Help! Water pump to crank belt too loose??????

[vetdaddy]

I noticed the water pump to crank belt on my 1972 454 A/C car was loose.
I have read that this is supposed to be a "direct fit" belt only installed by removing the water pump pulley.

There is a idler pulley next to this belt that is supposed to sit to the outside of the belt but not apply tension to the belt. This pulley seems to function as an outer guide for the belt.

I ordered a replacement belt labeled for my engine with A/C and it is the same size as my original belt that is too loose.

Sooooooo my question:

1. Is the idler pulley in this car designed or intended to tighten the water pump to crank belt? or........

2. Is the idler pulley only designed as an outer guide to the belt offering no tension to the belt?

3. Am I missing something here such as wrong belt sizes? My water pump pulley, crank pulley and idler pulley all appear to be original and stock diameter.

Any help would be greatly appreciated, Scott

 

[bill81vette]

I am guessing this is a 'v' belt??
however,I have never seen a v belt go on where there isn't some sort of adjustment.....
e.g. alternator,A/C compressor or power steering pump.
perhaps it isn't the correct belt????

 

[TimAT]

My 69 BB (no a/c) has that belt. No idler. The only way to replace it is to pull the fan and water pump pulley. It's a Dayco part number 15325. Probably not the correct number for your car with the idler, but might get you in the ballpark too.

 

[vetdaddy]

Bill- Yes, it is a v-belt. I agree that it is strange for a v-belt to be used where no adjustment is possible.

Tim- So the belt on your 69 BB is a direct fit only installed by taking the water pump pulley off, maybe I need to take my belt to a local auto parts store and try a belt slightly smaller. Sounds like I need a belt "difficult enough to install so as to be tight enough."

Thanks for your help, Scott

 

[TimAT]

Don't get a belt that's too short- it'll EAT the water pump. Don't ask!!

I have 3 belts- water pump to crank, crank to water pump to P/S pump, and P/S pump to alternator.

 

[72VETTE454]

Same set up on my car. There is an adjustment on that idler pulley. I may be able to get a picture.

 

[72VETTE454]

Here are a few pictures of my idler pulley and bracket. It's currently not on the car, along with the belt or the A/C. The first pic shows the adjustment slot, second shows how to access the lower bolt through one of the pulley holes and the third just shows the water pump stud attachment. You can't get to the water pump stud nut through a pulley hole, but it's easy enough with an open end wrench. If I remember correctly when I replaced that belt on mine a while back, I still had to remove the water pump pulley. Good luck .

 

[vetdaddy]

Tim and 72vet454,

Thanks for the replies, it really helps to talk these things out. I was thinking about a tighter belt and can understand now why that would be a bad idea (see- i did not ask!!!).

Tim- I have the same three belts, with an additional belt for the A/C compressor....so my water pump puller has three grooves.

72vet454- are you saying you are running without the water pump to crank belt and without the idley pulley? Although all will function without that belt, my understanding was that the purpose of that belt was to give the water pump pulley more support (more support from the crank).

 

[72VETTE454]

Right, I am currently running without the crank to W/P belt, idler pulley, A/C and A.I.R. My understanding of the belt setup on that engine was because of all of the extra accessories: A/C and A.I.R system. I am only running with power steering and alternator. So I have one belt from crank to W/P to P/S. And a second belt from P/S to alternator. Hope that helps.

 

[vetdaddy]

That makes perfect sense, thanks. BTW- nice car!!

 

[73shark]

The '73 AIM shows an adjustable idler used to tension the crank to water pump belt.

My friend's '66 427/425 just has the crank to wp and crank to wp to alternator belts. And yes the first one is tough to get on. I'm guessing that someone finally convinced the bean counters to spring for an idler.

 

[vetdaddy]

72shark- I have to agree, I am going to stick with the stock/OEM belt size. I did find out that the belt size for A/C and non-A/C cars is the same, eventhough some parts suppliers list them separately.
The idler pulley has to be there for a reason........sooooooo.......sometimes looking for answers on the the internet can steer you away from common sense..........that's all I know about that!!!!

I really appreciate everyone talking me through this one....informative ane therapeutic!!!