Replaced belts, eyeballing tension which is better? Tight/loose? - PeachParts Mercedes-Benz Forum

networkboy · #1 01-12-2008, 11:24 PM

Well...
I've been putting off replacing the belts since I got the car and finally I got that hum at idle and whiff of burning rubber that says delay no more!

So I just finished replacing all the belts (inner alternator/pump belt was the one burning). Whoever said "not that bad" must have meant to say: "Huge PITA, but very straightforward", but I digress...

Question #1: I Eyeballed the tension; is a little too loose better than a little too tight? (I think I'm a touch on the tight side, alt/AC belts about as firm as a barely ripe orange, power steering about a ripe orange).
Question #2: Does anyone in Sacramento CA have a gauge for the belts I could swing by and use?
Question #3: Anyone know the part number / price / source for the gauge?

Thanks

-nB

tangofox007 · #2 01-12-2008, 11:37 PM

NAPA sells a gauge called a Kriket that works pretty well.

Here it is:
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=NBH&PartNumber=KR1&Description=Belt+Tension+Gauge

networkboy · #3 01-12-2008, 11:46 PM

$10? sweet! I assumed they'd be unreasonably expensive...
I'll be visiting the parts store tomorrow then. We shall see how good a guesser I am

ARINUTS · #4 01-13-2008, 02:18 AM

My opinion: a little on the tight side is better.

Cervan · #5 01-13-2008, 03:59 AM

Too tight and you will put alot of load on the bearings, too loose and the belt will slip and wear quickly. trick is to get the right tension and then check it every fill up to make sure it holds that tension.

Brian Carlton · #6 01-13-2008, 09:10 AM

Nearly everyone overtighens the V-belts. They have massive capability for transmission of torque and leaving them loose won't cause any operational issues. I've got an easy 1/2" of movement in the middle of the alternator and PS belts. I won't be tightening them any time soon.

The only time that the "loose" belts are an issue is if you thoroughly soak the underhood environment and the pulleys. With that one exception, the loose belts will allow the accessories to last for significantly longer time.

Many folks suffer alternator bearing failure because the belts are too tight.

#7 01-13-2008, 09:32 AM

This tool saves (parts) lives.

Hatterasguy · #8 01-13-2008, 10:28 AM

I always tighten V belts just enough so they don't slip.

tangofox007 · #9 01-13-2008, 10:33 AM

Quote:

Originally Posted by Brian Carlton

...leaving them loose won't cause any operational issues.

There have been a number of reports on this forum of a/c compressor noise that occured when the drive belt was loose.

networkboy · #10 01-13-2008, 12:44 PM

Quote:

Originally Posted by ForcedInduction

This tool saves (parts) lives.

That tool looks like more than $10

I'll be getting the Napa one today (hopefully) and that will be good enough.
-nB

Knightrider966 · #11 01-13-2008, 01:04 PM

If you can find the widest spot in the belts between pulleys and pushing sideways on the belt will deflect it about 1/2 to 1 inch you are tight enough.
No less than 1/2 and no more than 1 inch!

The alternator and water pump belt can be on the slightly looser side but the power steering pump and AC pump should be closer to 1/2 inch.

Also, I use a little belt grip to make mine last a little longer because the dry desert heat takes it's toll on belts!

Brian Carlton · #12 01-13-2008, 04:33 PM

Quote:

Originally Posted by tangofox007

There have been a number of reports on this forum of a/c compressor noise that occured when the drive belt was loose.

I agree. If the a/c belt gets too loose, the pulley can make some racket. If it does...........I just tighten it a bit.

networkboy · #13 01-13-2008, 05:19 PM

Yeah, My belts are too tight then...
I've got to press quite hard to get 1/2" of deflection...
I'll be driving on it tomorrow, but the CarQuest will have a gauge in stock for me on the way home.