question on engine fan nut/shim

[rnln]

Hi,
I usually have the fan belt on the loose side to save the fan bearing, while most of my friends have it on the tight side. Usually, I have around 3 or 4 shims on the inside of the nut, and the belt can easily be push in more than 1/2 inch with my index finger. This loose belt makes it's so hard to turn the crank sharp.

I am doing my valves adjusting right now and decided to tighten the fan belt beside taking off all spark plugs to make it's easy to turn the crank sharp. Yes, I can now turn the crank without any problem at all. What I have now is no shim on the inside at all. All shims are on the outside. The belt is tight. I can push it in only around 1/4 inch with both fingers, but lot more effort.

Question, is it a good idea to have no shim in the inside, and the belt is kind of tight?

[James Brown]

"This loose belt makes it's so hard to turn the crank sharp."

not sure what that means but loose would be easer to turn th engine over. i finger about 1/2" is about right. Maybe 1 shim inside

[Discseven]

Rnln,

I don't think shim placement matters... rather it is the tension of the belt that would matter. I also have about 1/4" deflection with a hard push on the belt. Have always run my belts this way over 30 some years in my Pcars and never had any belt or bearing problems that I know of.

I also set a new belt up very tight initially as after a few miles... they'll stretch out. By setting a belt up over tight initially, there's no need to return and make a later adjustment.

[rnln]

James Brown,
Using a 24mm wrench to turning the fan nut turn the crank sharp to TDC. If belt is loose, you have to push on the belt while turning the fan nut to be able to turn the crank sharp and it can be very hard. If the belt is tight, it can be easier.

ah, I can see why engine turns over easier when having loose belt. Thanks.

Discseven,
Placement of shim\s determines belt's tension. The more you have shim\s inside, the more room you have for belt to come down, loose belt. The least you have the shim\s inside, the higher the belt is pushed up, tighter the belt (more tension)

What do you guys think about cooling? Does it make sense when I say loose belt may affect cooling to the down side, and tight belt will make it better for cooling? I think this makes sense, but how much does that affect in reality?

thanks guys.

[KNS]

The belt you are using also matters. The Conti belts are a slightly wider than the genuine Porsche belts.

[Canada Kev]

In my opinion, having a slightly looser belt (1/2" deflection) won't affect cooling significantly. It does make it more difficult to turn the engine over with the pulley nut. On mine, I just squeeze the belt together with my other hand when turning over.

I can't say I'm a fan (pun intended) of setting a new belt up overly tight just to avoid re-shimming a hundred miles later. It's really just not that big of job to retention the belt. I think I'd prefer to spend ten minutes to do this than have a stressed alternator.

[Drisump]

Even if the belt is merely on the tight side with no shims between pulley halves, I'd probably replace my belt. The belt will loosen a little bit with a few miles on it. But I guess it depends on how you use the car, I go on trips that are thousands of miles long and don't need that minor pain. I generally shoot for the recommended 1/2" of deflection. If the belt is doing it's job at 1/2" (turning the fan and alternator properly), why put more stress on the bearing and belt by increasing that tension? Cheers

[James Brown]

ok i understand now, thanks

[rusnak]

Either push the left side of the belt while turning, or squeeze the belt together with your hand in order to turn the crank. No need to move any shims.

[T77911S]

its push in on the right side while turning the crank CW. belt does not have to be tight to do this.

[rnln]

saying 1/4" or 1/2" might not be that accurate, but let measure it by turning on the engine and let it idle. Belt tight at 1/4" movement, when engine idle, the belt is turning in straight line. At 1/2" movement, belt will turn in not perfect straight line.