What is going on?

By Clinton HulleyVW Polo Classic Project Car
Thinking hard
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It is now been a few months since the bigger crank pulley was fitted to the Polo. I started hearing some funny sounds. It was mainly when I got to the point that the supercharger kicks in. You would hear like a knocking sound. It started as a faint sound but as time went by it got louder. I had the bonnet open on numerous occasions but could just not work it out.


What sound is that?

I decided I am going to do some preventative maintenance on the Polo. Rather do this before something breaks and then it is a big job to fix the car. I knew it must be something around the charger setup. It only makes the knocking sound when the charger clutch engages. The biggest problem was, it was such a compact installation. I had to start at the top and work my way down.

What could the problem be?

I had to strip off the plenum box so that I could strip off the intake manifold. After that, I could get to the charger mounts. The funny thing was that I tried to move the supercharger on its mounts and it was solid. I stripped it off in any case. I was amazed when I found the problem. The mounting setup that I made for the supercharger is not strong enough, especially after I turned up the boost. What I have read in my research was that superchargers could pull over 50Hp from your crank power. That could put a bit of load on the belts and mainly on the mountings.


Why is the charger moving?

As my top charger mount and bottom charger mount was individual mounts. It kept the supercharger solid in position. When the supercharger clutch started engaging at higher RPM’s the load caused the supercharger to shift. At first, it was only a small amount. As time went by the bolt holes in the bottom mounting ears of the supercharger started going oval. This made the amount it could move under load a lot more and causing the knocking noise to be louder.

Removing the Supercharger.

At this point, I needed to get the car running again. I decided to take the supercharger setup off the car until the mounting is sorted out. The engine was not in too good condition anymore as well. I ran this engine for approximately 5 years with the individual throttle body setup. This was without any air cleaners, so imagine the wear. I decided this is the last for this engine. I just got it running as a naturally aspirated car. It still had the individual throttles, 272 deg cam and the low compression of 8.5 to 1. The Polo wasn’t that powerful but it took me from point A to B. The oil consumption at this stage started getting high.


I didn’t want to take this engine apart and rebuild it again as I couldn’t afford the downtime. I started scheming what is the next step, how am I going to get more power…


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