Blazer Engine Temperature Questions

hollygeehollygee Member Posts: 2
edited May 2014 in Chevrolet
Hi. I bought an '02 Blazer about 2 years ago. At that time it only had 68,000 miles. Now it has 84,000. Everything seemed fine for the first year. It was a great truck. Now all of a sudden everything seems to be going wrong all at once. My driver's side window no longer works, my back hatch will not open (no matter which button you push, key ring button, dash button, or hatch button), my key cannot come out of the ignition properly (I have to put a screwdriver in the emergency release button underneat the steering wheel shaft to release my key once in park), my heat just went out, and now my temperature keeps spiking when I drive anywhere more than 20 minutes away. I have to pull off the side of the road and wait 15 minutes before starting the engine up again. I changed the thermostat yesterday. It really needed to be changed (it was very rusted out), and I thought that would fix the problem, but I am still experiencing temperature problems. I guess my main question is what is the NORMAL running temperature for a Chevy Blazer? Below 210? Right at 210? I just want to fix the problem before I cause a much more expensive one, such as blowing a head gasket. Thanks for your time.


  • jlflemmonsjlflemmons Member Posts: 2,242
    Normal running temp is 195, or just below 210 on your temp guage. If the thermostat was that nasty, you need to have the entire cooling system flushed and refilled with fresh Dexcool or equivalent. DO NOT use the green ethylene glycol antifreeze as this will cause problems when it mixes with the long-life antifreeze.

    It sounds like the cooling system had not been flushed before.

    With regard to the hatch, there is a solenoid in the tailgate/liftgate that actuates the latch. If none of the switches will open the latch, it sounds like the solenoid has either gone bad, the connection to the latch has broken, or the wiring is damaged. Check your fuses to be sure the fuse to the solenoid hasn't blown. The owners manual will show which one to check.
  • melm813melm813 Member Posts: 1
    i have an 04" i bought it with 20k ,,it runs JUST below 210 it has always run hot nothing makes it run cooler....makes towing a challenge
  • jlflemmonsjlflemmons Member Posts: 2,242
    The correct thermostat for these engines is 195d. Running without a thermostat, or one that opens too soon, will set a check engine light on the 2002 and newer. On the older 4.3, it won't set the CEL, but will affect fuel economy.

    195-225 on this engine is no problem. If you see the temp creeping upwards at idle, check the fan clutch. Just had one go bad on my '02. 195d if moving more than 25mph, 220d when sitting still. After repair, solid 195d regardless, and this is in ambient of 107!
  • rs53rs53 Member Posts: 8
    my 96 blazer runs at 198 when it's rolling but when it's at a stop light the needle goes up to 218 then it repeats itself each time on stop and go situation. Is this normal or is there something wrong?
    it never done this before it normally stood below the 210 mark.
    I replaced the fan clutch and thermostat
  • rs53rs53 Member Posts: 8
    my 96 blazer runs at 198 when it's rolling but when it's at a stop light the needle goes up to 218 then it repeats itself each time on stop and go situation. Is this normal or is there something wrong?
    it never done this before it normally stood below the 210 mark.
    I replaced the fan clutch and thermostat
  • jlflemmonsjlflemmons Member Posts: 2,242
    What is the ambient temp? If well over 100 (as it has been around here) that wouldn't be too unusual, especially with the AC running. But even 218 is not excessive for an engine. Remember, the cooling system is under pressure, so the boiling point is higher.

    Is your coolant/water mixture 50/50? The coolant provides the anti-corrosive and antifreeze properties. The water is the better heat disipator. Straight coolant will not keep the engine as cool as 50/50.
  • rs53rs53 Member Posts: 8
    The coolant is 50/50 mixture. I was told the check the radiator temp. in various spots with infrared temperature gun. it varied about 18 degrees the bottom being the cooler part of the radiator.
    so my next step is to flush it to see if it makes a difference.
  • jlflemmonsjlflemmons Member Posts: 2,242
    The bottom should be cooler. With the return coming in at the top, the cooling fins are doing their job. Flushing can't hurt, but the ambient temp could still be the only issue. Hot is as Hot does!

    Is the AC working correctly? Also, check for debris/obstructions between the condensor and the radiator. Over time, grass, dirt, road crud, can work their way into the area between the condensor (in front of the radiator) and the radiator itself. I found this on an S10 that had been used a lot in a hay/milo field.
  • rs53rs53 Member Posts: 8
    My question is what do you mean by ambient tempreture?
    the AC is working good no problem there. I took it to the dealer to get it flush but didn't really want to do it because it may create more problems like open up some little hole in the radiator or possibly start a leak on the intake area.
    But here's the funny part I explain the problem I'm having also told them that I replaced the Fan clutch & the thermastat and on my request to check everything out to see why it was over heating they also test drove the blazer for 10 miles with an OBD connected with the air on as I did going to the dealer it didn't over heat.
    They said was working as it should ( the fan & thermostat and the highest it got on them was 210.
    as I was going home from the dealer it's about 7 miles with the air on It over heated to 246 half way home.
    since they didn't flush the radiator I did it with a do it your selfer.
    I bought the kit from pep boys and replace the coolant.
    I test drove it & again it over Heated to 246.
    so my next step is to replace the Radiator.
    It was clean between the condensor & Radiator.
    Any recommendation as to where to buy a Radiator?
  • duntovduntov Member Posts: 133
    I hope you installed a theromstatic fan clutch for a 2002 Blazer with A/C and it turns counter clockwise. AC Delco #15-4684.

