View Full Version : Why is raw water discharged through exhaust in IO setup

09-03-2002, 01:52 AM
Can anybody tell me the reason for discharging used coolant water (raw) through the exhaust in an IO motor setup. Why cant it just be pumped out the back of the boat.

I have a Volvo B20 gas motor running a Volvo 270T leg. The motor gets to around 2800rpms then fades away. It runs fine when out of the water up to full revs. I have a feeling the motor is straight out of a car. Are there any other Mods that should be performed when marinising the motor besides manifolds / cooling system etc. Ie Cams or timing mods.

Karl Pfeiffer
09-03-2002, 01:16 PM
Can anybody explain to me on how to take the lower unit off a 1984 mercruiser outdrive so i can get the skag rebuilt? Anybody know where i can get a manual for the mercrusier 140hp engine and for the outdrive? Thank You In Adavance.Karl

09-03-2002, 08:18 PM
"Other than being a convenient way of getting cooling water overboard, "wet" exhaust systems are used to hold down temperature whenever the tubing or supporting structure is in contact with the hull.

I guess the first mod I would try on a healthy engine that can reach only 2800 rpm is to put a smaller pitch prop on it. Any marine gas engine can be hotrodded, but be careful (especially with cams) to not lose the low end torque needed by all but race boats.