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97 Sable, radiator drains in drips, can hardly get any coolant out

Original 3.0 OHV Vulcan engine replaced a year ago with another Vulcan because original rusted out. Heater is bypassed by hoses when used engine was put in at that time. My fan belt broke a week ago, the car nearly overheated for a moment but I pulled the car into a parking lot and replaced the fan belt. The car does not overheat.

Figured it was time to replace the coolant, I tried to drain the radiator, a little came out at a good rate but then it started dripping with only a few cups’ worth in the pail. The front of the car is on ramps to make room for a five gallon bucket. I turned the car on, let the radiator drain cock open, and opened up the radiator overflow cap. The idea was to have the coolant drain out the radiator, and add new water as the care ran at operating temp. Doing this will eventually flush out the old coolant. Only problem was, the amount coming out of the radiator was so small, the only water coming out of the car after perhaps a minute was not out the radiator drain, but out of the coolant reservoir overflowing onto the driveway. I let the car run for a long time and it was at operating temperature on the gauge so I know the thermostat was open.

Aside from preventing me from draining the coolant out the correct way and taking the bucket down to the Hazardous Household Waste site to be disposed of properly, there does not seem to be any way to get enough of the old coolant and dirty water flushed out with new water so I can add the new antifreeze.

Why does the water come out of the radiator at a decent clip for only a minute, then go drip drip drip? I’m not getting enough new water into the system to properly flush it out. Advice is appreciated.

Here’s a heads up . . .

Your belt most likely broke because the ac compressor failed

We have several Tauruses in our fleet with the same engine as yours, and that has happened to several of them, already. It’s quite common

By replacing the belt, you’ve quite possibly fixed the symptom, not the root cause

it’s possible nothing is draining out of the radiator because your entire cooling system might be at least partially plugged up

Yeah, I’d say you have rust plugging the drain valve. Try draining out the bottom radiator hose connection (forget the recirculating-while-adding-water).

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  • D4690: Much thanks for answering. The AC had not been working for years, so it was not on. I thought about the cooling system being partially plugged up, but there definitely was some movement in the water going on in the coolant overflow tank. The water level kept popping up. Also, the car did not overheat, it stayed at slightly below middle on the gauge for a year and a half since the new, (used), engine went in.

The old coolant did not look that bad, it was 1.5 years old since it was changed and a little dirty, but no sludge visible. Also put on a new water pump at that time.

If the radiator is partially plugged up, would it show on the temp gauge? If not, then I have another question. I did not put any de-ruster in so far to clean out any old rust. As there is now about only one third to one half of the coolant percentage left in the engine, should I put that stuff in now and then run the car for several hours? I’m worried that if the radiator isn’t stuffed up and the problem is elsewhere, I’ll be stuck with that de-ruster in the engine and no way to adequately get it flushed out.

+Insightful: I was thinking about that, (draining it from the bottom radiator hose), but the videos warned against it because it gave another possible leak point. But as it stands, I’m going nowhere fast with this maintenance operation, it’s only one end of one hose, and that looks like the best thing to try right now. Thanks-I’ll go out and do it and let you know how it works. If I end up buying a new hose, so be it.

Here’s an easy question . . .

When you’re opening the radiator drain, do you have the coolant reservoir cap removed?

Maybe it’s the drain that is partially plugged up. Slush has a tendency to settle on the bottom. Stick a small screwdriver in and wiggle it.

db4690: Yes, I removed the coolant reservoir cap. I noticed it made quite a difference when I did. Another thing I’m going to check, just looking around the internet, is the hose from the coolant reservoir tank to the radiator. I removed the reservoir tank to make it easier to move the fanbelt tensioner when fitting on the new fanbelt, and when I put the hose back on, it went on very hard. So hard that it’s about 1/8 inch or so from the base of the hose fitting. As I had it so close, I just put on the clamp, figuring it wouldn’t make any difference. However, I found out today that that hose has to be airtight or the water won’t flow from the reservoir into the radiator. So all it’s going to take is a little extra oomph by me, (and maybe rub a candle around the ID of the hose), to fit the hose back snugly against the base of the reservoir. I’ll get back to let you know if that worked-I’ll do it tomorrow, it’s raining here today and I don’t want to work on the cooling system in the garage.

