Chevy Suburban Overheating

bishop0241bishop0241 Member Posts: 1
My 2001 Chevy Sub. tends to run hot whle the engine is under a load. 3 years ago, I pulled my camper 14 hours without any problems. Last year I took a 70 mile trip and the engine ran approx. 240-245 degrees on the ride home. I had the thermostat and waterpump changed. It ran hot again this spring on the same trip. I changed the trans. cooler and the fan clutch. I have the orange antifreeze and have flushed the system 3 times in the last 2 months. I passed an 18-wheeler going uphill the other day (without a trailer) and the temp got up to 245 degrees. My mechanic used a bore scope to look into the radiator and didn't see any trash or other notable problems. My sub. has 139,000 and my camper weighs 7800lbs., and I don't know which way to turn at this point. Any suggestions?


  • kiawahkiawah Member Posts: 3,666
    Couple things to check..

    Make sure that the overflow tank and tubing are working correctly. After the vehicle cools down, if you check the radiator is should be completely full of coolant. If it is not, then it isn't able to suck the overflow back into the radiator to fill it up.

    The next thing to check would be the radiator itself. It's possible that even though he looked in the radiator with a scope, that he didn't see a blockage or restriction but there is. You might consider just replacing the radiator with a new one.

    The other problem you might have is a blown headgasket, where exhaust gas is being pushed into the cooling circuit. This could heat up the coolant, as well as airblock the cooling circuit so you don't get the coolant flow you need. A tell tale sign of this would be a radiator that wasn't full of coolant when it was hot.
  • gblairgblair Member Posts: 7
    I agree with Kiawah, follow up on his suggestions, but if the problem still hasnt gone away, You probably need to know how a similar situation happened to my '01 'burb LS, with the 5.3 liter V8, here's how we found the problem & fixed it:

    After you've flushed out your cooling system a couple times, changed the thermostat & water pump to be certain they're not involved, pull out your spark plugs, and/or take off the valve covers:

    I got this this tip from the GM service manager at our local Chevy Dealer: One neat feature about the pink DexCool coolant our suburbans use, is that it will show you when you have blown a head gasket, or cracked a cylinder head, by leaving a faint red residue near the crack, or a slightly more pronounced reddish residue (ash) on the spark plugs' electrodes located near the leak, as the coolant is burned.

    When our suburban began overheating, we were already on the interstate for about 2 hours, fully loaded with people & full of luggage with the A/C going full speed on a hot day when our gauge suddenly started climbing till we shut off the air conditioner, a dealer was at the next exit, & we immediately pulled off to have it checked out.

    That dealer discovered something else that may be useful to you: When our water pump was changed by a (non-GM) mechanic for us a short time earlier, he mixed regular (green) antifreeze with the remnants of the pink DexCool coolant already in the engine. The two coolants will form a kind of "antifreeze Jello" when they are mixed. and it will clog (or partially clog) your radiator & heater core. Flushing your system only once may not rid you of this gelatinous mess, flushing it 3 or maybe even 4 times ought to clear it out.

    As for us, the Jello problem caused the engine to run warm, and pushing the cooling system as hard as we did that day exposed another problem, seemingly inherent with some of the early Chevy 5.3 engines...

    The cylinder heads on some of these early 5.3 engines have a tendency to crack. Both the dealer service manager mentioned this, and others here on edmunds have confirmed for me in their reports, that this head-cracking issue is about a 1 in 30 problem, & evidently not big enough to cause GM to issue a recall for poorly designed cylinder heads.

    The mechanic found traces of the red stuff near each of our spark plugs inside both heads. Replacing both heads would have cost us about the same as purchasing another complete engine, so we went for the engine. Now I'm looking for ways to prevent the same from happening with my new engine. I.E: increasing the thickness of my radiator, adding a seperate transmission cooler, adding a seperate engine oil cooler/switching to synthetic oil, & even a cowl induction hood for better ventilation on the only 4-wheel drive vehicle that can comfortably seat my whole family at once.

