02 Silverado 5.3L Overheating

[kc8adu]

seen water pump impeller rotted away do this.
original on my 89 with 350k on it.as load increased so did temp.it was subtle but i knew something was failing.and the fan made its normal roar.
radiator was nearly new and i keep it clean.that waterpump didnt owe me anything so i shotgunned it.the volume of coolant returning to the fitting from the heater cores under the cap doubled!and when i tore it down it was so far gone it was hard to believe it kept its cool at all!

 

[CBR.worm]

The fact that it gets hot going up the grapevine tells me that it is not solely a fan problem. The fan could be contributing at idle, but it sounds like water flow is being impeded, either bad t-stat, pump, radiator, internal passages, or hose/fitting.

It could be junk between the condenser and radiator, but it would have to be a bunch of junk.

 

[Rhymingmechanic]

Originally Posted By: CBR.worm
The fact that it gets hot going up the grapevine tells me that it is not solely a fan problem. The fan could be contributing at idle, but it sounds like water flow is being impeded, either bad t-stat, pump, radiator, internal passages, or hose/fitting.

It could be junk between the condenser and radiator, but it would have to be a bunch of junk.


I've been thinking about this part some more, too.

First, for the OP, have any variables been out of the ordinary? Do you not normally drive the Grapevine, or is the outside temperature usually cooler when you do?

Your normal gauge temperatures sound like mine on a 2001 Silverado. The needle usually sits about 1.5 marks cooler than 210. I have always assumed the gauge reads accurately, since it has fluctuated just slightly to one side or the other of that point. Thermostat is the stock temp, 187.

However, it may be a dummy gauge after all. I went for a 12-mile one-way drive in 94-degree weather last week, about 8 miles on a 60-65 mph interstate with city driving at each end. On the return trip, Torque read a steady 205 on the interstate portion, and was up to 208.4 when I reached my driveway. Another minute or two of idling got it up to 210 but the gauge was sitting in the usual spot, what I would estimate to be around 185-190. The last time I really watched temperatures with Torque was in the spring. On a 70-degree day, I took a two-hour drive on back roads. Averaging 60-65 mph, the engine temp ranged from 197-199. I didn't look at the truck's gauge to compare.

All that is to say your actual temperatures might not be what you're seeing on the gauge.

 

[udidwht]

Originally Posted By: Gito
2002 Silverado 5.3L with 302,xxx miles.

Drove back from Sacramento to Los Angeles about a month ago and right when we hit the Grape Vine the temperature gauge began to climb close to 210 and 235 deg F.
When descending down the Valley, the gauge needle dropped to around 185 deg F. It was warm outside (85 deg ) on the way up.

Up until this past Monday, the needle pretty much has stayed between 185-210 deg F on warm to hot days.

Monday:
Outside Temp was 95 deg F-100 deg F in Southern CA.
Was driving around with my family from store to store with the AC on.
There was a few stores where only got off while my family stayed in the truck with the AC on.
I quickly went in and out of the stores to then jump back into the already running truck to do some more errands.
On our last stop, I jumped off the truck to run into the store for a 5 minute oil filter purchase.

I jumped into the truck and noticed a funny smell.
I then looked at the temp gauge and the needle was 2 lines from the red 260 on the gauge.
The AC was on but blowing warm air.
Checked coolant level and it looked fine

I quickly took off and was crossing my fingers that the movement of the truck would cool the truck down.
The gauge needle slowly began to move towards normal operating temp and it slowly settled at just below 210 deg F.
AC was turned back on and it began to cool like normal.
Checked coolant level and it was fine.

Drove truck for the next few days and have not noticed anything since.

Not sure where to start.
Water pump, coolant and thermostat were changed 2 years ago.
Replaced coolant again 1 year ago.

Not sure if these symptoms are indicating a problem with the fan clutch, if so, how do I test.
On my other cars (old Mercedes), I use the old simple newspaper on the fan test (when car has been driven and idling) to verify the fan clutch is OK

Can this method or test be used for Silverados?

What else could be causing these symptoms?

Any tips or recommendations are greatly appreciated

Please advise



Based on your description...

I see a normal functioning vehicle cooling system. Pulling a grade such as the 'Grapevine' will push the temp towards the higher side 230+. This is perfectly normal. What should happen is the clutch fan will/should kick in at roughly 230 and the temp should stabilize and perhaps even drop slightly during your ascent. You should hear it. Sounds like a P-51 roaring. Once you crest the grade engine temp will drop quickly and clutch fan will disengage at roughly 225-220 or so.

Now here's the important part....

If you happen to get off after the grade or during your ascent do NOT quickly shut the engine off. Let the engine idle slightly high until the engine temp equalizes. Many are clueless to this. It's even stated in many owners manuals. This is rather important due to it being a leading cause of manifold/intake cracks. Doing this allows everything to come back to equalized normal temps. Shutting off quickly will allow those temps to spike higher than tolerances can allow for.

The only time one should shutdown would be if they see steam and/or smoke.