Exhaust fumes coming out thermostat housing

[3ric]

Hello all, I’m new here, but very excited to be on this forum. I’ve been learning so much! I have a 1985 Suzuki DT65. It is new to me but I don’t know much about it’s history.

I’m an effort to try and descale the motor, (which I should note it only had a light amount of scale) I took off the thermostat housing and started it on muffs. When I did, a light amount of exhaust fume came out of the thermostat port and no water. So, put it into a trash can and now water pours out but so does quite a bit of exhaust fume.

I should also note that in my failed attempt to set up a descaling circuit, I could not force water up to the thermostat housing port with muffs or by hooking the pump directly to the tube on the output side of the water pump

Is this something I should be concerned about? Might there be an exhaust gasket leak?

 

[Sea Rider]

Welcome to IBoats,

Was that 35 year oldie motor used in fresh or salt water ? If wanting to descale the motor, probably Salt Away could handle it or flush the motor in a bucket with 50% water and 50% pure vinegar for some minutes.

You can force water or air at high pressure through the water pump's tube with removed thermo and lid bolted back in if suspect there's a clog somewhere in the water circuit.

Happy Boating​

 

[3ric]

I suspect fresh water, as it is in Oklahoma, but I couldn’t say for 100% certain.

and full disclosure, I bought some hammerhead to descale, but as it is my first attempt at descaling I wanted to try to do it with just water first to prof of concept the pump circuit. I did shoot air through the pump tube and it was blowing air out the thermostat hole. And again, when I submerged ran it in a trash can vs muffs, water flowed out the thermostat hole.

 

[Sea Rider]

When flushing on muffs did water flowed out of the thermo port in poor quantity or not even a drop, if so, it's due to muffs loosing to much water pressure at both ears sides, the U shaped rod that holds both ears in place is not compressing the ears against both lower leg's water intakes as they should...

Happy Boating​

 

[3ric]

Not a drop came out with the muffs. And I dropped the gear case and plumbed directly to the tube and still nothing. I even pulled the impeller out when on the muffs to make sure it wasn’t preventing flow.

When hooked to muffs, I even duct taped around them to seal into place, but the water came out in all sorts of places such as a hole at the front of the leg and the little adjustable fin thingy that helps with cavitation or offsetting the prop rotation (I don’t know the name). I should also note, that there was just a little bit of black oily substance dripped down the port side of the inside of the leg, down onto the top of the water pump. I am sure it was not gear oil.

Also, when I hooked directly to the pump tube, water was coming down the exhaust tube in the center of the leg, but also and I couldn’t say for sure seemed to be coming down between the exhaust tube and the outside of the leg on the port side.

 

[3ric]

Ok, so I took your advice Sea Rider and bought a new set of muffs. The muffs fit really well and snug. Good advice, as I don’t know that I was getting enough water to the engine before when running on my old muffs. However, the pressure of the garden hose (which is pretty stout) was not enough to force water up and out the thermostat port, but when I fired up the motor, the water poured out just fine.

So, what about the exhaust fumes coming out the thermostat port, is that a bad thing?

 

[mike_i]

Was there any water coming from the pisser hole while using either the muffs or the motor in the trash can?

 

[3ric]

Was there any water coming from the pisser hole while using either the muffs or the motor in the trash can?

Yes....well, wait lemme double check on the muffs...

 

[3ric]

Yes....well, wait lemme double check on the muffs...

Water comes out the pee hole when it is running on the muffs and trash can but not with the muffs not running

 

[OneWireAT1]

Water comes out the pee hole when it is running on the muffs and trash can but not with the muffs not running

Any follow on update? I'm having a similar experience with my ol' DT65 as well!

 

[racerone]

The impeller blocks water flow to the motor when it is not turning !-------And cooling water is discharged to the exhaust when motor is running.-----If there is no water in the engine the exhaust will come out the thermostat hole if that is open.