Suzi DT85 1985 Cooling Issues

[andrew j cox]

Got a Suzi with some problems, no thermostat in it, with the muffs and thermostat housing off getting no water out the top but bit of smoke coming out.
i have to dump the gearbox to have a crack repaired, he had the pump done but wasn’t tested, if the vanes were reversed this would occur? No water out front of the leg through the little exhaust outlet below the bottom cowl, I can put hose down the tstat hole and it comes out the prop n a bit from the fore mentioned outlet, stick hose in this outlet get water out exhaust but not out the top, so my idea of likely causes, blockage inbehind exhaust plate, blockage in head, she’s been in the salt all it’s life, water tube to pump seal up the **** or pipe dislodged, impeller back to front, what way should the vanes rotate? Left or right looking at from top of box with prop pointing north. could the head gasket be suspect? Plugs are clean compression is dead even at 140 from 1 to 3.

 

[AndyPandy]

If it were me, It'd drop the lower leg, check the impeller is in the correct direction (turn driveshaft clockwise), then hook a hose up to the upper leg, and see where/if water comes out. Ideally the telltale, and thermostat hole.

Without a thermostat fitted, I'm not sure if you'd see water from the exhaust, unless you replace the thermostat housing.

Why is there no thermostat? They must fit them for a reason....

 

[Bertram56]

I have an 1987 DT75 on a pontoon boat I recently purchased. ( a month ago ) No water flow since my day 1. Pulled thermostat cover and filled with water. Water flowed easily out of tattle tale, but no where else. Pulled lower unit and found impeller tips shredded. Replaced pump gasket, plate and impeller. Had a local shop replace all seals in lower unit and pressure test. No leaks. Re-Attach LU, still no flow, nothing but hot smoke from tattletale and upper exhaust port.
Thought the problem may have been a blockage in the riser tube above the pump. Disassembled motor below power head. Glad we did. Tube clear. Found 3 round tips of impeller blocking water inlet on bottom of power head. Removed the tips and cleared blockage. Also, found gasket between power head and exhaust tube in terrible shape. Pulled head to check for blockage, but found none. Currently waiting on gaskets And parts to put her back together. Compression on all cylinders is 150. Engine fires up at the touch of the key. Can’t wait to put her in the lake and finally test running.