Hey guys, previous owner removed the air pump on my car. There is only a single belt for the water pump so it is squealing pretty bad at high rpm. I searched and the common solution suggested is to get a set of dual sheave pulleys from a place like Racing Beat.

However this underdrives both those accessories which, to me, seems like a bad idea in a street vehicle and Racing Beat says to not use them on a vehicle that is used in stop and go traffic. I could put just the alternator pulley on but the alt is already weak and I don't see any reason to weaken it further by underdriving it.. or deviating from factory spec in this respect. I'm not going to add the air pump back but is there any reason the FC3S doesn't have an idler pulley option like is common for the FD?

Do I have other options for preventing water pump squeal?

Thx

edit: of course after days of searching I find the banzai racing dual alternator pulley that doesn't underdrive the alt and lets me get two belts on there... right after making this post. Google Search is learning apparently

they have a different kit for the FD alternator so I need to confirm which one I have in the car because I think the previous owner had it switched over

 

Snap a picture of the plug that clips into the alternator, post it up, we'll be able to tell you what alt it is

Also, the only difference between s4 and s5&6 is the diameter of the inner hole on the pulley, and the plugs

 

I recall S4 and S5 both being 17mm, FD is 19mm.

Regardless, the dual sheave belt is the way to go.

 

It can't underdrive the accessories if the original pulleys are still on there..
The Waterpump is not able to keep up with the belt as it is being hindered by the cavitating flow of the Coolant.That is due to ONE belt driving the waterpump now instead of two due to your air pump removal.
That is why most guys solve that by using the 2 belt alternator pulley.
The engine doesn't need an idler pulley system if everything is stock as adjustment of each belt could be made by the air pump adjuster and the alternator adjuster brackets.
By eliminating the air pump you now rely only adjust 2 same belts with the alternator pulley bracket adjuster.

 

ya your right, my bad, I thought s6 and s5 was 19mm

 

It is actually a rebuilt FC alternator with higher amp output, confirmed with the previous owner. So I ordered the FC dual sheave pulley.. then an oil catch can because the purge valve was simply removed and the crankcase vented to atmosphere = vacuum leak

next will be some minor tweaks to fix the windshield relay cluster and the passenger side power window, which I believe are explained already

thanks dudes!

 

FD is 17mm , the S4 & S5 are 15mm

FC has a spacer behind the pulley, FD has the spacer built into the pulley.

Pulleys & Belts (86-91 RX-7)

 

Thank you for the correction, I was off by 2mm