Cleaning a radiator out

[irowiki]

I have another one for y'all. I tried searching but radiator and coolant is fairly generic.

So I flushed my coolant and now it runs hotter! I think my radiator plugged, here's what transpired so far:

Drained using radiator/engine drain plug, out of 5.5 quarts I get 4 quarts of coolant out of her. Then I flushed as per the repair manual, sticking a hose in the top of the radiator for a bit until everything ran clear, let all that drain out. Old coolant was not as dirty as I would have figured, if I had to do it again maybe I'd just not mess with it. At least I'm learning!

Someone suggested using the prestone cleaner stuff, so I put that in, put a gallon of water in, went on a 30 minute trip, drained that, it was filthy! Put another batch of water in as per the instructions, another thirty minute trip, drained that, then put 4 quarts of 50/50 in, went on a test drive.

My temp gauge is something like, 7 cold, 8 normal, 10 "70 mph or up steep hills" 11 is overheating. The manual shows 8-10 to be normal operating range. Before the coolant flush she'd stay around 8 no matter what I did, going between 9-10 if doing some rough driving.

Well running around town she was doing 9, and when I tried going up the hill on the way to work then doing some 70 MPH in 4th, the temp went all the way to 10:30, a notch or so below HOT. No bubbling coolant, no steam or anything, I don't even think anything went in or out of the coolant overfly, car was running fine.

I freaked out a bit about that, drained the radiator, disconnected the lower hose and gave it a nice flushing with a hose in the top again. Filled back up with water, went on a test drive, temp showed 8:30 around town and just below 10 when I went up my "killer" hill. So not as bad this time but not as good as before the flush!

After all this, I figured out about foamy coolant and air bubbles and stuff, so I think part of my problem was not burping the system. So I did some searching here and figured out that it should burp itself. Other places on the internet suggested idling with the cap off, so for lack of things to do I let the car idle for 15 mins with the radiator cap out, and watched it foam up, fan kick on, foam go away, usually when idle car would stay in the 8 range on the temp guage, it was getting to 8:45 just idling! After the foam stopped and coolant just started bubbling (16 mins) I shut the engine off, replaced the missing coolant, and went on a quick drive.

After that I took a heat gun to the radiator, and while most of it was in the 140-150 degree range, a 2-3 inch section magically under the fill cap and inlet from engine was 85 degrees. So I think it plugged! The manual says in some cases you may have to take the radiator out and back flush it from the bottom. It was also suggested that the thermostat might have plugged up.

Does this sound like a plugged radiator, bad thermostat, or something else? If it is the radiator, is there anything else I could do besides backflushing? The internet had some interesting suggestions like CLR, vinegar, and even drano...

If all else fails a new radiator is $105, which isn't terrible, I'd just like to try fixing the current one first.

[dlb]

strange that it would run so much hotter after doing a coolant flush. perhaps some large flakes of corrosion were freed up by the prestone stuff, and then lodged in the rad? i dunno, that's just a guess.

however, i would try replacing the thermostat first since it's likely quite old and faulty and could cause the symptoms you are describing, and it's a lot cheaper than a new rad. if you still find it's running hot, replace the rad too. then you know you don't have to worry about your cooling system for a while. btw, tap water is fine for short times like when doing cleaning flushes but when you are done those and mixing coolant and water, be sure to used distilled water. tap water can kill rads in just months (depending on what is in your water) by creating corrosion and buildups of deposits in the rad and cooling system.

[marlinh]

It sounds like the stuff you used to clean the rad is still in the system. You shouldn't have foam, basically you are circulating air pockets around and you will get erratic cooling. What was the temperature at the thermostat? It should be 180 to 190 F depending on the thermostat you installed. If you had chunks of corrosion come out of the system, something may be jammed in the thermostat.

[irowiki]

Well I took off the radiator this morning before checking the thread, gave it a nice flushing, washed some vinegar around in it, rinsed that out well, put it back on, hooked everything back up, started it up and let it idle a while.

Thermostat popped open at almost 15 minutes exact, roughly 190F. I'll probably replace it anyway.

However, there still looks to be a few plugged, uh, what do you call them, rods?


Edit: took the car for a spin and it isn't running nearly as hot now. I'm still going to replace the thermostat so I don't have to drain the coolant again for a long time.

