stop leak in coolant system


Old 03-06-02, 09:08 AM
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stop leak in coolant system

I have a 1996 s-10 blazer with 65000 miles. I found out that at some point before I bought the vehicle someone put stop leak in the system. I don't really understand why, because at the time it was still under warranty.

I took it to my mechanic bcause of erratic readings on the tempurature guage. He replaced the thermostat and said that because of the stop leak, I would probably have to flush the system often. That was about 1 1/2 years ago. At that time the mechanic put regular coolant in (not Dex cool). Now the coolant is a reddish brown color, but I dont see any large flecks floating in it.

AT the moment the blazer is running a bit hotter than it has in that past, and if it idles for 5-10 minues at a time the temp. guage starts to go up more than it has in the past. I don't see any obvious signs of leaks, and I checked all the hoses and they seem to be ok. I do have to add coolant/water at a rate of about 1/2 quart every month.

Could the stop leak be causing the coolant to go bad quicker than if it were not present? Is there any way to get rid of the stop leak in the system besides continual flushing (if there is a leak, I would rather just deal with it as I plan on keeping this vehicle for quite a while)?
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Old 03-06-02, 09:14 AM
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Stop leak is hokey stuff. It likely was used to bandaid a problem...a bad radiator, a bad water pump, or some other trouble. I don't like it, I don't use it.

Suggest having the radiator boiled out and flushing the cooling system every single year. You should service your cooling system yearly anyhow.
Old 03-06-02, 09:40 AM
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Does it have an electric fan? If it does is it turning on when the engine is running? I agree with Joe on cleaning the system out. But the increase in temp at idle might be a bad fan or fan relay.
Old 03-06-02, 09:54 AM
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From what I recall this has a clutch fan.

Murky or dirty coolant (if it was originally green and now it's brown) is not a good sign. That is that Stop Leak goo coming out.

No need for any of that unless you are masking a problem or "preventing" a repair. But the correct repair will be inevitable and cost less if you do it initially than to content with all this .
Old 03-06-02, 11:53 AM
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Stop Leak will clog radiator cooling areas causing overheating. Get the radiator boiled out and add fresh anti freeze.
Old 03-06-02, 12:24 PM
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Dex-Cool has caused millions of problems in Blazers. It has clogged the heater core and led to no heat inside the car, high engine temp, and water coming in from under the dash. If you go on the web you can find plenty of links from people with the same problem. A lot of times it needed more than good chemical flush, it needed a new heater core. In many cases GM knew it was their fault and after some prodding, they paid for the repairs. The dealerships are notorious for denying that Dex Cool and crappy heater cores were the cause of the problem. (they blame adding green anti-freeze and "contaminating" the system). As long as you treated it as normal anti-freeze after you added the green, you did your job.
Old 03-06-02, 02:38 PM
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Your over heating is due to the small hole in one head gasket GM uses to reduce flow through the heads being partly cloged. Or the Thermostat shaft & bushing are binding with that stop leak goo. Are you using a coolant recovery tank with a good Rad Cap? Also when you get it professionaly cleaned, not the stuff at the parts store. I would put a 180 degree thermostat back in with pure un-cut Antifreeze. Been using that trick since 1972, and you will never see a speck of that, white oxidation inside any of our cooling systems. Water, brass, copper,lead, tin,cast iron = White buildup Oxidation like a battery. There are a lot of old wives tales out there, just thunk up to make you buy parts. Good luck Marturo
Old 03-06-02, 03:02 PM
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Actually, pure antifreeze provides LESS protection than a proper mix.

Also putting a 180 stat in an OBDII vehicle is a no-no. The computer relies on the coolant temperature and sensor to provide the right feedback. Stick with the OE stat.

Stop leak is added for a reason, I suspect something was leaking and the previous owner wanted to plug it up to sell the truck...

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