    It may sound like I'm going a little overboard, but we live in a semi-remote, rural area, & this thing now has a new drivetrain (transmission rebuilt 10,000 miles ago). It's been our long distance voyager & severe weather cruiser for years, & will be paid off in a few months. It has otherwise served us flawlessly in every other aspect for 275,000 miles till the water pump/jello thing exposed this apparent design issue in the cylinder heads. So I'm going to reinforce that weak cooling system so this wont happen again when we need it for another road trip, or in an emergency when storm season gets rough again.
  • mdean8582mdean8582 Member Posts: 3
    While towing my 24' boat (dry weight 4500 lbs) my 2007 suburban LTZ overheated. I was going up a gradual incline from Needles CA driving west.
    There was just 2 of us in the car and the boat it was pretty empty, I was bring it to riverside to have some work done on it. It was hot (approx. 108), It has the factory towing package.

    shouldn't I be able to tow this type of boat with no problems?
  • mtap007mtap007 Member Posts: 5
    Has anyone had a problem with a 20005 Chevy Suburban with the transmission needing to be replaced? I drove about 200 miles from home this past weekend and when I got to my destination vehicle started idilling real high and would not go over 50 and still then I could tell that it was something with the transmission. I had to have it towed back to the dealership here in town and they have now informed me that I will need a new transmission. Has anyone experience this? If so, are there any other options besides a $3,600 new transmission?
  • kiawahkiawah Member Posts: 3,666
    Sounds like you may have driven a slightly damaged transmission to the point that it can't be repaired, and you need a new one.

    I had a 96 that was not shifting into 2nd gear (and also later found out reverse was out). Drove it less than a mile, and then had it towed to a transmission shop. I saw the failed part and metail pieces, and luckily because I didn't drive it much the metal pieces only messed up two other gears and not everything. Got it repaired for about half of your new one....but it sounds like you may have more major damage.
  • mtap007mtap007 Member Posts: 5
    thanks. yeah, it appears that I will have to have a new one. good that it is still under warranty. I have given the go ahead to the dealership to replace it with a new one since they are footing the bill.
  • gblairgblair Member Posts: 7
    What engine do you have?
    How many miles you got on it?
    Check your spark plugs for worst-case signs of a bad head gasket, or cracked head...

    & if it overheated, lets assume the issue was in the heads, thermostat or radiator, be sure to protect the REST of that engine, by changing that engine oil immediately!! Excessive heat causes the chemical additives in engine oil to react with each other, & turn into God-knows-what. This can, in some cases, form an acid that will actually HURT that engine if the oil isnt changed quickly.

    Good Luck!
  • mdean8582mdean8582 Member Posts: 3
    Thanks for the reply gblair,

    I have the 5.3L, 16K mile.
    I did take it to the dealer and had the oil changed and the problem looked at. They couldn't find anything wrong.
    As soon as I turned the air off and slowed to about 40-45 and put it into 2nd it started to cool. Also once I got over the hill it went back to normal? it normally runs at about 210 I never let it get over about 235.

    I also email and have talked to Chevrolet, I'm suppose to get a call from an area rep. today. I sent 1 email and have been called twice and referred to the area rep, they've been very responsive.
  • gblairgblair Member Posts: 7
    Its great that GM is being so responsive to you- I bought my burb second hand with 60k on it, now we're approaching 300k when mine started showing similar symptoms to yours (see my original entry in this thread) After having the truck back for one day the replacement engine started doing the same thing the old one did, -thank God for warranties! I'm going to seriously look into swapping the stock radiator it came with, for something heavier duty when I get it back.

    Please keep us posted with what GM officially says about your overheating problems!
  • arriearrie Member Posts: 312
    ...slowed down to 40-45 and put it into 2nd it started to cool...

    You have either low coolant level or water pump problem.

    This happened to me just last friday, yes on the Independence Day. I suddenly got message "Engine coolant temperature high". Never seen this before. Engine temperature went close to 260 by the meter in the dash.

    I tried to drive slowly but it did not cool. The way to get it cooling was to rev it up. No matter what speed I was moving the engine had to be running 3000 rpm for it to cool. When stopped at lights it heated up if I didn't put it on neutral and rev up the engine.

    First thought was it must be water pump but then I thought that perhaps it is something else.

