AQ125A270

"My AQ125A/270 after several h

"My AQ125A/270 after several hours of operation today started to make an odd noise. Running at cruise for 1 hour it made a noise that sounded like the prop hit a fish/limb, over the course of an hour it happened 4 more times. Almost sounded like a gear jumped a tooth or a u-joint popped. Any ideas on running down the problem? Thanks, Gary"

"One thought on the above. My

"One thought on the above. My seawater cap was allowing large amounts of water to blow out at higher rpm's, the higher the rpm the higher the flow. I never have had any over heating problems but I sealed this cap so there is no leakage. Is it likely that the exhaust manifold water passage is blocked to the point that an abnormally high amount of back pressure on this system has caused the impeller to jump/rotate on the shaft/key causing this thumping sound? Gary"

"Gary, even with a 100% blocke

"Gary, even with a 100% blocked manifold I would not expect the impeller to shear the key.

If the sound you described was of a mechanical nature, I would expect that you would have serious mechanical problems by now. I expect that a sound that you hear briefly 3-4 times in an hour without any other noticeable effects could be more related to ignition than to mechanical reasons. However, it it only happens when you turn the steering wheel significantly to port or to starboard, it could be a u-joints problem. When was the last time you inspected/greased them? And the bellhousing bearing?"

"No turns, straight cruise. It

"No turns, straight cruise. It sure did not sound like the engine although the fuel is suspect. Everything was greased this season, although it may be worth looking at the u-joints anyway. I guess I need to buy the electronic ignition anyway and install some news ignition wires along with checking the fuel strainer. I think it sounded like one of the gears in the drive jumping a tooth, although if that happened once it would most likely let go completely. Thanks, Gary"