Perkins Heat Exchanger Refit Fall 2004:

     Pool acid removes calcium deposits in a hurry! 
Next I removed the raw water heat exchanger to clean out the calcium deposits which form in the tubes which form the heat exchanger. I replaced the heat exchanger in 1995 due to corrosion causing the salt water inlet tube to fracture from the body of the heat exchanger. I have cleaned it out periodically with Meuratic Acid (pool acid) in 1998, 2000 (kwaj), and now in 1994. In each case none of the tubes were completely plugged, however, the exit of the tubes to the exhaust were significantly calcified. This is caused by the salt water temperature exceeding about 140F which cases the calcium to deposit on the walls of the tubes significantly restricting the ability to cool the engine. The indication that this was becoming an issue was a 5-10F increase in engine temperature under heavy load (2450 - 2650RPM). After removing the heat exchanger take the end plate off, drain completely and then SLOWLY pour the Meuratic Acid into the heat exchanger. Once full allow to sit for a couple of minutes (until it stops foaming), pour out the acid and repeat until no further bubbling is observed. Pour out the acid, rinse with water and pour in a mixture of baking soda (Sodium Bicarbonate) and water to neutralize the remaining acid. Reassemble the heat exchanger with a small amount of silicone sealant on the rubber gasket and end plate threads to prevent leaking salt water on the motor mount directly under the heat exchanger


This is the bottom of the heat exchanger as it came out of the engine room


This is the top of the heat exchanger as it came out of the engine room

.Cleaned Up Heat Exchanger
 After cleaning and painting the heat exchanger looks much better!

 

Click on the following images for high resolution versions with more detail.

Open endplate of the heat exchange

The input side of the heat exchanger, as the salt water temperature is low at this end of the heat exchanger the buildup is pretty minor

The output side of the heat exchanger, at this end of the heat exchanger the temperature of the salt water is much higher. Above about 140F the deposits become severe over time

A close up of the output of the heat exchange

The pool acid dissolves the calcium deposits without damaging the heat exchanger if the acid is not left in too long


After the pool acid cleans out the heat exchanger I examined the tube stack for damage, especially galvanic corrosion. The zinc pencil in the end of the heat exchanger is there to protect it.