Hey Guys,
I have a 2004 Chevy Avalanche z71, with the 5.3L V8. Bought it in June 2016 with 123k miles, now up to 126,000.
Since I bought it, I have noticed the coolant low when doing a typical under the hood inspection. Previously I have just been topping it off, but eventually I realized, I shouldn't need to be topping it off. No signs of leaks anywhere and I have looked extensively.
After the truck is warmed up and sitting over night, the next morning's start up usually greets me with a thick cloud of white smoke, some times a hint of blue... which I assume to be burning coolant and maybe a little oil. I often take 5-10 hours drives and notice that the coolant level doesn't change that much after these long trips, when the engine temp is hot. Only when I take many short trips, is when it lowers. My oil pressure also decreases as my oil's age increases. On a new oil change, at temperature and at idle, I am over 40psi. after a few thousand miles, is becomes less than 40 psi.
I have had my oil analyzed through Amsoil's oil analysis (Horizon is who they go through I think). They game back with the following results.
Apparently, they mark oil as severe if the sodium level reaches 300ppm... mine is 3x that. Clearly, there is coolant in my oil. However, I don't have an exact ratio of how much coolant is in there. could be only a percent or less. The oil on the dipstick is never that chocolate milk color. It just looks like regular good oil. Under the cap however, I am seeing that mayonnaise colored sludge, as well as under my passenger side valve cover as seen below:
So... some coolant is in my oil. I think that is clear.
Did a compression check, and all looked good, as far as I can tell. Here are the results.
1- 160 psi
2- 160 psi
3- 210 psi
4- 180 psi
5- 155 psi
6- 155 psi
7- 180 psi
8- 180 psi
Spark plugs looked good. A bit of oil on the threads and a little white on the tips, but they were consistent throughout all 8 cylinders. One think I noticed while uploading the pictures, I noted that cylinder 3 looked a little more oily and darker than the rest. This one also had the highest compression by 30 psi... Could this mean anything?
Next I did a coolant pressure test. That seemed to pass very well. Only loosing 1-2psi over the course of 12 hours, which I can probably blame most of it on the hard to seal overflow vent.
Only other thing I can think of is possible a chemical block test. which I haven't done yet.
Basically I am trying to figure out if it is a head gasket, or the infamous cracked head. Anything else I can do to confirm before I remove the head to find out? Being my daily driver and a college student, it is difficult to justify either A) spending $600-1200 on new (used) heads. B) tearing appart my daily driver when transportation is needed daily. I just don't want to tear apart the heads if I know for sure the head gaskets are alright.
Here are some links:
Technical Service Bulletin: http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf
Info on cracked heads: http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf
A trouble shooting guide which I have tried: http://easyautodiagnostics.com/gm/4.8L-5.3L-6.0L/blown-head-gasket-test-1
What should I do? Any and all help is greatly appreciated!!
Jake
I have a 2004 Chevy Avalanche z71, with the 5.3L V8. Bought it in June 2016 with 123k miles, now up to 126,000.
Since I bought it, I have noticed the coolant low when doing a typical under the hood inspection. Previously I have just been topping it off, but eventually I realized, I shouldn't need to be topping it off. No signs of leaks anywhere and I have looked extensively.
After the truck is warmed up and sitting over night, the next morning's start up usually greets me with a thick cloud of white smoke, some times a hint of blue... which I assume to be burning coolant and maybe a little oil. I often take 5-10 hours drives and notice that the coolant level doesn't change that much after these long trips, when the engine temp is hot. Only when I take many short trips, is when it lowers. My oil pressure also decreases as my oil's age increases. On a new oil change, at temperature and at idle, I am over 40psi. after a few thousand miles, is becomes less than 40 psi.
I have had my oil analyzed through Amsoil's oil analysis (Horizon is who they go through I think). They game back with the following results.
Apparently, they mark oil as severe if the sodium level reaches 300ppm... mine is 3x that. Clearly, there is coolant in my oil. However, I don't have an exact ratio of how much coolant is in there. could be only a percent or less. The oil on the dipstick is never that chocolate milk color. It just looks like regular good oil. Under the cap however, I am seeing that mayonnaise colored sludge, as well as under my passenger side valve cover as seen below:
So... some coolant is in my oil. I think that is clear.
Did a compression check, and all looked good, as far as I can tell. Here are the results.
1- 160 psi
2- 160 psi
3- 210 psi
4- 180 psi
5- 155 psi
6- 155 psi
7- 180 psi
8- 180 psi
Spark plugs looked good. A bit of oil on the threads and a little white on the tips, but they were consistent throughout all 8 cylinders. One think I noticed while uploading the pictures, I noted that cylinder 3 looked a little more oily and darker than the rest. This one also had the highest compression by 30 psi... Could this mean anything?
Next I did a coolant pressure test. That seemed to pass very well. Only loosing 1-2psi over the course of 12 hours, which I can probably blame most of it on the hard to seal overflow vent.
Only other thing I can think of is possible a chemical block test. which I haven't done yet.
Basically I am trying to figure out if it is a head gasket, or the infamous cracked head. Anything else I can do to confirm before I remove the head to find out? Being my daily driver and a college student, it is difficult to justify either A) spending $600-1200 on new (used) heads. B) tearing appart my daily driver when transportation is needed daily. I just don't want to tear apart the heads if I know for sure the head gaskets are alright.
Here are some links:
Technical Service Bulletin: http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf
Info on cracked heads: http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf
A trouble shooting guide which I have tried: http://easyautodiagnostics.com/gm/4.8L-5.3L-6.0L/blown-head-gasket-test-1
What should I do? Any and all help is greatly appreciated!!
Jake
but will give the 5.3 higher compression as they are not dished as the 5.3's pistons.