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wblazer

Regular Contributor
"Hi Guys,

Had bad boat day

"Hi Guys,

Had bad boat day had to be towed in. Got the boat started after some electrical problems that you helped me with. Cruising along and see smoke coming from engine. It smelled like rubber burning ,then engine stalls. Removed cover and see that the lower exhaust tube is melted. I replaced both top tubes last season.They just cracked and leaked, not melted. Temp gauge was not running hot. What do you think caused this problem? And beside changing the cooked tube what else should I look at?
Thanks for all input."
 
Sorry Walt; just couldn't

Sorry Walt; just couldn't resist or remember your boat. The engine exhaust lost some or all of its cooling water on the burned side. Check the other side closely for exhaust damage. The exhaust gets its cooling water from the T'stat assy. Check the hoses. Stick a garden hose nozzle in the end of each hose to see how much water comes out the elbow. May be a blockage.
 
"Guy,
Still ahead of my self

"Guy,
Still ahead of my self my boat is 1986 Four Winns 4.3 Alpha one. Had a bad time when boat broke down. My son and I were in storm anchored waiting for the tow boat.Seemed like the rain would never stop."
 
"Guy,

I will do as you sugg

"Guy,

I will do as you suggested. What do you think rust in the system ? if so how do I cure that?"
 
One is to see how much scale i

One is to see how much scale is in the block. The hose flush will tell you if there is blockage in the manifolds and elbows; compare the two sides. Make sure the ball "T" valve is working on the T'stat.
 
"Guy,

Thanks again for your

"Guy,

Thanks again for your information. To check the ball valves. Do I start the engine with hoses off and check for flow on the riser side of the valves? Please advise.
Thanks,
Walt"
 
"Guy,
FYI, I wanted to make y

"Guy,
FYI, I wanted to make you aware the boat is in the water in a slip, not on a trailer. If that matters for testing."
 
"Walt:

I would just pull th

"Walt:

I would just pull the hoses off and try to determine that the balls are not sticking to the end of the tube. The ends of the tube should be clean and smooth. The balls should also be smooth. They can be removed and turned around if needed. The springs should put a small amount of tension on the balls.

I may be wrong, but I always thought their purpose was to keep exhaust pulses from affecting the water flow or to keep exhaust out of the cooling water.

If you want, you can check the volume of water flow at the other end of each hose. That will give you a chance to look at the inlet ports for any blockage."
 
"Guy,
Went to the marina toda

"Guy,
Went to the marina today. I did the tests and inspections as you sugessted. All seemed ok flow was good. What I did find when taking off the melted lower tube.Was that the shutter was side ways in the tube.Could this have cause the heating.The shutter and pin shaft seemed ok. But what holds the pin in place? Seems like a loose fit.What do you think I should do now? Thanks."
 
"Guy,
Shutter I have has hole

"Guy,
Shutter I have has holes perforated in it. They are not shown in the print. Do I have a different style? Also I dont have end caps just ears where the shaft goes through. Maybe the caps melted. or are they made of brass as this assemble I have is? Please advise, Thanks"
 
Walt:

I've seen two sty

Walt:

I've seen two styles; the one in the pic. and the one you describe. Pull the other side loose to see what it looks like.
 
"Guy,
Do you think that is wh

"Guy,
Do you think that is what made the tube melt? The shutter moved and blocked water flow?"
 
Walt:

It's very possibl

Walt:

It's very possible that the water backup caused the hot exhaust to back up and burn the coupler.
 
"Guy,
I decided just for safe

"Guy,
I decided just for safety first that I would take parts off for a good inspection. I removed the riser and thermostat housing. Going to wash off at home and blast them with air.Talking to guys at the marina they suggested doing away with the plastic balls and springs. Also doing away with the thermostat. What do you think? I hope to put parts back on tomorrow. Thanks for your help."
 
Walt:

Turn the T'stat h

Walt:

Turn the T'stat hsg. over and look for a pipe plug in the bottom. Remove it to look at the bypass hole inside the hsg. The hole should be 1/2" in diameter. If the hole is oversized the engine can overheat at low RPMs because too much water is flowing out the bybass. If under sized the water hoses expand when T'stat closes because the water can't get out fast enough.

If you have a small dental mirror you can insert it into the SS sleeve to view the inside w/a bright light.

Removing the check balls; my manual says they are used as pressure relief valves for the T'stat hsg. apparently there is a certain amount of pressure required inside the hsg. for proper water flow. Removing the balls may cause a reduction in cool water flow to the block. Try it if you want; you can always replace them.

I have a used hsg. I replaced just because I got a new one at a low price. It worked before removing it. You can have it for the shipping cost. Let me know.
 
"Guy,
I have the housing in m

"Guy,
I have the housing in my garage now and will do as you said.Checked the riser this morning with garden hose it had blocked sections. I was able to clear about 90 per cent. All the components of this cooling system are really rusty.Yes I am interested in the housing. Please advise, Thanks Walt"
 
Walt:

Email me your maili

Walt:

Email me your mailing address and I'll ship it tomorrow. You send me a check or MO for the shipping cost.

I was able to stick my finger in the T'stat opening and feel the bypass hole; it has some scale on it but is open. It needs some cleaning and polishing w/a Dremel where the T'stat sits.

The riser water passages need to be somewhat smooth. Rough walls will cause turbulence in the flow and restrict movement. Can you get a bastard file in it to remove more scale? You could clean it 3 hours in a small bucket (cutoff gallon jug) of muriatic pool acid. Rinse it well and break loose any leftover rust and scale.

I am thinking that since the rest of your exhaust system is in the same condition that they all should be cleaned w/acid or replaced.

You could take the exhaust parts and T'stat hsg to a radiator shop and ask about cleaning them.
 
"Guy,

The acid worked,now h

"Guy,

The acid worked,now have full flow. Never worked with that before, powerful stuff.
Thanks again,
Walt"
 
You might consider cleaning th

You might consider cleaning the other one and the exhaust manifolds and elbows. Leak test the before reinstalling.
 
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