Knocking Noise (Trimmed up) DP 290

Hello all,<br /><br />I am getting a knocking noise on my 19' 1992 stingray runabout with a 431A Volvo Penta DP290. I know the knocking is coming from the lower unit. Not sure of the specific nomenclature so I will speak my terms. With the lower unit trimmed all the way up it knocks when flushing the motor, the further I trim the lower unit down the less noise it makes. At about 4-6 inches from all the way up it stops making the noise, I don’t here it in the water just when I am flushing the motor and only after I have been flushing the motor for more than a couple of minutes. Obviously it has something to do with the angle of the u-joint or ring and pinion gears or something along those lines. I thought I read something on here that said it was normal but I wanted to re-affirm this and find out what was making the noise.

Re: Knocking Noise (Trimmed up) DP 290

should be easy enough to take the clamp off the back of the driveshaft bellows and slide the bellows forward off the upper gearcase enough to reach in and see if you have slop in your u-joints. if you have any, it's too much. also a good way to check to see if any water has been getting in through the bellows. if you see lots of rust and signs of water in there, you will want to make sure you don't have water in your lower unit (rust eats up the seal and lets the water in).

Re: Knocking Noise (Trimmed up) DP 290

Yes, sounds like u joint. Dont think it is a good idea to run the unit with it tilted all the way up. Makes you wonder why they use regular u-joints instead of constant velocity joints. Maby size or load. If you find serious corrosion on the upper housing bellos flange, give me a ring at stinkin_badges@yahoo.com. Friend wound up replacing his 290DP and we have a brand new housing laying around. regards fred

Re: Knocking Noise (Trimmed up) DP 290

First of all, you should never run the engine with the drive up.<br />Your noise is the ujoints, may be due to water in the bellows, may be they are worn out from running with the drive trimmed up that high when you flush it each time.

Re: Knocking Noise (Trimmed up) DP 290

Thanks alot for the input. No more running it with the trim up amd I will take a look at the Inside of the bellows.<br /><br />Thanks again