???? Cooling question/2002 40hp 4-stroke

[ekole51]

I recently bought a boat with 2002 40hp 4-stroke. It pee's when idling but water doesn't shoot out peep hole when throttling up. What could be the problem. I noticed this while running for a few minutes the other day. I had no signals of overheating and when put back down to idle, the water was flowing out again. Thanks for any help.

[keakar]

check crank case oil for milky color (water) and if it looks good then its the water pump impeller is bad and needs replacing.

if you find water in the oil you have a corrosion hole somewhere and mine just died from a corrosion hole in the head that acted just like yours.

what happens is:

water pump - the rubber loses its springiness and doesn't create the pressure so when the rpms go up they blades stop pressing on the housing walls and stops pumping because its no longer pushing pressurized water.

water in oil - corrosion eats a hole between the water passage and the oil passage and as water pressure increases it goes into the crank case instead of through the engine. the other scenario is the breach is between the exhaust and the water jacket and as you increase revs the exhaust pressure is greater then the water pressure so water stops flowing and your water pump is just spinning in place not moving any water until you reduce to idle and take the pressure off of the water passages.

[ekole51]

Thanks for the info. I'll check it out. Much appreciated.

[ekole51]

Oil is good. No water in it. Could it be the thermostat not opening enough?

[keakar]

no the pee hole is before the thermostat so it has nothing to do with the thermostat working or not

replace the water pump and I would recommend you replace the shaft seal and water tube seal as well (parts #2 & #9) with a motor this old. the water pump kit comes with parts 3,4,5, & 17.

parts diagram - 2002 DF40 Suzuki Marine Outboard WATER PUMP Diagram and Parts

water pump kit - 17400-96352 SUZUKI KIT,WATER PUMP

water pump housing shaft seal - 09282-17007 SUZUKI SEAL

water tube grommet - 17566-94400 SUZUKI GROMMET WATER T

it would be a good idea to pull the thermostat out and clean it of any corrosion as well as run a hose in the hole while the lower unit is off to replace the waterpump. this will help flush out and loose corrosion in the engine.

another thing to do is replace the corrosion anode inside the block passage shown in this diagram: http://www.boats.net/parts/search/Su...OCK/parts.html

the cover is part number 6 and its found low on the right side of the engine opposite the oil filter.

buy both parts #8 & #13

anode - http://www.boats.net/parts/detail/su...321-87J00.html

anode screw bolt - http://www.boats.net/parts/detail/su...128-06021.html

you buy the screw bolt because once the anode corrodes you will never separate the bolt from it because it swells around it so to remove just put a pliers on the anode and carefully turn it but don't crush it, the screw and anode will come off as one unit. then do your best to clean out the cavity it goes in the block before reinstalling. if this part swells up a lot it can be very restrictive to water flow through the block.