Had the same problem on my 2004. Turns out it was the sensor inside of the encoder motor mounted to the transfer case. $50 part AC delco on Amazon. Try the sensor first before you shell out the $$ for the entire encoder motor.
I just completed this repair on my 2004 5.3 LM7. Have you pulled your heads already? How many bolt sizes do you have? They changed bolt styles in 2004 so it depends on when your truck was produced. If you have only 2 bolt sizes follow the second diagram. If you have 3 bolt sizes with #'s 9-10 being smaller than 1-8 you should follow sequence #1. My truck was produced in 2004 and I only had two bolt sizes. If you haven't already pick up the 862 heads I would highly recommend a set of 799's or 243's. I installed a set a 799's with a full valve job and milled them .030. My castech 706 heads failed.
173K miles. I am OCD for changing the oil on time or EARLY lol. The first photo is of the motor after I pulled the heads. There was quite a bit of carbon buildup that took quite of bit of elbow grease to remove but I figured I was already there why not do it. What it did notice is that there was almost 0 sludge buildup at all. The power difference now with the new heads is very noticeable or it could be its just because it hasn't been that clean since new. It has been a couple of weeks and I just changed the oil for the second time get the residual dirt/grime that may have accumulated during the repair. No CEL, no issues and I just upgraded my 105 alternator to a 145 amp.
04z71crew started following 04 5.3 rough idle after head swap (castech failure)
Thanks for the suggestions see above reply in my case it was the driver side pre cat 02 sensor. 2 of my exhaust manifold bolts were broken off on my old 706 heads if they are flush weld a nut on top and try to slowly back it out. Worst case scenario they actually make brackets for busted exhaust manifold bolts that will work to create a seal if you cant get them out not worth drilling IMO. APDTY 028218 Exhaust Manifold To Cylinder Head Leak Repair Clamp Fits Front Right or Rear Left On 4.8L 5.3L 6.0L Engine On Escalade Avalanche Silverado Pickup Tahoe Express Van Denali Sierra Pickup Savana Yukon Hummer H2 (See APDTY-028253 For Other Side) https://www.amazon.com/dp/B00I3LLVS8/ref=cm_sw_r_cp_api_i_jrMBCbRYVA70Z
quick update thanks for the replies it ended up being the oxygen sensor on bank 1 before the cat. Replaced with ac delco unit and it cleared the CEL and now idles like it should!
04z71crew posted a topic in 1999-2013 Silverado & Sierra 1500Hey guys, I had some bad luck recently with my 2004 silverado z71 5.3. I had the 706 castech heads and they finally gave out on me causing the truck to overheat. Took it to the shop and they wanted 3 grand to do head gaskets using the same heads apparently they were clueless to the TSB on the castech heads. I found a guy that rebuilds heads and picked up a set of 799’s and had them milled .030. It took me 3 weeks off evenings and weekends but I finally got the new heads and gaskets on with every bolt double checked used properly torqued specs/angles etc. I also replaced all lifters,trays, and pushrods, oil sending unit, knock sensors, heater hoses, and upgraded to the larger radiator from 2005 and up trucks LOL. The truck fired up first try and runs great when cold, however when it gets to operating temp the idle is very rough and acts like its missing. Should I be looking for a vacuum leak? any suggestions? Thanks for the help.
04z71crew replied to Gashouse's topic in 1999-2013 Silverado & Sierra 1500You should only engage 4x4 on a loose surface such as mud, sand, snow etc. That binding is completely normal and not good at all for your diffs! or transfer case. Binding occurs because your diff is locked and your outside wheel will need to make more rotations than your inner during a turn.
Personal preference. Do you offroad the truck? IMO more sidewall not only looks right for the application but functionally is superior. In the end if you like it thats all that counts, ignore others opinions.
What brand of water pump did you install? and what kind of gaskets did it come with? When I installed mine I replaced the flimsy gaskets they provided and opted for a metal style ac delco gasket like this one. https://www.amazon.com/ACDelco-251-663-Original-Equipment-Gasket/dp/B003ZNZ1WG/ref=asc_df_B003ZNZ1WG/?tag=hyprod-20&linkCode=df0&hvadid=312061942313&hvpos=1o2&hvnetw=g&hvrand=10064822385743492026&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9026252&hvtargid=pla-497182985972&psc=1&tag=&ref=&adgrpid=63195598318&hvpone=&hvptwo=&hvadid=312061942313&hvpos=1o2&hvnetw=g&hvrand=10064822385743492026&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9026252&hvtargid=pla-497182985972 Did you torque the water pump bolts to spec??? If they weren't torqued evenly that could also cause problems.
Hi Mike, I had a similar issue with my 2004 silverado. I pulled the encoder motor from the transfer case and replaced this sensor and it fixed my problem instantly. Mine would sometimes start in 4wd, try to shift into 4wd on its own and get stuck in 4wd low or high. https://www.amazon.com/Dorman-600-120-Transfer-Motor-Encoder/dp/B004GBAPC2/ref=asc_df_B004GBAPC2/?tag=hyprod-20&linkCode=df0&hvadid=312429177733&hvpos=1o2&hvnetw=g&hvrand=15610581697995138023&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9026252&hvtargid=pla-569794969089&psc=1 If that doesn't fix your problem it could be your transfer case control module. I would start with the sensor. Gavin
Like others have stated the truck being a 2003 will come stock with a fan clutch. The repair is not very difficult at all. >>>Remove the air intake tube coming from your air filter to throttle body>>>Remove fan shroud>>>Use a large crescent wrench and a good size hammer and it will break the nut loose>>>Spin fan off>>> remove bolts and put your stock blade on your new clutch. Based on my personal experience aftermarket flan clutches will stick and stay on at all times, I switched mine out for an original Ac Delco purchased on Amazon. Has been very quiet since.
Yes they did! or sometimes they wouldn't come on at all. It was an intermittent problem but very frustrating. The encoder motor sensor is most likely the culprit. Let me know if you have anymore questions would be glad to help.
I had the exact same issue on my 2004 z71. Random shifting into 4wd, sometimes would not shift out etc. "Service 4wd" was constantly showing up and after replacing the switch itself that did not solve the problem. If it is not your switch its most likely your encoder motor sensor, a factory sensor is around $50 on Amazon. Since replacing mine I have had 0 issues. https://www.gmtruckclub.com/forum/threads/how-to-encoder-motor-sensor-replacement.39654/ This is a link showing detailed instructions on how to replace the sensor. Pretty simple yet tedious job.
04z71crew posted a topic in 1999-2013 Silverado & Sierra 1500Looking for some help here, I've got an 04 z71 crew cab with the 5.3 and recently it has been overheating when the truck is sitting at idle with the ac on. What I have done : installed a fan clutch last year, and cleaned the condenser and radiator out. While driving it sits at 195 but today it did jump to 212 even while moving and cutting the ac off brings it back down. When its sitting the fan just doesn't seem as loud as it should be in these 100+ temps here in oklahoma. The other day i left it running for 20 minutes to cool it off and when i left the house it was sitting at 250 with the engine coolant hot warning. Revving it up to 3K for about 2 minutes brought it back down to normal. It seems like an airflow issue, isn't the fan supposed to be pretty damn loud? I know my 94 z71 was. Is the radiator going to sh*$? thermostat sticking? water pump weak? where should i start to diagnose it? Thanks.
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