Checking Radiator Cooling

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My 97 Aerostar is overheating (see my endless postings...) and I'm finally getting to checking it out. Not overheating bad, but I now have time to spend on it. Anyway....
I got the engine up to temperature -- about 2/3 of the gauge. Checked the air flow at the grill and it's getting plenty of air being pulled in. So that likely says the fan clutch is at least working.
Then I shut it off and removed the fan shroud. The fins were hot enough to burn for the top 6-7 inches all the way left and right, then very cold from there down - I'd say 80 degrees F or less. The border between hot and cold areas was instant -- no gradual cooling.
Anyway, any ideas what's going on? Does that sound like a plugged radiator? Have to break for SUPPER now.... will search online if I'm still awake after a BIG dessert. =OD
Bob
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My 97 Aerostar is overheating (see my endless postings...) and I'm finally getting to checking it out. Not overheating bad, but I now have time to spend on it. Anyway....
I got the engine up to temperature -- about 2/3 of the gauge. Checked the air flow at the grill and it's getting plenty of air being pulled in. So that likely says the fan clutch is at least working.
Then I shut it off and removed the fan shroud. The fins were hot enough to burn for the top 6-7 inches all the way left and right, then very cold from there down - I'd say 80 degrees F or less. The border between hot and cold areas was instant -- no gradual cooling.
Anyway, any ideas what's going on? Does that sound like a plugged radiator? Have to break for SUPPER now.... will search online if I'm still awake after a BIG dessert. =OD
Bob
--

After the big dessert.... I spent some time searching and found these
helpful links....
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My 97 Aerostar is overheating (see my endless postings...) and I'm finally getting to checking it out. Not overheating bad, but I now have time to spend on it. Anyway....
I got the engine up to temperature -- about 2/3 of the gauge. Checked the air flow at the grill and it's getting plenty of air being pulled in. So that likely says the fan clutch is at least working.
Then I shut it off and removed the fan shroud. The fins were hot enough to burn for the top 6-7 inches all the way left and right, then very cold from there down - I'd say 80 degrees F or less. The border between hot and cold areas was instant -- no gradual cooling.
Anyway, any ideas what's going on? Does that sound like a plugged radiator? Have to break for SUPPER now.... will search online if I'm still awake after a BIG dessert. =OD
Bob
--

After the big dessert.... I spent some time searching and found these
helpful links....
  Click to see the full signature.
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My 97 Aerostar is overheating (see my endless postings...) and I'm finally getting to checking it out. Not overheating bad, but I now have time to spend on it. Anyway....
I got the engine up to temperature -- about 2/3 of the gauge. Checked the air flow at the grill and it's getting plenty of air being pulled in. So that likely says the fan clutch is at least working.
Then I shut it off and removed the fan shroud. The fins were hot enough to burn for the top 6-7 inches all the way left and right, then very cold from there down - I'd say 80 degrees F or less. The border between hot and cold areas was instant -- no gradual cooling.
Anyway, any ideas what's going on? Does that sound like a plugged radiator? Have to break for SUPPER now.... will search online if I'm still awake after a BIG dessert. =OD
Bob
--

After the big dessert.... I spent some time searching and found these
helpful links....
  Click to see the full signature.
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Ah so, said the blind man! That makes sense to me if there is only one or a few tubes snaking back and forth. The photos I saw looked like dozens of small tubes.

In the past the temp gauge was at around 60% of full scale. Now, it keeps creeping up slowly and eventually gets to full scale. If it gets close to full scale, I can put it in neutral, rev the engine and in 1 minute it's back to 60%. I have never let it get to full scale. Worse is when it's sitting still idling.

Not mounted transversely. Ford Aerostar. 3.0. Rear drive.

Coolant has brown color. I drained it a few months ago and it was opaque. After sitting a week, the solids settled out and liquid was clear greenish again. No oil floating on top.

Checked the thermostat first since that was easy. It was already fine but replaced anyway. No noise or wobbling pulley at the water pump.

