I can't seem to post replies with quotes...

Shern, Frank and Vox_incognita, thank you for the advice on the flow restriction. I think this is definitely the case!

I went ahead and ordered a fancy-schmancy MB thermostat to replace the aftermarket one. Will throw that in as a next step.

Here are a few photos of my water pump install. This is the "old" one, which came out looking pristine. Someone else was trying to solve this problem it appears!



Here is the pump housing. Does this look trashed enough to reduce flow? While its a little scored it doesn't seem terribly bad.


And here is my new pump install. Standard pump and gasket from Mr. Kent himself. Anything look suspect?


One thing I notice is that my car doesn't have the banjo bypass tube. The plugs look factory though...maybe this is an '85 thing?