipping along with the motor opened up to about 75% of throttle pushing a 3500 lb displacement sailboat, this baby was steaming like a house on fire. THAT is why I opened this can of worms back up from Mike's original post. I will inform of any new results good or bad: for the common good of the forum. Thanks again to you guys who followed up with me.

-Shawn

 

[rocket rich]

Re: 2006 Tohatsu MFS 8A3 Lots of steam coming out of exhaust relief

my 9.8 tohatsu does it too and it's new , but it's cold in missouri this time of year...sunday 1:30 pm 26 degrees. not that I'm fishing