Post by Guv BobMy 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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After the big dessert.... I spent some time searching and found these helpful links....
Cooling System TS
http://youtu.be/MrBI1hRTgx4
1 - Clean Coolant?
2 - Radiator Debris?
3 - Leaks?
4 - Air Burp?
5 - Lower Radiator Hose Spring?
6 - Electric Fan?
7 - Thermostat?
8 - Water Pump?
9 - Fan Clutch?
Rodding out a radiator
http://youtu.be/c5Ghuq6habE
Good video showing inside & cross-section of radiator
http://youtu.be/A65613TaWYw
Practical and well-done radiator cleaning video
http://youtu.be/p66bxOH9q68
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I haven't found a sketch showing the inside of this particular radiator, but
if it's like others, I'm guess there's a large blockage mid-way down either
the inlet or outlet side. I can't imagine half of the cooling tubes being
blocked or the whole tank being half full of sludge. Anyone have an idea
how to try and clear it? I'm hesitant to use any chemicals, no knowing what
is causing the blockage. I'm not able to do a pressure flush under the
shade tree.
++++++++++++++++++++++++
Water enters the radiator from the top hose, and exits the radiator from the
bottom hose. A blockage anywhere is a blockage everywhere. That is, there is
no blockage that is on the inlet side or on the outlet side, there is only a
blockage. This is always true because no matter the water level, there is
always water at the bottom even if there is no water at the top.
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.
Post by Guv BobYou said the car is overheating, then you said it isn't overheating bad. I'm
not sure what theat means. How do you know it is overheating? What makes you
think it is overheating?
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.
Post by Guv BobIf your engine is transverse mounted (sideways) then you do not have a fan
clutch because the fan is driven electrically.
Not mounted transversely. Ford Aerostar. 3.0. Rear drive.
Post by Guv BobCoolant cleanliness, or the lack of it, has no bearing on how well it cools.
It tells you more about the general health of the system, but not the
efficiency of it. Having said that, very dirty coolant means there is much
corrosion, and this is a bad sign. The coolant does not cool less, but the
corrosion shows that the system might be clogged.
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.
Post by Guv BobWater pump or t-stat issues are the leading cause of cooling system issues.
But these components should cause dramatic overheating troubles, not
troubles that can be described as, "not bad."
Checked the thermostat first since that was easy. It was already fine but
replaced anyway. No noise or wobbling pulley at the water pump.
Post by Guv BobPersonally, you appear to be throwing stuff against the wall to see what
sticks. Your testing and theories have not uncovered any indication of
overheating. Well, not any that I have seen.
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.