At this point, the car is drivable, but I don't want to wait much longer. I was hoping to be able to flush out the radiator at home and make small repairs at home. I can swap out the radiator myself, but probably better off having the garage do it and check out everything.
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On Thu, 24 Apr 2014 11:07:34 -0800, "Guv Bob"

They ARE dozens of small tubes - all in parallel. There is no "single path" throuigh the rad. I have no idea what Jeff means by "A blockage anywhere is a blockage everywhere". I've been a mechanic since 1969, Licenced since 1971, and I've repaired and replaced countless rads.

before it gets too serious. Your rad is 60% plugged, according to your observation. They are under $100 for brand new rads from many aftermarket rad suppliers even in Canada - so likely $60-ish in the USA

Buy a new rad, flush out all the mud from the block and the heater core. Replace any "iffy" hoses, and enjoy the van for the summer. DO NOT allow it to seriously overheat, or you can scrap the truck,
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Ah so, said the blind man! That makes sense to me if there is only one or a few tubes snaking back and forth. The photos I saw looked like dozens of small tubes.
+++++++++++++
It does not matter how many tubes there are, water enters on the top or side and exits the bottom or opposite side. There absolutely are dozens of tubes, but this does not matter, and it means that you can have some number of tubes that are clogged, and the radiator will still work, that is, it will cool the engine.

In the past the temp gauge was at around 60% of full scale. Now, it keeps creeping up slowly and eventually gets to full scale. If it gets close to full scale, I can put it in neutral, rev the engine and in 1 minute it's back to 60%. I have never let it get to full scale. Worse is when it's sitting still idling.
++++++++++++++++++ That's bad. The overheating is bad. It might be slow, but it is still bad. The needle should never ever get to full scale, and if it does then you should shut the engine off immediately. Immediately, not in a few minutes or miles. Immediately.
Your description of revving the engine says that the viscous couple is failing. The job of the viscous couple is to physically couple the fan to the drive belt when the vehicle is not moving or isa moving slowly. A viscous couple (also called a fan clutch) is a device that's filled with a jelly-like material. If the couple gets hot, the jelly expands and the fan is locked to the water pump pulley and the fan belt. When the vehicle is not moving, the airflow over the radiator is very poor, the fan clutch causes the fan to forceably pull air through the radiator. The fan clutch wears out and the fan is driven purely by the friction coefficient of the viscous material -- the jelly stuff. At speed, the airflow is sufficient BECAUSE of the speed of the vehicle. The vehicle's motion is enough to push air through the radiator, so the fan clutch cools and allows the fan to be driven by nothing more than the act of the jelly rubbing on other nearby components. When the vehicle slows, the airflow is reduced, the fan clutch warms up, and the fan is physically driven by the belt.
Your fan clutch is toast if the heat rises when the vehicle goes slow -- stop-n-go traffic that is more stop than go -- and then the heat falls again when the traffic breaks free and you can go fast again -- fast is a sustained speed above about 30. If you drive along and all is well, then you slow down to a stop or crawl and the heat rises, then you can drive along again and all is well, this is EXACTLY the problem you have with a failed fan clutch -- or viscous couple.
You said that you rev the engine and this brings the heat down. You are speeding up the fan through an action that is similar to what the viscous couple is supposed to accomplish.

Not mounted transversely. Ford Aerostar. 3.0. Rear drive.

