GM 5.3L 323 Overheating Problems???

[SkintBack13]

Hey fellas!
This motor isn't a Duramax OBVIOUSLY but I'm sure a few of yall probably have 1500's too. I cant stop my '06 from overheating!
Changed the thermostat AND water pump TODAY and if anything, its gotten worse. (Hotter and quicker)
what could I be missing that yall would think of?
Like always..any input is appreciated!

 

[04D_MAX]

are the electric fans coming on?

 

[chevyburnout1]

Electric or mechanical fans? Does it say overheating on the cluster? Or are you just basing it off of the gauge?

 

[cat_dr.]

If its only the guage reading hot and not flashing coolant temp high warning its more than likely the stepper motor.

 

[Gello]

Make sure you bleed the system correctly, you may have fixed with the thermostat and broke it at the same time. Vacuum filling the system is the best way also make sure your 50/50 on the coolant mix.


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[Gello]

You could also scan the computer to make sure she's actually running hot. High millage? Them engines are common to crack heads from what I've seen with my customer base.


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[THEFERMANATOR]

Another thing that is commonly overlooked is a plugged heater core. The LS engines use the return flow from the heater core to heat up the t-stat and make it open. If the heater core gets blocked it will overheat in a hurry. Fought this on a 4.8L before where it was running 240-250 no matter what. It had heat, but not good heat out the vents. Took the 2 lines off at the heater core and back flushed it for a minute, hooked it back up and it dropped down to 185 and stayed there. Also like said above could be a bad stepper motor in the cluster, and the coolant temp sensor could be bad telling it that it is hotter than it actually is.

 

[blk smoke lb7]

You could also scan the computer to make sure she's actually running hot. High millage? Them engines are common to crack heads from what I've seen with my customer base.


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Yeap gm had a bad series of heads from what ive been told.It was between a certain pair of casting #s that had the problem not sure what the #s are.

 

[68skylark455]

Most common issues we have seen on a number of trucks is the nipple on the radiator that goes to the top of the coolant bottle being plugged/melted from an ov erheat caused by something else. It is a specific size and when they overheat it tends to shrink the orfice and cause one to overheat. It is supposed to be .083. We use a drill bit by hand to open it back up. The other issue is the tubes running from head to head on the front and sometimes on the back under the edge of the manifold get stopped up.

 

[SkintBack13]

Thanks for all the info fellas! Turns out its a cracked head Lots of $$$. I think Ill just be buying a new badass motor to swap with this 323 junker

 

[THEFERMANATOR]

Yeap gm had a bad series of heads from what ive been told.It was between a certain pair of casting #s that had the problem not sure what the #s are.

It was the 01- early 06 heads with the CASTECH casting mark under the valve cover that had the cracking problem. And when they cracked it would have a slow coolant loss to the crankcase of the engine.

 

[duratothemax]

Thanks for all the info fellas! Turns out its a cracked head Lots of $$$. I think Ill just be buying a new badass motor to swap with this 323 junker

um ok first of all. ITS NOT A 323. Its a 325ci.

second of all. Do you have any idea how much you can get a used 4.8/5.3 head for? My buddy has piles of them that he cant even GIVE away.

You can buy a whole freaking engine (used) from any junk yard for probably $250. Thats not "lots of $$$"

And finally. If you think the 5.3's (or any LSx) is a "junker" just because yours had a problem and the millions of other 5.3's out there are running just fine, you are crazy.

Sorry, I just get heated up when people call the LSx engines junk and unreliable. I know it sounds crazy, but Ill defend the reliability and bulletproof-ness of an LSx before I defend the reliability of a duramax. Yeah....I just said it.....

ben

 

[THEFERMANATOR]

um ok first of all. ITS NOT A 323. Its a 325ci.

second of all. Do you have any idea how much you can get a used 4.8/5.3 head for? My buddy has piles of them that he cant even GIVE away.

You can buy a whole freaking engine (used) from any junk yard for probably $250. Thats not "lots of $$$"

And finally. If you think the 5.3's (or any LSx) is a "junker" just because yours had a problem and the millions of other 5.3's out there are running just fine, you are crazy.

Sorry, I just get heated up when people call the LSx engines junk and unreliable. I know it sounds crazy, but Ill defend the reliability and bulletproof-ness of an LSx before I defend the reliability of a duramax. Yeah....I just said it.....

ben

It's hard to believe how many LS's are out there with over 250K miles and have only had a water pump and some plugs put in them. theres not many engines out there that can be pushed up that high in the HP on stock engines, and live a reasoneable life doing it.

