Marsolve sells their product in large quantities to commercial users and is not
known for being extremely responsive to one or two gallon users.

That said, Marsolve (and Ryd-Lyme, a similar product) are well thought of by
the community of raw water cooled engine users.

I have used oxalic acid myself, but Marsolve is reported to work as well or
better, and do so without loss of metal.

Anyone tried it? I have a question in on their web site but they don't seem
to want to answer it.

Let me poise the question to the group -

I have a 50 hp fresh water cooled diesel that is beginning to run hot. The
engine temp seems to be creeping up to 200 F at cruising speed with salt
water temps in the 60's. Used to run at 180-185 with water temps of 80+.
Water flow out the back seems less then expected and has been going down
over the years even with a new raw water impeller-pump.

Without pulling the heat exchanger, exhaust elbow, and hydro lift out can
Marsolve clean up the system? Marsolve is $20 a gallon and I am willing to
pay vs having to pull the heat exchanger and elbow. (need to pull the heat
exchanger to get enough room to get the elbow. In fact I might need to pull
the exhaust manifold)