Noticed my breather tube on my reservoir was leaking today. The reservoir had about an inch of coolant left in it although the tube was still dripping coolant. The head gaskets were replaced last year and my temp gauge has never gone past the halfway mark. I took the top hose off a couple weeks ago to test a bypass flow for an external t-stat. Heard gurgling sounds in dash afterward and have been trying to bleed the system. It has gotten better but not completely gone (only hear occasionally going up hill). What may be causing the leak? If it's a head gasket I may push it off a cliff.

 

rent/borrow coolant pressure tester from parts house, pump up to 15 psi, and wait. May be around a clamp you don't notice. Here is plumbing plan.

 

It's coming out of hose #20 on the reservoir, but it's not overheating.

 

Then I would think that meens your system is being preasurized, not a good sign.

 

When you say "not overheating" - that would depend on your instruments. If all you have is the stock heat gauge, that gadget is programmed by the ECU to point at 50% until way too hot. It is a digital driven warning light with a pointer. You don't see it moving up slowly one week to the next as a problem gets worse. This operation also makes it hard for a guy to see the results (good, bad, no change) of repairs.

If you connect a scanner, or an Ultra Gauge, plugged into the OBDII port under the dash, you will have a better idea of what is going on with the temp. Rock hard hoses are also a sign that gas is entering the system, and usually it sounds like water rushing thru pipes under the dash, all the time or when the engine is under heavier load. One of those $50 ish chemical tests from the parts store ( see Head Gasket or Combustion Leak Test Procedure (Gasoline Engines Only) )
will change color from blue to green or yellow if it sniffs products of combustion in the coolant from a 2 minute exposure. Does maybe 15 tests, so can verify other repairs later.

Coolant system normally runs at 10-15 PSI when heated up, this raises the boiling point of water, plus the antifreeze you are running extends it even higher. Steam is not present normally. Being a closed system, coolant loss can be in several directions - burned in cylinders, with white smoke out the back; dribbled out of hose clamp somewhere; dribbled out of a gasket (head gasket, water pump gasket, front cover gasket, valley pan gasket, throttle body heater gasket); or into oil (makes it look like a milkshake and wears out bearing surfaces at a rapid rate).

At this time of year, the choice to replace head gaskets yourself with $300 in parts and some machine shop service, in an unheated garage or outside in the yard might be delayed by use of a product like KSeal. This sort of product seals up small leaks. It can also seal up small openings in the radiator, so if rad is sludged up it will make matters worse. Normally used when all else fails, or when you have to limp back home and are planning engine work anyway. An aveage DIY guy can do the head gaskets over two wekends, with about $200 or so of machine shop work inbetween to plane the heads. There was one guy who inquired on here about the flatness specs, which I sent him about lunch time. By 4 or 5 that afternoon he had the heads off and milled. But he worked in engine shop that handled big truck engines. I'd still have been looking for all my sockets...

 

My reservoir did the samething. Found crack in the plastic between over flow hose and inlet hose fittings. Replace reservoir with new cap, problem is gone.

 

Don't stress replace you cap its probably shot.

 

Phew! New cap and no leaks. Took about a half gallon of distilled water to top it off. Drove it around for 20 minutes and no sign of leakage. Nice ending to a hellacious week. Since I got the day off tomorrow I'm going to flush and refill the system with Peak and distilled H2O since the mixture is definitely off now. Thanks for reminding me to KISS!

 

I missed that important point that it was venting coolant, either from too much pressure (really expensive to fix) or just a worn out cap. One issue with a dead cap - was it because you are running Dexcool coolant, which can clog up the rest of the cooling system. If so, time to flush and go green.