Transmission rattle at idle

"I just put a brand new velvet

"I just put a brand new velvet drive transmission in. I also put in a new heavy duty damper at the same time. It is hooked up to a Crusader 8.2 fuel injected inboard. At idle it "rattles", not constantly but once every 10 seconds or so, if you put your hand on the transmission you can feel the vibration when it rattles. In gear at idle you can feel the vibration in the boat. The mechanic that installed the transmission thought the engine was missing so he installed new plugs, dist. cap and rotor. Didnt fix it. Once I speed up past idle then everything is fine. The idle speed is factory set at 600 rpm. The port engine is "rattle" free at all speeds. HELP???"

Sounds like coupling mis-align

Sounds like coupling mis-alignment. Did you realign it when the boat was in the water?

Jeff

"according to the mechanic the

"according to the mechanic the engine was aligned after the new tranny was put in, or should I say he billed me 110.00 dollars for "realigning" the engine, so I am presuming it was done. The boat wasnt pulled out when the new transmission was put in so all was done in the water. Plus the noise and the vibration occurs even when boat is not in gear. Wouldnt a mis-alignment issue only cause noise and or vibration when the engine is in gear and turning the prop???"

"Scott - What gear are you usi

"Scott - What gear are you using and if twin installation, which side is it.

The Hurth 63A gears do rattle at no and low loads, even in neutral. It is more prevalent on the port gear as that one runs backwards and the 2.7:1 seems to do it more than the 2.0:1 and 2.5:1.

If it sounds like someone threw a handfull of marbles in the crankcase, it's probably normal. Sometimes it goes away with usage, sometimes you get used to it."

"Rick,
The transmission is a

"Rick,
The transmission is a velvet drive 5000 series with the 8 degree angle down feature. It is the starboard transmission with a 2:8 ratio. The port tranny is very quiet though, with no rattle or vibration. I had heard that since the port tranny ran backwards it could be noisier, which is why this concerns me as it is the other way around."

Scott - The yacht manufacturer

Scott - The yacht manufacturers I service all use the Hurth/ZF with their Crusader packages. I did call a few of my associates who confirmed that this noise is in the Velvet Drive as well and is acceptable providing it goes away once you start to increase the throttle.

Good luck
Rick

"Rick,
Thanks for the informa

"Rick,
Thanks for the information, I appreciate it alot. Having to replace both of my velvet drive trannies in the last two years has made me very leary of any noise I hear from them. I plan on taking the boat out tomorrow and running up to WOT for the first time with the new tranny to see how she performs."

"Well, the vibration is so ann

"Well, the vibration is so annoying I cant even stand to use the starboard engine for trolling so I had a different mechanic look at the problem. The first thing he said when he listened was the engine was idling rough causing the vibration in the tranny. They hooked up the engine to the computer, unplugged each injector, tested the fuel pump, compression tested the cylinders, vaccum tested the engine. What they found was all the tests showed the engine was fine. The compression test showed two cylinders at 147 with the rest between 154 and 165 but they didnt think that was too far out to be a problem. They did find that when they unpugged the injectors on the 2 and 4 cylinders that there was less of a rpm drop than when the others were disabled so they felt that the injectors could be clogged there. They recommended that I put Sea Foam in the gas to clean out the injectors. Has anyone ever used this product? Does it work?"

"Scott, does the noise go away

"Scott, does the noise go away above idle? Also,did he read the plugs, if so how did they look? The injector issue is a legimate concern. I have never used seafoam, but I have heard that it does work. When I have a suspect injector, I remove it, then connect a 9V battery to the contacts, this will cause the injector to open. Now you can spray back through it with some spray injector (Carb and Choke) cleaner. This will backwash the internal screen in the injector and allow it to flow fuel properly. I'm assuming it is MPI, not TBI.

Good luck,
Rick"

"Rick,
Yes the noise does go

"Rick,
Yes the noise does go away above idle. Even if I bump it up a couple of hundred rpms it goes away, as does the vibration when in gear.
Yes it is MPI. They did look at the plugs and they all look normal. Can you remove the individual injectors? I had gotten the impression that the entire upper manifold had to be removed to get to them.
Thanks, Scott"

"Ok, I finally found out why m

"Ok, I finally found out why my engine was running rough. It was timed wrong. The timing was set at 2 degrees BTDC when it should have been 10 degrees. The third mechanic who looked at the engine found this problem within five minutes. The other mechanics spent literally hours testing this and that and it turned out to be the simple timing. Once the timing was corrected the engine smoothed out and the rattle went away. So, don't assume that simple things like this are checked first, make sure that they are!"

"I'll bet your royally pis

"I'll bet your royally pissed off at those other two dopes! The first thing they should have checked was the timing. I didn't suggest that since it was so obvious (as in, obviously the first two dopes MUST have looked at that!)

I hope you can get some of your money back, though I doubt it.

Jeff

PS: Well, now you know who to go to when you have a mtor problem!"

"I could fill this bandwidth w

"I could fill this bandwidth with the stories of incompetance I deal with in this industry on a daily basis. Just because a guy has a certificate on his wall doesn't mean he has a clue about what he's doing.

I'm glat you got it corrected, shame you had to waste so much time and money."