I had my water pump done last year, but although I asked them to at the time, they did not do a flush and fill on the coolant. Too busy they said.

I've noticed as it's been really hot lately, that my temp has started to creep up, and I'm guessing the sludge/coolant is the cause. Can't be helping anyway. I just wanted to think out the steps here, and see if I'm going to do this correctly...

I'm guessing there is a drain at the bottom of the radiator. I was going to dump all this, and refill with water. Run it for a while, wait for the nasty overflow tank to go in, and then shut it down, cool, and then drain it again. Maybe do that a second time, and then fill with long life fresh.

Anyone know how much coolant I need to buy? Are those basically the right steps to do? I've not done this before.

99 Chevy S10 Blazer 4x4

 

go to your local car parts store and get some prestone coolant flush. It's got instructions on the bottle. Then get some cascade dishwashing powder. You know, the stuff for automatic dishwashers. Used it many times on cooling systems. It has good degreasers and is non foaming making it easier to drain out.

 

If it's been awhile I would get a flush chemical. They usually sell 2 sizes small and big the bigger one marketed as being for neglected or very dirty systems. Just get the bigger one and follow the instructions for adding it to the system. You usually have to run it for a few days, so you'll want to throw it in a few days before you complete the service. I typically skip any additives or conditioners. Some people live by them, but I personally skip them.

You can also get a back-flush kit. This allows you to hook your garden hose to your system and back-flush water through the system. Ideally this will knock loose other stuck on debris and flush it out.

I would also inspect any hoses to check for cracking or soft spots and replace hoses as needed. Hose are cheap and it's silly to be stranded somewhere sometime because a hose failed you.

I would also recommend replacing the thermostat, but if you back flush the system do it with the old thermostat installed first, so you don't risk damaging the new one. I like to get fail safe ones, which are designed to fail in the open position. This will leave you without heat if it fails during the winter, but will (hopefully) prevent your car from overheating by failing in the closed position. Clean off the mating surface of the thermostat housing to ensure a good seal here.

Next, get a new radiator cap and be sure to clean off any residue on the mating surface for the cap so that it makes a good seal. A old or bad cap will not maintain system pressure and thus cause issues with your cooling system.

I would also remove the coolant reservoir, puke jug, overflow, whatever you want to call it and try to wash out any residue that's in there, if it's been awhile there will be plenty and it will be difficult to get out especially if at some point someone screwed you by mixing Dex with regular coolant. This will form almost like a crust. A flexible bottle brush works pretty decent here.

 

I did buy a bottle of stuff. Wasn't Prestone, some single name, Walls maybe. Anyway, it went in, I drove it around on the order of miles, not days. I had done one water flush first, and what came out after the "10 minute flush" wasn't any dirtier than what was coming out before. I did the water flush a total of five times. Each time, it was obviously diluting a little more of the crap what was in the system. I only seemed to get out a little more than half a gallon each time out of the drain.

The radiator cap did have gook on it, but it doesn't seem hard, and still has good spring action to it. The thermostat is an unknown. From the looks of it, that mist have been replaced just a little while before I got the car. I might look and see if they did it when they did the water pump. Possible. The gasket looks pretty new.

The overflow jug. Yeah, disgusting. Has some sort of crust on the inside of it. Not easy to get off. I had thoughts of seeing what a new one would cost. I can't imagine that stuff coming off under any conditions though. A brush might get some of it, but it's pretty glued on.

The next day after the flush, it was a scorcher, and I was out driving around. The Blazer started getting pretty hot, past the 200 point. I pulled and checked the coolant level, and I think that the level was just a little low or something. Maybe some trapped air? I added some coolant (Dex) and it seemed to be better, but a little hot. The next day, I never noticed it getting above 200, but maybe a little higher. Again, it was really hot.

Looking in from the radiator cap, the cores that I can see in the radiator look good. I know that doesn't tell me what it looks like lower down though. The water pump should only have 30K on it since it was replaced. Can you think of any other reason it might be running hotter than normal?

Big project for this weekend is shocks. Never done them before....