Ok, I Am Stummped! Why Is My Silverado Overheating?

mrhoneydu · July 10, 2008

Ok, my '04 Silverado has not given me a lick of trouble.....until now. It red lined on me a couple days ago. I cought it before I lost any fluid. This happened not too far from my home, so I cracked the hood, threw on the heater and continued home. Doing the above, I got the temp down to about 230-235 degrees. I replaced the thermostat, (after boiling it on the stove) same problem. Changed water pump, same problem. Changed the Fan clutch, and...you guessed it, It is still running hot. HOWEVER, its not "red-lining" anymore. It gets to about 240degrees. I thought, I might not have "burpped" the system correctly, so I did it once more. I think I burpped the system correctly. Why am I still running hot? Oh, and I also stuck my garden hose into the top of my radiator, and got good clean water out of the top radiator hose, so that tells me there is not blockage anywhere. Any help would be greatlt appriciated.

Tom

L29er · July 10, 2008

sounds like you`ve checked everything, haven`t ever had problems with the system not clearing its self of air, when you re-filled your system did it take the specified amount of coolant? hmmm, its rare but maybe the inside of one of your hoses colapsed, do any of your hoses feel soft? oh and i`m asking just to clear it up, your mixture is good and your rad is clean?, i`m sure you`ve checked but it helps to solve er`! i have`nt heard of many of these trucks blowing head gaskets but that culd cause it too, does it blow any coolant out the cap? anybody else got ides?

L29er · July 10, 2008

oh i noticed this is your first post, WELCOME TO THE FORUM!!

merlin5577 · July 10, 2008

Welcome to the site. The first thing I would check is that there is nothing blocking airflow across the radiator. Is there anything (like a bag or lots of leaves) blocking the radiator? Are the fins on the front of the radiator bent over? If that checks out I would swap out your radiator cap. If the spring valve on the cap is warn it would allow the coolant to boil at a lower temperature causing steam pockets in the cooling system. If that doesnt fix it I would change out all the hoses to makes sure the rubber is not so weak it is collapsing under load. Good luck.

pennzoil29 · July 10, 2008

Welcome aboard. The first 2 replies pretty much said what I would have. I hope you figure out your problem.

compulynx · July 10, 2008

It is rare, but have you also checked to make SURE it is getting hot? Could be a bad sending unit or gauge....

Also, sticking a water hose in and getting clean water out of the top hose does not mean there is not a blockage. A good radiator shop can check the flow to make sure it is sufficient to cool properly.

C

mrhoneydu · July 10, 2008

Hi All, and thanks for the Welcomes! Lets see, yup, the radiator is clear of any blockages on the front side, and not a fin out of place. And yes, it is getting hot. Both radiator hoses are getting hot, as well as the fluid in the resivoir. I replaced the cap on the resivoir this morning. No difference. I think I am going to flush it once more and see what happens. If y'all think of anything else, fell free to pass it on. Thanks again to all!

Tom

PS......So I guess I need to get a pic up for my avitar huh? I'll post a pic of the truck, its better looking then I am!

merlin5577 · July 10, 2008

Tom,

I meant swap out the Radiator cap, not the cap on the reservoir. I think you may have some luck there. Like I said before, if that doesnt work swap out the hoses to make sure they are not collapsing under load.

-Rob

Draenor · July 10, 2008

Tom,
I meant swap out the Radiator cap, not the cap on the reservoir. I think you may have some luck there. Like I said before, if that doesnt work swap out the hoses to make sure they are not collapsing under load.

-Rob

There is no cap on the radiator, just on the overflow reservior tank.

merlin5577 · July 10, 2008

Tom,
I meant swap out the Radiator cap, not the cap on the reservoir. I think you may have some luck there. Like I said before, if that doesnt work swap out the hoses to make sure they are not collapsing under load.

-Rob

There is no cap on the radiator, just on the overflow reservior tank.

Well that was dumb of me then.

Tom,

What engine is in your 04'?

mrhoneydu · July 10, 2008

Hi Merlin,

It's a V8 6.0L. Compulynx may have had something saying just cuz I was getting water to return after sticking my garden hose into the radiator didn't mean I didn't have a blockage or partial blockage somewhere within the system. I just drained the system, and put in some radiator flush and filled the system up with water and ran it for 20 minutes and the temp never got above 200 degrees. ( My OEM thermostst is 198degrees). Before I would hit 240 within 10 minutes. After the engine cools, I will put fresh antifreeze/coolant back in and will let you all know how I made out. Oh, and yes, there is no rediator cap, only a cap on the resivoir tank. Wish me lucK! Again, thank to all!!!

Tom

merlin5577 · July 10, 2008

Whatever happens, good luck. And sorry about the dumb comment.

mrhoneydu · July 10, 2008

Ok, all. I think it is fixed. For some reason after running a 2nd radiator flush, it seems to be holding at 210 degrees. Before my temp gauge would hold right at 210 and not budge. Now, with the replacment stat, it bouces one line either side of 210. I guess thats ok. I have one last question though. After I replaced the water pump, I flushed the system. Then again, this morning. What in the world was in my radiator, or cooling system in the first place to make it clog up? When I drained the system to change the stat, my coolant was clean and bright. Any ideas?

Thanks again to all!!! Hope I can repay the favor some day. Time to wipe down, and put away the tools, and sit back in my lazy boy and have an ice cold beverage!

Thanks!

Tom

Draenor · July 10, 2008

What in the world was in my radiator, or cooling system in the first place to make it clog up? When I drained the system to change the stat, my coolant was clean and bright. Any ideas?

Gremlins.....They tend to get nasty when wet.

merlin5577 · July 11, 2008

Ok, all. I think it is fixed. For some reason after running a 2nd radiator flush, it seems to be holding at 210 degrees. Before my temp gauge would hold right at 210 and not budge. Now, with the replacment stat, it bouces one line either side of 210. I guess thats ok. I have one last question though. After I replaced the water pump, I flushed the system. Then again, this morning. What in the world was in my radiator, or cooling system in the first place to make it clog up? When I drained the system to change the stat, my coolant was clean and bright. Any ideas?
Thanks again to all!!! Hope I can repay the favor some day. Time to wipe down, and put away the tools, and sit back in my lazy boy and have an ice cold beverage!

Thanks!

Tom

Tom,

My guess is you had an air pocket and the second flush flushed it out. No worries, glad I could help. A cold beverage does sound mighty tasty right now.