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Tahoe Coolant ALWAYS gone!

montnutmontnut Posts: 3
edited July 2014 in Chevrolet
I've been having this problem for awhile now. I have a 99 Chevy Tahoe 2-Dr and it's been working fine EXCEPT for one problem, the coolant. I purchased 2 bottles already in the last 2 months. How long is coolant supposed to last? Also why does it go away so fast?


  • The coolant will stay in your radiator/heater system forever as long as you have no leaks. Obviously you have a leak. Check your hoses and fittings, also your heater core. One other possiblity is that the coolant is being sucked into your engine because of a vacuum problem. You can do a visual inspection yourself but if you don't find anything you should take the vehicle in for a professional inspection.
  • Thanks for your input, I just brought my car in today to get it checked. There was no coolant in my tank so I put more in. Drove the car back to where I work at, checked underneath and saw something leaking. It was apparent it was the coolant I just put in. Anyways, I brought it to a technician, and he said that it's ok :\ I dunno...He said the reason why I don't see the coolant in the tank is because it's in the engine. I dunno but as long as he said it's ok then, I guess, I'm ok.
  • Montnut said: I purchased 2 bottles already in the last 2 months
    If you have put "2 bottles" of coolant into the system in the past two months and you still cannot see it in the holding tank....I think you still have a problem. Does the word "bottles" refer to the one gallon containers that coolant usually is sold in? If you have put two gallons more into the system it is certainly going somewhere. I don't understand how the tech could say there is no problem if you can see coolant leaking out under the vehicle.
  • Your guess is as good as mine :\ Yes, the 1 gallon as the regular container. But we'll see, hopefully nothing happens or I'm holding him liable :D
  • You should take the vehicle into a different shop for a second opinion. There is a problem here.
  • tivytivy Posts: 2
    I replaced my head gaskets trying to get rid of a coolant leak. That fixed it for like a month and it started again. I added a bottle of bar’s leak and all has been well for 50,000 miles. From what I gather these things have leaky heads and need a sealant. I think bar’s leak, or something like it comes installed form the factory.
  • The problem is the intake manifold gasket, usually on the drivers side between the back 2 cylinders.
  • I have a 1997 Tahoe and just this year I noticed the compressor is short cycling. Car parts place suggested it might be low refigerant, so I check and tried to put some in, but the guage said it was full? Any suggestions?
  • I have a 04 Tahoe LT, i noticed my coolant was low over a month ago, i went out and purchased the dexcool coolant that was recommended by chevy. I mixed it and filled the reservoir i didn't use the whole bottle. Today i noticed it was low again, not empty just low, so i mixed the coolant with water and filled the tank again. I still have some coolant left in the bottle that i bought over a month ago, and i've been checking for leaks under the truck before i drive off anywhere. I haven't seen anything on the ground whereever i park. Does anyone have any suggestions?
  • kiawahkiawah Posts: 3,666
    It's normally a closed system, so you should never have to fill it unless there is something wrong. You obviously have something wrong.

    It's hopefully leaking out (water pump shaft, hose fitting, cracked overflow tank, etc), or you may have a problem where your engine head gasket blew out and it's sucking coolant into an engine cylinder and out the exhaust pipe (not a good thing to have water in the engine).

    You've got to quickly find the leak. If you don't find it externally to the engine, then I'd take the engine to have a compression test done on all the cylinders.

    Could also be leaking from the heater core (carpet wet by any chance front passenger), or rear aux.
  • mcgyvermcgyver Posts: 13
    The worst product on the market to use is Dexcool. It destroys the inside of a motor, heater core, water pump, radiator, freeze plugs and all associated with it. This is what eats the intake gaskets and if you smell anti-freeze but can't find the leak, guess where it is? GM recommends it and you wonder why.... it gives them service business after the warranty is over. If you have it in your system, flush it well and replace it with a good glycol type coolant that has been around for years and won't damage your vehicle. Don't believe me, then go ask any reputable independent shop what Dexcool will do to your car. It is like Coke in an empty stomach, a disaster! :sick:

    If you have to have your intake gaskets replaced, don't use GM but the better FelPro gaskets if you want reliability.
  • sox10sox10 Posts: 9
    i had the same problem in a Venture minivan. check your oil and see if it looks like a milky way candy know swirls.....if so i had to replace a head gasket...
  • jiverjiver Posts: 4
    I'm having the same problem with an '03 Yukon XL I recently bought used. I've put in two gallons of the mix in the past two months. No external leak apparent. Just took it into a shop recommended on Car Talk - they can't find anything after a pressure test and checking the oil and doing another analysis to determine whether it's an intake gasket. They recommended to keep driving it and bring it in if it gets worse, but there's no for sure sign now of a gasket problem.

    Any suggestions? I like this idea of putting the Bar's Leak in...
  • Had a leak so I bought a radiator from installed it, no problems. Now the tahoe is overheating. I have changed the thermostat also, no help. What is next?
  • jiverjiver Posts: 4
    This may help:

    I have a 2003 Yukon XL and had been putting a gallon of coolant mix in every month. Took it to the shop and they pressure tested it and couldn't find anything wrong. I did some more research and found that it can often be a gasket in the water pump - took it back in, and that was it. Same labor to replace the pump as to just do the gasket, so $450 later and everything appears to be hunky dory.

