Major overheating issue and stumped

[Climber513]

I have 250 straight 6 with the MC1 upper and alpha gen 1 lower. Had it out and started overhearing so I replaced the impeller and housing and water tube assembl . Still getting hot so I went to change thermostat but there wasn't one in it, have one ordered, and I replaced the water pump on engine. STILL getting hot. Ran it for about 15 min and I used some rtv gasket sealant to put the thermostat housing back on to run it until the kit shows and the pressure just sprung water steams out from under that. Shut it down and you can hear the water boiling in the lower unit and the water from ear muffs is even hot just from being in contact. I dont know what the next step would be. Why would the outdrive be getting so hot you can hear it trying to expand and hiss and boiling. Any help would be great.

 

[Bondo]

Ayuh,..... My guess is, the riser/ manifold is plugged up, not allowin' water to get outa the motor into the drive,.....

Donno why the drive is gettin' as hot as you say,....... Is it full of oil,..??..??
It will get hot without water flows, but it sounds extremely hot, which it shouldn't be,.....

 

[Climber513]

Yes filled it with fresh oil when I changed the impeller. I was thinking toward riser or manifold. The manifold does have a brownish cast towards the front as if it's been getting hot. The rest is a glass black. It's almost like no water is getting to the lower but it is pumping water out of the prop so I don't know.

 

[Rick Stephens]

Is the lower itself hot all over or is it just spitting steam from the exhaust?

 

[Climber513]

Hot to the touch. Very hot

 

[Rick Stephens]

I have never seen a drive get hot on muffs. I can only think you have a bearing failure. When you changed the impeller was the seal housing under it melted?

 

[Climber513]

Yes and also the water tube housing. Someone has had this thing very hot before I took it apart. The washers were melted into the plastic.

 

[jtim108]

I have 250 straight 6 with the MC1 upper and alpha gen 1 lower. Had it out and started overhearing so I replaced the impeller and housing and water tube assembl . Still getting hot so I went to change thermostat but there wasn't one in it, have one ordered, and I replaced the water pump on engine. STILL getting hot. Ran it for about 15 min and I used some rtv gasket sealant to put the thermostat housing back on to run it until the kit shows and the pressure just sprung water steams out from under that. Shut it down and you can hear the water boiling in the lower unit and the water from ear muffs is even hot just from being in contact. I dont know what the next step would be. Why would the outdrive be getting so hot you can hear it trying to expand and hiss and boiling. Any help would be great.

had the same issue blow through all theccoolant hoses with your mouth see if you can push water through your head and through your manifold, mine wouldnt let me bloww through the exhaust side soo i removed parts starting with the riser, then air went through and my passeges in the riser were extremely clogged, everyone says get a new one but you can spend some amount of time scraping the hell out of the passges until they are all clear

as far as the lower unit i have no idea. try and fix the engine overheat first and go from there maybe the exhaust is transferring a lot of heat to the lower unit because theres no water flow but i have no clue.

 

[Rick Stephens]

A lower is submerged. It has water cooled pockets with drain holes that get filled when you submerge the drive. It also has water and exhaust mix going through it. When cooling system works running at idle on muffs that water is just hot to the touch, not steam. There is so little heat produced in the lower gear box when running on muffs that there has to be something wrong in the lower for it to melt paint. This is totally regardless to the cooling system being compromised for the engine. My bet is if the lower is getting hot, you can split upper and lower, remove water pump to get rid of the friction from it, then turning the input shaft to the lower will show a bunch of friction on your lower. There should only just be a tiny amount of drag in the lower in that condition as the bevel gears in the bottom change the angle of rotation. That would take hours without cooling water to get hot.

 

[Climber513]

So I pulled the hose off running from the lower up to the engine and when I start it there is definitely water pumping up into the engine. Soaked me. So I pulled the hose off going to manifold and water is going to it so I pulled off the manifold end cap and it was pretty nasty. Big chunks of rust so I started flushing the end cap and the manifold until it was pumping clear water out. Next I may take off riser too. I wanted to put it back together but I need a gasket for my end cap and I'm having a really hard time finding one. I keep seeing four hole gaskets but mine has two on top and one in the center on the bottom.

 

[Rick Stephens]

Go down to your local auto parts store and get some gasket making material. Somewhere in the .035 to .050 range. Mark it out and make one.

 

[Rick Stephens]

And pull your drive off, drain it, split the cases and remove the water pump. Turn the input shaft to the lower by hand. Should turn smooth and easy.

 

[Climber513]

I'll try that. Thanks

 

[Climber513]

Well I pulled off elbow and manifold. Both completely clogged. Spent two hours flushing the manifold and finally got it flowing water. Broke two bolts on the end cap so need to drill those out. Elbow is a mess. Looks like someone welded all around the edge and its completely clogged so I'll need to replace that. I'm pretty sure this is my overheating issue. What a mess. Clogged with rust and rtv sealant.

 

[Rick Stephens]

You can check your manifold before reinstalling and after cleaning it out by filling the water jacket with acetone and seeing if any leaks into the exhaust passage. Acetone will go through a crack fast that water will only drip through.

 

[Climber513]

I'll try that.