2003 Tahoe coolant system leak or head gasket leak?

[tomloans]

In my amateur opinion, that's definitely water/coolant mixed with oil. When my refurb head cracked, it looked like that as the oil was practically brand new. Get the dye and light and pressurize it and you might spot the leak. Otherwise, just prepare for swapping both heads, again, in my amateur opinion.

This is mine with unknown miles on the oil with the OEM heads.
View attachment 362712

Same gunk but a darker background. The only reason mine doesn't look like yours is my valve cover is nearly new. I just hope the engine is still in one piece after running partial coolant as oil. Good grief. Not going to bother with any further inspections. 203k miles and I have the 706 Battery heads. It is time to take care of this. Thank you for pics.

 

[tomloans]

This is very frustrating to say the least. Any input, insight, anything please. I will glean info. I just put 17 PSI on the pressure tank and it held forever. No loss in pressure. This is very confusing and I don't want to go through replacing the heads for no reason at all! Any input will be appreciated greatly.

 

[Fless]

OK Major Update!

See Pics. I just replaced the valve cover 6 months ago and about 2300 miles ago and here is what it looks like. The gunk seems to have built up the cylinder head between the 5th and 3rd cylinder most ( dont have a picture of this )... Any conclusions?

View attachment 362709View attachment 362710

What do the heads and rockers look like? Any real clean spots on them? Pics?

 

[Fless]

Any progress or update on a UV dye test, or combustion gas test on the coolant?

 

[iamdub]

This is very frustrating to say the least. Any input, insight, anything please. I will glean info. I just put 17 PSI on the pressure tank and it held forever. No loss in pressure. This is very confusing and I don't want to go through replacing the heads for no reason at all! Any input will be appreciated greatly.

It's common that it only leaks when hot. From my experience, either you're running some really crappy oil or that's the beginning stages of the coolant/oil mix, meaning you caught it early. Honestly, if it runs great, has normal oil pressure and it's not full of black gunk, I'd say you're golden. Replace the heads and keep truckin'.

Can we get a good pic of the springs/rockers/etc.? Have you looked at the areas around head bolts, particularly between #3 and #5?

My brother's truck had 181K when I tore into it. It now has about 220K. Never opened up anything on the bottom end other than removing the oil pan to clean it and the rotating assembly. I did remove the cam to clean it and inspect the lobes and bearings. Slid it right back in. I pretty much did the same to mine at 200K, minus the deep cleaning part cuz it wasn't gunked. It got a mild cam and head upgrade. These things can take a beating!

Pending confirmation of a cracked head(s), I'd be weighing my options between those refurbed NuTech heads or finding a set of 799/243s and having them refurbed (cleaned, milled, etc.). We couldn't find non-Castech 706s but found some low-mileage 799s and slapped 'em on as-is. Better flowing head, but a small loss of compression. He wasn't worried about it considering the price. In my area, I could have a set of heads done for about $300. A set of 799/243 go for $300, so it'd be the same cost invested. But, the bump in power would make it the better deal for me. You gotta reward yourself for your troubles, right?

 

[tomloans]

It's common that it only leaks when hot. From my experience, either you're running some really crappy oil or that's the beginning stages of the coolant/oil mix, meaning you caught it early. Honestly, if it runs great, has normal oil pressure and it's not full of black gunk, I'd say you're golden. Replace the heads and keep truckin'.

Can we get a good pic of the springs/rockers/etc.? Have you looked at the areas around head bolts, particularly between #3 and #5?

My brother's truck had 181K when I tore into it. It now has about 220K. Never opened up anything on the bottom end other than removing the oil pan to clean it and the rotating assembly. I did remove the cam to clean it and inspect the lobes and bearings. Slid it right back in. I pretty much did the same to mine at 200K, minus the deep cleaning part cuz it wasn't gunked. It got a mild cam and head upgrade. These things can take a beating!

Pending confirmation of a cracked head(s), I'd be weighing my options between those refurbed NuTech heads or finding a set of 799/243s and having them refurbed (cleaned, milled, etc.). We couldn't find non-Castech 706s but found some low-mileage 799s and slapped 'em on as-is. Better flowing head, but a small loss of compression. He wasn't worried about it considering the price. In my area, I could have a set of heads done for about $300. A set of 799/243 go for $300, so it'd be the same cost invested. But, the bump in power would make it the better deal for me. You gotta reward yourself for your troubles, right?

Do the 799 heads require a different head gasket or anything else different. I can get a pretty good deal on a set of these. Will send pics shortly.

 

[tomloans]

It's common that it only leaks when hot. From my experience, either you're running some really crappy oil or that's the beginning stages of the coolant/oil mix, meaning you caught it early. Honestly, if it runs great, has normal oil pressure and it's not full of black gunk, I'd say you're golden. Replace the heads and keep truckin'.

Can we get a good pic of the springs/rockers/etc.? Have you looked at the areas around head bolts, particularly between #3 and #5?

My brother's truck had 181K when I tore into it. It now has about 220K. Never opened up anything on the bottom end other than removing the oil pan to clean it and the rotating assembly. I did remove the cam to clean it and inspect the lobes and bearings. Slid it right back in. I pretty much did the same to mine at 200K, minus the deep cleaning part cuz it wasn't gunked. It got a mild cam and head upgrade. These things can take a beating!