    Here's more information.
  • I just add about 1/2 gallon fo coolant every month. Took it to dealer and they could not find any leeks anywhere. They did however say they had a service bulliten on how to fix the internal engin leak. They said to keep putting in 1/2 gallon of coolant per month. It is cheaper than the fix. I did replaced water pump last year, the 2005 LT has 96K miles, so this coolant leak is the second problem I have had in five years..
  • org57org57 Posts: 7
    I had a 99 silverado with the 5.7 engine. I discovered that it had the plastic intake manifold gasket which after about 60k it would warp and begin leaking at the rear of the engine, behind the distributor. I put in some block sealer because the dealership wanted $350 to replace the gasket. It never leaked again. Hope this helps.
  • enuphsaidenuphsaid Posts: 1
    Like yourselves, I too own a 04 Chevy Tahoe. For several years I've enjoyed the luxury of having my truck dig into my pocket for the purchases of the Dexcool coolant that was recommended. I too would wake up most mornings and have the pleasure of waking my neighbors to the sound of the cold crank knocks that it provided. Several months ago I noticed that coolant would disappear from the resevoir mysteriously after having been filled the day prior. Took the truck to the dealer to have a "professional mechanic" take a look at it to see what was causing the coolant to disappear and find out where it was going. They pressurized the radiator, scoped the engine, replaced the water pump and said that they weren't able to detect a problem. 6months later of the same problemI am now having to replace the engine! Thanks alot Dexcool and the Chevy/ GM Professional Mechanics out there who supposedly train on the engines and who are out to take advantage of all of the loyal chevy/gm drivers out there. :sick:
  • timmonsktimmonsk Posts: 4
    I'm having the same problem. I bought the car from a friend and he gave me a deal because he took it in and they said it was the water pump so he took a thousand dollars off the price and sold it to me because i had a place by my house that does it for much cheaper then a grand. Well I took it in they did a pressure test couldnt find the leak. They filled up with coolant and 500 miles later its all gone again. Im hoping it's the gasket inside the water pump like some mentioned before because I dont mind paying 400 bucks to replace it I just fear its a cracked head. If it was a bad gasket in the water pump wouldnt they be able to find the leak with a pressure test?
  • kiawahkiawah Posts: 3,666
    If you are loosing that much coolant and don't see a leak, then I would suspect a head gasket. Coolant could be leaking into the cylinder, and then passing out the exhaust pipe.

    Doing a pressure test with the spark plugs out (thereby allowing the coolant to pass into the cylinder if a bad head gasket), may have helped find the problem.
  • timmonsktimmonsk Posts: 4
    That's what i was scared of. You got a ballpark idea of how much that's going to cost me. My friend kind of screwed me here so i might just fill her up with coolant and pass her on down to the next victim cause I dont have much money to fix her.
  • kiawahkiawah Posts: 3,666
    edited July 2010
    Labor rates would vary significantly across the country, so wouldn't hazard a guess. However calling to a couple local shops would get you some estimate ranges fairly easily.

    But you shouldn't automatically jump in and have this done without some further diagnostics to confirm that is the problem. Trying to remotely diagnose problems, using third party reported symptoms and sounds, is risky at best. Nothing beats hands on by skilled/competent mechanics.
  • timmonsktimmonsk Posts: 4
    If its a head gasket wouldn't the coolant be mixing with the oil which i know is bad? I mean i dont mind filling it up with coolant every once in a while. If the coolant is just getting shot out the exhaust then thats not so bad right? Im thinking about getting a extended warranty just in case this turn out to be a huge problem. Im thinking to check to see if the head gasket is bad is probably going to cost me over a grand and that might not even be the problem. I live in the Southeast so anyone have a ballpark figure on how much it would cost me in labor to them just check to see if it's a bad head gasket?
  • kiawahkiawah Posts: 3,666
    edited July 2010
    A damaged head gasket, can let coolant into the cylinder. The gasket forms a seal between the coolant chamber around the cylinder, and the piston chamber itself. It also forms a seal between the coolant chamber and the outside of the engine, but you'd see it leaking if that was your problem. From the piston chamber, it can:
    - rust the cylinder walls, so they're not smooth anymore, causing burning oil, poor compression, poor gas mileage, rust on the valves, etc
    - seep past the piston rings, and into the oil, causing similar corrosion damage in the engine, bearings to fail, major engine failure, etc
    - get blown out the exhaust, ruining that expensive catalytic converter.

    If the coolant was just leaking outside, like from the radiator or water pump bearing, then technically the water does no damage......just be sure to keep coolant to keep the engine from overheating and damaging engine. If the coolant is leaking inside the engine, then major problems, get it fixed pronto.

    If they pressure test the cooling system with the spark plugs out as I indicated before, then you may detect more easily the drop in coolant pressure as it's leaking into the piston area. This allows the air and coolant someplace to exit, as opposed to being restricted by a closed piston chamber. A gasket problem may not necessarily show up this way, but if it does show.... you know for sure that the gasket is bad.

    Head gaskets, fuel pumps, cluster gauge problems, and transmission problems.....all some common problems, unfortunately.
  • timmonsktimmonsk Posts: 4
    Thanks for all your help I'm trying to create a list of stuff to tell my mechanic to check for. Definitely going to do the spark plug with the pressure check to see if its getting into the spark plugs. My car gets about 11mpg which is pretty much all city driving and I also have 35 inch tires on the car which probally makes it closer to 12. I drive very cautiously and never reach over 2,000 rpm and i thought 12 mpg was pretty low so now im worried about the inside cylinders being rusted or would the gas mileage be much poorer like around 6mpg. When im idling the oil pressure drops down to around 30 and when im riding goes up to around 45 does this sound normal to y'all. I appreciate all your help. I think I'm just going to park it for a while until I figure out what to do. Kiawah If you can think of anything else I can tell the mechanic to check for so hes not wasting time looking around it would be greatly appreciated. I read somewhere you can by coolant that lights up with a blacklight. I thought that might help me find the leak better if it was seeping out anywhere? Thanks for all your help.
This discussion has been closed.