cooling system flush

paddleSeptember 19, 2005

What is the proper procedure to perform a FULL engine/rad flush? I really don't want to pay a garage that will simply throw in that"rad flush" stuff and drain the rad, I can to that! My rear heater in the van is not working so I'm hoping the flush may get things started again. Don't they hook up some kind of vacum/machine that helps circulate the old fluid and then replace it with the new stuff?

thanx for any help!

Jim in Toronto

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Maybe I am too much of an optimist, but I still (with reservations) believe in the innate goodness of man.

So, find a good auto repair shop and work with them - let them know what you expect and what is wrong with the cooling system....
IMO, a pressure machine($$$$) will be necessary, do you have one ??

If no luck in finding a good shop, maybe you can DIY.
Isolate the rear heater and use a garden hose, maybe the water pressure from a garden hose can dislodge the sludge from the hoses and core.....
Then use some anti-rust to prevent a reoccurance..
Works for me..

Need some more opinions on this....

    Bookmark   September 19, 2005 at 9:48AM
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I remember back in a high-school auto mechanics class. The instructor liked to demo or use my car alot... and was asking me if I wanted to use my car for the radiator cooling system evaluation chapters ... I said I'd rather not this time ;) - Someone else quickly offered up their ride for the evenings hands on cooling system learnings.

Anyhow whomever.. pumped the tester up the first time to about the 'spec', which would have been around 14# or so. Instantly there were leaks springing all over the place, including heater core and lots of wet radiator fins.

~ Cheap way...
Usually you just add some radiator flush,,, drive around for a while, read the directions. Then drain, fill, circulate, refill. Something like that. --- Then a couple weeks later your water pump starts leaking.

    Bookmark   September 19, 2005 at 11:13AM
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I think these days they have a machine to flush out the old coolant, and thus recover the old coolant rather than dump it down the drain or on the ground.

There are a number of ways to do it at home depending on how anal you are. The quick easy way is to get a flush and fill kit, which is pretty much just a tee you cut into a heater hose. Attach a garden hose to the tee, open radiator drain, turn on the faucet, start engine, let it run till the water runs clear. Turn off engine, turn off and disconnect hose, drain water from radiator, fill with coolant to acheive the proper mix for your area and cap the tee. You'll need a hydrometer to check the mix. A $2 one will do. That way assumes you're not paranoid about using tap water instead of distilled in your cooling system. Neither too strong or too weak a concentrate of antifreeze is a good thing. So spring for the hydrometer.

Another way is to drain the radiator, refill with water, run engine for a while, drain again, repeat 3 times or untill what you're draining out is clear.

If you want to used distilled water and the garden hose deal, do both of the above and use distilled water during that 3x drain fill cycle. Some people remove drain plugs or knock sensors from the engine block to drain too.

No need to dump any additional chemicals in the cooling system to clean.

Whatever you do, be careful and pay attention when you refill and start the engine. Often times the closed thermostat will prevent coolant from getting back into the engine. So, if you don't watch out, the thermostat will stay closed till the engine gets pretty hot, then it pops open letting cold coolant into the hot dry engine. Bad things can happen if this occurs. If you pay attention you can tell coolant isn't getting into the engine after you started it by observing the temp gauge and turning the heater on full blast. If the temp gauge reads cold after a few minutes, you're just getting cold air out of the heater, and the hoses are cool, there's no coolant in the engine even though the radiator is full. Leaving the cap off that tee I mentioned before as you fill the system will help reduce the amount of air trapped in the engine. Another way to refill is to remove the thermosat housing and fill the engine block through that hole. Some are easy to do that way, some are not. Another thing you can do to help if you remove the thermosat for any reason is to drill a small hole in the thermostat flange. Like 1/8" or smaller. That small hole will not affect the operation of the thermostat, but will allow air to escape from the block when you go to fill it. Just a few ideas for you to consider.

    Bookmark   September 20, 2005 at 12:43AM
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thanx for all the great advice!!!!!!
I think i will tackle this one on my own!!

