Can't get to top water pump bolt - HELP!

[rgnprof]

Changing the water pump on my '91 300CE with the M104 motor. I have everything out of the way, and I think 3 of the bolts are fairly accessible (There are 4 bolts, right??), but I can not figure out how to get to the top rear bolt. It's a 13 mm bolt and I have a 1/4 & a 3/8 13 mm flex socket, but I cant get to it. It sits right under the intake manifold (which I really don't want to remove!). I can't even see the thing w/o a mirror!

Any help?

Thanks, Ryan