02' Silverado 5.3L, overheating while idling

[maxdustington]

Originally Posted by Les_Ismore
Hey, I owned this truck! And did exactly this when my truck had exactly this problem. Are you speaking from direct experience?
1) Pull off the upper radiator surround (8 bolts with 10 mm heads) plenty of room now smart guy.
2) Sure, but if you dont have coil cleaner, use what you already have.
3) An unskilled pressure washer user can destroy a radiator, a garden hose never will. Soak, wait, flush for 5 minutes- its a 30 minute job including dis/assembly.

It took me a lot longer than that to flush my radiator on my current car out, I sprayed it with my hose and it took 30+ mins before all the bubbles were gone. I wanted to clean my condenser, but the rad was right behind it and it took forever. I was using foaming coil cleaner though. That's why I suggested the pressure washer, you need the pressure to get through both the rad and condenser, else you sit there wasting water and time. It might have been the coil cleaner, because I did my intercooler which has larger passages and it still took forever to rinse.

If you can spray from the inside I would deffo recommend the coil cleaner. If your condenser is in front of the rad and you spray the cleaner from the inside, the foaming action will hopefully penetrate to the front of the radiator. Honestly I would do both sides, you might as well clean both the condenser and radiator while you are there, then you can be 100% sure you do not have a blockage and get increased ac performance as well.

EDIT: Parents' have an 04 Sierra 5.3 Z71. 03 was the facelift year but I'm sure it's the same inside the engine bay.

 

[Gito]

Originally Posted by Chris142

Original with 360something thousand miles! That's pretty much unheard of as they usually break a tank well before 150k. Its definatly restricted due to age and milage.


Hoping to hit 400k miles on the original engine. We are the original owners. It's been a [censored] of a truck

 

[maxdustington]

Originally Posted by Gito
Originally Posted by Chris142

Original with 360something thousand miles! That's pretty much unheard of as they usually break a tank well before 150k. Its definatly restricted due to age and milage.


Hoping to hit 400k miles on the original engine. We are the original owners. It's been a [censored] of a truck
GMT400s and 800s are the last generations where they were designed to be worked, not pick the kids up from the mall. Both of them have their foibles, but they will rust to pieces around that engine and transmission (transmission not as good as the engine).

 

[spasm3]

Originally Posted by maxdustington
Just throw money at it and replace EVERY cooling system component with OEM on a 16 year old truck. BITOGers love to spend other people's money rather than diagnosing, but will complain when shops do the same.



Some people on this board give really bad advice. Like the advice a dad who doesn't work on cars gives you when working on your car.



Actually thats what i did. I had a slight leak from my water pump gasket and probably could have just replaced that. But since i tow and can be 6 hours or more from home towing a travel trailer. I went through the entire cooling system and replaced everything. Water pump, thermostat, fan clutch. New belts. ALL the hoses Including the heater core quick connects. Cleaned out the radiator and condensor, all new hoses. OR on a 16 year old truck, you can just keep piecemealing it together. I would rather not spend time on a trip being towed, so i related what i did. Now i should be good for another 15 years or so.

I actually considered replacing the radiator, but with the miles on mine, i held off, plus its an easy radiator to change if i need to.

 

[Gito]

[/quote]

Thread title says overheated, your description says the temp gauge "moved up to significantly".

Did it overheat or just increase the temperature?

I'm thinking it's normal. An increase in system temperature, while idling and not moving (lowest flow from water pump and low flow through radiator), in high temperatures (less cooling), with AC on (heavy heat load) will make it climb and stabilize at a higher level. Once you moved and gave it some gas, the water pump started moving more water and you got more flow through the radiator, which brought it to a lower level.
[/quote]

I guess the description of my truck overheating is incorrect since the temp gauge needle settled right beetween the red zone and operating temp (mark).

I would like to think that it's normal but because I just replaced the mentioned parts I kind of got worried and wanted to double check. I tried cleaning the radiator with a hose as much as I could when I replaced the mentioned parts but there wasn't much room to spray water between the condenser and the radiator so I don't think much can be done there other than just spraying water from and thru the back of the radiator and spraying water thru the front of condenser.