    Looking at the coolant expansion canister there was about 2" of coolant in it. This is lower than normal as it should be about twice that high. Then I did something that the cap on that canister says not to do, i.e. I opened it when it was hot and for my big surprise it started pushing coolant in the canister. The coolant obviously started boiling inside engine when I let the pressure out from the canister.

    Coolant expansion canister cap has a pressure valve built into it. Turning the cap just a couple turns will open the valve and let pressure safely out. At least mine did.

    After the coolant stopped boiling it all went into the engine and the ganister was empty. I did all this while parked at an Auto Zone so in I go and buy a gallon of coolant and poured it in the canister. Started the engine and all of it again disappeared inside the engine. Bought another gallon and poured 3/4 of it in and after starting up this set the level to normal.

    I could have never believed that I can pour almost 2 gallons of coolant in the engine which has been running just fine before that hot coolant warning.

    There was a symptom from low coolant level, which I did not know being caused by low coolant level but realized it after found the problem. My Tahoe's air conditioning started acting funny just a couple of week earlier. What it did was that when ever I sped up from stop or other vice caused the engine to rev up the AC started blowing warm air. I thought this must be throttle full open cutting off the compressor as in some cars I had before but I was wondering why I had not experienced this during the 4 years before that I had this vehicle. Thought that perhaps it was something that has not been working correctly and now for some reason is.

    After finding the low coolant it explains this symptom too. Coolant was so low that with normal engine speeds it was not pumping hot coolant to the heater core. The AC system on these cars with automatic climate control uses hot and cold air and mixes them to make set point temperature air, i.e. the heater core makes the hot air and AC evaporator makes the cold. When the coolant was not at heater core the AC control opened the hot air side gate more as it was trying to get some hotter air for proper air temperature control. When I then revved up the engine a sudden flow of hot air in the heater core heated the air and caused air temperature to go hot until the temperature control system reacted to it.

    I can not see any external coolant leak. I don't see any problem with oil and I don't see any coolant coming out with condensate that drips under the car when AC is running. I'm guessing that the leak is internal and probably a cracked head.

    Leak also seems to be quite small but I have not had time to monitor it yet as how much I need to add coolant for how many miles but I'll find out next week.

    For all of you guys and girls with these 5.3 L engines I would instruct to open that expansion canister (slowly turn cap until pressure comes out) especially when the engine is hot. This way you will see if the engine coolant is over heating, i.e. if it starts boiling and pushing coolant in the canister. For some reason that canister in my car was holding coolant level when the engine was starving of coolant.

    There used to be times when car engines wore out, i.e. after 150 000 miles or so they start burning oil etc. They did not fail by cracked heads or blow spark plugs like my Crown Victoria before this vehicle.

    What the hell is wrong with U.S. car makers? I have been trying to buy locally made and not imports. If this turns out to be another $5000 job to fix it will be my absolute last U.S. made vehicle. I have to give up and go with common sense. I won't be buying Japanese though.

  • gblairgblair Member Posts: 7

    Those symptoms sound a lot like what happened with the cracked head issue I had in my '01 suburban with almost 300,000 miles! Chevy's service managers arent likely to admit to it right away, but if you press them, (according to my personal experience) they would admit they heard of a production run of 5.3 cylinder heads that were "not as heat-resistant as the current design". Mine cracked while we were passing through Bowling Green, KY on a family road trip to Florida, the chevy dealer in Bowling Green quoted almost the price of a new engine to replace just the heads. We opted to leave it there & get the engine replaced, that dealer did not replace the radiator & thermostat with the engine, and the overheating happened again as soon as we returned the truck to our Hometown of Brandenburg, (KY) and cranked the Air conditioner to the Max.

    Only this time, we shut that suburban off the instant the temp started climbing above normal & called a tow truck! This saved our replacement engine! The Chevy dealer (In Brandenburg) saw that our radiator was 50% clogged. So they replaced the radiator & thermostat, then we drove it around town for a week without troubles, & then loaded it up for another road trip. We are now spending the weekend Lansing, Michigan, and our trusty, '01 suburban is behaving as good as new.

