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97 Chevy Astro overheating according to gauge.


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jsan82
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Jun 6, 2014, 12:59 PM

Post #1 of 18 (1465 views)
97 Chevy Astro overheating according to gauge. Sign In

Okay, so the temperature gauge was usually only climbing one or two pegs over cold no matter how long I drove it. Never reached normal temperature. Figured it was either an open thermostat, bad ECT, or gauge. Replaced the thermostat and ECT today. First thermostat was a FailSafe and while the engine was idling the temperature would gradually rise all the way to the red zone. I took it on a test drive and made it about half a mile before I was almost touching the red zone. Immediately turned around, made it back in the driveway as the "Check Gauges" light came on. Shut down, let it cool, and tested the thermostat in a pot of hot water. The thermostat did absolutely nothing, even when the water was in rapid boil. The old thermostat did open in the boiling water.

Figured the new thermostat was bad and went and got a Stant Super Premium thermostat. Installed it and the van is doing the exact same thing. Slowly climbing well above normal operating temp, faster with acceleration, and never stabilizing.

I seriously doubt that I managed to get 2 faulty thermostats in the same day but I've been wrong before. The gauge is giving readings and not acting bad so I don't think it needs replacing. I did bang the ECT up a bit while installing it since the engine compartment is so cramped. Not sure if that would damage it and cause a problem like this. There was no overheating problem before today, in fact it was the exact opposite, it was underheating according to the gauge. So according to my gauge I've gone from one extreme to the other.

The system is full of coolant and I tried my best to burp it. I could only burp it by rocking the van while it was off/idling because there is no bleed valve that I know of.

I would really appreciate some insight on what I need to look into. Will probably put the old ECT back in just to see what it does.


(This post was edited by jsan82 on Jun 9, 2014, 11:25 AM)


Hammer Time
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Jun 6, 2014, 1:14 PM

Post #2 of 18 (1460 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

You probably still have air in the system. Sometimes you have to fill it, run it up to temp and let it cool down again and then top it off and do the same thing over again.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jsan82
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Jun 6, 2014, 1:51 PM

Post #3 of 18 (1449 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Just checked it out again. Top hose is hot, bottom is cold even when gauge is almost at red zone. I guess it's possible that I didn't wait long enough for thermostat to open. Idled for 5 minutes with radiator cap off while trying to get the air out and 3 or so with it on.

Temperature drops when heat is turned on, drops faster when accelerating while heat is on.

Seems highly unlikely that I got two broken thermostats from two different companies in one day but I would not be surprised if I did. Wouldn't be that bad if the thermostat wasn't such a PITA to get out.

I do believe there is still air in the system though. Shook it around a bit and got quite a few bubbles. Is there any air bleeding kit for the coolant system?

Thanks for the help.


Hammer Time
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Jun 6, 2014, 2:34 PM

Post #4 of 18 (1443 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Fill it up, put the cap on. Drive it around the block until the temp reaches at least operating temp. than park it without touching it until totally cold. Then top it off again and repeat the process until it doesn't take any more after complete cool down.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jsan82
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Jun 8, 2014, 10:12 AM

Post #5 of 18 (1411 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

I believe the water pump has failed. There is a distinctive grinding noise coming from the area of the water pump. Been through about 6 heat/cool cycles and it doesn't seem to be purging air anymore but the engine is still overheating. Once I decided the water pump was bad I pulled the new thermostat again and it tested fine so that isn't the problem.

The radiator is only a couple years old and I don't think the pump has ever been replaced. Looks like I'll be pulling the pump this week. On the upside, it'll give me an excuse to finally change all the hoses.


nickwarner
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Jun 8, 2014, 1:52 PM

Post #6 of 18 (1402 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Grab the engine fan and see if there is play in the water pump bearing.


jsan82
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Jun 8, 2014, 2:15 PM

Post #7 of 18 (1400 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

There doesn't appear to be any play when pushing and pulling on the fan. The belt was engaging the pulley properly when I checked it earlier. There was something that sounded like it was grinding in that area. It wasn't very audible from inside the car but when outside the car it was definitely noticeable. Sounded like a handful of gravel inside a clothes dryer only not as loud.

The water pump is really the only thing that I can think of that would cause problems like this, especially with a sound like that.


jsan82
User

Jun 9, 2014, 6:27 AM

Post #8 of 18 (1382 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Pulled the air cleaner and fan shroud. There is definitely play in the pump bearings. Pushing one side in and pulling the other out lets the fan move about 1/8".


