- #8 of 82
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Re: No Heat And Overheating [moldyg]
by repairdog
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Mar 28, 2007 (1:45 am)
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Replying to: moldyg (Mar 27, 2007 9:40 pm)
You have a clogged heater core with the sound and lack of heat OR you are very low on coolant. Dex cool becomes sludge and if not maintained actually eats the core and radiator, clogs the factory cap, and the thermostat. Get that system completely flushed and refilled changing the cap and thermostat. I would first check the system for leaks with a free use pressure tester and see if after you pump it up to 16 lbs it drops and where. 4.3 is known to get lower intake gasket leaks by 100k miles so look carefully along the lower intake to block mating surface, at the water pump, and listen for the heater core hissing with the pressure test. Again - change that Dex cool every 3 years/50,000 miles at least - don't you wonder why the GM warranty expired at 3/36!
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- #9 of 82
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Re: No Heat And Overheating [repairdog]
by gin6
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Mar 28, 2007 (5:58 am)
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Replying to: repairdog (Mar 28, 2007 1:45 am)
This is my first post,Son has a 1999 Blazer that I bought used 2 yrs ago.After 1 mo.had the radiator flushed twice,I kept getting that overheating smell,but the shop said it was fine.My question is,Why keep useing the Dex Cool if it keeps cloging the radiator and causing slug?I know that there is green,orange&yellow coolant on the market(Very confusing for us 50+ hotrodders).Can we use another brand? Blazer finally quit on my son so we are now tearing into the engine,( head gasket has lrg. split and corrosion between cylinder)and I am having the heads checked for cracks.When we put it back together what coolant is best? Thanks for your input.
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- #10 of 82
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Re: No Heat And Overheating [repairdog]
by moldyg
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Mar 28, 2007 (8:34 am)
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Replying to: repairdog (Mar 28, 2007 1:45 am)
thanks for your help...i try the rad flush
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- #11 of 82
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Re: No Heat And Overheating [gin6]
by repairdog
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Mar 28, 2007 (12:34 pm)
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Replying to: gin6 (Mar 28, 2007 5:58 am)
Well thats a loaded question. Once you clean the whole thing out (and change that leaking core if it is) then there are many articles on antifreeze out there. Dex cool hates air in the system and that 5/100 change from GM was crap. GM was on like thir 5th cap design and the 4.3 was the worst due to high heater core and tiny tubes. If teh Dex was not in the right mix there is a voltage diff that occurs and speeds the metal eating. Too much info - I'd use green after a full rebuild but read up on them online. I have 4 and still use Dex and keep them full and changed every 3/50 max. Put a new waterpump on at the same time cause it will soon go and at $55 for a new one- and a Stant cap and high quality thermostat. Make sure the tubes in the radiator are clean too or you will overheat that new motor -they are abput $150.
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- #12 of 82
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Re: No Heat And Overheating [gin6]
by mkob
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Mar 29, 2007 (5:52 am)
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Replying to: gin6 (Mar 28, 2007 5:58 am)
I had many issues with Dex Cool, I had it clog my heater core, cause my 99 Jimmy to overheat, didn't allow vents to work and cracked my intake valve. I had it removed and reversed flushed out of the system. Sad to say it was about 1000 to do, but I strongly feel I was ripped off because I am a woman and they don't think I know what they are talking about.
I have had the normal coolant in the vehicle for a little over a year now and have had no issues at all. I have heard the Dex Cool will eventually eat away at all the hoses and some metal parts in the engine. I have no idea why Dex Cool is still being used and why it has not be recalled.
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- #13 of 82
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heater runs cold when idle, overheating
by sshaffer
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Apr 11, 2007 (6:02 pm)
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In Jan 07 I hit a deer that sent my 02 rendevouz into shock. Since, my front end was replaced as well as the radiator.I drove the car for a 5 days taped together by the body shop. On day 5 my heater ran cold if rpms were below 2,000, warm when driving at higher speeds, eventually overheating. Thermostat was repaced 3x's, water pump replaced, heater core and engine flushed. Each time I returned because of overheating or no heat.Odd that after each repair listed above the car would run fine for about a week.My mechanic was stumped after my second return. He also did the pressure test for the head gasket and said that it did not test abnormal. No leaks are detected and my antifreeze is at normal levels. Talking to him today because I am overheating again he is leaning toward the heater core. My Rendevouz has 65,000 miles on it. It's costing me an arm and a leg! I don't think it is the heater core. Can any one help?? 
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- #14 of 82
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Re: heater runs cold when idle, overheating [sshaffer]
by karenscar
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Apr 13, 2007 (10:30 am)
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Replying to: sshaffer (Apr 11, 2007 6:02 pm)
Hi sshaffer, have you had any luck with this? I am having very similar problems with my 02 Civic. I have tried all of the things you mentioned INCLUDING had head gasket replaced and still have the same symtoms. I had the radiator replaced 2 weeks ago at Round 3. Immediately after that and for about a week the fluid level was at the correct min/max range, I was getting heat when idling, and no overheating. But 'something happened!' and now the antifreeze is above normal--almost to the top of the reservoir, and also now no heat when idling. I'm just waiting for the temp spikes to start again--this is exactly the same thing that happened x2 before following Round 1), water pump/timing belt replacement and then Round 2) head gasket. So, if anyone can help with this it would be most appreciated!
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- #15 of 82
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heater runs cold when idle, overheating
by sshaffer
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Apr 15, 2007 (3:27 pm)
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So sorry to hear about your civic. The problem has not resolved, sorry to report. My car sat in the garage Wed- Fri. Then before I took it to my mechanic I made sure that the coolant was topped off. The reservoir took just under 1 gallon and the radiator about 1-2 cups. It was running fine at that time. I took it to my mechanic about 20 min on back roads. Ran beautifully, real heat,even idling. In the past my coolant levels were fine,according to my mechanic and my husband. Well this has me suspicious. Obviously, I'm slowly losing coolant. Maybe something as simple as a loose hose. The oil is clean. No white smoke. No drips,nothing on the ground. Mechanic said that it is going somewhere. Either the engine, on the ground or out the exhaust.So.....My husband had never heard of this.
Sat am I finally broke down and took it to the dealership. It will be looked at Monday 4/16. I'll keep you posted.
By the by....I subsequently [ut the same scenario on the buick rendezvous site. More info coming in there.
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- #16 of 82
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GMC Jimmy A/C Blowing Warm
by mkob
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Jul 08, 2007 (10:03 pm)
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- #17 of 82
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99 GMC Jimmy A/C blowing warm
by mkob
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Mar 13, 2007 (6:09 am)
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I have a 99 GMC Jimmy with 122k miles, this vehicle has never had a/c problems up until 2 days ago. Our temp outside is 96 and when I went to use my a/c it blows warm air. I checked the charge and it is fine, all hoses are in great condition and fan is working. I kept running the a/c trying to figure out what the issue was and finally after 17 minutes the cool - not cold air came out. What could be the reason?
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