Cooling system flush...help!
Thread Starter
Joined: Apr 2006
Posts: 326
Likes: 3
From: Northlake, IL
Cooling system flush...help! Hey, I'm just about to flush my cooling system, I have a couple important questions, and also a very cool shortcut I found.
First, I was wondering if it's alright to use a cooling system flush product. I've got one, can't remember the exact name, but it's by prestone. It's the "less harsh" sounding product, you're supposed to just get as much of the original coolant out of the radiator as possible, dump the cleaner in along with enough water to fill it up, let it run (until the thermostat opens and it gets a chance to circulate around, heat on too) and then dump it out again.
I'm planning to do this several times with distilled water, but I was wondering if it's a) worth it to use the flush product, and b) is it harmful in any way? My neighbor says his "mechanic friend" says never use it, but my neighbor's not necessarily a super techie.
If it's a problem though, I'll just flush it with the water several times.
Also, do you guys feel it's important to open those drain plugs on the block, or is just flushing the radiator with distilled water several times, followed by a complete warmup and dump sufficient? My original dexcool (1999, 7 years old, 40,000 miles) is really clean, it may have been flushed before.
I discovered a really nice shortcut too...instead of removing the battery and removing the overflow cannister and flushing it with a hose, all you have to do is disconnect the one little clamp that's on 1/4" hose connected to the back of the radiator fill neck and remove the hose. It leads directly to the bottom of the overflow bottle, so you can just dump it (get it to the lowest position possible) fill it with some water, and dump it again several times, and eventually it comes out crystal clear.
First, I was wondering if it's alright to use a cooling system flush product. I've got one, can't remember the exact name, but it's by prestone. It's the "less harsh" sounding product, you're supposed to just get as much of the original coolant out of the radiator as possible, dump the cleaner in along with enough water to fill it up, let it run (until the thermostat opens and it gets a chance to circulate around, heat on too) and then dump it out again.
I'm planning to do this several times with distilled water, but I was wondering if it's a) worth it to use the flush product, and b) is it harmful in any way? My neighbor says his "mechanic friend" says never use it, but my neighbor's not necessarily a super techie.
If it's a problem though, I'll just flush it with the water several times.
Also, do you guys feel it's important to open those drain plugs on the block, or is just flushing the radiator with distilled water several times, followed by a complete warmup and dump sufficient? My original dexcool (1999, 7 years old, 40,000 miles) is really clean, it may have been flushed before.
I discovered a really nice shortcut too...instead of removing the battery and removing the overflow cannister and flushing it with a hose, all you have to do is disconnect the one little clamp that's on 1/4" hose connected to the back of the radiator fill neck and remove the hose. It leads directly to the bottom of the overflow bottle, so you can just dump it (get it to the lowest position possible) fill it with some water, and dump it again several times, and eventually it comes out crystal clear.
TECH Apprentice
Joined: Dec 2004
Posts: 393
Likes: 0
You kinda answered you own questions 
Sure use the flush product it won't hurt. If you want to drain the block go on and do it, but it's not necessary. After your done fill her with distilled water 50/50 dex-cool and 
BTW don't listen to your neighbor. Mine digs through my trash sometimes
I shred all my personal stuff and he's not looking for cans.
Don't listen to your neighbor, but do keep a close watch on him
Sure use the flush product it won't hurt. If you want to drain the block go on and do it, but it's not necessary. After your done fill her with distilled water 50/50 dex-cool and BTW don't listen to your neighbor. Mine digs through my trash sometimes
I shred all my personal stuff and he's not looking for cans.Don't listen to your neighbor, but do keep a close watch on him
Thread Starter
Joined: Apr 2006
Posts: 326
Likes: 3
From: Northlake, IL
Cool, thank you. I did end up just using the stuff...I hate when people say things like "oh, that'll ruin your engine" and start making you second-guess yourself. I've never had a problem with it before, and it seems to have worked just fine today, I guess we'll see.
The one major problem I had, which probably isn't a big deal, is that when you dump the radiator out, you only get out about 5 quarts maybe. The system is around 12.5 quarts I think and the recommended ratio is 50-70%, so by putting back in 5 quarts of straight Dex Cool, I'm only at around 40%. I could have dumped out another gallon, and with one more gallon of straight Dex Cool that would bring me up to around 60%, but I was out of Dex Cool.
I suppose I could just leave it...
The one major problem I had, which probably isn't a big deal, is that when you dump the radiator out, you only get out about 5 quarts maybe. The system is around 12.5 quarts I think and the recommended ratio is 50-70%, so by putting back in 5 quarts of straight Dex Cool, I'm only at around 40%. I could have dumped out another gallon, and with one more gallon of straight Dex Cool that would bring me up to around 60%, but I was out of Dex Cool.
I suppose I could just leave it...
TECH Regular
Joined: Jun 2004
Posts: 418
Likes: 0
From: Houston, Tx
If you pull the thermostat off, you'll get plenty of more coolant out of the system when draining. I then add 6 quarts of dex-cool and then fill the rest up with distilled water. Oh, after bleeding the system (running with the radiator cap off while thermostat is open), I notice the level drops over a couple of warm-up/cool-down sessions. You'll need to keep topping off the radiator until it stays at the neck.
also, when you bleed the system, don't have the car parked downhill, as some air will get trapped in back of the block and you will end up boiling a lot of the water out you just added. When I do mine I just drive it on some boards to make sure the front end his higher than the back end. I tried it once when the rear was higher than the front and I could not get it to bleed the air out at all.....
what i did:
i cut one of the heater hoses and installed a t-fitting. i then took my old thermostat and smashed it out of the houseing.. and put the housing on. i then took a hose and hooked it up to the t-fitting and ran the car for about 10-15 mins and. it worked very well.. and flushed the system very well.
i cut one of the heater hoses and installed a t-fitting. i then took my old thermostat and smashed it out of the houseing.. and put the housing on. i then took a hose and hooked it up to the t-fitting and ran the car for about 10-15 mins and. it worked very well.. and flushed the system very well.
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I flushed mine with the prestone and followed the directions. I also mixed my dexcool 50/50 before I added it back to the radiator. I had to add about 3 times after that because of air to get it right where it is suppose to be.
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