Tom Greenleaf
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Jun 9, 2014, 6:35 AM

Post #9 of 18 (1377 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Pumping or not if that's making a grinding noise it has to go. You should be able to hear it with a mechanic's stethoscope or listing rod and be sure,


T



jsan82
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Jun 9, 2014, 3:14 PM

Post #10 of 18 (1358 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Whether it was bad or not, it's now replaced. The old one was pretty nasty looking. Figure for $90 it was a good idea to swap it out along with the hoses. Haven't had a chance to fill it up yet, waiting for sealant to dry. Going to flush the entire system to get any remaining DexCool out so I can use a different coolant. Also going to pull the heater core hoses and thoroughly flush it tomorrow. If none of this fixes it, I won't even know where to start.


Tom Greenleaf
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Jun 9, 2014, 6:17 PM

Post #11 of 18 (1353 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Just a comment on Dexcool: That can muster an argument or disagreement. Till otherwise informed I say just use quality ethylene glycol for antifreeze. Many say for any type and come colorless. Some marked that it never needs changing! IDK.


The common products are the same base ingredients with additives for their claims. Color is added just to identify nothing more.


Cross fingers but so far have not seen the Dexcool sludge they got a bad name over? I think an additive doesn't like air in the system and not sure if the jury is back on all that?? Tom



Hammer Time
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Jun 9, 2014, 10:22 PM

Post #12 of 18 (1344 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In


Quote
Going to flush the entire system to get any remaining DexCool out so I can use a different coolant.


The silicates in other coolants can damage you cooling system. I recommend staying with Dexcool.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Jun 10, 2014, 12:06 AM

Post #13 of 18 (1342 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Has to be a marketing ploy. Was fixing something else and read Dexcool and a "universal" bottle. Same stuff for the most part. No silicates or phosphates listed on either and each said could be used in either! What a game? T



Hammer Time
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Jun 10, 2014, 12:10 AM

Post #14 of 18 (1338 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Yes, there are many silicate free, long life coolants out there but most are yellow in color to blend with other coolants which makes it hard to tell if there is any coolant at all. Dexcool is recommended for GM vehicles.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Jun 10, 2014, 12:23 AM

Post #15 of 18 (1332 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Move on. It's a great idea to totally flush this system out now. Just remember you don't get all out with just a radiator drain alone. Should have impossible to get at plugs in sides of lower water jackets. Many you need to poke at to get them to flow at all and just make sure you have the right plugs for that if you go there at all, most don't but you can get a better flush.


It's been my experience that if that much crud comes out the system is in trouble and most where I am corrode from outside in first or a "freeze" plug (some cheap OE ones) can too is a monster headache on most.


Hoses are better than VERY old. AYOR with aftermarket,


T



jsan82
User

Jun 13, 2014, 4:10 AM

Post #16 of 18 (1298 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

So I went through several more heat/cool cycles until it was no longer burping air. Still couldn't make it 2 miles without the gauge climbing dangerously high. It was however no longer overheating at idle as long as I had the heat on, it would even drop a line or so if I waited long enough. Got p***ed off and reinstalled the old partially open thermostat and now it's back to only rising 1-2 lines on the gauge. So basically I got 2 thermostats failed closed right out of the box. The FailSafe didn't open at all in the hot water, and the Stant opened when it was rapidly boiling (unfortunately I didn't have a thermometer to check the temp). So I'm thinking the Stant will open but not at the correct temperature.

And that grinding noise was actually the belt tensioner which is right beside the water pump. Put some WD-40 on it and the sound is gone. At least I don't have to worry about the water pump for awhile and I had a chance the replace all the hoses. Now I just have to return the old thermostats and figure out which company to get a new one from.

Thanks for the help, you guys probably could have helped more but I gave bad info apparently. The top hose was never "hot" even when the temp gauge was really high. It was warm but I could put my hand on it all day. Asphalt on a sunny day would have been hotter. I really wish this simple project didn't turn into a week long problem but that's what I get for misdiagnosing the problem to begin with.

And I am just going to stick with DexCool. It's been in the van for 17 years so I might as well try to keep that streak going.


(This post was edited by jsan82 on Jun 13, 2014, 4:26 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 13, 2014, 4:48 AM

Post #17 of 18 (1288 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In


Quote
And I am just going to stick with DexCool. It's been in the van for 17 years so I might as well try to keep that streak going.


Just make sure you don't leave the same coolant in there longer than 5 years. It has to be changed out at those intervals.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jsan82
User

Jun 13, 2014, 6:10 AM

Post #18 of 18 (1281 views)
Re: 97 Chevy Astro overheating according to gauge. Sign In

Yeah, I meant I've been putting DexCool in during coolant changes for 17 years. Definitely not using the same coolant for that long.






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