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View Full Version : 1990 Prostar 351 Pulley squeak


bbeach
02-05-2008, 10:30 AM
All last season I fought what I thought was a squeaky belt on the front of my 351 - but after changing the belt twice and some belt dressing I believe the problem is one of the pulleys on the front of the block. Anyone else ever have this problem and which pulley should I consider changing first?

Keep in mind it sounds like a belt but its not. It squeaks on startup and for the first few mins the boat is running? It seems once it gets warmed up it stops.

any suggestions other than replacing them all? Are there bearings in these pulleys that can go bad?

thanks

cbryan70
02-05-2008, 10:31 AM
is the belt tension correct?

flipper
02-05-2008, 10:41 AM
water pump or alternator? Sounds like it could be a bearing or something in one of those.

bbeach
02-05-2008, 10:47 AM
yes I believe the belt tension is correct...

bbeach
02-05-2008, 10:48 AM
The alternator is original so it may be time for a new one anyhow...

Prostar Rich
02-05-2008, 10:53 AM
The alternator is original so it may be time for a new one anyhow...


I second taking a closer look at your alternator. You may have bearing that going south on you.

Prostar Rich

bbeach
02-05-2008, 11:14 AM
I think the alternator would be a good start. I'll pull it this weekend and have it tested. I would imagine when I take it to Orielly's and have it tested it will squeak and possibly might be running short.

thanks all!

stuartmcnair
02-05-2008, 11:48 AM
replace them all...as long as you are working on it you might as well

TMCNo1
02-05-2008, 12:18 PM
A couple times in the past, our raw water pump impeller was worn, causing it to squeek and changing the impeller stopped the noise.:twocents: It may be worth a try.

bbeach
02-05-2008, 12:31 PM
I change my impeller every season anyway. IMO there is no reason not to when its a $28 part and it can just as easily fail anytime.

JLeuck64
02-05-2008, 03:19 PM
Hear (shameful pun intended) is the way I try to figure out a squeaking belt or accessory.

Try removing one belt at a time and start the engine after each belt has been removed. The belt or the accessory being driven by the belt that is noisy will stop making noise after the belt has been removed.

If you don't mind spending some dough, pick up a pair of inexpensive mechanic's stethoscope. You can also listen to all the accessories one at a time while the engine is running. That way you would not need to remove the belts at all...

If all the belts have been removed and you still hear some squeaking noise, check the distributor. I have run across one or two with worn bushings that squeak just like a belt sounds...

flipper
02-05-2008, 03:39 PM
Hear (shameful pun intended) is the way I try to figure out a squeaking belt or accessory.

Try removing one belt at a time and start the engine after each belt has been removed. The belt or the accessory being driven by the belt that is noisy will stop making noise after the belt has been removed.

If you don't mind spending some dough, pick up a pair of inexpensive mechanic's stethoscope. You can also listen to all the accessories one at a time while the engine is running. That way you would not need to remove the belts at all...

If all the belts have been removed and you still hear some squeaking noise, check the distributor. I have run across one or two with worn bushings that squeak just like a belt sounds...


You can also use a screw driver or something for a stethoscope.

TMCNo1
02-05-2008, 04:01 PM
You can also use a screw driver or something for a stethoscope.


A long wooden dowel works well.

Prostar Rich
02-05-2008, 04:41 PM
Hear (shameful pun intended) is the way I try to figure out a squeaking belt or accessory.

Try removing one belt at a time and start the engine after each belt has been removed. The belt or the accessory being driven by the belt that is noisy will stop making noise after the belt has been removed.

If you don't mind spending some dough, pick up a pair of inexpensive mechanic's stethoscope. You can also listen to all the accessories one at a time while the engine is running. That way you would not need to remove the belts at all...

If all the belts have been removed and you still hear some squeaking noise, check the distributor. I have run across one or two with worn bushings that squeak just like a belt sounds...



1990 Prostar 190 has one belt. Use a screw driver up against the alternator to hear if you have a bad bearing as others have mentioned.

Prostar Rich

rob935
02-05-2008, 07:01 PM
could be all or any of the above but check all your pulleys for rust which may cause the belt to slip even if the tension is correct , i had thid issiue last year removed and had them blasted and rechromed worked a treat.

learjet2230
02-05-2008, 07:41 PM
Could be either water pump as well. That is probably a Johnson raw water pump, and I cant remember if it is a bearing or a bushing. One way to isolate is start it with no belt. If it still makes nose then it is probably that. If not put belt back on, if it is back, spin the circulating pump (upper), by hand and see if it is dragging. You also might be able to spin ALT by hand and see if the bearing is smooth as well. My bet is either ALT or Circ. pump. Skidim has the circ pumps for 119$. Best price I have found anywhere. I just did mine, and if ya need help PM me.

Rallyspitman
02-06-2008, 03:46 PM
I had this last year on he same boat. Belt slips - squeaks - deposits rubber on the alternator pulley. Tighten belt. Belt still squeaks due to rubber on pulley, slips again then starts to burn up and be ingested into intake. I get mad and swaps belt in middle of lake. Squeaking stops, and is OK for rest of wekkend, then boat goes into storage... Just noticed this weekend that belt has gone soft, stretchy and is smoking at low revs, so 've tightened up but I'm not happy. I think it's the rubber on the alternator pully generating a lot of heat and overheating the belt. Plan to clean up the pully and replace (5 hour) belt again!

Might be worth a try!

KHall
02-06-2008, 07:39 PM
Also might look for worn pulley v grooves. If the belt is "bottoming out" as in the narrow part of the v touches the bottom of the pullet then, pulley/balt are worn. The belt must ride on its sides only for full grip.