Coolant leak from Cummins QSB 380

[buddymac]

Last winter when checking the 390 DA, I noticed antifreeze coolant in the bilge on the port side. There was no sign of where it leaked from. The amount was approx 1 quart. In the great white north last winter, it got down to -25 Far.
In the spring, I topped up the coolant a little bit and had no problems all summer.
I checked the boat again last weekend and again there was about a 1/2 a pint of coolant in the bilge and the temp has been down to about 5 Far. Any thoughts on what causes the coolant to leak out when cold?

 

[bmac]

Are you sure it's your engine coolant and not the anti-freeze you winterized with?

 

[buddymac]

Brian,
It is definitely engine coolant.

 

[alnav]

I get a periodic but very slow leak on my port QSB 425 that seems to be seasonal as well. The leak is from the coolant hose leading from the turbocharger to the large metal pipe under the heat exchanger at the hose clamp to that pipe. It's about the only location where a coolant leak isn't obvious; I would guess you might have yours from the same spot. I suspect thermal expansion and contraction would be the cause. Try tightening up those clamps.

 

[sbw1]

Have friend with a new Hatt who had a similar problem. Turned out to not be a leak. His container of spare coolant tipped over and leaked into the bilge. Probably not your issue but worth a look.

 

[fwebster]

Tighten each one of your hose clamps and while you are doing it, check all of them for corrosion on the underneath side....the band clamps frequently rust enough to get thin and break.

 

[buddymac]

Thanks for the tips and advice. I will check these.

 

[Skuza]

Not a diesel but I noticed some orange in the bilge also this last weekend. I figure a mere ounces but a little laying next to the stringer. Levels were all good and exchanger was still full to the cap. Felt a little wetness at one of the main hoses to water pump connection. I too figured its just an expansion/contraction thing and just enough to leak. Only on the stbd motor. Have to remember to tighten it come spring. I hope it's not the water pump or anything else! Just changed the pumps 3-4 years ago.
Come to think of it my summer toy '96 Vette occasionally would weep from the lower Radiator hose over the winter. Come summer wouldn't see a drop.
Hope we have eased each others minds! I HATE leaks!