I have a 2003 Chevy Blazer with 131, 00 miles. I have two problems which may or may not be connected to each other. One, I only have heat when I accelerate. It also only comes out of the dash and the defrost vents no matter where I turn the control to. There is no floor heat.

The other problem is that I have a slight anti freeze leak. It is visible on the ground very rarely and it is a small amount. About the size of a quarter. I can smell anti freeze from inside while driving. I filled the overflow tank about 2 weeks ago and upon checking it yesterday, it is low again, almost empty.

My mechanic of 20 years, believes the heat issue may be caused by the control panel, blend doors, or actuator. He has done a pressure test on the anti freeze problem, which turned up no problems and cannot find the leak. Could it be leaking and then while driving evaporating off some other part?

In the past year, I have had the radiator replaced, the thermostat, and the intake manifold gaskets. With research on these issues and upon finding problems due to Dexacool coolant, I plan on switching back to the old green coolant. I feel corrosion and damage to the parts I have replaced and the parts that continue to go bad are in relation to the Dexacool and the lawsuit filed against them.

 

dexcool doesn't corrode anything. things corrode when you go from dexcool to something else and you dont rinse everything before filling it up. never EVER mix colors, and dont bother with the "mixes with any color" bull. if you cant buy the same stuff thats in there, fill it with water to get home and change it there. the problem with dexcool is that it does gel after a 5-6 years though. but if you follow the regular PM, you shouldnt have a problem.

have you checked the weep hole on the water pump?
if you only have heat when accelerating its probably because you are low on coolant IN the radiator or have air in the heater core.
check the radiator and burp the system.
if you can smell coolant in the car you might have a leaking heater core. its real easy to check yourself. just open the passenger door and feel the carpet up under the dash and by the transmission tunnel. if its wet there, you more than likely have a leak.

 

yeah seems like most the time i pressure test the system and nothing comes out 98% of the time its the water pump coming out of the bearing hole.

maybe it has a big air bubble in the heatercore seen that happen a few times

 

Twip, There is a class action lawsuit against GM. It was just settled. GM reimburses those that filed that had problems with sludge causing damage to intake gaskets, water pumps, radiators, hoses, heater cores, etc. GM fully admits that this Dex Cool does damage to your engine and encourages the changeover to the Green coolant. I knew about the lawsuit last year and I was too afraid to change over to the green. But now, with the continuous problems, I think I'm going to give it a try. I became aware of the lawsuit too late after it was filed so I cannot partake in it.

http://www.dexcoolsettlement.com/notice.pdf

Dexcool Settlement Press Release | GM Lawsuit Settlement Press Release | Girard Gibbs LLP

The water pump has been checked, it has been burped. I know it's not the heater core because the floor isn't wet. The mechanic has also checked that. The hoses that run into it as well. I keep check on the overflow tank. It is not a huge leak. I check it every time I drive and I fill it up to the fill line. I've been having coolant problems for the past two years and once something is fixed, something else goes wrong. I believe pressure is building up somewhere for some reason. My radiator cap is extremely tight and difficult to get off. Not sure if that has anything to do with it. Also, from what I can see, the leak is right underneath of the engine right behind my oil pan. I think it drips then burns off so that's why I don't see it on the ground?? I'm taking it back to the mechanic soon. It just gets so frustrating. I stop by the shop at least once a week so they can check it. The radiator coolant has never been low. It has also never overheated in the 7 years I've had the vehicle. I only smell the coolant inside when I cut the vents on. I also have a very keen sense of smell. Other people cannot smell it. Sorry, it's hard to think of every detail off the bat. Besides these constant coolant problems, I haven't had any other problem...just regular oil changes, brakes and new tires....and a new distributor and cap last week.

 

Do a pressure test on the cylinders. Start with the #5 and 6 since you say the leak seems to be coming from the back of the engine. If the head gasket is letting go, you can pressurize the cooling system with exhaust gases, creating air bubbles that get stuck in the heater core, causing you to lose heat until enough coolant flows to push the air bubble out. Run the truck for a few minutes with everything normal (do not get it fully up to temperature), then crack the radiator cap lose a 1/4 turn, and listen for bubbles coming from the overflow tank. Any bubbling is a sign of an outside factor artificially pressurizing the cooling system, usually the ehad gasket. A saving grace is the fact that head gaskets rarely let go on these trucks.

 

abig84, They've checked for air in the heater core...and nothing. Doesn't hurt to keep checking everything over again I suppose. I don't have to pay much for parts, so perhaps I just need to start the process of elimination and put a new water pump, heater core, hoses and seals on.

 

Blown262, my mechanic says he has already tested that. He said there wasn't any bubbling. I have a picture of the leak. Not sure how to upload it here.

 

Host the photo on a website like Photobucket (as that's the one I use) and then copy the direct link into the little yellow box with the mountain in it up top of the message edit box.

 

Possible that your lower intake manifold gasket needs replacing. Have 172,000 miles on mine and just replaced it because I was losing (leaking) coolant around the intake manifold. OEM gaskets were crappy and made of plastic, so this is a common problem with Blazers. If you need to replace, use Fel-Pro gasket set P/N MS98002T, runs about $70 or so. Also recommended toi change the manifold bolts, Fel-Pro P/N ES72224. Hope this helps!!

 

I did not know there was a lawsuit for Dexcool. I did know that treating Dexcool like an extended life antifreeze was a mistake. I have been told by several mechanics that it is no better than any other antifreeze and should be treated the same. I change mine out every two or three years.