    Chevy's suburbans & tahoes may have their quirks, but all models by all manufacturers do. I think through this forum, we've just discovered probably the biggest new traits (weaknesses) in using a full size truck or SUV equipped with the chevy 5.3:

    (1) Never, NEVER mix coolants!!! -Mixing DexCool and the Green Ethylene Glycol turns into JELLO!! & kills the radiator attached your 5.3, some dealers will claim they can flush it all out, but my personal experience proves such flushing DOES NOT clean it out as such dealers may claim. Mixing coolants WILL require a new radiator & thermostat (along with the heads, head gaskets, or engine, if they also need replacement)

    (2) The 5.3 may be lighter and more fuel efficient with similar torque & output as it's predecessors, but (at least some production runs of) the 5.3's cylinder heads appear to be extra sensitive to high temperatures, and are more likely to crack from high temperature or lack of coolant than the earlier, heavier engines the 5.3 was designed to replace. This is probably due to GM's striving to meet the new government/epa standards all automakers have been required to meet for this, and other years to come, the drawback is that the technology produced to meet these standards will not be as forgiving as older technology that we're all used to. This is not hard to deal with. We just need to keep a closer watch on the temp gauge & maybe get a larger radiator or some coolant additive (which is compatible with DexCool coolant!) Here's an interesting tip when the temp gauge on your 5.3L goes nuts: The Chevy dealer in Bowling Green, KY tells me that a red residue on the spark plugs indicates that DexCool coolant is leaking into that cylinder and getting burnt away. So if you see red ash on your plugs, you got a cracked head or blown head gasket, acccording to the service department there.

    Lets keep this thread going! Keep sharing your 5.3 Trailer towing and/or Overheat stories! and what you have done to deal with the high temps, or how you made your 5.3 run cooler!
  • mdean8582mdean8582 Member Posts: 3
    Thanks to gblair and arrie... great insight, you both know a lot more about trucks than I do.

    I'm still talking to GM and they are suppose to be working on a solution. They wanted to re-enact the overheating problem..... But I live in long beach, CA and I keep my boat in Arizona. So they are looking for a different way to get it to overheat while I'm towing a boat up a hill. The other problem is there are no big hills near my house?

    We'll see what they come up with. I'll keep you informed.
  • arriearrie Member Posts: 312
    Little update on my coolant leak.

    As I tried to inspect the water dripping under the car on passenger side in front I could not see any color to it, i.e. indication that it would be a heater core leak. But, as the water dried away it leaved a slightly yellow color behind on concrete floor in my car port and the water felt kind of oily in my fingers.

    I then poured a bottle of Bar's coolant additive in the reservoir and also filled the reservoir with Prestone antifreeze to 3/4 full. I know you said not to mix anything with Dexcool as it turns Dexcool to jelly but that warning came too late for me anyway.

    Just made a 1000+ mile trip last week and on that trip my coolant level did not go down at all. Outside temperature 90+ every day. Engine temperature never went above 210 F that it seems to run at.

    I'm hoping I really had a heater core leak and the Bar's additive was able to fix it. The engine seems to perform as it always has so I do not see any obvious issues that would have been caused by the coolant temperature rising up close to 260 F what it did on 7/4.

  • cpmarncpmarn Member Posts: 1
    I tow a 35' Holiday Rambler Alumalite XL behind an '88 Suburban Silverado 20 with the 7.4 liter engine and 4.10 axle. I've used this 'burb since '93 and any summer we start towing in the Carolina's, our temp runs up near 250-260, the AC must be turned off and windows opened - a real bummer of a trip. Thought we had the problem solved this year when it took three shop visits to get home from Boone, NC. Turned out that the distributor had a malfunction that caused one of two catalytic convertors to clog up and eventually shut down the engine. I was hopeful that the new dist. and replacement of two catalytic converters with one larger one would resolve my overheating problem. Not so. I had to drive home to FL with AC off and windows open. Gasp! In retrospect, when I looked into the new catalytic converter it was amazing how restrictive these things are. Could that be part of the overheating problem on these 454 GM engines? Your experience, please.
  • arriearrie Member Posts: 312
    I don't believe myself that catalytic converter has anything at all doing with engine overheating. I don't know how distributor could cause clog up of the converter either, but that is just me.

    Engine cooling system is quite simple though.