 

[OregonDMAX]

my parents both have the 5.3 in there trucks and they both have well over 150k with not one single thing ever done to them or anything ever gone wrong.

and yes there are cheap to find parts for there is a chit load of them out there.

as far as badass motors go, that is the base for what most people use to make a badass gasser motor anyway, that and the 6.0. so if that's your goal you have a reason to build that motor now.

 

[duratothemax]

It's hard to believe how many LS's are out there with over 250K miles and have only had a water pump and some plugs put in them. theres not many engines out there that can be pushed up that high in the HP on stock engines, and live a reasoneable life doing it.

I have an 03 tahoe thats coming up on 300k and literally the only thing thats ever been done to it (engine wise) is change the coolant once and oil changes. I hammer on it every time I drive it, WOT up every highway onramp, etc haha.

It still has the original plugs and water pump.

The original 4L60 lost the 3-4 clutchpack at around 230k but other than that and other minor things (replaced one front wheel bearing, transfer case encoder motor, shocks, brakes, ABS module) its been reliable as hell. The factory original front end parts (pitman/idler, tie rods, ball joints) could probably use a rebuild sometime in the next 20k miles, but for almost 300k its still respectably tight.

A friend of mine who has a boat business has personally seen two beat-to-shit 6.0 work trucks (hot shot boat haulers that deliver boats for him) with almost 750k on them and never had any repairs other than water pumps. He said they were knocking/ticking and didnt sound happy when the trucks pulled into his shop, but when he asked the drivers about them, they shrugged and said "meh, I dunno, they've been knocking like that for the past 200k miles, we're just gonna beat on them and run them until they die completely".

Long live the GM Gen III/IV small blocks! :thumb:

ben

 

[OregonDMAX]

and there is a reason why gm built there 100 Millionth small block well over 2 years ago.

now aint that quite a feat to be able to say that.

 

[Gello]

For small blocks!!


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[SkintBack13]

um ok first of all. ITS NOT A 323. Its a 325ci.

second of all. Do you have any idea how much you can get a used 4.8/5.3 head for? My buddy has piles of them that he cant even GIVE away.

You can buy a whole freaking engine (used) from any junk yard for probably $250. Thats not "lots of $$$"

And finally. If you think the 5.3's (or any LSx) is a "junker" just because yours had a problem and the millions of other 5.3's out there are running just fine, you are crazy.

Sorry, I just get heated up when people call the LSx engines junk and unreliable. I know it sounds crazy, but Ill defend the reliability and bulletproof-ness of an LSx before I defend the reliability of a duramax. Yeah....I just said it.....

ben

Yea I don't mean any disrespect to GM or their motors, Ive run them all my life, sorry you were so burnt up bout that. And Yes it costs me a bunch of money because it was in and out of the shop for the same problem about 5 times. Mechanic says the heads are awesome UNTIL they are taken off and cleaned? then they start coming apart. I find that very strange but apparently its happened a bunch on this particular year of motor. And for the 323ci/325ci confusion. MY BAD. Not trying to sound like I know it all because I don't, that's why I post here for help. sorry.

Thank you all for the input, it was much appreciated.
BTW: this was all done about a week after this thread, I haven't been on here since.

 

[02greysixer]

All the kids around here have older 4.8, 5.3, and 6.0 gm small blocks and the torture they will soak up is amazing. I've seen 5.3s screaming on the rev limiter for minutes at a time in the mud hole. I saw one kid who was about to trade in his 08 just torture the shit out of it in a sand pit till the manifolds and part of exhaust pipe were glowing bright red and every overheat warning light/message on the dash was lit up. I know of another 6.0 work truck that the guy just stopped maintaining at almost 300k. He wanted a new one and wouldn't buy one till the current one quit moving. I know for a fact the oil in that one is well over 20k hard towing miles old. It still runs, the tranny let go though. The best one was a 99 light duty 3/4 ton with the 6.0 belonging to a friend of mines dad. It got flooded during a hurricane here and the farm road the guy was on washed out underneath him, the truck floated and shut off. Fully hydrolocked. They pulled it home, pulled plugs and cranked the water out, changed all the fluids and let it sit for a while to dry out electronics and it fired right up. It never ran quite right again so he got a new truck and that became a play toy for the mud hole and woods. It lasted a few years till it developed a bottom end rattle and finally just locked up tight one day. I wish I could have torn it apart before they scrapped it just to see what let go. I suspect it had at least one bent rod from hydrolocking.

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[jkholder09]

Castech 813 casting iirc.
You will see maple syrup in the rocker areas it is obvious with vc off


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