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1988prostar190 01-28-2013 06:40 PM

Rattle in Mastercraft 88 prostar 190
So over the summer we have heard a rattle coming from the transmission and pulled the transmission to investigate. The sound was like rocks were clunking around in the tranny. We had a mechanic pull it apart in july and he found no big issue. he replaced our damper plate abearing or two and the transmission oil pump gear assembly. The day we got our boat back the rattle began again. Its seems to be at a low idle when in foward and reverse and goes away over 1000rpm. We ran the boat till late october just ignoring the sound and on our last cold day we thought we blew up our transmission with huge clunks and the engine wouldnt pull a skiier out of the whole. We putted our way back to shore and put the boat away for winter. Now we have our transmission apart on a bench and find nothing wrong??
Could this be an engine related issue? All fluid levels are good. No water in transmission, Propeller on tight.

These are other tiny facters that could be related
-Oil gauge fluctuates rapidly/
-Thier was sludge in our bell housing when we pulled tranny
-Five times this summer the engine had trouble warm starting(flooded carb?)
-Metal shavings on transmission magnet

petermegan 01-29-2013 04:08 PM

I am going to go out on a limb here and suggest you have a miss in your engine causing an inconsistent drive through the transmission. This may be your 'clunk' and lack of power. Completely unqualified with this answer. May be time to start pulling some plugs and working out which cylinders are breaking down. Have fun

madcityskier 01-29-2013 04:34 PM

Also could be related to a bent prop shaft or bad bearing, though I would think this is less likely.

Jerseydave 01-29-2013 05:56 PM

I read on here that some transmissions had a rattle so it's recommended to use 15W40 motor oil instead of trans fluid. You might give that a try.

Also check your engine's timing chain for excess wear. Sometimes a worn timing chain can contact the timing cover at certain RPM's making a rattle-like noise.

Re-check the damper plate too. I believe there is a newer better design available over stock?

1988prostar190 01-29-2013 08:24 PM

Ok thanks for the ideas. Is it possible 1 of 8 cylinders is not firing and the engine can still sound quite quiet and smooth at a low rpm??? Through talking to a local transmission mechanic he seems to think my issue is probably looking more to the engine than the transmission. I just can't really think of anything engine related that pretty much clunks the boat around at low rpm??
Thanks for any thoughts guys

Tateau18 01-29-2013 09:35 PM

Possibly Starter Bindix?
Does it seem to be a sticking rumble? When you start your engine does the starter stay engaged too long? I had a boat that had a similar rattling noise and it turned out to be a starter Bindix. Also, check that your shaft nuts and packing are in proper order. Just my thoughts if it's not a tranny issue.

1988prostar190 01-29-2013 10:19 PM

Shaft nuts and packing all good. Starter doesn't seem to be staying to long. The sound is best explained as stones clunking around my transmission but seems to go away at higher rpm and comes and goes depending on temperature of the engine.

petermegan 01-30-2013 01:57 AM

I was just thinking that a miss in your engine can transmit through your transmission and the backlash causes the trannie to rattle. Hell don't blame me if I am wrong. :D Have fun

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