Pending confirmation of a cracked head(s), I'd be weighing my options between those refurbed NuTech heads or finding a set of 799/243s and having them refurbed (cleaned, milled, etc.). We couldn't find non-Castech 706s but found some low-mileage 799s and slapped 'em on as-is. Better flowing head, but a small loss of compression. He wasn't worried about it considering the price. In my area, I could have a set of heads done for about $300. A set of 799/243 go for $300, so it'd be the same cost invested. But, the bump in power would make it the better deal for me. You gotta reward yourself for your troubles, right?

I don't see much here. One thing to note before I took this picture earlier today, there was bunch of gunk built up in between 3 and 5.

 

[tomloans]

It's common that it only leaks when hot. From my experience, either you're running some really crappy oil or that's the beginning stages of the coolant/oil mix, meaning you caught it early. Honestly, if it runs great, has normal oil pressure and it's not full of black gunk, I'd say you're golden. Replace the heads and keep truckin'.

Can we get a good pic of the springs/rockers/etc.? Have you looked at the areas around head bolts, particularly between #3 and #5?

My brother's truck had 181K when I tore into it. It now has about 220K. Never opened up anything on the bottom end other than removing the oil pan to clean it and the rotating assembly. I did remove the cam to clean it and inspect the lobes and bearings. Slid it right back in. I pretty much did the same to mine at 200K, minus the deep cleaning part cuz it wasn't gunked. It got a mild cam and head upgrade. These things can take a beating!

Pending confirmation of a cracked head(s), I'd be weighing my options between those refurbed NuTech heads or finding a set of 799/243s and having them refurbed (cleaned, milled, etc.). We couldn't find non-Castech 706s but found some low-mileage 799s and slapped 'em on as-is. Better flowing head, but a small loss of compression. He wasn't worried about it considering the price. In my area, I could have a set of heads done for about $300. A set of 799/243 go for $300, so it'd be the same cost invested. But, the bump in power would make it the better deal for me. You gotta reward yourself for your troubles, right?

 

[tomloans]

It's common that it only leaks when hot. From my experience, either you're running some really crappy oil or that's the beginning stages of the coolant/oil mix, meaning you caught it early. Honestly, if it runs great, has normal oil pressure and it's not full of black gunk, I'd say you're golden. Replace the heads and keep truckin'.

Can we get a good pic of the springs/rockers/etc.? Have you looked at the areas around head bolts, particularly between #3 and #5?

My brother's truck had 181K when I tore into it. It now has about 220K. Never opened up anything on the bottom end other than removing the oil pan to clean it and the rotating assembly. I did remove the cam to clean it and inspect the lobes and bearings. Slid it right back in. I pretty much did the same to mine at 200K, minus the deep cleaning part cuz it wasn't gunked. It got a mild cam and head upgrade. These things can take a beating!

Pending confirmation of a cracked head(s), I'd be weighing my options between those refurbed NuTech heads or finding a set of 799/243s and having them refurbed (cleaned, milled, etc.). We couldn't find non-Castech 706s but found some low-mileage 799s and slapped 'em on as-is. Better flowing head, but a small loss of compression. He wasn't worried about it considering the price. In my area, I could have a set of heads done for about $300. A set of 799/243 go for $300, so it'd be the same cost invested. But, the bump in power would make it the better deal for me. You gotta reward yourself for your troubles, right?

 

[tomloans]

It's common that it only leaks when hot. From my experience, either you're running some really crappy oil or that's the beginning stages of the coolant/oil mix, meaning you caught it early. Honestly, if it runs great, has normal oil pressure and it's not full of black gunk, I'd say you're golden. Replace the heads and keep truckin'.

Can we get a good pic of the springs/rockers/etc.? Have you looked at the areas around head bolts, particularly between #3 and #5?

My brother's truck had 181K when I tore into it. It now has about 220K. Never opened up anything on the bottom end other than removing the oil pan to clean it and the rotating assembly. I did remove the cam to clean it and inspect the lobes and bearings. Slid it right back in. I pretty much did the same to mine at 200K, minus the deep cleaning part cuz it wasn't gunked. It got a mild cam and head upgrade. These things can take a beating!

Pending confirmation of a cracked head(s), I'd be weighing my options between those refurbed NuTech heads or finding a set of 799/243s and having them refurbed (cleaned, milled, etc.). We couldn't find non-Castech 706s but found some low-mileage 799s and slapped 'em on as-is. Better flowing head, but a small loss of compression. He wasn't worried about it considering the price. In my area, I could have a set of heads done for about $300. A set of 799/243 go for $300, so it'd be the same cost invested. But, the bump in power would make it the better deal for me. You gotta reward yourself for your troubles, right?

Again I don't see anything obvious. As mentioned, my engine is super clean as you can see in the pictures. Not bragging but very clean for 200k miles. I don't see anything that jumps out at me except the lumpy stuff which I wiped off prior to these pictures. Most were in the valve cover and in between 3 and 5.