randy carlson

Just finished disassembly of my two Mark 4 502"s. 700 hours pulled apart for comfort. Running fine no oil usage. I put 500 on them, found light piston scuff 1 eng 1 bank, second engine all cyl light piston scuff, rear main to babbot, three aft cyl cam lobes ready to go,valves showed like hotter. pulled some freeze plugs to try answer questions, found sand trapped built up on the bank with scuff and entire block second eng but really bad at the back. All head steam holes also plugged up. All sand was old and had been there a while. do strainers help stop sand? any freeze plugs that have big drain in them for better flushing at aft end. I pull block drains each fall and run eng during winterization but aparently thats not enough. have never lost an impellor do to sand. what more can I do? never had an indication this was happening dont want it again with fresh motors

Young Performance

The average strainer will not catch sand. The holes in the strainer basket are way to big to catch sand. Hardin makes a sand strainer for intercoolers, but I don't think it will flow enough water to cool a motor. I would think that the strainer would have to be huge to catch sand and not clog up, preventing the motor from getting water. Sand is bad, but no water is worse.
Eddie

jeff1000man

You could try 2 strainers in a row. Never tried it but if you keep changing the direction of the water swirl pattern as it goes through the strainers than gravity could cause it to settle at the bottom of the strainer.

Just an idea. Never tried it or even thought about it until now.

You could go closed cooling and run antifreeze. THen sand only in the radiator.

You could go to low water pick ups on the hull instead of through the bravo drive. THat would make it harder for the water inlet to come into contact with the sand.

Quit beaching the boat with the drives down. ( just kidding, we know you wouldn't do that).

Good luck. That was all I could think of at the top of my head.

Good luck, and let us know what you figure out.

Hardin Marine

In reference to Eddie's response he is correct. I want to clarify some of what our sand strainer is capable of. The unit itself "WILL" flow enough water in a unclogged/unpacked condition. The down fall is that in the event that it was not monitored (It does have a pressure port to monitor) and the unit was allowed to actually pack solid with sand a 3/4" bypass port is pressure actuated. At this point the bypass allows water to continue to flow but like anything that is clogged (even a oil filter) the water flow is greatly reduced and would have difficulty passing enough water to supply a high performance engine's cooling needs.

These units are used around the world as engine sand strainers in well monitored and serviced applications. The use of this sand strainer has saved literally hundreds of engines from Intercooler failures.