 

[maxdustington]

Originally Posted by spasm3

Actually thats what i did. I had a slight leak from my water pump gasket and probably could have just replaced that. But since i tow and can be 6 hours or more from home towing a travel trailer. I went through the entire cooling system and replaced everything. Water pump, thermostat, fan clutch. New belts. ALL the hoses Including the heater core quick connects. Cleaned out the radiator and condensor, all new hoses. OR on a 16 year old truck, you can just keep piecemealing it together. I would rather not spend time on a trip being towed, so i related what i did. Now i should be good for another 15 years or so.

I actually considered replacing the radiator, but with the miles on mine, i held off, plus its an easy radiator to change if i need to.
When you say cleaned out the radiator, do you mean clean in internally? If so, what process did you use?
I've seen it mentioned on this board that cars with high mileage can have their radiators get blocked up and lose their cooling capacity. I want to see proof of this idea, and I think this thread might be heading in that direction. According to my research citric acid or CLR is used to clean radiators and heater cores but I have never tried it, but always thought about a preemptive heater core flush.

 

[bullwinkle]

If I was idling with the A/C on, in 100F+ heat, I think I would pop the hood & raise it, at least a foot-that kind of heat is COOKING everything under there! This is why the PD here used to punch louvers in their hoods to let the excess heat out.

 

[spasm3]

Originally Posted by maxdustington
Originally Posted by spasm3

Actually thats what i did. I had a slight leak from my water pump gasket and probably could have just replaced that. But since i tow and can be 6 hours or more from home towing a travel trailer. I went through the entire cooling system and replaced everything. Water pump, thermostat, fan clutch. New belts. ALL the hoses Including the heater core quick connects. Cleaned out the radiator and condensor, all new hoses. OR on a 16 year old truck, you can just keep piecemealing it together. I would rather not spend time on a trip being towed, so i related what i did. Now i should be good for another 15 years or so.

I actually considered replacing the radiator, but with the miles on mine, i held off, plus its an easy radiator to change if i need to.
When you say cleaned out the radiator, do you mean clean in internally? If so, what process did you use?
I've seen it mentioned on this board that cars with high mileage can have their radiators get blocked up and lose their cooling capacity. I want to see proof of this idea, and I think this thread might be heading in that direction. According to my research citric acid or CLR is used to clean radiators and heater cores but I have never tried it, but always thought about a preemptive heater core flush.


I used a prestone radiator flush product before i replaced anything, I took the radiator out and rinsed it again with a hose. Cleaned both of the outside sides with Tuff stuff. Cleaned both sides of the a/c condensor with Tuff stuff and rinsed.

I did it prior as i did not want to run a flush through the new pump seals or the new hoses. Flushed with distilled water and then went to work.

 

[maxdustington]

Originally Posted by bullwinkle
If I was idling with the A/C on, in 100F+ heat, I think I would pop the hood & raise it, at least a foot-that kind of heat is COOKING everything under there! This is why the PD here used to punch louvers in their hoods to let the excess heat out.
I think this is pseudoscience/outdated information. On modern vehicles I think they manage the heat a lot better than in the past. When my cooling fans are on, I can feel the heat if I stick my hand out of my passenger side window and even more so if I open my door and put my hand under the car. I'm not trying to claim that new cars are impervious to under hood temps, but we don't have Dodge Coronets with 440s, fixed mechanical fans and minimal fan shrouds as cop cars anymore.

 

[Rhymingmechanic]

Originally Posted by Gito
[/quote]

I tried cleaning the radiator with a hose as much as I could when I replaced the mentioned parts but there wasn't much room to spray water between the condenser and the radiator so I don't think much can be done there other than just spraying water from and thru the back of the radiator and spraying water thru the front of condenser.


Taking off the plastic cover above the radiator (held in with about 8 plastic push-pins, between the shroud and the grille) will let you access a small gap between the condenser and radiator. There's enough space for a plain hose end or a handheld spray nozzle. I don't know how much difference it will make beyond what you did, especially if you sprayed through the radiator with the upper shroud removed.

Judging by the owner's manual page I posted, the computer trips a warning when the coolant is "hot" and then another when it actually "overheats." If you got neither, then what you saw was probably normal considering the heat and extended idling. I would keep an eye on it but keep on driving.

