Engine Water Locking - Port Motor

brettblack

We have a 342 with twin 6.2 liter engines.  Last Spring the port motor began water locking due to what was thought to be overheating.  That motor was sent to machine shop.  After work was completed the problem got worst and mechanic felt it needed to be replaced.  First new motor was installed but mechanic used existing risers and flappers.  That motor was sent back to Mercruiser.  Second motor was then installed with new flappers & riser and ran fine the rest of the 2013 season and early 2014.  We have now begun to experience the same issues...water in the cylinder and burns the starter up.  There has been no overheat on the new motor.  The multiple mechanics we have used are stumped.  Starboard motor has not experienced any problems during this time. Has anyone experienced similar issues?

brettblack

Thank you RinkerYan.  The mechanic did put taller risers with our last new motor and has since resulted in the same issue...while our other engine with the shorter factory risers has remained operational.  Appreciate your response!

Michael T

I assume you have stock exhaust through the drives not through hulls which if improperly installed can cause water to be sucked into the engines due to too low a drop from the risers. As well you have 6.2s (377 magnums) you have mentioned "multiple mechanics" - have any of these guys done anything to the timing of the valve overlap? if the valve overlap timing is off water will enter the engine. This has to be carefully paid attention to when doing horse power work on engines. 6.2s are somewhat "custom/built" engines as they are "stroked" 350s making them in effect 377s. A further stroked 350 will give you a 383. If anyone has been "playing around" with your 6.2s the water intake could be the result. First I'd check that the risers are O.E.M. for internal parts (not some cheap after market look-alike) and O.E.M. for the total height of rise from the exhaust manifold AND O.E.M. for the drop and slope of drop to the drives or through hulls if you have them. P.S. are the risers leaking water or air? Unless some wrench jockey has screwed-up your valve overlap timing looking for horsepower or torque there has to be a simple solution. Have you called Mercruiser technical support directly? They are awesome. Have your engine and drive serial numbers ready. Mercury Racing 1-920-921-5330 Mercury General Inquiries 1-920-929-5000. Say you are a loyal, life long mercury customer that NEEDS some help! Ask for technical assistance. Mercury has never let me down. Good Luck! MT