    Bookmark   September 20, 2005 at 8:56AM
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what kind of car could hold back the water from the thermostat alone? most, if not all cars have a open bypass hose, for the heater system, and with the radiator cap off for filling, only a small amount of air would get trapped in the hoses, not the entire engine. I don't belive it would be possible to fill a radiator with water, and have the thermostat closed keep any water from filling the block.
unless all the lower hoses are blocked off and or crushed. and the car has no bypass hose for the heat system.

    Bookmark   September 20, 2005 at 11:41AM
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I speak from experience my friend. On many cars the top hose goes to the thermostat housing. The bottom hose goes to the water pump. With the thermosat closed, the coolant can't get past that point. It also creates an air lock, preventing it from filling through the bottom. It's like turning a glass upside down and and pushing it into a sink full of water. The trapped air keeps the water out of the open end of the glass, and you can't poor water in through the closed bottom of the glass. Some vehicles have an air bleed either in the thermostat housing or elsewhere on the engine to help fill it. You can actually purchase a thermostat with the hole I spoke of already in the flange. That's what it's for. All engines don't have this problem. Some do including my own corvette. It is something to be aware can happen lest in an attempt to save a few bucks doing a simple job yourself, you end up doing serious damage to the engine. Watching for the warning signs for such as temp gauge staying on cold, no heat from the heater, cool heater core hoses, gives you a chance to stop before harm is done. The next warning sign could be the paint burning off the head because there's no coolant in the block. Seen that happen too.

    Bookmark   September 20, 2005 at 12:52PM
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wow, all the cars I have serviced and engines I have changed, I never considered it a possibility. hmm. now that you mention it, the last Z28 I changed the engine in, did have a vent screw on the thermostat housing to bleed air out. but I just figured it was to get the air out of the high points of the motor, not the engine itself... live and learn.

    Bookmark   September 22, 2005 at 1:57PM
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Yeah, when I was in my teens I didn't think anything about it either. I'd just drain it, refill the radiator, start the engine, let it warm up, then top it off. Seemed to be the way everyone else did it. I observed a couple of times that the temp gauge would sometimes read pretty high, then drop to pretty low. Didn't think much about that either. Then one day I put in a new short block, a cast iron 4 cyl. GM, in a car. Filled it up and let it run for a while. Patting myself on the back on how well it was running while looking for leaks, I noticed the blue paint on the head started to turn black. I thought, WTF!! A couple minutes after I shut it off, the coolant in the radiator quickly droped and I could hear these steaming bubbling noises in the engine. After that I was more carefull. I also decided it probably wasn't too good for an engine to go through that hot/cold shock when the thermostat finally decides to pop open. So, for the last 25+ years I make darn sure there's coolant in the block and watch what's happening when I drain and refill. The engines I worked on back then were pretty much all cast iron so they could probably take more abuse like that. With all the aluminum they put on engines now, I think it's even more important to make things are done right to start with.

    Bookmark   September 22, 2005 at 2:48PM
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I have a 2002 Sienna and I changed the coolant @ 30,000 miles. I drained the radiator and also drained the block via some drain plugs on the block. When I refilled it, I did notice the engine temp gage going up and then dropping drastically. Never gave it much thought because all my vehicles that I have performed this on in the past acted the same way.
I assume I did no damge because that was 20,000 miles ago and the van still is running great.
Now my question is how do I prevent this when I do the next change on the Sienna? I can not get to the thermostat housing easily to add coolant to the block.
Thanks in advance

    Bookmark   November 15, 2005 at 8:24AM
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I never drain and flush the system, simply use some anti-rust on an annual basis.And this has worked OK for many years.
When and if the WP leaks, I refill with new coolant, depending on how the old "enriched" stuff looks..
Maybe you can just change the thermostat along with the old coolant every 60K miles, or three years...

