Colorado Yeti
Member
So here is the story....
Bought a 1999 Tahoe Z-71 with 52,000 miles. It is a beautiful truck that looks brand new. I have put approximately 7,000 miles on it since I bought it. I did notice that the antifreeze looked quite dirty when I bought it but it drove perfectly and the oil was clean.
I flushed the coolant after I bought it and put in brand new coolant. Approximately one month ago I noted bubbling that came from the coolant overflow tank when it was warm. No bid deal I thought, just a bad radiator cap. I replaced it but it did not fix the issue of bubbling. That when I started worrying. I then blew a heater core last week and replaced it. Now I am noticing more and more bubbling noises, especially when I am accelerating. The brand new coolant is now dirty again with a thin film of oil when I put it in a pan.
Okay, so now I am really worried. The truck drives perfectly fine, no smoking, no misfires, no overheating. The oil still looks pristine. But what else besides a head gasket could explain the symptoms that I am experiencing as illustrated above? I thought perhaps a leaking intake manifold gasket, but the intake manifold is a negative pressure system, not positive pressure so it should not cause bubbling with acceleration. And I should see coolant in the oil.
I have not had time to do a compression test but that is my next step. Then I guess I will tear it apart this weekend. Not looking forward to that job but I have done them before on a small block Chevy. I'm just worried about getting the intake to seal properly as I have heard that it is a horrible design on the Vortec and virtually impossible to get to seal properly.
Bought a 1999 Tahoe Z-71 with 52,000 miles. It is a beautiful truck that looks brand new. I have put approximately 7,000 miles on it since I bought it. I did notice that the antifreeze looked quite dirty when I bought it but it drove perfectly and the oil was clean.
I flushed the coolant after I bought it and put in brand new coolant. Approximately one month ago I noted bubbling that came from the coolant overflow tank when it was warm. No bid deal I thought, just a bad radiator cap. I replaced it but it did not fix the issue of bubbling. That when I started worrying. I then blew a heater core last week and replaced it. Now I am noticing more and more bubbling noises, especially when I am accelerating. The brand new coolant is now dirty again with a thin film of oil when I put it in a pan.
Okay, so now I am really worried. The truck drives perfectly fine, no smoking, no misfires, no overheating. The oil still looks pristine. But what else besides a head gasket could explain the symptoms that I am experiencing as illustrated above? I thought perhaps a leaking intake manifold gasket, but the intake manifold is a negative pressure system, not positive pressure so it should not cause bubbling with acceleration. And I should see coolant in the oil.
I have not had time to do a compression test but that is my next step. Then I guess I will tear it apart this weekend. Not looking forward to that job but I have done them before on a small block Chevy. I'm just worried about getting the intake to seal properly as I have heard that it is a horrible design on the Vortec and virtually impossible to get to seal properly.