 

[mrsilv04]

Originally Posted by Rhymingmechanic
I think the feature must have been introduced 20 years ago, with the 1999 models.

Here's a page from the 2001 owner's manual:



Well, that's great news. When Dad had the thermostat snap shut on the 2000 Sierra... he didn't get a single heat related message or reduced engine power.

So, he caught that the truck was getting warmer than usual, well before the engine management system did. So the engine didn't get nearly as hot as I feared it had.

We should be OK. I feel much better now.

 

[Rhymingmechanic]

I found the same page in the 2000 Sierra manual, so your truck should have the feature.

 

[Nick1994]

Gito, it's the inside of the radiator that gets gunked up and can't be flushed. I'd replace the radiator itself.

 

[Gito]

Originally Posted by Nick1994
Gito, it's the inside of the radiator that gets gunked up and can't be flushed. I'd replace the radiator itself.


Drove back to LA from Vegas in 100+ deg F and no issues driving up to 5,000 ft.

Will have a new radiator ready for when the current one starts to give me issues under normal driving conditions.

Truck is truly "Like a Rock"

 

[Triple_Se7en]

My last rear-wheel drive vehicle that overheated on idle but not during regular driving speeds, well it turned out to be the fan clutch causing the problem.

 

[samhainlimon]

I just joined and I was looking for the answer to this question myself. I Have A 2004 Chevrolet Silverado 1500 LS 4x4 5.3 L with 150,000 miles. The same thing happens to me. Both the transmission and coolant temp start to rise if I'm idling. They can get into the 230 range. Maybe higher but I always shut her down at that point. It happens if I'm idling, it's hot outside (in the 90s or hotter) and I'm running the ac. I think it might be normal (at least for this age of truck) and a consequence of this technology (belt driven fan with a fan clutch etc). Over the life of the truck I have replaced the thermostat 3 times (when flushing the coolant but never due to a thermostat failure. There has been corrosion on them but nothing horrible. I replaced the coolant pump once when it started leaking. It was also still working and same corrosion levels as before. I recently changed the fan clutch in an effort to solve this issue. The only thing that happened was my gas mileage improved slightly from 13.8 avg mpg to about 14.5. I also recently replaced the radiator as well and the issue remains. The overall operation of the truck is the same. I used OSC and it looks like good quality replacement. She otherwise still runs like a champ so that's why I think this issue is probably relatively normal. I do think it can be difficult to fully flush and replace the fluids because manual says she takes 16+ qts and I usually can only get about 10 qts in (I ensure I fill the radiator. And follow purge techniques etc so maybe something there. Just my two cents.

 

[Rmay635703]

The overheating problem can occasionally trace to a blown head gasket if it's persistent and the gage pegs around.

 

[P10crew]

Sam from my experience with the 5.3 I can assure you that your situation is not normal. I would take a real good look and make sure that you have good airflow through the radiator. Carefully rinse it out if it's full of bugs. Are the fins in good shape? What temp thermostat did you use? Did you fill the coolant while the system was under a vacuum?

 

[clinebarger]

The fan should be raising heIl at 230° given that the coolant is flowing well through the radiator core & the fan clutch actually works. Changing a fan clutch will never result in better MPG!

I was in Austin gridlock friday in my 2500HD AC full blast.....Fan was roaring like mad, Display in the truck indicated 106° ambient, Coolant temp stayed under 205°, Trans hovered right at 200°

As a general rule....A well maintained correctly operating vehicle can maintain 100° Above ambient in ANY situation.

 

[Lubener]

Originally Posted by Chris142
No it's not normal. Is the fan clutch actually working? Just cause its new does not mean its good. If it was made by Hayden its definatly a suspect. We stopped selling Hayden fan clutches,too many bad ones from Hayden.

Could also be a partially plugged radiator that's not allowing the bimetal spring to get sufficient heat.

I agree with the fan clutch suggestion. Fan clutch was making my engine run very hot during idle but was fine at highway speeds. It's an air flow issue not a water flow issue. Could also be clogged or missing fins on radiator. A plugged up radiator inside usually will make the engine run hot on the high way.