I have a 1999 V6 Mercruiser that has a tendency to desiel(after burn). I use high octane fuel, and it still has the problem. We have tried adjusting the timing. Any help?
My 4.3L mercruiser had the same problem. I put a cooler running thermostat in and used premium gas, as well as letting the boat idle a bit before shutdown, and the problem went away. Only did it on those really hot days after pulling skiers for long runs, and then, only just a bit. Hope this helps.
I have a 2001 Larson with the Volvo 4.3 and it does the same thing. From all the info I have gathered, this is a common problem with the 4.3. I was told to let it idle for a minute before shutting it down to let the pistons cool off. So far this method has worked just about every time.<br /><br />kvista<br />2001 Larson LXI 190<br />'KNOT ON CALL'
I hear "let it idle for a minute to cool down " a lot.<br /><br />My engine , Volvo AQ125 A, runs hotter if I sit at idle not moving.<br /><br />Even if I have the blower on.<br /><br />It will actually overheat if I sit too long.<br /><br />Brand new water pump.
What you are experiencing is called detonation. It is caused by too high an idle speed, or hot spots in the cylinders. The hot spots in the engine are often caused by carbon deposits and/or too high a heat range of spark plug. Try decarboning the engine with Karbout, checking the plug numbers against OEM recommended and adjust the idle speed appropriately.<br /><br />Contrary to popular belief, timing has no affect here, as the ignition is out of the "picture" when the key is shut off....
If you have carb. model i would check float levels and idle adjustments both can cause that problem as well as the timing being to high(remember you must disable any timing advance system, vac, mech or computer before setting the timing) P.S. boatingfool there two water pumps on most I/O's one in motor and one in the foot
Once again, thanks for the replies. <br /><br />I broke down and made a trip to my local Glastron dealer. I asked him about the problem and low and behold he didn't try to get me to bring it in to get fixed. <br /><br />His explaination is that it is common with this motor, when turned off when the motor is very hot. It is caused by todays highly volitile fuels that keep burning. He claimed that there is not a fix. That is kind of aggravating. He only had a one real suggestion:<br /><br />1. Let the engine idle down for a while.<br /><br />He also agreed that<br /> Slow down the idle may help.<br /> A cooler thermostat might help some.<br /> Karbout may help<br /><br />I will do all of the above. A cheap solution if it works. <br /><br />PS Shutting the engine down in gear works, but I can't do that because it screws up my Perfect Pass Cruise Control. I have to reset it if I do. No major problem, but I have to open the engine compartment to do it.<br /><br />Now the queston about what temperature of thermostat to get.