    Bookmark   November 15, 2005 at 1:11PM
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What you're describing sounds pretty normal to me. The temp gauge will rise till the thermostat opens, then the temp drops a bit as the coolant that hasn't been warmed yet moves from the radiator to the engine. Where there's cause for concern is if after doing your flush, you start the engine and several minutes later the temp guage stays on cold, the heater hoses stays cold, you don't see coolant circulating in the radiator, ect. after the engine feels warm. The temp guage sensor screws into a water jacket. If no coolant is getting to the sensor, the guage stays on cold till heat is actually transfered through the block to the sensor, rather than from coolant to the sensor. It's not something to worry about, just something to be aware of that can happen.

I've had luck filling just by using the flush and fill kit...a tee in a heater hose. Also, if you start it, let it run for a few minutes till it's starting to get warm, then shut it off, it takes care of itself.

    Bookmark   November 15, 2005 at 3:09PM
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Paddle, there's a couple ways to do this. The first is the Flush and fill kit that Gary described. The Second is to remove the thermostat and dis-connect the upper Rad. hose AT THE RADIATOR. Make sure you leave the other end ,that goes to the thermosatat housing ,attatched. Now get on some grubby jeans and crawl under the Car and Disconnect the lower Rad. hose AT THE WATER PUMP. Now put your garden hose in the upper Radiator hose and turn on the water then start the car, it usually makes it alot easier if you have someone else start the car while you hold the garden hose and Flush the Engine. When you see that the water is running clear, shut the car off first ,then the garden hose. Next is to flush the Radiator, You can do the same thing with it like you did with the engine, but I prefer to take it out and have the core done at a Radiator shop. It isn't expensive and they will clean all the passages in the Radiator that would otherwise not get a thourough cleaning. One thing that was suggested earlier was to just toss in some "ANTI-RUST" once a year and go on your way. DO NOT DO THIS ! all that does is dislodge crap that's built up in your cooling system and then starts plugging up various Pasages. It may sound like alot of work, but the method I describe is one I've been doing for more than 30 years and I have yet to have a Car or Truck that has a problem with it's cooling system. Last thing to do is put in a NEW Thermostat. Good luck and have fun....

    Bookmark   November 17, 2005 at 7:57PM
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Anti-Rust dislodges nothing, only deters rust and lubricates and extends the anti-freeze life.
The use of this anti-rust has "worked for me" for over 40 years...
I do end up renewing the coolant every so often(5 years) as the hoses start to go in the over 100K miles,10 plus year old cars that I drive (Saab,VW,Honda)....
IMO, the cooling system flush is a waste of time and money...

Do the operators of the big rigs practice this ??

    Bookmark   November 19, 2005 at 1:40PM
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No need to change what's been working for you earthworm. I kind of do things the same way you do. I don't put any additives in though. If the coolant looks rusty at all, I flush.

I do think people have to be more on top of these things now than they used to be. All cast iron engines were pretty much bullet proof. From what I've read, neglecting things like this is hard on aluminum componants which most engines have now. I'd rather change coolant a little more often than an intake or head gasket.

I don't think any comparison can be ever be used between semi trucks and passenger cars. Big rigs, 36 quarts of motor oil, probably 12 gallons of coolant, heavy duty diesel engine, gets started once and runs all day. Cars, 5 quarts of oil, 4 gallons of coolant, mostly wimpy gasoline engines, gets started and runs 15 minutes, sets for 8 hours, started and runs another 15 minutes. How they're built and used is to different to be compared on any level. jmo

    Bookmark   November 20, 2005 at 10:50AM
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Took my '95 Taurus in and had the cooling system flushed and hoses replaced at 100,000 miles. I got it back and it leaked and ended up having to remove the radiator and have the seals replaced at a radiator shop. The guy said that just working with stuff and moving it around sometimes causes seal leaks. The whole thing ended up costing me several hundred dollars. I got 220,000 miles on the car now and haven't done anything to the coolant but add some occasional antifreeze. Still got the original water pump and thermostat. I hate to mess with it at this point in time. I could spend more than the car is worth. I'm a stickler on changing oil, etc. but I am not real faithful on changing coolant, transmission and brake fluids. Almost seems to me that those are good for the life of the car. And I always drive cars to 200,000 miles or so. I usually end up getting rid of them because of body rust, etc. rather than mechanical things.

    Bookmark   November 24, 2005 at 12:31PM
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