    As an overheating problem we talk here about the coolant temperature that you say goes up to 250 - 260 F.

    One way coolant temperature goes up is, of course, that the radiator in the front of the car does not do its job. This can be caused by restricted air flow thru the radiator or insulating layer either on inside or outside surfaces of the radiator.

    Have you ever flushed your engine cooling system? Your vehicle being 20 years old means that if you have not it would be a good time to do so. Flushing engine cooling system will also make coolant temperature raise faster because it will be able to absorb engine heat faster after engine cooling channels are cleaned. The main thing though is that the radiator will be cleaned so that coolant can lose the heat load easier at the radiator and so be cooled.

    Another very possible reason for coolant overheating is that it does not circulate fast enough. This would be a water pump problem. Have you ever had your water pump replaced? They do wear out and perhaps it is time to look into this too.

    Then of course the cooling system thermostat must be working correctly. They usually do but if it would fail and send too much of the engine coolant thru the car's heating system instead of the engine it could easily cause an engine overheating problem.

    Next time you pull that big trailer with overheating engine try to run on the third gear. You might need to slow down a little bit but this could result engine coolant temperature to drop. If it does it tells me that your water pump does not pump enough coolant flow when running with normal engine speed. Raised engine speed when using lower gear boosts coolant flow and would lower temperature if the problem is with the pump.

    Then, make sure your cooling system is truly filled with coolant. I just found out in my own "04 tahoe a month ago that even when I had level in the expansion reservoir the cooling system was very low.

  • shanvanshanvan Member Posts: 1
    I bought mine new 2005, a few months in tranny was replaced
  • HundriverHundriver Member Posts: 1
    2011 Suburban overheating while pulling 4K rv climbing from 7k to 12k. Replaced coolant, thermostat, tranny fluid. Still ovheating even with heater set to 90 and blower on full. Oddly will drop to 210 for a bit then back up to 225. Guess radiator is next up for replacement. At $750 now can’t wait to see the bill for radiator
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 26,670
    edited September 2019
    Not an expert on Suburbans. I know on my leSabre sitting in slow and stopped traffic the digital temp would go up to let's say 224, then the higher speed fan or second fan would kick in and the temp would go back down to maybe 212.
    Then the temp dropped low enough the system must have gone back to lower speed on the one fan and kept the other fan on high? That leSabre had two fans. One was high speed only and the first was low speed and high speed capable. I don't recall how the temps and control of the speeds went. I just know the leSabre went higher than I'd like to see before really kicking in for air flow. But it was well within the 250 boiling point under the 17 psi pressure cap or whatever the system was set for.

    The temp drop at low speed climbing sounds like a higher speed fan kicked on, brought the temp down, then went back to lower speed.

    I wonder if while climbing your road speed is low so you're not getting enough air flow through the air pushing against the condenser and radiator. And the original equipment fan or fans aren't working right.

    I just learned that my son's Cruze has 3 speeds on one fan. The third speed is like a jet engine and it cools things down.

    Are there pusher fans that sit in front of the radiator and blow air in that are extra equipment in the towing world? Or the other possibility is your Original Equipment fans aren't working quite right.

    Or is there some patch set up that lets you manually select the highest speed on the fan(s). I recall another parent from Boy Scouts who had a Firebird that overheated. He put in a different control for the fan that turned it on sooner or kept it on. This was a commercial product.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • SkipNolteSkipNolte MichiganMember Posts: 1
    One to add about overheating. I just purchased this 2004 Burb with 226K. My 4th one over the years. On the way home ( after driving about 25 miles ) it threw a 430 code. Found a leaking intake manifold gasket. Replaced it and was fine. We went on a 900 mile, one day round trip and just before getting back it threw the 430 again and I noticed the temp rising (normally about 200 to about 230). We were running the air the whole time. As I would decrease speed the temp would go back down. Tried turning off the air but made no real difference. Oil and coolant look fine. Checked plugs and tho they were a bit worn they looked fine, all the same and no coloration or anything. I replaced them and the wires while I was there. I'm wondering if I could have a clogged cat. Since this vehicle is new to me I have no other history. Thought I would ask for suggestions before taking it in since I don't have all the equipment to diagnose. Thanks for any help!
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