Coolant Leak only when heat turned off
#1
10-20-2012, 08:27 AM
Coolant Leak only when heat turned off
Ok guys. Got some syptoms that make me believe I have to replace the intake gaskets on my 99 LT, but there is one thing happening that I have never come across and has me a little puzzled.
Started with steam pouring out of hood when I'd stop. Opened the hood and a lot of hissing coming from rear drivers side of engine. When it cooled down and I filled it up with coolant, you could hear air escaping from that same spot until water level reached that point, then coolant leaks out. Tried some of that pour in sealer stuff (yeah, I know, not a good idea), and filled it back up with coolant. Did the idle with the heater on high, etc. Ran it for a couple days with the heater on high and topped off coolant. Everything seemed fine.
Here comes the part I've never run into before. I decided to turn the heat down to a normal range (I have the automatic climate control). Within 20 miles I noticed the steam pouring out of the engine at a stop. The hissing from the rear of the left engine was back as well as the air leaking out as you filled the rad. Let it cool down and ran it again. Problem still there. Filled it back up, turned the heater back on high and ran it again for a day...no problems. I ran this "test" a couple times and always get the same results.
Anyone have any ideas on why it is only leaking when the heater is turned off? I don't mind changing the intake gaskets, but don't want to do that and blow them out again because of some other problem. Any help is appreciated.
Additional notes. Put on a new water pump and thermostat. Also, no oil in water or water in oil. Other than losing coolant, blazer runs fine.
Started with steam pouring out of hood when I'd stop. Opened the hood and a lot of hissing coming from rear drivers side of engine. When it cooled down and I filled it up with coolant, you could hear air escaping from that same spot until water level reached that point, then coolant leaks out. Tried some of that pour in sealer stuff (yeah, I know, not a good idea), and filled it back up with coolant. Did the idle with the heater on high, etc. Ran it for a couple days with the heater on high and topped off coolant. Everything seemed fine.
Here comes the part I've never run into before. I decided to turn the heat down to a normal range (I have the automatic climate control). Within 20 miles I noticed the steam pouring out of the engine at a stop. The hissing from the rear of the left engine was back as well as the air leaking out as you filled the rad. Let it cool down and ran it again. Problem still there. Filled it back up, turned the heater back on high and ran it again for a day...no problems. I ran this "test" a couple times and always get the same results.
Anyone have any ideas on why it is only leaking when the heater is turned off? I don't mind changing the intake gaskets, but don't want to do that and blow them out again because of some other problem. Any help is appreciated.
Additional notes. Put on a new water pump and thermostat. Also, no oil in water or water in oil. Other than losing coolant, blazer runs fine.
#2
10-20-2012, 08:38 AM
Triple check your heater hoses. I could be wrong but with the climate control there should be a flow regulator that controls the amount of coolant that flows to the heater core. There could be a rupture in the heater hose before that regulator.
Bear in mind I have a 95 LS and don't have climate control so this is a completely wild guess!
Good luck and report back bud.
Also changing the intake gaskets won't hurt a thing! If I were you I'd do it reguardless as you are going to have to do it sooner or later anyway.
Bear in mind I have a 95 LS and don't have climate control so this is a completely wild guess!
Good luck and report back bud.
Also changing the intake gaskets won't hurt a thing! If I were you I'd do it reguardless as you are going to have to do it sooner or later anyway.
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