3306PC Coolant in Sump

1. Most likely place is the water pump. clean the weep hole and see if it leaks externally. Easy fix to replace water pump.

2. Oil cooler. Probably have to remove and examine it. Easy fix to replace oil cooler.

3. Liner seals . Not so easy but fixable.

Easiest way to check is to drop front of pan and look up into crankcase while pressure testing but may not be possible on a boat engine. Good Luck.

Thanks Jake, my money is on a liner seal. You are right about the pan, probably impossible to get off with out jacking up the engine. It would be nice if it was the oil cooler.

Just to draw a line under this thread. The engine was raised and there were signs of rust at the base of the number 1 cylinder lining. All liners pulled with a fair bit of pitting and some seals shrunk. Fortunately the block and crank was good, even the pistons! All parts still available from Caterpillar so a happy ending.

Thanks again for your help.

thanks for the follow up Waltini...i like stories with a happy ending:love:

-you might be good for another 40 years!

Caterpillar coolant additive [red beet juice] would have prevented that pitting. Add two quart on annitial fill then every 250 hrs add another quart.