    If you are going to install the raditor yourself, get the best available which is an AC Delco 20-837 at a retail cost of $309.79.

    If you are going to have a radiator installed by a auto repair shop, who knows what radiator you will get. The cheap radiators are nade by "various manufacturers" (meaning Chinese) for $100 plu$ labor. If you have a auto repair shop furnish and install the radiator, you will get one made by "varuious manfaturers" but the radiator will cost the same as if it was an AC Delco radiator. That is the way it works in America. Auto mechanics hate the work they do so they are going to get the most for the work as they can. Fortunately I do most of my own work so I can buy AC Delco or Genuine GM Parts.

    Rock Auto Supply has every brand of radiator and price that is available for a 2002, Chevrolet, Blazer, 4.3L
  • rs53rs53 Member Posts: 8
    hey duntov how you doing.
    I try to get ac delco has much as possible for my vheicles 95 percent of the time I do.
    outside of the dealers I only found one shop that sells ac delco parts in the phoenix area.
    I see that you said if I placed a 02 blazer thermostatic fan clutch on my blazer. I did, but I have a 1996 blazer when I standing in front of it the blades are turning counter clock.
    I also see that you placed a AC DELCO part number for a 02 blazer would you have one for a 96 blazer? I will be installing my own radiator.
    It seems the last thing left to do to solve the problem I hope.
  • jlflemmonsjlflemmons Member Posts: 2,242
    Wait a minute. Before the dealer worked on it, 210 was what you were seeing, now your getting 250??? Is the radiator cap on? Something has changed here.
  • duntovduntov Member Posts: 133
    A 1996 Chevrolet Blazer w/AC, V6 eng. (LF6), uses AC Delco 15-4684 fan clutch. The front of the clutch should have one of the following letter codes stamped in black paint: GDL, NK, GAR,or GGK. A fan and fan clutch turns CCW from the front of the engine if the serpentine belt goes over the TOP of the fan pulley because the engine turns CW.
  • rs53rs53 Member Posts: 8
    here is the situation with my 96 blazer I was going to L.A. last friday about 145 miles on the way to LA I had to turn around back to phoenix the temp gage was creeping up toward the red. I pulled over for a bit to let the blazer cool a bit. on the way back to Phx we drove without the air on it held one line above 210 about 80 miles till we hit Phx I put the air on that's when it it started creeping up again this time to the forth line so I turned the air off and it held on the forth line until I pulled in to my drive way & turn off the engine then it went closer the red.
    so the next day I checked to see what the problem is water pump was moving the coolant with no leak from the pump so I replaced the thermostat (195 degree) and the fan clutch both ac products
    the fan clutch look just like the old one I felt the tension between the both of them and both felt the same. I replaced it anyway.

    then I took it the dealer to get flush out, as I drove it to the dealer it didn't over heat when I got there I explain the problem to the advisor and upon my request I had them check it out to at an extra cost even though they give a visual one free.
    They test drove it for 10 miles with an OBD meter connected only to come back to say everything was good the tempreture on the OBD stood below 210 but this was around 0730 when the outside temp was around 85 degrees.
    They also said that if they did do a flush that it may open up another can of worms like creating holes in the radiator or start a leak around the intake or both.
    so I took it home which is 7 miles away the blazer over heated to the forth line .
    so the next day I back flush the radiator with a do it your selfer kit from pep boys and change the coolant then test drove it with a OBD meter on it got has high as 246 that's when the check gages light came on for the 1st time.
    that is why now I'm looking at replacing the radiator in hopes to cure the problem.
  • duntovduntov Member Posts: 133
    My 1991 S10 Blazer has 150,000 miles on it.. I installed a flush "T" fitting in the heater hose at 10,000 miles and every two years the antifreeze has been changed using the most popular "green" ethylene gylcol anti-freeze on the market and we all know what brand that is. I did not need to install the T-fitting because I can drain the coolant by removing the plastic drain cock and then refill the system with fresh antifreeze through the radiator cap. BTW, my 1991 S-10 Blazer has the original AC Delco RC36 radiator cap. The RC36 radiator cap was superceded by the AC Delco RC27 cap about 1995. It was merely a GM part number change and both caps are rated at 15 lb. I see USED AC Delco RC36 caps selling on e-bay for as much as $50 to the Corvette restorers because you cannot buy new AC Delco RC36 caps anymore. If you find a AC Delco RC36 cap in a local parts store or listed from an on-line retailer, it will be a RC27 when you open the box.

