Replacing zincs in HX

[guylogan]

Just read that this is a annual job.. been two years since install of new MMI engine with new block and have enjoyed the pleasure of instant start and smooth running. So I think I should also remove both the top and bottom covers of the HX, the question how many gaskets will I need. There doesn't seem to be any exploded HX diagrams. Also do I need to refill the raw water
when I'm done or will the pump do it.

[edwardc]

There are two gaskets at each end. One is a large flat rubber disk that seals the end cap. The other is a small O-ring that seals the central bolt that holds the cap on.

Usually, debris piles up at the lower end, including spent remains of the zinc. The job is easiest if you can remove the HX. A straightened piece of coathanger wire can be used to rod out all the individual tubes.

A clean HX should have a raw water flow around 3 Gals/minute at idle, and around 6 Gals/min at 2000 RPM. Measure it by catching the output in a cutoff gallon jug and timing how long it takes to fill. This gives you seconds/Gallon. A little math can turn this into Gallons/minute:

60 divided by Sec/Gal equals Gallons/minute

[guylogan]

Thanks just what I needed to know, I'll now order the parts from MMI