Pull the radiator out, take it to a shop to get it flow tested.

Just what did you mean “engine rusted out”? You didn’t replace an engine just because an oil pan or core plug rusted out did you?

G Pierce: Considered that. Aside from wondering if my car ramps will five me clearance to get the radiator out, I figure the testing will cost perhaps $50. I checked out some prices, my car’s radiator goes at auto parts stores for a little over $100, plus minus $20 online discount card. Probably be better off going new, if it comes to that.

oldtimer_11: The car’s engine started leaking through a drain plug some years ago. Had a guy fix the drain plug, but it rusted back up about a year and a half later. So I had a new (used) engine put in. Found out the Vulacn engines were extremely disposed to rust.

I have a question. If you look at the radiator, the inlet from the overflow tank actually enters the radiator from a spot about 80% down from the top. Now I’m wondering if that is the reason the radiator drains out so little-only 20% of the radiator is filled once it cools down.

Here is a pic of my coolant tank.

The bottom nipple is 1" OD that runs through a hose 20% above the bottom of the radiator, and the small nipple on top on the same side runs through a small hose to the top of the radiator. I figure that since the car takes 11.6 quarts and the radiator usually holds about a third of that, the radiator should hold about a gallon of coolant. Can I fill the radiator with water through the top 3/8" (I think) hose which runs from the top of the overflow tank to the top of the radiator, (or appears to)?

I figure that will give me a full radiator. I plan to close the stopcock, pour about a gallon of water into it through that small hose using a funnel, then open the stop cock. After awhile if close to a gallon comes out, there’s nothing wrong with the radiator.

This sound okay? Or is there something about that overflow hose that water cannot be poured into the radiator using it?

Well, trying to add water through the small hose that goes from the coolant tank to the top of the radiator didn’t work. No water would enter. I thought there might be some sort of valve in there that let water out of the radiator but not in, and apparently there is.

I noticed there is a nice big hose connecting the thermostat housing to an inlet near the top of the radiator. Since I was thinking of removing the thermostat anyway until after this operation is completed, think it’s a good idea to disconnect the housing, take out the thermostat, then add a gallon of water through that housing and hose to fill the radiator from a point near the top?

Then if I drain the water out and it comes out nearly a gallon, I know the radiator is good. How does that sound?

This is all new. Back when I used to work on my own car a lot, the cars were built in the seventies, so the radiator had a cap on the top and when you drained it, what was in the pail at tthe bottom was the full amount of what was in the radiator. Now with coolant tanks having connections going near the bottom of the radiator, things are getting complicated. Oh well.

You shouldn’t have to do this. The overflow reservoir should be filled with coolant up to the level indicated on the tank. As the engine cools down, coolant is siphoned back into the radiator. Make sure you have sufficient coolant in the reservoir.

When the engine runs and coolant gets hot and expands the overflow reservoir captures the overflow and the cycle repeats with each driving and engine cooling down.

By the way, the basic cooling system has not changed. There is still a large hose and top and bottom of the radiator. One is an inlet and the other an outlet.

If you are only out to change the coolant, this might help.
I’ve changed out an original brass/copper radiator from a car because of a crack in a plastic tank on the side. The coolant looked ok, and nothing unusual was ever seen on the temp gauge.
But the drain was slow like what you’ve described. So the solution was to detach the lower hose at the radiator and drain from there.
The old radiator had plastic tanks on both sides. Removing them showed a lot of deposits in the old radiator. So much that after removing them, the radiator was noticeably lighter. It’s likely that some of the deposits broke off and were stuck in the radiator drain. The same might have happened in your radiator.

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This system has a pressurized coolant reservoir. The radiator has no cap.

There shouldn’t be any check valve in any line to the coolant reservoir. Can you remove the suspect line and blow through it?