Over Heating Chevy Truck again.

dej(Jed)

Well-known Member
Okay-so I had over heating issues with my 2003 silverado 5.3. I installed a new heavy duty clutch fan, flushed the radiator and checked the radiator fins for plugging. Truck has been okay until yesterday. High humidity and the outside temperature was approx 88 dgerees F. Truck gauge went to 230 F up a hill. After I got on top of the hill it dropped back to 205F after about a mile. Any ideas would be appreciated.
 
I've had the water pump fins wear off before. Some
of the newer water pumps have steel vanes and they
will wear off and not pump properly. I've never had
a chevy tho, so I don't know anything about them
specifically.
 
(quoted from post at 05:25:43 07/22/14) Okay-so I had over heating issues with my 2003 silverado 5.3. I installed a new heavy duty clutch fan, flushed the radiator and checked the radiator fins for plugging. Truck has been okay until yesterday. High humidity and the outside temperature was approx 88 dgerees F. Truck gauge went to 230 F up a hill. After I got on top of the hill it dropped back to 205F after about a mile. Any ideas would be appreciated.

If the reservoir cap is losing pressure, could that caus ethe overheating?
 

Is the fan shroud on there and in good shape?

Was the radiator professionally cleaned out and
does it have a good flow?

No signs of a blown head gasket?

Hope it's not a cracked head.

Could timing issues be the problem?

KEH
 
If you are sure there is no debris between the condenser and radiator, something else to look at. Check the water bypass for plugging. The bypass is the little steel tube that connects to both heads, goes through the bottom of the throttle body, through a hose and back to the radiator. That entire system needs to be checked for flow. That tube is how the system purges air bubbles that collect in the top of the heads, if it is not flowing freely, it can get warm.
 
I fought my Dodge Ram 1500 with a 4.7 for a year. Did the normal stuff - new radiator cap, thermostat, flush the radiator. Nothing ever solved the problem. Had the block/head checked by checking for combustion gasses in the coolant. No combustion gasses. Radiator had a little seep where the core meets the side tank and since it was under a lifetime warrenty I took it out and got a new one. STOPPED THE OVER HEATING. Even though I had flushed the radiator it wasn't allowing coolant to flow through enough to keep the engine cool. Flow of coolant in the radiator was from the drivers side to the passenger side. Was warm by touch of hand only on drivers side 1/4. The cores in new radiators are so small they plug easily. Replaced radiator was only 2 years old - installed after I had hit a deer. Was made in Mexico. New radiator wasn't from Mexico - China maybe. I had put a bottle of stop leak into the system thinking I had a head gasket leak eariler. Probably didn't help the situation.
 
You might try replacing the thermostat.

Unless combustion product are getting in the cooling system, the thermostat is the MOST likely culprit.
 
GOOD post!

Here"s a photo of the "coolant crossover" or "air vent" system that vents the top of the coolant passages in the heads to a high point, IIRC, the coolant "surge tank".

If there"s a combustion products leak into the cooling system or the tubing gets plugged, "air" is not vented from the heads and overheating occurs.

<img src = "http://ls1tech.com/forums/attachments/generation-iii-external-engine/222005d1268871862-i-need-one-more-like-steam-vents.jpg">
 
Sounds like low flow, I would check the water pump, could be getting weak, especially if over 100,000 miles. I have noticed GM water pumps hardly ever leak anymore when they go out, these days the impellars wear down and they just don"t put out much water.
 
Those trucks are notorious for gauge problems. 230 is hot, but not overheating. Assuming, that is, you don't have a leak and the system is holding pressure. IF the system is holding pressure, it won't boil over until around 250-260 degrees F.

Is it losing coolant? If not I wouldn't worry about it. If you're losing pressure, then you need to run a pressure test ASAP.
 
Did you pull the radiator and check for grass and sand between the radiator and condenser? Impossible to see otherwise, and that's where it tends to accumulate.
 
I think you're right, I had trouble with one of those crossover tubes being plugged probably 6 or 7 years ago, can't remember exactly what I was trying to fix but it took a while to figure it out.
 

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