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intermittent/no heat problem fix(Dex-Cool Extended Life Engine Coolant)


kbrdg
05-08-2005, 12:08 PM
I have a 1998 astro with 110,000 miles. For the last month the heat was occasionally not working. It got worse with time until it didn't work most of the time.
I noticed that the hoses going to the heater core had different temps. One was hot the other cold. I thought there was a valve on the inlet hose that shut off coolant flow to the heater core that was actuated by a vacuum hose. All my other cars have this valve that is controlled mechanically by the heat temp selector. I spent quite a bit of time trying to solve this only to find out that there is no valve, the coolant flows through the heater core at all times. The heater core is in a box that has doors that are actuated by vacuum hoses to either allow heat or block the heat.
So now I assumed the heater core was plugged and called the auto parts store to see if they had one in stock. He said they did but that if I had the Dex-Cool Extended Life Engine Coolant, it was known to sludge up and cause that problem. He said that having the cooling system flushed should solve it. Chevy recomends 100,000 miles or 5 years. I had been meaning to get the flush anyway since I hit 90,000 miles and now I was at 110,000 and 7 years. Procrastination stikes again.
So off to Jiffy Lube I went. Half an hour and $108.00 later I had nice hot air blowing out again. :grinyes:

blazee
05-08-2005, 07:52 PM
The recommended interval is for ideal situations. To avoid any problems the Dexcool should be changed every 2-3 years or 50,000 miles. Dexcool is very easily contaminated and once comtaminated it will turn to sludge very quickly. One of the main causes is air getting into the system for this reason you should keep the coolant full at all times and replace the radiator cap with every coolant change. The flush can be done better yourself for less than half the price of having a shop do it. It's a little messy, but you will get better results and save a little money.

If you want to do it yourself, follow one of these methods;

For system with Sludge:

Buy the following:
2 gallons of distilled water $1
2 gallons of Dexcool* $20
Prestone Flush 'N Fill kit $3
Prestone Radiator "Flush" $3

Turn your heater on and leave it on for the entire process

Drain the anitfreeze from the system.

Install the "T" from the Flush 'N Fill kit and follow the directions that came with it.

Disconnect the water hose, close all the drains, add the Prestone Flush, fill with water, get engine up to operating temperature and run for 20 minutes, allow to cool then, drain the system.

Connect your water hose to the Flush 'N Fill "T" and flush one more time. Drain.

Fill the system with a 50/50 mix** of DexCool and distilled water. Continue to fill the system over the next few days as the air is worked out of the system.








For clogged, neglicted, or extremely dirty systems:

Buy the following:

2 gallons of distilled water $1
2 gallons of Dexcool* $20
Prestone Flush 'N Fill kit $3
Prestone Radiator "cleaner" not "flush" $4

Turn your heater on and leave it on for the entire process

Drain the anitfreeze from the system.

Install the "T" from the Flush 'N Fill kit and follow the directions that came with it.

Disconnect the water hose, close all the drains, add the Prestone Cleaner, fill with water, run the engine 3-6 hours (you can leave it in for a few days if neccessary), drain the system.

Connect your water hose to the Flush 'N Fill "T" and flush one more time. Drain.

Fill the system with a 50/50 mix** of DexCool and distilled water. Continue to fill the system over the next few days as the air is worked out of the system.



* If your vehicle was made prior to Memorial Day 1995 or if you don't want to deal with the problems associated with Dexcool, get the standard green antifreeze.

**When you do your final drain and fill....not all the water will come out so to get the proper 50/50 mix you should add the right amount of straight Dexcool then top off with the distilled water.

kbrdg
05-27-2005, 01:59 AM
After a week the heat quit working again. Jiffylube said they would charge the same price to flush again, so I followed your directions in step one.
So far so good. The heat is still working, only it is not needed now.

For any one else who tries this, one word of warning. The drain plug for the radiator was impossible for me to get to. So I removed the wiper fluid and coolant resevoirs and removed the bottom radiator hose to flush the system.

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