Air bubbles in the coolant reservoir

[iamdub]

I'm going to check it all over again, I just ordered a blackstone test kit because I suspect it's a head but it's not showing any signs other than the bubbles, oil level stays the same and looks normal, no problem other than slow coolant loss.

If it's a slow enough leak, the oil will look normal. The liquid will steam off just like normal condensation.

 

[Rocket Man]

If it's a slow enough leak, the oil will look normal. The liquid will steam off just like normal condensation.

Werd

 

[Fless]

Pull the valve covers and inspect!

 

[shegarty]

I would definitely check the rear heater unit (if equipped) and rule out cavitation on the new water pump and/or residual air in the system. You could very well be dealing with two separate issues.

 

[exp500]

It's funny how the sealed systems are so much harder for hoses to seal perfectly. A tiny leak when hot equals a little air in system cold. I think the hoses aren't as good as they used to be.

 

[MainelyScott]

Just a thought, but I had a truck years ago and the head gasket was leaking. Couldn't tell until it got bad enough to smell at the exhaust pipe.

 

[Doubeleive]

if it is a head and it's just sucking air into the coolant and not mixing in the oil then I can live with that until a deal comes along for another truck or a engine, preferably another truck. I paid $3k for this 04 about 5 years ago with 100k on it, has 240k on it now, been a good truck if I keep my eyes open I can find another one

 

[Cbncanada]

I have the same problem with my 06 yukon xl 1500. Can't find the leak anywhere. Loses about 1 litre a week.

 

[Larryjb]

A couple of years ago I had the same issue. I finally had to accept it had to be leaking internally. I put the pressure tester on and left it on overnight. I saw no drips, smelled no coolant inside, the rear heater core was dry.

I finally pulled off the valve cover gaskets and saw this in the thread linked:

https://www.tahoeyukonforum.com/threads/latest-oil-change-oil-filters.99646/page-4

It is important to note that this was NOT a Castech head. To spot this I had to:

• Remove valve covers, clean suspect areas. Suspect areas are easy to find because leaking coolant partially cleans the area anyway.
• Install pressure tester and pressurize to 15 psi.
• Inspect for seepage.
• Final diagnosis: oil sample analysed and found evidence of coolant.

Removing the valve covers takes about 1/2 hour, maybe less. (I work slowly!)

Also note that if the leak is slow enough, the PCV will remove water from the oil before it becomes milk chocolate. However, over the period of an oil change, coolant additives and ethylene glycol can sludge your oil.

 

[TJ Baker]

I finally pulled off the valve cover gaskets and saw this in the thread linked:

Looking at the photo in that link I noticed the rockers still installed. The TSB on this indicates the castech casting logo can only be seen with the rockers removed. Here's a couple screenshots from the TSB.



I am currently experiencing this very same condition, although I also do not have the bubbles that @Doubeleive has. I have pulled the covers and found a leak/crack...