VolvoAQ170/250 pump throtle to plane & overheating high speed

[fish393]

Had to pump throtle to get boat to plane 23' and 165hp 6cl and could only get 22 mph out of it and top speed has been pushing 30mph. Started to over heat at higher speeds but would come down at lower speed ie.8-10 mph but still had to pump throtle.When got back to dock had oil in the bildge on both sides of the engine not in any particular place.The only area oil was present on engine was right by oil cooler but did have a little leak of air from the exhaust manifold not oil.Have tripple solex carbs and noticed the middle one on the intake matifold was a tan color and hot to the touch. Engine will still start and idle well with just a small surge in and out.Need a few ideas.No sludge in oil and very little vapor in carbs, plugs seem to be a little wet fouled and smell of gas,the fuel filter is clean.Just replaced themostate and repared water tube on stern drive but bought a impeller to put in. thanks [is 30mph good for this boat and engine?]

 

[placebo]

Re: VolvoAQ170/250 pump throtle to plane & overheating high speed

Fish, a couple things. You just replaced thermostat, I assume you got the right one and put it in right side up. Check the impeller on the sea-water pump and replace if needed. If you have to pump the throttle to make these engines go it means crap in the carbs or the fuel pump. If it idles ok, i suspect the carbs. Take the oil cooler apart and clean it out, then reassemble and check for proper seating of the ends. I have a 17' Glastron with same engine. I am running a 15X17 prop and I get about 42mph. Watch your tach while running to see if you need to go up or down with your prop size. Those engines are bulletproof with a little care. Good Luck, David

 

[fish393]

Re: VolvoAQ170/250 pump throtle to plane & overheating high speed

david just replaced the impeller and did a compression test.#1-180 #2-200 #3-190 #4-200 #5-180 #6-200 could be a bad carbon problem?Also had alot of crap in the water separator.What do you use to decarbon your engine? thanks for the reply Fish