Qsb 5.9 belt squeak at startup

[Joe Palermo]

I’ve read the other posts here on this topic with no luck. Every initial startup, the belt squeaks for 5-10min. Then no noises the rest of the day. I’ve  replaced belt, fresh water pump, raw water pump, tensioner, and alternator. I’ve noticed a lot more belt dust on that motor than the other and am at my wits end. Could the alternator be working too hard initially? It shouldn’t, as the batteries are always on the charger. I also could not find the air heater to disconnect. 

Topic

[Tony Athens]

Joe,

 

Glad you sorted out the  what belt. 

Great trick

Next–Could the alternator be experiencing an abnormal draw at warmup? 

 

100% yes, but the only simple way to know is if you are monitoring battery terminal  voltage just before turning the key and watching it after start-up/warming up

 

Say you are at 12.4-12.6-ish at the battery terminal and your cold alternator regulator set point is 14.0V.  The alternator will go to max charging as is can based on the alternator RPM and voltage difference the sensing terminal sees.  Belt squeal can be common in this scenario .

Are you use a genuine Belt? All the pulleys are clean deep in the grooves?

 

 

[Joe Palermo]

Alternator

I did the brake cleaner and tensioner trick. It is definitely the alternator. When I bought the boat, this motor had the same problem so I replaced the tension pulley, belt, and the alternator (wanted a spare anyways). It didn’t touch the issue. Could the alternator be experiencing an abnormal draw at warmup? 

[Tony Athens]

Never tried this that way– If it really can isolate it, this a simple & great idea.

 

How we usually go about it– 99% it is usually the alternator belt 

With the belt guard off push on the spring tensioner to tighten the alternator belt at idle– That will tell you 100% –Spring tensioners do loose their tension over time and the swivel part gets stiff too

[Fireisland1]

First thing is to figure which belt is the troublemaker. I use a bit of brake cleaner. [ very little ] Spray it on either belt when squeaking. That will eliminate the good belt. It evaporates quickly . If it’s a serp belt , the use the extender tube and spray just on the inside. If it doesn’t go away it’s an outside roller. 

[Joe Palermo]

Serpentine

Serpentine. Appears to be coming from alternator side. 

[Corey Schmidt]

Are you talking about the “serpentine” belt or the seawater pump belt?

[Author]

Replies