: Cooling system issues


RedRunnertc
02-28-2009, 06:40 PM
Not on the 4Runner - the Impala (1996 LT1 OBDII).

Background: Dexcool fubar'd my cooling system. I switched to green, and used some stop-leak to buy some time, but heater core and radiator had to be replaced in the end.

Problem: There is no heat, not even lukewarm. I figured thermostat was easy and cheap to replace, so I tried that yesterday. Now, I have no heat AND the temperature gage is running low.

WTF? Where do I go from here?

ike
03-01-2009, 05:27 AM
I will give you a call and find out the particulars tommorow. My dad has been a master tech for GM for atleast 30 years. I can give him a call and see what he has seen on those cars.

spindleshanks
03-01-2009, 09:55 AM
The problem Troy is that "stop leak" plugs up heater cores. By their nature, that's what they do. They plug up leaks....and then they plug up heater cores.
I've seen a million people walk into my CARQUEST stores asking about "stop leak". We carry three brands or more, and the counterperson always gives them a disclaimer about plugging their heater core up....some brands of stop-leak are suspected to be worse offenders in this aspect than others, but they are all a temporary fix.

Also keep in mind the importance of completely flushing out the Dex-Cool from your system. GM is known to have added a complementary "stop leak" to some of their cooling systems that I've heard described as crushed up walnut shells. I've seen it myself in my '01 Grand Prix...it looks like crud, sediment, mud, but it's actually this sedimentary additive that Chevy added to their cooling systems in the factory. I've heard that the purpose of this stuff was to stop any leaks that may have been noticable at the dealership, in the showroom. It was sort of a last ditch additive effort to seal the cooling system before retail sale, the long term ramifications of which were not considered at the time. It's kind of a vicious GM rumor, and I can't get a straight answer from any GM people on it...but any technician can confirm it.

Also, remember that Dex-Cool is an Organic Acid Technology coolant (OAT). By nature it is aggressive and acidic. It's been known to destroy intake manifold gaskets (very common on GM vehicles from the 80s to the 90s, 4.3L Vortec, 5.0L/5.7L, and particularly the 3.1L/3.4L V6 engines of the mid 90s). Exposure to oxygen accelerates the acidic properties of Dex-Cool, so over time it becomes aggressive enough to eat through water pumps, intake manifold gaskets, etc. This is ironic, considering that GM advocates using Dex-Cool for 150k miles. So a proper flush of the system, including a backflush of the heater core is essential to limiting the corrosive effects of Dex-Cool.

Hope that helps. You're talking about a hell of a can of worms here, just watch all the Dex-Cool posts start popping up.

RedRunnertc
03-01-2009, 11:03 AM
Yeah, that's been my experience. I have flushed it a couple times, I wonder if there's still stopleak in there...

Oh, and the Impala SS forum SUCKS by the way ... I didn't realize how good us Toyota folks had it ...

spindleshanks
03-01-2009, 11:52 AM
Are they all rollin' on dubs?
(whatever that means)

mrdoug
03-01-2009, 02:07 PM
When you got the motor running, do you see any movement of the coolant thru the top or the radiator (pull the radiator cap and look)?

RedRunnertc
03-01-2009, 03:53 PM
There is no radiator cap old man. :D

Also, the cooling system works in reverse - the cool coolant comes out of the radiator into the head, then down through the block back into the radiator. This keeps the heads cooler and boosts volumetric efficiency.

mrdoug
03-01-2009, 04:57 PM
That'll teach me!

It'll also be the first time I've ever heard of a radiator without a cap... live and learn I guess

Chalkie
03-01-2009, 07:00 PM
There is no radiator cap old man. :D



There IS a radiator cap, just not one in the traditional sense. If there were not, the system would not pressurize, which would lead to overheating.

RedRunnertc
03-01-2009, 07:58 PM
No, really, there's not - there is just a screwdown lid on the fill reservoir.

Regardless, there is no way to see if the coolant is flowing.

Chalkie
03-01-2009, 08:25 PM
No, really, there's not - there is just a screwdown lid on the fill reservoir.

Regardless, there is no way to see if the coolant is flowing.

Right, which is why I said not in the traditional sense. But that is a pressure cap and, as I recall, they are available in a couple of different pressures (12 & 15psi?). I don't know if there is a way of testing those caps like you do a regular cap. They are cheap enough though, did you replace it? In a closed type system like that it is possible it could impact the heater function.

And, yes, you would not be able to see coolant actually flowing. Is the level in resevoir going up as the engine heats up? That should, I think, at least confirm if the thermostat is functioning properly.