jimmys03
TYF Newbie
2003 Tahoe LT 160K orig trans
Last edited:
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
2004 Z71 with about 164K on the clock. Replaced the POS 5.3 with an LQ9 &4L65E at about 160K. The POS 5.3 had cracks in the heads and needed antifreeze added every other day...along with oil.
2004 Z71 with about 164K on the clock. Replaced the POS 5.3 with an LQ9 &4L65E at about 160K. The POS 5.3 had cracks in the heads and needed antifreeze added every other day...along with oil.
wow-really? is this common? this is where i wonder about my truck; 256k and runs great.
You didn't necessarily need to put in an entirely new motor if you caught it early on and replaced the heads. If you drove on it for a long time, then yes, it might have caused permanent internal damage. I wouldn't label the 5.3LS a POS since there are MANY here who have 200,000+ miles on their motors with no issues whatsoever.
It is fairly common on trucks that had Castech heads from 2002-2005, from what I've read here. I have heads with 706 stamped on them (which is indicative of Castech), but knock on wood I haven't had any issues with them in 144k miles.
http://www.gm-trucks.com/forums/topic/122232-trucks-going-in-to-see-if-i-have-castech-heads/
i'm in the discovery mode. looked at my heads. 86? pita to see. next things to do are cooling system service and trans service. this winter i plan on towing a TT.
True, but 243 heads are about $500 before install. So $1K later I have a 160K motor with reworked good heads. Is that a better investment or just find a good N (8th digit) LQ9 6.0 ** and be done with it? My used LQ9 + 4L65E cost me $2600 out the door installed. The shop also put in a new oil pump, rear main seal, new plugs & wires and gives a 24 mo/24K mile warranty. I would have been a fool to pass up that deal. I got tired of feeding oil and coolant 2x per week on my 5.3. The 6.0 hasn't used a drop of coolant and maybe 1/8" of oil over 3K miles. That could be attributed to PVC system. I am darn glad I did the swap. There is a small gas mileage penalty with the 6.0...more so as I now have to burn premium gas. According to the DIC, I was over 17 mpg tonight on a 25 mile freeway trip with the cruise control set around 65. MPG goes to heck quickly above 65.
The shop scrapped my old 5.3 motor because they did not feel comfortable selling it with a 24mo/24K warranty.
One of the best scenarios is to start with a flex fuel 5.3 and swap in a 6.0. The flex fuel injectors are 33 lb./hr. The 4.8/5.3/6.0 normal injectors are 25 lb/hr. So, use the whole intake manifold assembly off the flex fuel motor...and then get a Black Bear Tune.
I bought the Z71 used with just over 150K, so I didn't have much history.