Red-Lt1

I think my thermostat on my 94 LT1 is sticking. How much coolant do I need to drain out before replacing it? I don't want to get coolant on the Opti!!

runner140*

Drain as much as possible, reason...so you will get little or no leakage on your Opti. When I did mine, I purchased one gallon of distilled water and a gallon of DexCool.

P.S. Use plenty of towels/shop rags to cover your Opti...make sure you keep it dry.

5POINT7

I think i drained about a gallon when i did mine, not for sure tho.. It was a while ago. Like above stated, cover your opti just in case

Red-Lt1

I had planned on covering the Opti with rags. I had figured that one or two gallons would get it low enough
Thanks

pcolt94

As much as you can get out.

Since you are opening the system anyway, if you have not changed the coolant in the last year or two you should change it all. Run some hose clean water thru the radiator also and best to drop the lower radiator hose if possible. You will be surprised how much crap comes out when hose is off.

After all, its 15 years old and stuff accumulates quicker now. Any time I flush the system I always do the heater core also……..each to his own.

Red-Lt1

That is a good suggestion. I don't know long it has been since it has been flushed.

93 ragtop

and make sure you get a LT1 t-stat!!

Wathen1955

How do you flush the heater core? I'm assuming you turn on the heater with max heat?

93 ragtop

I think the heater core has the water flowing through it at all times. The heat is turned on and off by a door that controls air across it. So, again, I think it will flush when you flush the rest of the car.

pcolt94

But.......

Your correct about the water flowing in the heater core all the time. But it will not get flushed when you drain the rest of the system. You need to disconnect the two hoses to the heater core. One goes to the fill tank, and the other to a plastic coupling.

Flush both ways with a garden hose. Don’t go crazy with full pressure, but go both ways a few times till it runs clear. You won't believe what junk comes out and how much better the heat will work.

I don’t think my car was taken care of to well before I got it an I have to flush the core at least every 2 years or I just don’t got that HOT heat. But that’s my specific problem with this car.

I just did the whole flush thing in July so I am ready for winter here in Orlando.
Yeah right, winter in Orlando, we have our days.

Red-Lt1

I have never even tried to use my heater. I am a little farther south than you.

Larry/car

There is a procedure to bleed the LT1 engine after you flush the system. Don't forget to accomplish this or you could damage youe engine.

runner140*

I'm in Ft. Lauderdale, where are you?

pcolt94

There are a few mornings I do like to keep my feet warm at 6 AM in winter. But what is important is even though you don’t need the heat, the system will work more normal with the heater core getting to the correct temperature. Then the mix door will not have to swing as far to heat to reduce the desired air temp in the car.

As my core was clogged once, I had to run the stat to 85 or 90 just to take the edge off the ice cold air in the cool morning. Even this time of year I end up with 70-72 as a comfort level with all working normal. In the afternoon back from work it is at 60.

Of course in FL, A/C is on every month even 98% in winter to keep moisture down on inside of car windows.

Wathen1955

What procedure?

I need my heater even though I live in southern CA in the high desert area. During the day, the temps are great, but in the morning, temps can be in the 30's.

pcolt94

The problem with not bleeding is there could be an air pocket and it might tend to over heat and not cool correctly. If you run to hot and peg the temp gauges, that might do damage but I think most are smarter especially the Forum people.

As you re fill the system and the tank fills to top, I just stop and open the bleed valves one at a time and let the air out. Keep filling and maybe do it again and see if any air comes out. That’s about it, Fill tank, run engine, get hot, fill tank till full and put radiator cap on. Always put extra coolant in overflow tank because it is going to pull it down as engine cools. Watch overflow tank for couple days.

This is pretty close what I do every time but maybe not exactly. People do it differently, this is not the only way as the variation is probably great. But the important thing is just to open the bleed valves at some point.

Red-Lt1

Pinellas Park, In the Tampa Bay area