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2003 Chevy suburban 1500 4wd. 5.3 eng


2003 Chevy suburban 1500 4wd. 5.3 eng Mechanic's Assistant: Are you fixing your vehicle yourself? What have you tried so far? Yes. Overheats within 2 miles so changed thermostat snd [water pump](/topics-water-pump/). Uppe...

2003 Chevy suburban 1500 4wd. 5.3 eng Mechanic's Assistant: Are you fixing your vehicle yourself? What have you tried so far? Yes. Overheats within 2 miles so changed thermostat snd [water pump](/topics-water-pump/). Upper rad hose is hot and bottom rad hose is cold Mechanic's Assistant: Has the vehicle ever overheated? And when was it last serviced? It just started this after the hard freeze in my area. No antifreeze was in coolant from another repair of a heater hose

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Automotive Expert
Hello, and thanks for your question, my name is \*\*\*\*\* \*\*\*\*\* I will do all I can to help. Is the check [engine](/topics-engine-chevy/) light on when driving now? Also, does the engine run well when cold? cranks up normally and doesn't skip or smoke correct? Thank you.

Engine light is always on due to sensors. However engine runs fine snd cranks normalIt just runs hot within a mile or two
Automotive Expert
Alright, if the top hose is hot, most likely the thermostat is opening, and if your sure it's full of coolant with no air in the system, then it sounds like to me the [radiator](/topics-radiator-chevy/) is plugged. As the lower hose is cold so that means to me coolant isn't flowing through the radiator cores like it should. If you turn on the interior heat, is it hot or is it cold?

COLD
Automotive Expert
So no interior heat as well?

Correct. All started after this hard freeze in Little Rock atAR
Automotive Expert
Interesting. is it still cold there or has it been above freezing for a while now?

HotFor last few days
Automotive Expert
Alright, your sure it's full of coolant with no leaks and no air in it? It sounds like it might have a lot of air in the system to me. If you leave the radiator cap off after it's warm and running, is the level still full in the radiator?

I heard of this so filled from top rad hose to ensure all air is out.Let me do that again. I was checking the steam vents
Automotive Expert
Alright, I personally would get a few gallon jugs, maybe 4. Drain the radiator fully, and then make sure you get at least 3 gallons in it, of dexcool, I'm thinking the block may hold a gallon or so. But it should at least hold 2 1/2 gallon if you drain the radiator completely, so if you put a gallon in it, it's not full. capacity empty is over 4 gallons.

Ok I did this yesterday and it's was about 4.Don't feel any water in the upper rad hose while engine is runningSide res is full
Automotive Expert
Alright, then it should be full capacity. I wonder if somebody mixed conventional antifreeze with the dex cool at this point and maybe it's gummed up and not flowing like it should. If your driving down the road at say 45 mph or more, does it overheat as well? or does it have to be sitting?

Customer attachment 2/24/2021 5:28:05 PM

Customer attachment 2/24/2021 5:28:13 PM

While drivingWhen I changed water pump yesterday I didn't see any gummy stuff when I drained systemOk with coolant overflow tank top on to build pressure seems water is in top rad hose
Automotive Expert
Alright, interesting. try getting 4 gallons in it and then letting it sit at idle and running and make sure all the airs out. I may would double check it with an infra red temp. gun on the upper hose right near the thermostat housing and make sure it's not just the gauge saying it's over heating when it's not. My thoughts are if all that is good and you put a new T stat and water pump in it, and it still overheats, then it's either a [head gasket](/topics-head-gasket-chevy/) or the radiator is clogged up. If it runs fine when you crank it cold though, doubt seriously it's a head gasket issue, but anything is possible.

I checked oil stick and it looks normal. No sludge

Customer attachment 2/24/2021 5:34:35 PM

Is there an actual radiator cap under all the plastic shrouds
Automotive Expert
I follow you there, I doubt seriously it's a head gasket, but wanted to list all the possible causes of the overheating issue.

Of courseI'm with you just trying to report all so you can helpit's overheating while sitting still too just not as fast
Automotive Expert
No, there isn't a normal radiator cap on this radiator. you fill it by the overflow tank only.
Automotive Expert
and the top hose is hot and bottom hose still cold? and it's overheating while running, if it was fine down the road, would say possible fan clutch, but sounds like the radiator to me. I just really can't think of anything else that would be a better theory.

Well that all that's left to change in the cool system. Any idea how this would just become inopFor the future
Automotive Expert
I would double check it with another temp gauge or infra red heat gun though, just to be sure it's really over heating, I have been fooled by a gauge that wasn't accurate before. Corrosion and sediment eventually stops the flow enough, and I suppose it's possible that if it did freeze and it didn't have adequate protection then maybe that could have bent the small cores some or distorted the openings to them. I'm guessing there, but I just don't know of any other possibilities really.

That sounds reasonableAll changed at the freeze. Could be coincidence. But probably damage. I don't have an infrared heat gunDo parts stores rent that tool
Automotive Expert
Alright, I follow you, they may rent it, pretty cheap at harbour freight I know or ebay.

Ok we have harborIf in the future it overheats while sitting snd not driving then should change clutch fan?
Automotive Expert
Yes, I would definitely try another fan clutch if it overheats when sitting but if fine down the road.

ThxIs it hard to change the temp sensor if the infrared therm show good
Automotive Expert
No, not too bad, it's behind the alternator in the intake.

Is there a way to pressure test the coolant system
Automotive Expert
Yes, it's done with a threaded adapter, then you pump the system up with a pressure tester, I believe they do rent those at parts stores.

Would that let us know that the rad is bad
Automotive Expert
No, it will just show a leak if it's got one externally.

Ok that's what I thought so I don't see leaks it just doesn't seem to be flowing
Automotive Expert
Yes, and since you just put a water pump on it, we know the impeller isn't rusted off, so I would say the restriction is most likely the radiator.

I believe ur right just trying to cover all bases. What rad would I need. I have auxiliary a/cLooks like two rad of some sort

Customer attachment 2/24/2021 6:31:54 PM
Automotive Expert
that one in front is the condensor. one on the side is P/S cooler. go to rockauto.com it will give you listings, need to know if you have engine oil cooler lines going in the radiator or not.

Customer attachment 2/24/2021 6:35:23 PM
Automotive Expert
Actually, on radiators. I try to ship them, so you may want to go with Oreilly's or Napa or something on this one, it's a little more, but the radiators aren't bent when they come out of the shipping box. I pulled one out of the box and it looked like an accordian not too long ago from shipping. Look at the [oil filter](/topics-oil-filter-chevy/), see if you have lines coming off the oil filter adaptor.

I don't see any
Automotive Expert
Alright, so you don't need a radiator with oil cooler then.

This is a 4wd suburbanDon't know it this matters
Automotive Expert
No it does not. 2wd 4wd doesn't matter.

No transmission cooler
Automotive Expert
I personally would suggest calling Oreilly's to get the right one. that way it won't get damaged in shipping.

I will. I don't want any accordions. Lol
Automotive Expert
right, it will have auto. transmission cooler lines, those are the ones you sent me picture of.

Ok
Automotive Expert
Thank you. Have a good day!

You too
Automotive Expert
Thanks.

I flushed rad with a water hose and it's not getting hot
Automotive Expert
well, maybe it had air or sediment or something blocking it. That's great news!

Right and the heater works now tooSure temp is running a bit liver than usual. Is that something to give me concern
Automotive Expert
I wouldn't worry about it personally. unless it sets a code for it.

Thx for helping me sort it out
Automotive Expert
Absolutely, Thank you.

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