2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

[dazk14]

Hello,

Small outboard 2 stroke mechanic here.

Family brought in a 2006 Tohatsu 4 stroke 9.8HP.

This was used in Salt water 2007 and stored since. Salt water and not flushed.

Compression is 141/141, starts VERY easily and idles perfectly at a very low rpm.

Pumps water great, but seems to create too much white smoke out of the exhaust relief. Very puzzled.

Here's a video. Ambient temp is 60'F. Infrared head/plug temps seem to be ~160-175deg.

http://www.youtube.com/watch?v=Z7FQM3PrsGM&feature=youtu.be

Am I being too paranoid, or is there a problem. Old plugs were very dark and the oil appeared to be slightly overfilled.

The vid shows the engine running with oil at 2/3 up the dip stick (I drained- refilled). Checked new plug after 30 minutes and it seemed fine.

ANY help would be appreciated. I ordered a service manual, but I'm looking for a supplier of parts.

Thanks!

Mike

 

[dazk14]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

why no love?

I know there's some heavy hitters over here, I've seen their work.

Thanks in advance,
Mike

 

[dazk14]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

Quick update.

Ran it pretty hard without the thermostat and no smoke. It was spitting pretty good out the exhaust relief.

The thermostat appeared to check out ok in the temp test.

Interesting also is the mid section got pretty warm/hot when the steam was happening. small amount of steam off the mid-section where it hit the water.

What to make of it?

 

[pvanv]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

Very good video. Yes, that looks unusual. Not horrible, but unusual. Appears to be steam, not smoke. My 9.8 does have some steam exiting from the idle relief port, but I don't think it's as much as yours. The 9.8 runs on the cold side, so you will want to have a thermostat installed. Otherwise, you will have long warm-ups, and uneven temperatures in the cooling system. With the stat installed, warm-up at 60-degree F ambient temps is about 3 to 5 minutes to full temperature.

Since the compression is good, you probably don't have a head gasket problem at the cylinder interface, but you might have some cooling water making its way into the air stream somewhere. Check the plugs. If they are "sandblasted white" looking, you may have some water making its way into the intake side of things. Check the oil for any signs of milky water contamination. The 9.8 has a heated intake manifold, so a leak in the intake gasket could possibly leak a bit into the intake air stream. The crankcase breather runs through the intake manifold as well, so if you have a water leak there, water could possibly make its way into the crankcase oil, though that's doubtful, since there is considerable crankcase pressure on these.

You may need a new intake manifold gasket. Adequate torque on that is very important, btw.

 

[dazk14]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

I was hoping a heavy hitter would jump in, Thanks Paul!

I think you hit the nail on the head - it's steam.

I noticed the thermostat rubber encasing doesn't allow a solid air bleed.

As a temp fix, I drilled a 3/32" hole in thermostat and it works perfectly now.

There's a smidge more water out the exhaust relief, so it doesn't steam.

Old plugs were brown, new one's a nice beige. 141/141 10% leak down. Oil is good. Runs flawlessly.

I'd like to make this work since used only one season, looks new, paid $900, 25" shaft, Electric start with charging.

Do you sell parts (thermostat etc.) and how do I order?

Thanks again,
Mike D.

 

[dazk14]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

If you're bored and look a the video, when the motor heats up, the midsection is also giving off some steam. That's a lack of flow.

I think the thermostat wasn't opening enough/sticking. Dropping it into a 200deg pot possibly woke it up. Visible water jackets look flawless.

Although the water pump pumps a solid stream, I'll replace it since it's 4 years old with one year of service.

Hopefully we'll put together a solid topic repair so it will help others. I searched high and low before and didn't come up with much.

 

[gss036]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

I still think you should take the advice of others and give the thing back unless you are beyond that point. Posting all over the different forums is not going to change the fact there is something wrong with the engine.
I assume you think it is a good price for you to want to take the chance. It is your money and time, so the final decision rests on you. If it were me I would give it back as I said before in the other post.

 

[dazk14]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

Well, if posting to Mercs (which is the same motor) and Tohatsu is "Posting all over the forums", then I guess guilty as charged.

I jumped over to the Merc side when nothing was coming back on the Tohatsu side and the clock for a refund is ticking. The Merc guys were pretty quick.

The motor is running perfectly now, so why would I return it? Because of a $20 thermostat that I intended to replace as normal maintenance.

I guess I'm just not reading you.

99% of outboards traded in at my shop need something, even if it's a "just to be sure" item as a thermostat.

Best regards,
Mike D

 

[dazk14]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

Video of it functioning properly - well let me rephrase that. Looks pretty good from my eyes.

Also the previous steam/vapor Vid was probably a tad exaggerated since tank temp was ~85deg. - had a few motors in the tank that day.

For this Vid, Head temp was 142/142F. Compression 141/141, leak down 10%.

http://www.youtube.com/watch?v=LpquKqoofW0

I sure do appreciate all the info on 4-strokes - Thanks!

I am very impressed with this Tohatsu's simple design with what appears to be very well thought out and high quality.

Thanks again,
Mike D

 

[pvanv]

Re: 2006 9.8HP Tohatsu 4 stroke seems to smoke excessively - with video!

I was hoping a heavy hitter would jump in, Thanks Paul!

I think you hit the nail on the head - it's steam.

I noticed the thermostat rubber encasing doesn't allow a solid air bleed.

As a temp fix, I drilled a 3/32" hole in thermostat and it works perfectly now.

There's a smidge more water out the exhaust relief, so it doesn't steam.

Old plugs were brown, new one's a nice beige. 141/141 10% leak down. Oil is good. Runs flawlessly.

I'd like to make this work since used only one season, looks new, paid $900, 25" shaft, Electric start with charging.

Do you sell parts (thermostat etc.) and how do I order?

Thanks again,
Mike D.

Looks like you were right about a sleepy stat that woke up. Of course, it could fall asleep again, so a new one is a good idea. If you want to do the impeller, I recommend a whole wp kit, with the cup and wear plate for a couple biucks more. Much better results. You can email paul@obersheimersails.com or call my office at 716-877-8221 and I can help you with parts.