Coolant has brown color. I drained it a few months ago and it was opaque. After sitting a week, the solids settled out and liquid was clear greenish again. No oil floating on top.
++++++++++++++++++++ This is all good. If your coolant is ugly again, then you should invest in a professional flush. If you are able to remove the t-stat then you can connect your garden hose to the top hose and turn it on until the water flows clear out of the t-stat housing that has the t-stat removed. There are environmental issues in doing this that some will object to, just so you know. A smart guy would open the heater valve and flush the garden hose through it also. The color of the coolant does not indicate the ability to cool, it indicates the overall health of the system.
At the end of the flush, you desire a 50/50 mix of anti-freeze and water. This is not a hard ratio, but it is the desired one. 60/40 or 40/60 works okay, but heavy water exposes you to problems in freezing conditions. If you run the garden hose until the water comes out clear, then drain the radiator and add in pure anti freeze, the result will be very close to a 50/50 mix.
NEWSFLASH Making your own premix is far cheaper than buying it. Save an empty gallon coolant jug, and buy a full gallon of straight anti-freeze. Pour the anti-freeze into a bucket and then add a full bottle of water. Mix. Put half of the mix into the new bottle and the other hafl into the old bottle. You just made 2 gallons of 50/50 premix. (The next time you are at the auto parts store, check the prices of premix and straight coolant. The premix costs more than the straight coolant and you get less of the anti freeze -- half as much as a gallon of straight coolant.

Checked the thermostat first since that was easy. It was already fine but replaced anyway. No noise or wobbling pulley at the water pump.

At this point, the car is drivable, but I don't want to wait much longer. I was hoping to be able to flush out the radiator at home and make small repairs at home. I can swap out the radiator myself, but probably better off having the garage do it and check out everything.
++++++++++++++++++++++++++++++
With the additional information you gave, I do not think you need a radiator. You might benefit from a flush, but you certainly need a fan clutch (viscous couple). Since you have had the t-stat out, then you can take it out again -- be sure to use a new gasket when you put it back in -- and this will let you flush the cooling system at home. KEEP IN MIND THE OBJECTIONABLE NATURE OF FLUSHING COOLANT DOWN THE STREET MIGHT PISS THE NEIGHBORS OFF. If you flush the radiator in your driveway, be sure to dillute the mess you are sure to make.
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I'm not saying to NOT replace the radiator, I just don't know what you are looking at. If the radiator is the type where the coolant goes into the side instead of the top (coolant travels horizontally as opposed to vertically), then sediment can settle at the bottom and clog that row of tubes, then settle on the next row up and clog that row of tubes, and so on. Eventually you have half of a radiator, or less, and this is always a problem.
Because you said that the heat falls if you get more air to pass through the radiator -- you speed the car or rev the engine -- then my money is still on the viscous couple.
A radiator is cheap. Indeed, you can get a radiator from online sources such as Radiator Barn for $100-ish, it's cheaper to replace than to repair. Rock Auto is a good source for the fan clutch, and they might have your radiator. www.rockauto.com.
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On Thu, 24 Apr 2014 10:28:32 -0700, "Jeff Strickland"

You are forgetting, the Aerostar, like most relatively current vehicles, uses a CROSS FLOW rad. The bottom tubes will block first due to sediment. If it is hot at the top, and cold below, the rad is blocked badly. For the cost of having a rad "rodded out" today, you can buy a brand new aftermarket rad - and you are going to have to remove it either way. Remove it ONCE.

There has never been a transverse engine AEROSTAR. It is a rear wheel drive, old-school TRUCK.

Which a restricted radiator WILL do. Moderate overheating under light load in cool weather, which will turn into drastic overheating under load in hot weather, particularly at low speeds.

mechanic I ended up working on most of them

The fact that the top of the rad is hot and the rest cold would point towards a cooling problem

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Thanks Jeff & Clare. You guys are great instructors. I suspected the fan clutch just checking how it spins cold and hot and already have the new one on hand. Warranty replacement so no cost there.
I was expecting radiators to be more like $200-300, but if they are that cheap, replacing is definitely the way to go.
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On Thu, 24 Apr 2014 20:54:33 -0800, "Guv Bob"

an automotive mechanics instructor at both secondary school and trade level ------
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the new one on hand. Warranty replacement so no cost there.

