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Discussion Starter · #1 ·
in changing thermostat's, how do i bleed the system ? I just bought the car and would like to do this tomorrow. Also, what is the best antifreze to use in the 94 SS ? can you get the 160 degree thermostat at the local parts store ? and does the computer need to be adjusted if you put in a lower thermostat ? thanks evertone, sorry i'm new at this. I did searches, but didn't find every answer


Discussion Starter · #2 ·
I'll take a shot. In bleeding the system, you use the bleeder located on the water neck where the upper radiator hose goes into the water pump (this pic is of an f-body - your car won't have the bleeder in the hose on the left):

Maybe someone else can chime in with the official procedure, but I just would get it up to temperature enough to open the thermostat, and bleed the system a bunch of times until you get a little coolant coming out. The main thing to know here is that the coolant WILL run down and get on your Optispark distributor, just below the waterpump. That is bad! It would be best to have one of these:

You can bleed excess coolant back into the tank. Otherwise do whatever you can to divert the coolant away from the engine (rags, funnels, etc).

Your 1994 came with standard-issue ethylene glycol (green) coolant. That's what I'd go back with. The mixture is a matter of preference, but I'm down where it's generally hotter than Hades, so I use about 70% water to 30% coolant. You could go 50/50 if you'd like.

You probably can't get a 160 thermostat at a regular parts store. Most use a Hypertech part #1008:

No tune is necessary for a 160 thermostat, but it would be the best idea to program the fans to turn and off at the right time with the new thermostat.

Here's a good overview of the t-stat change. Again, it's for a Camaro, so you'll only have one bleeder screw, but the other stuff applies!

Hope that helps.

Discussion Starter · #3 ·
My technique which as never failed:

Open Bleeder on thermostat housing, then refill cooling system. When coolant starts coming out, close the bleeder. Start car, let it get a little warm, then open bleeder again. When coolant starts coming out, close the bleeder. I then pour water over the pump and front of engine to clean any antifreeze off of things such as the opti, pullies and belt.

For antifreeze, you can use anything you want, but I wouldn't want to mix green with orange. Replace with what's in there, and use a 50/50 mix. Don't use tap water, stick with distilled.

On the thermostat, you need to use a LT1 specific thermostat. Cost is around $16 at NAPA. If you use a standard thermostat, say bye bye to the engine as it will probably run hot and melt down into a blob of moulton plastic and metal. :D Well, maybe not, but I wouldn't try it on my engine.
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