Rusty crud in radiator. Help!

[LWilliams]

I have a 96 3500 with a 12v Cummins and I may be breaking the rules here but this question is about my wifes Suburban. I changed the oil last night and when I checked the radiator I was terribly suprised that the water was an awful rust color that really looked nasty. I had a reputiable shop change the coolant last spring and they used the red antifreeze that is recommended. I took the cap off and checked when I got it back from them and it looked fresh and clean. I am convinced that it had been changed. I was not expecting to see such crap in there this soon. I will change it myself soon but I am wondering what is causing this and should I use a radiator flush that I can buy or just wash out as much as I can with clean water and refill? As bad as it looks, I don't think rinsing it with water will really clean it very good. Do I have to use the "red" antifreeze or can I use the standard green stuff I've been using for years in everything else? My apologies for this question being about a Chevy but you guys are the most knowledgeable folks that I have to ask questions. Thanks for your help.

 

[dustoff]

mr. williams... . i have gone through this as have many others i am sure with rust forming in the radiator... . if it were my surburban i would flush it with radiator flush, then realy flush with water until the water was clear... . on the refill i would use the approved green antifreeze BUT use distilled water instead of tap water... tap water usually contains many contaminates, especially iron and this is detrimental to the radiator... just my 2 cents... cya

 

[sewman]

When a vehicle is that bad I have used Dupont 2 step cleaner

it cleans alot better that flushing. You might want to check your waterpump if the seal is bad it lets air in the system when it cools down then of course it forms rust.

Good Luck,Bob

 

[Gray 5.9]

Hi Williams,

I've done this before to several vehichles in the past, even C*$@y's, Drain all the coolant out that you can in a 5 gallon bucket, then take both the upper and lower radiator hose's off,pull the thermostate out, then run an old garden hose(one that you won't use for anything that lives) where the thermostate goes, use another 5 gallon bucket under the lower radiator hose so that what ever coolant thats left goes into the bucket, turn on the water. When you don't see any sign of the coolant going in the bucket, pull it out and just let whatever else comes out hit the ground. Crank up the Engine, and run the water into where the thermostate goes, then watch all deposits come out. The Engine shouldn't get warmed up for the first 2 to 3 min's. This worked good on a friend of mines 91' Z71. He had flakes of rust comming out of his Engine. After that he just put a new 180* thermostate in and used 50% distilled bottled water and 50%Prestone coolant. From then on he never had an over heating problem.

 

[LWilliams]

Thanks to you all for your suggestions. I have also talked to our local dealership and they said that green antifreeze is ok to use instead of the red, it's just not a long lasting type like the red is. He also said that if the local shop used city water in the refill, which I am sure they did, that is probably where the major problem is. He recommended using distilled water too. I will be going by the parts house and getting a thermostat and gasket after work today and take care of this project this weekend. Thanks again to all who replied.

 

[JohnE]

Chevy V-6 and V-8 engines have a plug on the block to drain coolant. It is usually on the driver's side. I replace the plug with a petcock.

Severe rust in the anti-freeze is a sure sign of oxygen in the system. The #1 cause is low coolant levels. Either the shop didn't put enough in the sustem or you didn't keep the overflow bottle full. Gassers all need a bottle of Bars Leak in the new batch of coolant. DO NOT use it in a diesel engine!! The crap you see may be a stop leak agent such as Bar's Leak.



The <em><font color=red>RED</font></em> stuff in GM products is usually DEX-COOL extended life coolant. It is good for many years unless you add conventional stuff to the overflow jug. That destroys the extended life properties. Just because the coolant is red does not mean that you have DEX-COOL.



Distilled (de-mineralized) water is a must in extended life coolants.



As others stated, flushing a severly contaminated systems requires the 2 step products. A cleaner and neutralizer.



My 2 reale (bits)

-John