By your postings, I'm not surprised. You have my highest respect. My experience is with instrumentation and control panels in process plants (power stations, water plants, etc.). Mostly DC, low level AC and fluid flow. I'm an expert at "holy smokes, what did I get into now!" situations. You can probably tell I over-research stuff and read everything I can before taking something apart. I learned from my dad long, long ago how to take things apart systematically -- and sometimes even put them back together again!
But, and this is a big butt... auto mechanics is a whole different ball game, especially these days where you can get to everything except what you need to work on. I would never tell anybody I was a mechanic. And the lovely wife will vouch for that - plus comment about my low level skills in carpentry and plumbing.
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On Fri, 25 Apr 2014 17:23:19 -0800, "Guv Bob"

Well, I grew up the son of a carpenter/electrician/farmer. I worked on the farm as a teenager, then did my mechanic's apprenticeship at a general repair garage/farm equipment dealer. During my highschool years and beyond I also repaired and rebuilt old tube radios Then I worked for a Toyota dealership and an AMC/Jeep/IHC truck dealer - then taught high school auto shop. Then I went to Africa and taught auto shop at trade school (Livingstone Trades Training Institute, Zambia), Came back and worked at a Canadian Tire shop, the industrial equipment, then ran service bays at 2 service stations, the service manager for Toyota dealership (same one). I took a correspondense course in microcomputers from NRI, then worked for a local computer manufacturer - putting CD ROMs on the network back before CD ROM was mainstream. After 5 years there I went off on my own in the computer service/IT business. For the last 14 years I've also been building an airplane, and all my life I've owned/worked on/enjoyed antique cars - and for several years I squeazed in competitive navigational rallying (as driver) at championship level. And raised two GREAT daughters with the help of my beautiful wife.
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Guv Bob wrote:

Radiator is junk. You're getting about 1/3 of it to cool the engine.
Since it is clogged I would also suspect the heater core is getting that way. First, order /buy a new radiator and hoses (if they originals they are due) New thermostat. New coolant. Two bottles of cooling system flush. Now start draining the system. Look over the heater core connections and disconnect the input line. Connect up a garden hose to that and disconnect the return line. Run the return into a bucket and turn on the water. The first gallon or so will be mostly coolant, after that you can just let it run till it's clear. Loop a hose across the heater connections on the engine. Remove the thermostat. Now add the cooling system flush and follow the directions. Once you're done, drain the system and flush the engine with water. Now swap out the radiator and hoses, install the new thermostat, reconnect the heater core fill the engine with new coolant.
Doing it this way should clean out the system. Most of the flushing chemicals are acids. If possible you don't want to run them through an older heater core, you could end up with a leak.
--
Steve W.

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What about throwing a couple of spoons full of automatic dishwasher detergent in the radiator, letting it run for few days and then draining & flushing it? Seems like that would get the oil & grease, without the acid that radiator flush products have.
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Guv Bob wrote:

Oil&grease are usually not the problem. It is the rust and scale from the water in the coolant that plugs things up. The acid breaks it free and dissolves it so it flushes out of the system. Only catch is that most heater cores are made of thin metal compared to the radiator, The acid could dissolve the one piece of scale covering the pinhole you don't know about...
--
Steve W.

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wrote:

It can also let scale loose that will travel to the heater core and block the smaller passages.
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What about bypassing the heater core and flushing the rest of the system with water with or without detergent? I'm hesitant to use the commercial flush since someone said it contains acid.
New radiator will be here this week. I went out to drain the radiator today, took the rad cap off and unscrewed the petcock all the way and nothing came out. I guess that pretty much tells the story.
I have to say though, that this is the original 1997 radiator and it had enough capacity to cool even with half the tubes blocked.
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Guv Bob wrote:

That is exactly what I suggested. Bypass the core (but flush it in reverse with clean water. Then flush the engine with the old rad. in place. Then when you swap the new one in flush the engine with clear water before you connect the new one just to make sure it's clean and you don't end up with any loose crud in the new rad.
--
Steve W.

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wrote:

Is it worthwhile putting a little detergent in the water?
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