I had to open up the supercharger cooling system to get to one of the lower hoses in the group of coolant hoses and now I want to top off the S/C coolant system. Is there a special tool to open that plug on top? Or should I look for a giant size allen wrench?

 

I made my own using a bolt & two nuts. You need a 19mm hex head which is the same as a 3/4" headed bolt. Took a bit of heaving but I eventually got it open.

The other way to do it is lift the front of the car, either on ramps or a sloping driveway that the radiator reservoir is higher than the fill/vent port & then it isn't necessary to get the plug open as it's no longer the highest point in the system.

 

you can also buy them to fit a socket set handle. I got a set for the bike. I would expect any major tool merchant to have them. If not try a big bike toyshop.

 

Another tip, the back of a cheep spark plug socket has a 19mm hex
Just drill a hole in the socket and use your breaker bar

I did this before I worked out the car on a set of ramps is just the height needed to fill without removing the plug

All I do now is put on ramps, remove the bleeder from the reservoir and fill.
Once you have it full run the SC pump (ign on but engine not running) for a few mins.
Replace the cap an bleader, idle up to temp and allow it to cool
Top up as needed

Never, Never, Never run the engine with the cap off

Cheers
34by151

 

Boy i know what the manual says, but in the real world if you open the vent on the reservoir theres no need to ever remove that plug. The 4.2 is not a air trap engine as long as the vent air bleed is removed. Sc or na. And if you have a vacuum adapter to fill will coolant even better. In 15 yrs ive never ever removed those plugs and never had a air lock. And for those that miss important words. when i remove the reservoir air bleed when filling, there's no need to remove that plug on the SC

 

My local jag place also don't open that. I found out when I asked to buy the seal and the parts guy not only didn't have any but said they never sell 'em, and then explained why. He's great!