2003 head issue

[pamoffa]

I've waited a while before posting to make sure i wasn't jumping the gun, I've had the dreaded coolant leak into the oil for a few years now and my way of dealing with it was to frequently change the oil. months ago I put in the ac delco coolant seal tabs and to my surprise I didn't lose any coolant for months and let it go a while longer and still no coolant loss. So considering that I also had a bad engine tick i removed the valve covers and witnessed a terrible mass of gunk all over everything I cleaned it out and replaced the badly worn push rods and after putting it back together no ticks the oil pressure gauge is extremely responsive to the throttle and still no coolant loss. i might have saved my baby. I have the casteck 706 heads and 100% think I have the bad ones I was concerned about the tablets but I mixed them up in water before I put them in and It looked rather benign to me so i put 4 tabs in and my heat still works so It didn't screw up the heater core yet.

[pamoffa]

12-30-16 I still don't have any coolant loss the truck is running quiet heat still works the oil pressure gauge is still very responsive to the throttle. those ac delco coolant tablets 100% stopped my coolant loss into the oil. I was adding coolant frequently and haven't added a drop since my last post I emailed gm about the casteck heads and they played dumb.

[pamoffa]

I dont have the email from gm anymore wish I had it but they alluded to not knowing anything about the issue in an indirect way. very indirect so I couldn't get any sense from the email and there wasn't any direction to go further with it. so I dropped it.

[pamoffa]

update it is now 5-6-17 and i still haven't had a drop of coolant loss since I added the ac delco coolant tabs the tabs definitely stopped the coolant getting into the oil my last two oil changes no clumps. history on the issue is in my last posts on this thread

[rickpilgrim]

Very interesting as I also have the 706 castec heads on our 04 suburban and my coolant loss is very minor(gal every 4-6 months) and we change oil every 22-2500 mi to keep the "white paste" out of the valve covers. I'll have to try the ac/delco coolant tabs and see what happens.

[pamoffa]

update 9-3-17 Still haven't had any coolant loss and very happy with the condition of the oil when I change it.

[68Gold/white]

I just bought a 2005 1/2 ton, 5.3. where is this "706" number located?
I doubt there are issues with mine, am checking it over thoroughly though...

Have a friend that has a 2002 Avalanche, had a cracked head...

[pamoffa]

if I remember right I seen stamp when I removed the valve covers, if your not loosing coolant then it's safe to say your ok. I was adding coolant weekly

[izzy_Britton]

The '706' and any other casting number is located on the front or rear of the head, on the top, NOT hidden and not under the valve cover.

[68Gold/white]

My 2005 has the 706 heads...I'll be praying I have no problems...
I helped my buddy pick this pickup out on the lot when it was new. It has been fairly well maintained. He commuted about 30 miles (one way) daily. He retired about 4 years ago. He and I have had conversations, me telling him I'd buy it whenever that day came. His health is not good and he is not allowed to drive any more. I am relieved and excited to finally own it! It has 105,000 miles on it.

I am a novice at LS engine stuff. Ask me about the old school stuff or a Pontiac, I'm in there...LOL

Are there different numbers heads that can be used to replace the 706's? or does one have to just look for good 706's?

I'll likely look for a set of good used heads from a salvage. for potential future use, even though I don't plan to use them!

[homemade87]

Originally Posted by 68Gold/white

My 2005 has the 706 heads...I'll be praying I have no problems...
I helped my buddy pick this pickup out on the lot when it was new. It has been fairly well maintained. He commuted about 30 miles (one way) daily. He retired about 4 years ago. He and I have had conversations, me telling him I'd buy it whenever that day came. His health is not good and he is not allowed to drive any more. I am relieved and excited to finally own it! It has 105,000 miles on it.

I am a novice at LS engine stuff. Ask me about the old school stuff or a Pontiac, I'm in there...LOL

Are there different numbers heads that can be used to replace the 706's? or does one have to just look for good 706's?

I'll likely look for a set of good used heads from a salvage. for potential future use, even though I don't plan to use them!

The identical head for the 706 is the 862 head . It was made at a different place and does not have the problems the 706 head does . My brother had the problem with the 706 and we put the 862 heads on with no problems .

If looking for a upgrade . Get some 799 or 243 heads . This is what most all 5.3 truck motors are coming with now . They flow better .

[68Gold/white]

Originally Posted by homemade87

The identical head for the 706 is the 862 head . It was made at a different place and does not have the problems the 706 head does . My brother had the problem with the 706 and we put the 862 heads on with no problems .