    Make sure your lower radiator hose has the stainless steel spring inside. If the lower hose does not have that spring, the lower hose could be weak and could be collaping and restricting coolant flow back into the engine.The upper hose does not need that spring because it expands when the coolant returns to the radiator.

    I found an AC Delco 15-4630 thermostatic fan clutch for my '91 S10 Blazer on e-bay for $70 with free shipping. I could not pass up that deal but I have not installed it.. The present fan clutch seems to be working as it should but with that many miles the vehicle, the fan clutch is due for replacement .In 100+ degree weather, my S10 Blazer runs at 195 degrees and idles at 210 degrees, with the A/C on . The higher temperature at idle prompted me to purchase the fan clutch, however, 195 - 210 degrees is the normal temperature fluctuation.

    According to what you describe, and if there is no coolant loss, your system is suffering from lack of coolant flow. That is because the radiator or the water pump has some form of resctiction and is not allowing the coolant to flow through the system.. Flushing the cooling system does not remove restrictions and does not help lower engine temperature. That procedure is done every one or two years just for replacing the anti-freeze .
  • rs53rs53 Member Posts: 8
    looks like we are on the same page.
    when I checked everything out there was no build up around the thermastat housing or the lower radiator hose by the water pump.
    because the blazer is 13 years old with only 59,000 miles.
    it was not driven as much as it should of. since I changed what I thought would be the obvious things that would cause the problem.
    the radiator is the last thing left. it may have accumulated some sediment and settle in the radiator between the time it was driven
    I found a AC delco radiator in phoenix for 333.00 the cheapest I found so when I get it I hope it takes care of the problem.
  • sburguronsburguron Member Posts: 6
    help cant figure this out. replaced radiator, thermostat, heating core, water pump , coolant temp unit, flushed system, still over heating oh rad cap too.
  • rs53rs53 Member Posts: 8
    to sburguron
    what i did was replaced the thermafan clutch , thermastat, radaiator cap the last two needed to be done anyway still had overheating problem.
    It's taking cared of now by replacing the radiator. now it's holding between 197 to 203 degrees per OBD meter. and under 210 on the gage that's with the air on or off.
    thanks to all that gave advise in solving the problem
  • jlflemmonsjlflemmons Member Posts: 2,242
    Does it overheat going down the road faster than 35mph? Fan clutch only effective at lower speeds. How about the radiator hoses?

    As others mentioned, if the radiator hasn't been maintained, Dexcool can sure gum things up. Might be able to backflush and clean it out, but a radiator shop would be needed to really flush it properly.
  • sburguronsburguron Member Posts: 6
    everything has been replaced except clutch fan
  • sburguronsburguron Member Posts: 6
    hoses look old
  • jlflemmonsjlflemmons Member Posts: 2,242
    Does it overheat going down the road faster than 35mph? Fan clutch only effective at lower speeds.
  • sburguronsburguron Member Posts: 6
    yes it over heats at faster speeds
  • jlflemmonsjlflemmons Member Posts: 2,242
    Well, that does sound like a radiator. If it only overheated below about 25-30, I would say fan clutch. But the fan clutch disengages around 25 as the air coming in the grill is moving faster than that.

    Looks like it's time to pull the radiator and compare the cost of a new one to having that one flushed and rodded by a radiator shop.
  • sburguronsburguron Member Posts: 6
    I have to turn heat on to maintain around 210
  • sburguronsburguron Member Posts: 6
    why the radiator its new only 5 months old
  • jlflemmonsjlflemmons Member Posts: 2,242
    It may be only 5 months old, but it is the only thing there that could cause that problem, unless you have a hose collapsing while running (not likely).

    If it were the fan clutch, it wouldn't overheat at highway speeds.
    If it were the thermostat, it would heat up quickly, and all the way to the max.
    Water pumps don't fail in this manner, they leak out the shaft when the seal lets go, or start wobbling and leaking at the same time. You would be losing coolant.
    In a Blazer, water is always moving through the heater core. Unlike a lot of cars, there is no heater control valve to turn the water flow off and on. There are damper doors that either bring in cool air or hot air, depending on where you set the controls.

    Now, what may have happened is that coolant sludge has formed in the engine, and all the cooling system work has knocked it loose and it has settled in the radiator. If so, the radiator just needs to be flushed, along with the rest of the cooling system. I don't mean drained and refilled, I mean flushed.

    [edit] Did you have the heater core flushed? These have been known to get clogged and will not allow all the water flow through them. You can sometimes here them gurgle when this happens.

    Which antifreeze was in the vehicle when you started working on this, the green or the orange long life stuff. I am sure someone has told you never to mix the two. They don't play well together and will really clog things up.

    Good luck
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