(a summarized version of the way I flushed is at the bottom for those who would rather not read my short novel)
Yea, I used CLR. I tried to compile as much data by reading guides, watching videos etc as possible before going into the project, because believe me, it was definitely a project!
I just finished the thing now actually, and I believe the results were good.
Here was my methods and my thinking behind why I did it this way.
First, I drained the existing rus... err, coolant into a drain pan. Once it was relatively drained, I flushed it with just a water hose for a bit. The drain plug came out pretty slow so I considered detaching the radiator hose but it was a bit too difficult to reach.
After flushing with regular water several times, it was still a bit muddy but clearing up. I took the radiator cap and put it in a jar I filled with CLR to try and clear off as much rust from the cap as I could. It was pretty bad.
Once I got the cap out of the CLR, the stuff broke off pretty well. There was still the appearance of rust, but I could tell it was mostly stains etc. For the most part the rust was gone.
After that, I took the thermostat out (94 chevy astro requires a 14mm deep well socket, for anyone who'd like to know). The thermostat was shot, the spring wouldn't close the thermostat anymore. So I replaced it with the cheapest stock temp one from auto-zone, cost me $5.99 IIRC. with a $1 gasket. While the hosing was off, I sprayed the hose into the radiator hose that I had taken off to get to the thermostat. The result was water gushing out of the engine where the thermostat usually resides. I did this until the water ran clear (about 10 minutes) and replaced the thermostat and housing etc. I did not scape clean the old gasket because it didn't appear to be necessary and didn't really have the tools to do so. While I was in there, I went ahead and took the doghouse off and replaced my air filter.
After that, I did another regular water flush to try and get as much crap and air out of the system as possible. Then I used CLR basically with the same directions as the directions listed on the prestone radiator flush bottle (drain radiator, put flush agent in, fill rest with water, run engine until up to temp, let engine idle at temp for 10 minutes, wait to cool, drain, fill with water, do the same thing, drain again). The CLR did knock quite a bit clean. Unfortunately, I was only working with half of a bottle though, as I spilled half
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The CLR seemed to work great, it really was disgusting seeing what came out with the CLR. My wife described it as looking like clay.
After flushing with CLR, I flushed the system using the prestone radiator super flush (exact same you showed, ironically enough I had the same stuff sitting around for about a month before doing this). My reason for this was, the prestone radiator flush is pretty nice and did appear to knock some stuff free that the CLR left behind, but it also purged my system of the CLR itself. Since the Prestone radiator flush is a lot less aggressive so to speak residual bits of it in my cooling system wouldn't be as harmful as that of the CLR, or, atleast that is what I hope anyway.
Once I finished flushing per the instructions of the Prestone radiator flush, started the engine and ran the engine with the drain plug opened and just sprayed water from the hose in the top while the drain plug drained at the bottom. I was hoping eventually it would eventually flow clear, but instead I had to be OK with it being slightly brown. Once I ran the car like that for a while, I let down the left side of the van (the drain plug was on the left) so that the water and flush would hopefully all drain out, went inside for something to eat etc and by the time I came back outside there wasn't anything else dripping.
I screwed the drain plug back in and added 1gal of anti-freeze (and just a bit in the overflow), 100% not mixed. Then I topped it off with the garden hose trying not to have any excess pour out to waste anti-freeze and pollute the environment. I also tried to add roughly the same amount of water to the overflow as antifreeze I'd added earlier.
Took it for a bit of a drive, then filled the overflow to roughly half way with water and I'm done.
Ok, so here is the summary I promised at the beginning of the post.
- Jack up the side of the car opposite the side with the drain plug
- Release the drain plug and open radiator cap, then let the radiator drain into a drain pan
- Once the fluid is all drained, put a hose in the top and let it run until the water starts running clear out of the drain plug, or close to clear.
- Stop filling the radiator with the hose and let the radiator drain completely.
- Replace the drain plug and pour an ample amount of CLR into the radiator (Calcium Lime Rust, I intended to use the entire 28 ounce bottle but spilled some)
- Add some water and let the CLR sit for a little bit (about 10 minutes) to start doing its magic.
- Top off the radiator with water, then put the cap back on and run the engine until it reaches operating temperature with heater on high and let it idle for 10 minutes.
- Wait for the engine to cool and remove the drain plug again. Also remove the radiator cap for faster draining. (Note: CLR probably isn't the best for the environment, so use a drain pan here also if you can).
- Flush with hose until it runs clear again.
- Replace the drain plug and put any standard radiator flush in the system, then top it off with water.
- Close off the cap and fill the overflow, then run until the engine reaches operating temperature then allow to idle for 10 minutes.
- Wait for the engine to cool, then drain the radiator again. Remove the radiator cap also for faster draining.
- Run water through the system until the water exiting the drain plug is clear of any rust or bubbles.
- Let the radiator drain completely, then put the drain plug back in and add 1gal of 100% antifreeze, putting some in the overflow.
- Top off the radiator with regular water, careful not to spill too much then add about as much water to the overflow as you added antifreeze.
- Close your radiator cap and you're all done.
- Finally, remember that in 9/10 cases, the radiator as it gets up to operating temperature and starts removing air from the system will be pulling from your overflow, so remember to keep your overflow within proper levels for the first week or so after flushing.
OK, so maybe it's not as simple as I thought, but in the case of my radiator it needed this and then some. Even after flushing easily 15-20 times with water, my radiator still produced water that resembles mud.
The heater does work way better now than before though, and I am no longer curious if my temperature gauge is broken. I can also tell a direct response in the amount of heat the heater is putting out verses the amount of load on the engine at the time.
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