If looking for a upgrade . Get some 799 or 243 heads . This is what most all 5.3 truck motors are coming with now . They flow better .

Many thanks!!!
If you found a set of 706 heads, relatively cheap, and the showed no signs of being cracked (no milkshake under the valve covers). Would you buy them, or avoid them like the plague???

My pickup is a short wide bed 2WD, has the 3.73 gears with the tow package. Has the 4 speed automatic. Has AC, PS, PB, AM/FM/CD radio. No electric windows, locks or seats.
It runs like a scalded dog!!! I'm not a novice as to what a well performing vehicle performs like. My buddy ran it down the track once, it went like a 15.80. That may not be a hot rod car number, but ain't bad for a pickup.
Thanks, Again!!!

[pamoffa]

I would say it's a risk do the heads eventually crack? I also read somewhere they suffer from being porous.

[homemade87]

Originally Posted by 68Gold/white

Many thanks!!!
If you found a set of 706 heads, relatively cheap, and the showed no signs of being cracked (no milkshake under the valve covers). Would you buy them, or avoid them like the plague???

My pickup is a short wide bed 2WD, has the 3.73 gears with the tow package. Has the 4 speed automatic. Has AC, PS, PB, AM/FM/CD radio. No electric windows, locks or seats.
It runs like a scalded dog!!! I'm not a novice as to what a well performing vehicle performs like. My buddy ran it down the track once, it went like a 15.80. That may not be a hot rod car number, but ain't bad for a pickup.
Thanks, Again!!!

I don't know what percentage of them fail , but not all of them fail . If you do get another set be sure to have them pressure tested . Just looking at them can not detect a small crack or leak . If it were me I would look for the 862 first . If you can not find them have the 706 checked out before you set them in the corner of the shop for 2 years and when its time to use them you find out there are no good .

[68Gold/white]

Originally Posted by homemade87

I don't know what percentage of them fail , but not all of them fail . If you do get another set be sure to have them pressure tested . Just looking at them can not detect a small crack or leak . If it were me I would look for the 862 first . If you can not find them have the 706 checked out before you set them in the corner of the shop for 2 years and when its time to use them you find out there are no good .

Thanks again!
I talked to my buddies son, he's 27 and a certified GM mechanic, He opened his own shop 2 years ago, got tired of the dealership deal.
He told me I can test the heads on my pickup now by removing the rocker arms and pressuring up the cooling system to 15-20 lbs for 1-2 hours. He said it's not a crack that I'm necessarily looking, for it's porousness in the metal. Specifically usually around the head bolt bosses usually in the center of the head. He told me I would EASILY see coolant coming through the metal IF there's a problem with a head.
He replaced a lot of heads at the dealer, when he worked there. He has installed 243's, replacing 706's a couple of times...

I bought the 2 heads, they were cheap. Will find a shop that can pressure check them soon!!!

[pamoffa]

2-19-2018 I still haven't lost any coolant after putting the tabs in. Oil change is clean. I haven't had to add any coolant.

[homemade87]

Thats good . Most likely that tablet material will fill the crack . The crack is more like a hair line crack so what ever it is made of has filled it up .


Just keep a eye on it so it dont start back . I would run it like that until the engine has to be replaced or come apart .

[cori 64]

I also have the 706 castec heads and i was losing alot of coolant every week..most of the reservoir! A year later i've added one more tablet and no loss of coolant ...she still runs strong! 320,000 miles!

[pamoffa]

I like to think of the issue as not a crack. I like to think of it as being porous it makes me feel better.

[pamoffa]

Just throwing this out there. If I ever trade the truck in to a dealer should I disclose the issue? If I was to sell it in a private sale I would definitely disclose.

[homemade87]

Originally Posted by pamoffa

Just throwing this out there. If I ever trade the truck in to a dealer should I disclose the issue? If I was to sell it in a private sale I would definitely disclose.

At 320,000 I dont think it would make that much difference . Anyone buying the truck at that point is going in thinking it needs a motor soon anyway . Besides , seems to be still holding strong . I would never buy a truck with that mileage and think I am getting and engine thats going to last another 100,000 . I would buy it an just roll the dice and drive it until it quit and then get me a pull out motor .

Truck is not going to bring much . Probably worth more to you to park it in the back of the shop and use it for your beater stuff when you get a new truck .

[pamoffa]

Mines only got 88k it should get something on trade in. I most likely will disclose the issue.

[pamoffa]

8-14-18 I still haven't lost a drop of coolant since putting in the ac delco coolant seal tabs