Hello and thanks in advance for any help you folks can give. My 2004 Tahoe with a 5.3 engine suddenly overheated today. Both the top and bottom hose felt bloated and full of pressure. Several months ago I installed a new radiator. 2 months ago I installed a new water pump and thermostat. Everything's been fine til today. On my way home after releasing pressure in the system by loosening the overflow tank cap which was also replaced recently, and adding some antifreeze I was able to make it home watching the temp gauge the whole time nearly max out then go back down some then repeat. Nearly 25 miles of driving suddenly the temp gauge goes back down to normal mid range for a few then climbs again. Appeared to me that the thermostat I was sold was defective so I went to the dealership and got an OEM one. After replacing it I drove just a couple of miles and it immediately maxed out the temp gauge overheating again. Hoses felt full and bloated again. There is no water in my oil and no leaks to be found. Wondering if the aftermarket water pump has a problem as it's a Murry brand from O'Reilly. It's not leaking or making any noises though. Just never seen anything like this and I'm so confused as to what to do next. Any help would be so very much appreciated. This Tahoe has been so reliable and a pleasure to drive and maintain.
[SOLVED] 2004 Tahoe overheating. New water pump, thermostat, radiator
- Thread starter stotzbotz
- Start date
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First, I want to know why the radiator was replaced, then the water pump and thermostat? Preventative maintenance or because of problems? Actually overheated or the temp reading at the dash.
From what you are saying, you believe the engine is overheating because of what you are seeing at the dash and not because of anything else. No coolant loss at all, correct?
You may have a sender/sensor problem or a dash cluster problem. Best thing for you to do is attach a scanner that can do live data and compare the dash reading with live data reading, for engine coolant temp readings.
If in fact, you are overheating, then the process begins to figure out why. From what you are saying, you may well not be overheating.
From what you are saying, you believe the engine is overheating because of what you are seeing at the dash and not because of anything else. No coolant loss at all, correct?
You may have a sender/sensor problem or a dash cluster problem. Best thing for you to do is attach a scanner that can do live data and compare the dash reading with live data reading, for engine coolant temp readings.
If in fact, you are overheating, then the process begins to figure out why. From what you are saying, you may well not be overheating.
Yes sir thank you for your knowledge. US Army Veteran here. Thank you for your service. I replaced the radiator because it cracked open near the top drivers side. I replaced the water pump because it was leaking antifreeze out the bottom hole. Thermostat always gets replaced too when I do the water pump. I re replaced the thermostat today because of the way the gauge was acting and because I was feeling the hoses have so much pressure in them. This Tahoe acts like it's not getting good gas when it overheats and I felt that today when I thought it was overheating. Also the readout on the dash is saying that the engine is overheating and that the coolant is getting hot. Maybe the thermostat did stick causing the engine to overheat and maybe frying the coolant sensor? Hoping for anything other than the head gaskets having a problem.
With all this in mind, you need a Live Data scanner attached and monitor the data and the dash gauge. When the system is hot and holding pressure, those hoses will be hard.
They are not very expensive at all. I like Autel and Foxwell.
Tonyrodz
Resident Resident
You have the dual electric fans correct? Are your fans turning on?
2004 should have a clutch fan, not electric, unless it's been converted.
Is the clutch engaging when it warms up, and are both halves of the fan shroud in place and intact?
Is the clutch engaging when it warms up, and are both halves of the fan shroud in place and intact?
Hey there. I'm picking up a new fan clutch today as the one I have was salvaged years ago from Pick n Pull. I bought a new one before that but my truck sounded like a 747 when I would give it gas. I was told a new AC Delco clutch was over $400 so I got the used one and it worked fine for years. Probably time for a new one and I was just told that only the high speed fans make the crazy noises. Gonna install the new one today once it comes in and also replacing heater hose shut off valve that I found has a very small leak. It was installed at the AC repair shop years ago to help keep the ac running as cool as possible. Florida ya know. Hoping for the best but if all fails going to purchase a scan tool and see if it can help. It took a fair amount of new antifreeze this morning after cooling down over night also so it might have just not had a sufficient amount.
I would advise against having a valve in the heater hose on these. The water pump will fight that and might be a contributor to the overheating. The water pump needs to circulate coolant through the heater core, and that will help cool the engine.
Yes, @Fless is correct, no electric fans on this 2004. Fan clutch could have to do with the problem but a Live Data reading, removes all doubt. Plus, once you have that scanner, it can be used for so many other things. If you have a hesitation of using a scanner because of unknown ability to use, they are pretty simple and can see videos at you tube. By the way, this is the first time you have mentioned having to add coolant. Now we are in the realm of pressure testing the system. Again, if no knowledge and no tools/pressure tester, get it to a "qualified" technician for inspection.
strutaeng
Full Access Member
Maybe get yourself an inexpensive IR gun and take some measurements at the coolant hoses, besides what others have said about scanner. Take some readings on the radiator inlet and outlet.
