Blown head gasket???

[bobo]

Newbee here! Great site. Hoping ya'll can help?

2000 Tahoe 5.3L w/180k miles. (2hr commute one way each day)

My problem...

Coolant light started coming on about 2 mths ago. Been adding appox 12oz every 2 weeks. Took Tahoe to shop. They first suspected a IM gasket leaking. Shop did a pressure test, a dye check (?) and found nothing. I also noticed the engine top end knocking. Almost like a lifter going bad. I asked the shop to check and change the oil too. They found nothing in the oil.

Other info.

No smoke out of the tail pipe.
No signs of leakage under the hood.
New water pump approx 1yr ago w/no seepage.
I do hear a pronounced gurgling under the hood now when I stop the vehicle.
New coolant overflow cap 2 weeks ago.

Should I take my Tahoe to a radiator shop and see if I have a slow leak somewhere else? Could it be one of the heater cores leaking? I did notice some water in the back passenger floor board the other day.. but no smell of antifreeze. I suspected the wife spilled something and was afraid to tell me.

Is there something I can put in the coolant (dye) that would show up easily in the oil whenever I change it?

This is my first Chevy. Was skeptical when I first bought it. Turned out the be the best vehicle I have ever owned. I change the oil religiously every 3k miles. New Jasper transmission last month. New rear end approx 12 mths ago. I hate to let 'er go!

Sorry for the huge list of info.

I'm stumped?????

Your input here is appreciated!

 

[Rivieraracing]

If coolant is getting into the oil, you would see a sheen on top of the oil, kind of an oil slick on top of the oil. You still may have a head gasket that is going bad, my old 4 runner had that problem before the head blew (was common with those rigs), I would put coolant in as often as I would fill up with gas before the head gasket finally failed and you could see it out of the exhaust.
So, my guess is the heater core, it may just be in the beginning stages of failing, I would check that and see if you have coolant leaking out of there.

 

[Huck]

Does your oil look like chocolate milk or smell sweet?

 

[bobo]

Does your oil look like chocolate milk or smell sweet?

That's part of my problem... I've been using one of the Valvoline oil change places right next to my office so I never really got a chance to look at the oil. I'll be doing the next one myself just to make sure. I picked up a new drain pan today so there will be no mistaking the color or smell.

My shop said they did all of the tests... but I'm sorta suspisous. They should have at least seen some coolant in the oil when they changed it? They told me to watch it just in case it was slowly starting to go bad .. and to bring it back when it did finally go. I sure don't want to hurt the motor if that is the case.

I had to reshedule my visit to the radiator shop until Monday. So, I'm hoping I can first rule out any heater core issues.... then I was going to take it back to my shop and tell them to dig in and find the problem.... otherwise I fear my next option is either a new GM crate or Jasper motor.