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Tranny noise

luhrs_40

luhrs_40

Contributing Member
89 luhrs 40 454 crusaders velvet trannys, run perfect last 4 seasons wich i own the boat. This winter needed to change stuffing box rubber hoses both sides , had to take original couplers out of shafts had to do a lot of banging and hitting to seperate them , and then ofcourse replaced old couplers with new split ones, new gfo packing put everything together. Shaft couplers and tranny couplers didnt sit together !00% but after the bolts were tighten they looked ok.. Early this week boat went in to water.. Starboard side is fine , but port tranny makes a metalic noise every 2 to 3 seconds when in drive or reverse but no noise in neutral. The noise seams to come from damper or close to it..Is there a posibily we done damage to internals of the tranny or damage the damper by hiting the couplers? i didnt push the engine more than 1000 rpms soon i heard the noise to minimise the damage.. What i was thinkin before removing the tranny to try to unbolt shaft and tranny couplers and run in drive for a few second s to see if noise still there..In case aligment is out of whack and gears are touching something? Any ideas? Also how far the shaft has to be back for the tranny to seperate from the engine? I was hoping to do it in th water..Thanx in advance
 
The tranny will come out--they design them to. Before getting out the wrenches do another coupler alignment and see if that helps. Also, if your engine might is running a bit rough, it can make the sound you described (in the trans coupler).

Jeff
 
I'd encourage you to remove the timing cover (black rubber plug in the flywheel cover) and inspect the damper plate for broken spring(s) or loose mounting bolts.

Also, if you wind up removing the gear for overhaul, get the damper plate changed.
 
...."Jeff running the tranny in drive without the shaft connected will tell the realy story u think? "

I recall hearing a damper plate clacking away in neutral.

Jeff
 
The V-D rear thrust bearing is fairly robust, being designed to deal with thousands of pounds of axial load in normal use. If you spin the coupler by hand and not experience roughness, you may be OK there. Best to do just the tranny flange with the prop shaft coupler disconnected.
Don't dismiss Jeff's comments about engine roughness. It's whats going on with my starboard engine now, and it rattles pretty bad at 750 rpm. I now need to idle at 900 out of gear. Checking with a vacuum gauge works well for this test, if your ears aren't great.
 
couldnt see much from the inspection hole but checked all the bolts they were all tight, couldnt see the damper springs from there.. Undone the coupler bolts run the engine in neutral no noise, put in drive the noise is there, so that tells me the alighment is ok..next step pull tranny out...By the way how much the shaft has to be back from tranny coupler, for tranny to come out? I want to pull it back as less is posible cause i am doing the job in the water. Thanx
 
It will probably have to go back at least 1.5" to give you enough room for the splines and pilot stub on the input shaft to clear. Once the input shaft is free, you can tilt it if necessary. You'll find two studs handy to have to slide the gear back with.
 
..."You'll find two studs handy to have to slide the gear back with. "

Right!

And if the space is really tight try this little trick: Select a couple of short bolts and cut the heads off. Round the ends off (to make inserting the trans easier) then saw a screw driver slot in the ends. When the trans is in place you can unscrew them after putting the other bolts in.

Jeff
 
Thanx again, Tranny came out over the weekend, damper plate looks ok no cracks springs are ok, but i will replace it with a new one. Gave the tranny to my transmission guy to open it and check it out, will know in couple days. By the way tranny parts and damper plate are aftermarket ok or should i stay with velvet parts?
 
Update..took transm apart after 900 hours still looks like new..Only thing we saw was the oil baffler tin plate wich it gets hold in place by a magnet it look like it may mooved when we were banging to take shaft coupler out..WE get an overhaul kit put back together with a new damper plate and hope for the best
 
Yeah, I can see how the baffle could be dislodged with enough external pounding. It just is wedged in there on some cast bosses in the housing. Did the sheet metal show any impact marks from the ring gear?
Where exactly is this magnet? I don't think my old unit has one.
 
Magnet is on the buttom of housing and the baffle tin sits on top of it. And the only thing holds the tin is the magnet.. I hope that was the noise cause everything else was fine, oil was clean , no smell and no deposits of any kind
 
I would be very surprised if the pan is held by magnetic attraction. My manual has pictures of two cast bosses for one end and the other end stuffs under another feature, as i recall.
 
this oil baffle is 4 inch wide by 6, and it seats on round magnet about 1 inch diameter in 72c tranny
 
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well reinstall tranny early n the week with new damper plate and new rear coupler, aligment was right on.... and noise stll there...clang-- clang every 3-4 seconds...Replace wire plugs cup and rotor adjust carb, seems to run better and less noise...but not 100%.. Also realise the quatrojet carbs gasket may have a leak..When i spray brake cleaner around the gasket on the bottom of carb the engine revs up..and then when i spray directly on the air mixture screw in front of carb the engine wants to die down....Any ideas? Am i on the right track?
 
Guess the flywheel bolts were checked when things were apart? Noises are known to propagate real easy thru metalic items.

As far as the vacuum leak, I'd get a gauge on it. Carb cleaner is usually used; brake cleaner may not yield the same results - depends upon which propellant is in the can.
Start with checking the four nuts holding the carb; they have been known to loosen with time. If you change the gasket under the carb, do NOT use the standard auto gaskets. They are very thin and very narrow and will typically leak within a year of install. The marine grade parts are more robust. Some auto racing versions are acceptable (thicker).

If you pull the carb off, make sure the two screws holding the throttle plate to the bowl are tight, too.

did you every try putting it in gear with the coupler disconnected like your intial post suggested?
 
Yes checked flywheel for cracks and bolts were tight. Also run engine and tranny in gear with couplers disconnected no difference noise still there.
 
And, its not just the magnet holding down the oil baffle, correct? Engine roughness will cause transmission noise at low rpm in gear, sometimes pretty loud. You could swap the carbs back and forth?
 
No wasnt the oil baffle, instead switching carbs i will replace gaskets , wich i know they are sucking air in...see if that makes a difference
 
Lattest update , tune up engine , engine runs well on idle atlist noise seems to be gone away..i hope for good....so tranny work was uneccesary but i am glad is 0ver ...one more thing on the quatroljet carbs once you close the air mixture screw, shouldnt the engine die? If it doesnt , does is it mean it runs to rich and its time for rebuild? Thanx again for all the help
 
If you are referring to the idle mixture screws, yes, in a perfect world, the engine should die if they are seated.

It isn't necessarily running "rich" if it doesn't. Usually, what happens is the idle speed screw is opened up to where the main system is starting to flow fuel. Usually detectable as a slight "nozzle drip" from the primary venturis, observable with the engine running. If this is happening, the idle mixture screws will have little, if any, control of the mixture.

Typically, BBCs in particular, the factory hasn't "tuned" the carb to the particular hull. Many times, one has to modify the carbs to "tune" them to the particular installation. Not a hard fix but it will take a few hours.
 
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