Chevy Astro and GMC Safari Forum banner

Cooling system Issues and Questions

1K views 5 replies 3 participants last post by  LEVE 
#1 ·
Ok so I have had issues with my 97 overheating in local traffic settings and I thought it might be my thermostat, I have had issues that pointed to it before. But now that I have pulled everything out I wonder if I may have a bigger problem or not. I have always (in the 2yrs I have had it) had issues with my overflow reservoir, it never has anything in it, so that really didn't surprise me when I went to start pulling things out yesterday. When I got to the hose attached to the thermostat casing though nothing came out of it either :? (not looking good). After getting the casing off there was none underneath the thermostat either. Now I don't usually get into the cooling stuff so much, so I am not really sure what of this may be normal or not, I am hoping for some "expertise" ;) in this department. I am also wondering if I should go ahead and drain the whole system as well, thinking I should probably.

As to another question with this I am in a discussion with hubby as to which coolant to put back in here. Honestly :naughty: I have sadly only added water to it since well :oops: i don't know, but as it is a GM the parts store is obviously recommending Dex-Cool. I have heard bad things about this stuff and hubby has switched the Camaro over. I honestly don't have a clue what was put in this one. And as I can't see any right now from obvious spots, I can't tell by looking. I am just curious what y'alls opinion is when it comes to yours
 
See less See more
#2 ·
OOPs :oops: I forgot to add in there that I have had issues with the A/c/heating, or should I say lack there of, and was curious as to some advice there too. I think I have narrowed it down but figure before I start going and ripping stuff out I should get a second opinion. The A/c has not worked in the front since before I bought it ( my parents were the previous owners) and the rear went out not to long after I got it. The heat worked fine the first year but last year when I turned on the rear system it only blows cold air.

The front system has issues as well that just started last year. It is with the fan, sometimes it would be erratic, it would not start and then if I slammed the passenger door or hit a bump just right it would go, while other days it would start just fine. It is now where it does NOTHING, no defrost or vents at all, unless you are at highway speeds when you can feel the faint breeze if you are paying attention.

IMHO I am leaning towards the blower motor having gone bad in the front, I have already found a bad circuit board there. I am really am at a loss for the others though, both rear blowers (probably the same one? :? they just use different vents) work great just don't blow the correct temp :)
 
#3 ·
Let's start simple. All that coolant has to go somewhere. There's only a few places it can go:
  • Into the Overlfow bottle[/*]
  • Out of the overflow bottle[/*]
  • Leaking via a hose, radiator, freeze plug, etc..[/*]
  • Head gasket, burned in the combustion chamber and out the exhaust[/*]
That's pretty much the laundry list, so start looking at the possibilities. Here's what I'd do:
  • Rent/borrow a Cooling System Pressurizer and use it. I have one and it's a great tool.
    • Check the coolant for traces of combustion gasses, you should be able to get that a LAP. NAPA has 'em at about $50. [/*]
    • You DO have white smoke coming out of the exhaust pipe?[/*]
    • Waft you hand through the exhaust. Does the palm of you hand smell like coolant? If you touch the tip of your tongue to the palm of your hand can you taste the sweetness of coolant?[/*]
    • Does the engine miss-fire and run bad and does the check engine light come on? [/*]
    • Are you continually adding coolant to the radiator?? [/*]
    • These are all symptoms of a blown head gasket.[/*]
    [/*]
  • Check the water pump for signs of dripping[/*]
  • In the dark, with the engine running, use a flashlight and aim the beam between the radiator and the engine fan. There could be pinholes. If coolant is spraying in fine droplets, you should be able to see the mist. Otherwise you'll never see it.[/*]
  • If the head gasket is blown, it can pressurize the bottle and blow the coolant out the bottle vent. At road speed you may never hear/smell/see it.[/*]
  • Check that radiator cap. The Pressurizing test should show a failing cap.[/*]
 
#4 ·
Alright it sounds like to test those issues the system should be "full" which brings me to my new apparent problem... Since I already had it open and found it to be very low I figured draining it might as well be a good idea, to see which coolant as in it. It had only one gallon of anything in it :shock: . From what I have researched as I have a model with rear heat the system should hold 3-4 gallons total of mix. When we went to refill the system I struggled to get it to take even 1 1/2 gallons back :? .

New Questions:
First of all is there a good way to "bleed" the system or is it even necessary? I saw another post that suggested jacking it up. Running heat to do it is a no go as that is malfunctioning as well.
Second is it really supposed to hold 3-4 gallons? It seemed in the same post that there was not nearly as much in there as that.
Third where would you rent/borrow this Cooling System Pressurizer from? Does an AutoZone or AdvancedAuto type store have it?
 
#5 ·
tommycat97 said:
First of all is there a good way to "bleed" the system or is it even necessary? I saw another post that suggested jacking it up. Running heat to do it is a no go as that is malfunctioning as well.
Consider repairing the cooling system the correct way the first time. Find the leak first. Search here for rear heat issues. Flush the entire system. This will require removing some hoses and inspecting/testing heater control valves. Refill with green, orange no more.
tommycat97 said:
Second is it really supposed to hold 3-4 gallons?
'97 M/L with rear heat: 16.5 Qts.
If you have basic tools and are willing to roll up your sleeves, invest in a FSM. Money well spent.
 
#6 ·
First of all is there a good way to "bleed" the system or is it even necessary?
Yes, making sure the system is bled is necessary. Now-days there's a little burp hole in the thermostat rim that will, over time, burp the engine. But that takes a long time. It's not really meant to bleed a system after the coolant has been replaced.

In most systems you can fill the engine, but not the system. That leaves air pockets in the system, usually it shows up as the heater core not getting any coolant. I never fill a radiator first after working on the cooling system. I pull the thermostat and first fill the engine block to the level of the thermostat housing. Then when the thermostat is reinstalled I fill/top off the radiator.

I'm a huge believer in using the Permatex Back Flush kit. One reason is that I can install an outlet on the heater hose. IMHO, that single little piece in the kit makes it worth the money. It lets me burp the system, and I can add coolant into that point as well.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top