Noisy port engine

[hausherrs]

Boat: 1996 400 Crusader 454Xli, Velvet drive 20-01-005.
I have a noise coming from my port engine/trans. It seems to be coming from the rear of the motor under the heat exchanger. I thought it was the damper plate (And it still could be) but the engine is running not as smooth as the stbd engine. The noise sounds like two pieces of sheet metal slapping/banging together. Its not a knock. In neutral when I throttle up to 1k the noise almost goes away completely. I have not tested to see what happens when its put into gear.


Everything I read was to get the engine running correctly before dropping the trans and checking the damper plate. I replaced the plugs/cap/rotor yesterday and no improvement. I started to do a compression test but the loaner I had was broken and wouldn’t hold pressure. Next week I will bring my timing light out and check timing. The engine dosnt run horrible. It just has a little more vibration than the stbd. Fuel in the port tank is new.

Here is my to-do list to try and get it running right.

1) Check timing
2) Replace fuel filters
3) Check / replace coil
4) Finish compression test
5) Clean / Replace tb/injectors
6) Call a mechanic and let them try
7) Pull heads and have them rebuilt
8) Replace damper plate anyway while its tore down

Anything else I should add above line #6? As you can see it’s a slippery slope.

Thanks in advance.

Steven

[g36]

Whats it do in gear? Quieten down or go away? Mine make noise at idle also. I have the same engines and velvet drives. Reading all kinds of forums there's differences of opinions whether this something to worry about. Mine have done this and also another boat I had did this. I agree to get the engines running correctly but I don't plan on doing anything about the neutral only noise I have. I reach the recommended rpms at wot have no noise or issues while running. noise is only at neutral and its mostly after running

[hausherrs]

I have not had a chance to check it while in gear. Its been storming here for the past 3 weeks, every time I have an opportunity to take it out. I suspect that it will go away when in gear.

I also read that its normal. Even the surveyor said the engines are good. But if you start the stbd engine first it purrs like a kitten. Then you start the port engine and its like a grizzly bear. Exhaust is louder as well. The stbd engine had some engine out work done to it at some point. The stbd fuel tank is dated 2000 so thats been replaced. Stbd engine is also a lot cleaner.

I hear you on "Differences of opinion". I did a lot of reading on other peoples experiences. And what I found is that just about everyone found that the damper plate was due for replacement. I also found pictures of some that exploded through the bell housing.

Thanks,

Steven

[tomschauer]

You can put it in gear in the slip at idle to see if the noise disappears.
But if your engine sounds so much different than the other, I would continue down that path.

[hausherrs]

Ill be out there in a couple hours and will drop it into gear.

Just out of curiosity, if the noise goes away what does that suggest? That its most likely the plate?

[tomschauer]

Mine chattered in neutral and was quiet in gear. When removed the plate had two broken springs. New plate, no noise.

[hausherrs]

Yesterday I started each engine and from the feel of it they idle pretty much the same. So I am not convinced that the port is out of tune. I also put the port engine into forward and reverse a couple times. The noise stays the same. I think its just something loose back there where I cant see.

Also, the access panel in the master state room is only 12x12 inches. Really good view of the stuffing box and trans, but I cant see it being much use for working on the rear of the engine. I do believe that it is possible to slide around back there with the exhaust removed.


Thanks,

Steven

[Ramsport47]

We've had a couple of boats come through our shop with broken flywheels that make a noise like this. Also, transmission noise is somewhat normal if it does it only in gear.

[hausherrs]

I took it out Saturday and ran it for a while. You cant hear the noise with the floor closed. Also It quiets down when over 1k rpm. Im not going to worry about it until the winter. Ill have the trans pulled and damper plate replaced along with servicing all the rudder and prop shaft stuffing boxes (& who know what else).

Thanks,

Steven

[mjk1040]

I understand your approach to service everything in that area while your in there but, sometimes if it ain't broken don't fix it! Mike