Whipple Supercharger W140AX Sight Glass Cleaning

I usually change my supercharger oil whenever it turns really dark.
The last time I changed the supercharger oil I noticed it was getting hard to see the oil level through the sight glass.

... this time when I went to change the oil, this is what i saw

I could not see anything at all, even in bright sunlight and using a flashlight all I could see was blackness. The supercharger gear case could have been empty for all I know.

Not knowing the proper way to clean that sight glass or even if I could remove it or not, I did not want to risk damaging anything or risk knocking my car out of commission so I decided to contact Whipple Superchargers and ask them what I could do.
Their response was:
"You can unscrew it to clean it. There is an o-ring seal behind it that is reuseable. You will need a 23mm socket and it will need to be ground or machined down to clear the cover."

They are right about the clearance issue, none of my 23mm sockets would fit it, and I did not want to mar it or risk stripping the nut with pliers or a wrench. The sight glass looked like it was made of aluminum and expensive to replace too.

I then went out and bought a cheap 23mm socket to grind down... I did not take any pictures of the unground socket but I'm sure you all know what a normal socket looks like.

But a ground socket looks like this

I think i did a pretty good job, though there is a slight taper to it probably due to my lack of grinding skills...

... it still works though, thats all that really matters.


I decided to measure the outside diameter of the ground socket

The diameter of the ground socket came out to around 1.151 inch.


Now back to the supercharger, not knowing how much oil was in the supercharger I decided to drain it all using a very crappily made suction/vacuum thing.

Removing the oil fill plug was probably the easiest step

I noticed that the o-ring seal was cut by the threads.

I will probably have to replace that o-ring sometime in the future


In goes the suction hose and out comes the oil

After all the oil was sucked out, I replaced the plug due to it snowing a bit outside and I did not want anything getting into the supercharger.


Now it's time to remove the sight glass with my newly ground 23mm socket.

It came out rather easily.


It looked dirtier that I expected

There was black film of something sticking to the inside of the glass...

You can sort of see through it if you brought it up to the light.


But if the background is dark...

A view inside

Dug out an old can of carb cleaner to wash the sight glass off

It takes a lot of carb cleaner to spray all the grime off both sides of the white plastic part

Finally it is clean

Time to screw the sight glass back in

Not too tight due to the aluminum threads and o-ring seal

This looks almost like new

I refill my supercharger with GM Supercharger Oil

Filled to the halfway point according to the manual.

This is what it looks like with the engine running.