[davegonz]

I have been trouble shooting a loud squealing sound that looks to be originating from the alternator. I have been calling around getting prices on alternators and they are all over the map. Advance has a couple ($35 World Wide brand, $29 remanufactured, and a $125 Beck/Arnley). Cummins had one (have to order) for $186. Napa had the Wilson for $209 (heavy duty line according to them).

I want to zero in on the problem, but don't want to buy a $200 alternator and find out it wasn't the root cause. Should I just buy the cheap one and see if it's the problem?

 

[DarylB]

Take the belt off and spin the alternator. Feel for a rough bearing - you might just need a bearing. Probably $40 fix if you've got an alternator shop or even cheaper if you get the part and do it yourself.

 

[davegonz]

I'll try that tonight. The problem only arises (squeal) when I turn on the AC and hit the throttle. I redid the whole AC system and it now blows cold, but the squeal is still there. The compressor is driven off of a double pulley on alternator. You think it's just stressing the alternator bearings everytime the AC comes on?

 

[BobS]

Check your belt for wear and alignment and the tensioner spring. Which alternator are you running?

 

[davegonz]

Well, I put a long socket wrench into the square hole of the tensioner and turned on the truck....the squeal stopped when I added some tension. I am in process of loosening up the tensioner mounting bolt and adding tension and retightening it. Let's hope it works. Are these adjustable or do I have to replace it?

 

[BobS]

Additional thought; do you have enough surface contact between the belt and the pulley that is slipping? The tensioner is normally a unit replacement item.
There might be an experimental fix for your situation. You may be able to relocate the untapped tensioner bracket hole and gain the amount of tension you need for your custom set up. In other words your problem may be with your belt routing and when you manually tension the belt you actually may be adding surface contact to the slipping pulley. The tensioner may not be bad. I probably made that about as clear as mud??

 

[my96z]

Additional thought; do you have enough surface contact between the belt and the pulley that is slipping? The tensioner is normally a unit replacement item.
There might be an experimental fix for your situation. You may be able to relocate the untapped tensioner bracket hole and gain the amount of tension you need for your custom set up. In other words your problem may be with your belt routing and when you manually tension the belt you actually may be adding surface contact to the slipping pulley. The tensioner may not be bad. I probably made that about as clear as mud??

I had the same problem. Mine was the fact that when the A/C and the electric cooling fan was turned on it put a huge load on the alternator and I didn't have enough belt touching the alternator. I relocated the alternator to the drivers side of the engine and am running it with a v-belt from the fan pulley. My squeal is gone. and in the place of the alternator I used a Cummins 8 groove idler pulley to keep enough belt on the water pump.
http://web.mac.com/my96z28ss

I will try to get some pictures of the new alternator location posted in the next few days.

 

[davegonz]

I see what you are saying...basically take the one hole that is not used and tap it...You can see it better in this post.

http://4btswaps.com/forum/showthread.php?t=1390

Additional thought; do you have enough surface contact between the belt and the pulley that is slipping? The tensioner is normally a unit replacement item.
There might be an experimental fix for your situation. You may be able to relocate the untapped tensioner bracket hole and gain the amount of tension you need for your custom set up. In other words your problem may be with your belt routing and when you manually tension the belt you actually may be adding surface contact to the slipping pulley. The tensioner may not be bad. I probably made that about as clear as mud??

 

[BobS]

Well, lets add a picture to help explain what I'm trying to say. I the picture you will see the rear of the tensioner bracket with a tensioner mounted. Notice the radius I drew from the threaded mounting bolt to the two holes. Some brackets already have two holes for the tensioner spring to hook into. All you would need to do is plot the radius that I have drawn then add an additional spring hook hole which can be placed to increase the loading on the tensioner spring.

 

[davegonz]

Got it...looks easy enough to try out.

 

[davegonz]

Well, I sheared the detent boss in the back of the tensioner. I was tapping it into the new hole location when it sheared. Any good source for these?

 

[mcinfantry]

i bought mine for 145 iirc at an equipment dealer. worst 145 you ever spent?

remember a 4bt is opposite tension of a 6bt.

 

[davegonz]

Ouch...well, I need to get my truck back on the road today. Let's hope I find it cheaper here.

 

[davegonz]

No luck so far. I checked on one for a Dodge CTD, but the boss is on the wrong side.

 

[BobS]

Do you have a part number on the damaged one?

 

[davegonz]

I found one BOB...at NAPA of all places. The number on the existing one was a Dayco one (Goodyear as well). $119. They also had the serpentine belt.

 

[BobS]

Good job! Do you have the part numbers, NAPA & Dayco for future "Sticky" references?

 

[davegonz]

Yep..38504 is the napa number for the tensioner and the belt is 080537. Napa rocks.

 

[BobS]

Saved in the "Topic Index" Sticky - Thanks Dave bounce

 

[davegonz]

Glad I can finally add some value to this great site.