It's weird that the temperature guage on the cluster maxes out, then drops, no? Doesn't sound like a good running engine would do that?
Fan clutches are pretty reliable and rarely ever go bad, but anything is possible. I believe to test those, you try turning it cold and it should spin with not that much effort. After reaching operating temperature it should basically be locked in? Something like that?
I chased my tail on this old OBS K3500 5.7 Vortec I'd just bought back in like 2019. I replaced the radiator because it was busted, then noticed it would only reach 1/4 mark on the cluster. I raised the front on ramps and tried to burp the air out, no change. I replaced the thermostat, no change. Dunked the thermostat on old pot of boiling water and saw that it opened. I replaced the sender, no change (the replacement was the wrong one, then the truck was all of the sudden overheating! LOL Took me a while to figure that out and eventually got the correct one which read the same as the original one!). I finally hooked up a scanner and it was saying like 210F. I concluded that the cluster guage was way off by 1/4 mark and it was new to me that I didn't know this was "normal".
It's weird that the temperature guage on the cluster maxes out, then drops, no? Doesn't sound like a good running engine would do that?
Fan clutches are pretty reliable and rarely ever go bad, but anything is possible. I believe to test those, you try turning it cold and it should spin with not that much effort. After reaching operating temperature it should basically be locked in? Something like that?
I chased my tail on this old OBS K3500 5.7 Vortec I'd just bought back in like 2019. I replaced the radiator because it was busted, then noticed it would only reach 1/4 mark on the cluster. I raised the front on ramps and tried to burp the air out, no change. I replaced the thermostat, no change. Dunked the thermostat on old pot of boiling water and saw that it opened. I replaced the sender, no change (the replacement was the wrong one, then the truck was all of the sudden overheating! LOL Took me a while to figure that out and eventually got the correct one which read the same as the original one!). I finally hooked up a scanner and it was saying like 210F. I concluded that the cluster guage was way off by 1/4 mark and it was new to me that I didn't know this was "normal".
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On my GMT800 2005 Tahoe Z71 5.3, the thermostat in it is a 207 degree thermo. That is normal.
RA lists the OE thermostat for your year as 189 deg.
Mine has the clutch fan and has an OE thermostat, and full operating temp varies between 200 and 210 deg F.
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I really appreciate everyone's responses and knowledge. This morning I topped off the coolant and it did seem to take about a gallon. Must have had an air bubble or something in it not allowing me to put more in last night. I burped the system and later found that the heater shut off valve was leaking just a little at the T handle which may have over time caused low coolant level. I replaced it and I've used one for years but if it's a bad thing I'll just keep it open. I was also eyeing the fan clutch and honestly didn't think it was spinning correctly at idle. It is 20+ years old probably. Sort of slower rotation than I thought it should be. I replaced it as well. I just took it for a drive and thankfully it is keeping a solid reading on the temp gauge now of just under the half way mark of about 207 degrees which is where it usually reads. I love this Tahoe and it has given me so many years of joy and service. Easy to work on and not overdone with a bunch of electronic sensors and gismos. Still ordering a scanner tool after I write this for future issues. Thanks again everyone. Great forum to belong to. Peace.
"Thermostats have a “rated” temperature (such as 180F or 195F). This is the temperature the thermostat will start to open, releasing heated coolant from the engine into the radiator. The thermostat will fully open once the coolant gets another ten or fifteen degrees warmer."
My mistake. I was told 207 degrees, at the dealer, because that is when it is fully open. The 187 to 189 degrees is when it starts to open.
Thanks for the correction.
My mistake. I was told 207 degrees, at the dealer, because that is when it is fully open. The 187 to 189 degrees is when it starts to open.
Thanks for the correction.
strutaeng
Full Access Member
Very good news @stotzbotz
...keep on trukin'
(BTW, IDK what this means, I just Googled that phrase and that's what it spit out?
)
...keep on trukin'
You may not be old enough to remember this. It is related to the Grateful Dead and a song called "Truckin'"
grateful dead song truckin - Search Videos
Watch videos instantly on Bing—enjoy direct playback, discover related clips, and dive into trending content all in one place.
You may not be old enough to remember this. It is related to the Grateful Dead and a song called "Truckin'"
grateful dead song truckin - Search Videos
Watch videos instantly on Bing—enjoy direct playback, discover related clips, and dive into trending content all in one place.www.bing.com
Flashback!
afpj
Full Access Member
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What/where is the heater shut off valve that has coolant flow and a T handle? I have a 2002 Yukon and have not heard of this.
