'01 LB7 Leaking coolant through breather hose

[BenW]

Has anyone noticed coolant coming out the breather hose which extends from the top of the engine down the right side? I can't seem to find this hose on either of my other two dmax's. Water pump and t-stats were changed last fall. Coolant leak began earlier this summer and is progressively getting worse. Truck has 97,000 mi on it. Any advise would be great.

[DmaxMaverick]

Welcome aboard, Ben!

Breather hose??? There are only 2 of these on an '01 Duramax, and neither have anything to do with coolant. The location you describe might be the turbo coolant return line. When they leak, it's usually the rubber hose connection behind the fan pulley. Although, it could be chafed or otherwise failed anywhere between the stat housing and the turbo. The "breather hose" at the front/right of the engine that extends down is the crankcase breather. If you have coolant coming out of that one, hoo-boy! If you are referring to the air intake breather, same thing....Hoo-boy. Coolant doesn't belong there, either. The only other place you might have coolant on that side of the engine could be the coolant storage tank, or its hoses. It has a breather, but it is attached to the tank, not the engine. If you are puking coolant from there, you have coolant system pressurization issues (most often head gasket).

[BenW]

Thanks for the reply. I would think this would be the crankcase breather. It originates from both sides of the engine, tees, flows though a small tank of some kind, and then down around the transmission cooler lines. It is definately not coming from the overflow hose on the coolant resevoir. I suppose I should say that I have not actually seen the coolant flowing from this breather hose, but the location of the puddle and gunk around the end of it led me to think this is the point of origin. I'll do some further investigation. Is it possible for coolant to puke out this hose? There are no visible signs of coolant in the oil. Oil level is consistent.

[DmaxMaverick]

The coolant can't leak out the crankcase vent pipe unless something is REALLY wrong. You'd know it, without a doubt.


You'll have to find the origin. Start by looking at the turbo coolant lines, and go from there. If there's any coolant leaking into the engine valley, it will run out the rear area of the engine, like you describe. If it's been leaking for any length of time, the coolant will leave a residue that's pretty easy to identify.