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Discussion Starter #1 (Edited)
I bought a 2003 Impala a week ago, and the radiator is in desperate need of a good flushing and coolant change. How do I go about the flush procedure? I have new coolant, and am going to buy a bottle of radiator flush additive. What else do I need to do? Should thermostat be replaced as well?


Thanks in advance
 

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I bought a 2003 Impala a week ago, and the radiator is in desperate need of a good flushing and coolant change. How do I go about the flush procedure? I have new coolant, and am going to buy a bottle of radiator flush additive. What else do I need to do? Should thermostat be replaced as well?


Thanks in advance
Until you know the state of the entire cooling system, I wouldn't put the additive in. If you have a leaking intake gasket or something like that, the additive will end up in the crankcase (and that's not good). You have a 16 year old car - there's a good chance it could have a leak.

Instead of flushing the entire system, check with a radiator shop and see if they can clean yours out. In the old days, they could be boiled out, but not sure that's possible with today's aluminum cores and plastic pans. Regardless, see what a shop has to offer. If it sounds good, you can pull the radiator yourself and take it to them to save a few bucks.

Alternatively, you can install a new radiator as well. You can get one for that year Impala for about 110 bucks at Rockauto.

Once you have the radiator back in it, fill it with 50/50 Dexcool and drive it. See how it does. If you find some leaks, fix them. Intake gaskets are pretty common sources on that vintage Impala.

If there aren't any leaks, in lieu of flushing it out, just drive it a few days, then drain and refill it with new 50/50 Dexcool again. That should get most of the crud out.

HTH.

Doug

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Discussion Starter #4
Until you know the state of the entire cooling system, I wouldn't put the additive in. If you have a leaking intake gasket or something like that, the additive will end up in the crankcase (and that's not good). You have a 16 year old car - there's a good chance it could have a leak.

Instead of flushing the entire system, check with a radiator shop and see if they can clean yours out. In the old days, they could be boiled out, but not sure that's possible with today's aluminum cores and plastic pans. Regardless, see what a shop has to offer. If it sounds good, you can pull the radiator yourself and take it to them to save a few bucks.

Alternatively, you can install a new radiator as well. You can get one for that year Impala for about 110 bucks at Rockauto.

Once you have the radiator back in it, fill it with 50/50 Dexcool and drive it. See how it does. If you find some leaks, fix them. Intake gaskets are pretty common sources on that vintage Impala.

If there aren't any leaks, in lieu of flushing it out, just drive it a few days, then drain and refill it with new 50/50 Dexcool again. That should get most of the crud out.

HTH.

Doug

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Has no leaks whatsoever, I have put some miles on it and coolant level has not gone down. Not overheating, the coolant just looks tired and dirty, I could just flush out radiator with clean water,, but my other question, is how do I get the old coolant drained out of the block, is there a block drain plug on the 3.4?
 

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You may have to run water a couple of times through the system. Drain and refill, I also recommend using distilled water. And use a concentrate or 100% coolant to get the right balance for the system. Which you should be running around -25 to 30 degrees with a coolant checker.

Pat
 

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Has no leaks whatsoever, I have put some miles on it and coolant level has not gone down. Not overheating, the coolant just looks tired and dirty, I could just flush out radiator with clean water,, but my other question, is how do I get the old coolant drained out of the block, is there a block drain plug on the 3.4?
That's good that it has no leaks.

If you wanted to blast a garden hose into the system to clean it out - which I've considered but never done - you would need to remove the thermostat, which is a bit of a pain on the 3.4. What I had envisioned was to disconnect the two radiator hoses (from the radiator), and shoot the garden hose into the top radiator hose and let the bottom one drain on the ground. I'm not sure what all that implies - does the engine need to be running so the water pump is turning? - or whether it will be very effective.

For sure, you do not want to directly connect the garden hose to the system - ie, you do not want a sealed connection. Tap pressure is much greater than the system is designed for, on the order of 100 psi versus 20. It can do a lot of damage.

I tend to favor just draining, filling, and running the engine, then repeat. Doing that 2 or 3 times will get most of the old stuff out, enough to not worry about the little bit that's left.

The first or second cycle would include the cleaning/flushing additive. The additive instructions may call for several water-only flushings afterward, so that will determine how many cycles total.

Regarding draining, I would just pull the bottom hose to drain it. You can try the petcock on the radiator, but I've become cynical about those silly things - seems like they start leaking after they've been opened and reclosed once :( That is, I end up chasing that for a while and have to put a new petcock in. Which makes removing the hose more appealing :)

[Edit]Thinking about this some more, it occurs to me that the upper radiator hose flows _from_ the engine _to_ the radiator, so blasting the garden hose into it (as described above) would be backwards with respect to normal flow. So if the water pump was turning, that might be an issue.

HTH.

Doug

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Discussion Starter #7
That's good that it has no leaks.

If you wanted to blast a garden hose into the system to clean it out - which I've considered but never done - you would need to remove the thermostat, which is a bit of a pain on the 3.4. What I had envisioned was to disconnect the two radiator hoses (from the radiator), and shoot the garden hose into the top radiator hose and let the bottom one drain on the ground. I'm not sure what all that implies - does the engine need to be running so the water pump is turning? - or whether it will be very effective.

For sure, you do not want to directly connect the garden hose to the system - ie, you do not want a sealed connection. Tap pressure is much greater than the system is designed for, on the order of 100 psi versus 20. It can do a lot of damage.

I tend to favor just draining, filling, and running the engine, then repeat. Doing that 2 or 3 times will get most of the old stuff out, enough to not worry about the little bit that's left.

The first or second cycle would include the cleaning/flushing additive. The additive instructions may call for several water-only flushings afterward, so that will determine how many cycles total.

Regarding draining, I would just pull the bottom hose to drain it. You can try the petcock on the radiator, but I've become cynical about those silly things - seems like they start leaking after they've been opened and reclosed once :( That is, I end up chasing that for a while and have to put a new petcock in. Which makes removing the hose more appealing :)

[Edit]Thinking about this some more, it occurs to me that the upper radiator hose flows _from_ the engine _to_ the radiator, so blasting the garden hose into it (as described above) would be backwards with respect to normal flow. So if the water pump was turning, that might be an issue.

HTH.

Doug

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So pulling off the lower hose will drain out the radiator, but what about what's left in the block?
 

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So pulling off the lower hose will drain out the radiator, but what about what's left in the block?
You could disassemble the engine, and that would get it all out :) But nobody's gonna do that. You could pull the freeze plugs and get a lot out that way, too. But that's not appealing either.

After that, you might try blasting fresh water into it with the garden hose, but, while it may force out the old stuff, it will leave new water in its place.

Another thought is to hook up an air hose to blow everything out, but that presents two problems. You risk over pressuring the system (designed for 15psi operation), and you may have a hard time pushing the water with air. For example, if water is standing in a low spot and air can pass over it, the air may just move on thru without pushing out the liquid.

The most effective way of doing it is what's been discussed - drain and fill multiple times. Each time a little will be left behind, but it gets diluted with the next fill. Follow the instructions on the flush additive label and you should be fine.

Also, as 1970cs noted, you will want to use distilled water, at least on the last couple passes.

Doug

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