[larry mcgrath]

if you have a radiator repair shop in your area (Yellow Pages )have them back flush it and flow check it. they can remove the upper and lower tanks and rod out the tubes to clean out all the gunk, then you'll be certain that the radiator is'nt at falt. Larry

[Petros]

I always take the radiator out to back flush after soaking it with vinegar, I back flush the heater core as well. The rad is easy to pull, just two hoses and two 12 mm bolts. flush it good and inspect the tubes though the openings, should be fairly clear. With the rad out while back flushing I tap the rad with a rubber mallet, it helps free any depots, you can see the large flakes coming out with the flush water (you can also run the output into a buck to examine it after). I also suggest replacing the thermostat, they wear out and should be replaced every two years to avoid having it fail. Do not buy a cheap one (many of those are bad right out of the box), get the best you can, either Toyota factory or NAPA high quality (usually in the $16-18 range). Use only filtered water and coolant. tap water will ruin it with no easy fix. I have not found trapped air an issue, but I do check the level and top it off after first drive after I refill the system.

If you live in an area where it is really hot there is a useful additive in you need more cooling cap city, it is called a "wetting agent", it improves heat transfer between radiator tubes and coolant. If you need extra cooling it usually makes a noticeable different.

BTW, if turning on your heater brings the temp down it means you have limited cooling capacity. That is a simple test when not sure if radiator is working properly.

[keith]

My experiences with that Prestone flush are NOT good. In fact, my experiences with any chemical flush have not been good, but the Prestone Super Flush has been the worse. Because of that, I have not used a chemical flush in about 30 years now.

Do me a favor and keep us informed on all the cooling system problems the you have in the near future. While you have the hoses of to do the thermostat, look inside them for any evidence of delamination.

[irowiki]

It wasn't the super flush but the next one under that. If I had to do it again I would have skipped it! Here's what it looked like:

https://sphotos-a.xx.fbcdn.net/hphotos- ... 4688_o.jpg

Left is the old coolant. Middle is what flushed out with the cleaner, right is after draining cleaner and filling with water. Each time a decent bit of dirt (rust?) drained out too. Took the radiator out, backflushed, gave it a vinegar soak, and reinstalled it. In the course of my troubleshooting I drained and filled enough times with water it was practically clear by the end.

I used a half a tank of gas just driving around/idling while troubleshooting

Replaced the thermostat, old one was kinda crusty, the gasket was in horrible shape! Cleaned it all really well and reinstalled it with a new gasket.

Hoses were still nice and flexible, flushed them out too, didn't know to look for delamination. After yet another water fill to test stuff out, I got some 100% coolant, distilled water, and some generic water wetter, geeked it out and filled it as follows:


Left in car: 48oz 27.27%
Water wetter: 8oz 4.55%
Coolant: 80oz 45.45%
Water: 40oz 22.73%
Total : 176oz 100.00%


On my first road test after thermostat replacement and fill up, temp went to the middle after a long uphill, then after a while doing 70 with a slight upgrade, the temp actually started going down. This was the same route that got me a notch below HOT on my first test drive on the first flush. Just driving it around town it seems a little hotter than usual (a notch or two) but it is hotter outside as well.

The heater core didn't plug at least, in fact I think the heater works better now than it did before! Cranking the heater on high for a good 15 minutes today did nothing to the engine temperature. (me however was another story, who needs a sauna when you have a tercel?)

After I drive it for a few days I'll test the coolant mix and see how close my math was.

[Petros]

you are supposed to back flush the radiator AFTER you do the vinegar soak, that way anything it loosens up and flakes off will come out with the flush. When I say back flush I mean I take the garden hose and with a hose clamp attached it to the radiator lower hose and pressurize the rad, and pull the cap off and let it blast out. I close off the upper inlet hose with a hose clamp and a plug of some sort (anything about the right size will work for a plug). and than I open all the outlets, stop cock, etc. and let the hose run full for several min until it runs clean, tapping the rad to get anything loose.

No point in removing it now since you appear to have solved the problem. but getting all the vinegar flushed out is important as it will corrode the heater and radiator core.

[irowiki]

Oh whoops, not to worry, omitted my steps after, I did back flush after the vinegar soak, it was just a little more redneck. After I soaked and shook the radiator with vinegar in it, I duck taped a hose to the bottom inlet, cranked the water on to max and let it run for a while! Then I rinsed it good from the other side as well.