Dex cool -- the devil's brew

[scottysheppard]

Unique Cobra runs a little warm when in slow or parade traffic. Tried draining the radiator using the petcock on the bottom but nothing came out. Removed the petcock and still nothing came out. :doh: Stuck various objects in the hole and finally got the coolant to drain. Found the bottom couple of inches of the Griffin radiator filled with light brown pudding like material. After researching I found that Dex Cool was probably to blame. When mixed with air (low coolant level) or with another type of coolant (what you usually find in a non-GM engine), the DexCool turned to putty and screws everything up. Much is written on the subject and info is easy to come by on the internet. I also heard through a phone conversation with someone I bought some Unique Cobra parts from that is was quite possible that Unique used the stuff when installing the drive train in some customers cars. It's possible that is where it origionally came from. Anyway, anyone know how to clean out the gunk from the aluminum radiator? Also, anyone know the correct Griffin part number to order a new one from them at a reasonable price? (Ser #4279477 w/SA 406). Need to get this fixed ASAP due to Hot August Nights coming up soon. Any info would be appreciated. Scotty

[dmswann]

You might try installing one of the flush kits that includes a hose pipe connection in a heater hose. Then open bottom radiator petcock, remove radiator cap (kit includes a flow diverter) and just do an extended flush. These kits are cheap, you can get one at WallMart, easy to install, and might save you a bunch of money.

[weaver]

Scotty, we have never used Dex Cool, I have never even heard of it. Your car was built by the owner and not a factory turnkey. You might have to remove the radiator and have it flushed out. A new aluminum radiator is $450.00, it is made locally and cools better than the Griffin.

[scottysheppard]

Scotty, we have never used Dex Cool, I have never even heard of it. Your car was built by the owner and not a factory turnkey. You might have to remove the radiator and have it flushed out. A new aluminum radiator is $450.00, it is made locally and cools better than the Griffin.

Already talked to a couple of radiator shops in the area and they are familiar with the Dex Cool problem. The goo left by the Dex Cool contamination is very difficult if not impossible to get out. A very sophisticated chemical treatment is required and the stuff is not available in your normal auto parts store. $450 seem a little much but it is, after all, a custom made radiator. I guess you get what you pay for. I assume you have them in stock? I'll yank the radiator out in the next couple of days and we'll see where we go from there. Thanks for your help. Scotty

[weaver]

Scotty they are made local so I don't stock them, it should only take a few days to get one. Are you running a rear puller fan, that will help with overheating.

[scottysheppard]

Scotty they are made local so I don't stock them, it should only take a few days to get one. Are you running a rear puller fan, that will help with overheating.
I am running a puller fan, 16 inch (2400 CFM), in addition to the two pusher fans which are pretty much useless and a 180 degree stat. Doing over 45 mph in 80 degree weather water temp is about 160-170. As soon as I slow down it starts creeping up and hits 210 after about 10 minutes of stop and go traffic. Comes back down as soon as I hit highway speeds. The low temp at speed is probably due to a bad or improperly fitted stat which I will be replacing the the proper size (diameter) when the radiator comes out. The Dex Cool sludge could also be part of the problem. A cleaned out or new rad will solve that problem. I'll let you know more after I remove the rad and stat. Thanks again for your input. Scotty

[JeepSnake]

Scotty,

This almost goes without saying, but don't forget to thoroughly flush the engine as well. Use a dentist-style mirror & flashlight to look in through the thermostat mount on the intake to see how things look in there while you've got it off. Dexcool was rough on some types of semi-metallic intake gaskets used by GM as OEM equipment.