Cold Coolant Leak

[furball]

I posted this at Boatdiesel but wanted to post here as well. Thanks,

I have a 2006 Albin 28TE with a 6LP-STP. I have 360hrs on the engine at the end of this season. I have owned boat 1 year and from the start, I have had a very small cold engine coolant leak. There is never any coolant loss when running, only after a day or more of sitting. I typically found about a teaspoon of coolant on the foward starboard motor mount. I hauled the boat mid december and had the same teaspoon of coolant on the motor mount a week after hauling out. I went down this weekend and I had lost about 8oz of cooolant into the bilge. The forward bottom edge of the of the heat exchanger was wet with coolant, same place it usually seems to come from, I just don't know if that's where it starts. I placed white oil pads at haft a dozen places to try to pin down the leak. I had found a drop, once, hanging from one of the coolant hoses above the heat exchanger. New radiator cap, clamps are tight, going to switch to constant tension clamps this spring. System has vacuum as the radiator is full and the overflow res is being pulled down. This is my first diesel boat and I have had several suggestions not to worry about a small cold leak, but finding 2 cups of coolant in the bilge has me concerned. Any suggestions on what to check or do to correct this will be appreciated.

John

[Denis]

Sorry you are not getting any help here, but the problem sounds kind of strange and a little hard to diagnose without seeing it. The system is under a slight vacuum when it is cooled off and under pressure while heated up. So you would think that it would show the leak when heated up but just the opposite is happening. Is there a chance you have a bad gasket or loose fitting at or around the water pump or even a small crack in a housing, cooler or even in the block? My thought is that when the engine heats up and expands that the crack seals itself and when it cools down opens up again. Aluminum expands and contracts quite a bit, could that be possible?

[furball]

Denis, Didn't figure I'd get many but yeah, sometimes you can hear the pin drop
I need to learn something about cold leaks to start with. Wondering what's most likely to leak, a hose, gasket, or weld. I"m going to pretend you didn't say anything regarding the block Don't even want to think about that, won't sleep tonight.
With the temps dropping to around zero here this weekend I'm wondering how much more I might lose. Plan to check the spill pads to hopefully narrow the area down. Next, I think I need to pressure test the system. Pretty sure I can buy the test kit at the autoparts store. The real question is how much $$$ to spend trying to fix something that in the past has "fixed it's self". I'll let know know how it turns out.
John

[jcollins]

John,
Pressure test cold seems like a logical step. I'm not a mechanic but that's where I would start before calling in a expert. I agree with Denis to look at aluminum.
Are you sure nothng is there when it's hot? Also, it seems that you have more as the ambient temperature drops? Mid-summer it was only a teaspoon?

[Denis]

Furball, sorry about the "block" comment, I didn't mean to scare you or put a thought like that in your head. Usually when we say the word block around here it pertains to Block Island, which is our version of Heaven in these parts, so lets just think Block instead of block. Good luck, Denis

[furball]

Hey John,
I kept an eye on it all last year. As far as I know, that's when it started. Never a drop while running, checked the overflow tank before and after every trip and opened the cap every couple of trips just to be sure. Always dry when I left the boat. Come back a couple of days later and there was always a little on the engine mount. Wasn't enough to even cause me to top off the overflow tank all year. The overflow dropped an inch or so from the beginning to the end of the season, that's it. Really what I'm trying to decide is how much to spend fixing it or take my chances come spring that it won't leak. I'd hate to spend the first month of the season having to revisit this. But first thing is to find it. I was hoping someone knew the "most likely" places to start but that's just spinning wheels, I just need to pressure test it. I'll let you know what I find
John
Block Island, Block Island, Block Island........

[jcollins]

Hey John,

Block Island, Block Island, Block Island........