'89 Corolla cooling problem when in overdrive?

Hi all,
Happy Presidents' Day weekend!
Hoping the gurus on this group can help me with another issue on my
'89 Corolla SR5.
It has 147k miles, carbureted 2AF, and 4-speed automatic with
overdrive. It runs fine, gets 36mpg on the highway. It's on its
original radiator and I do get the coolant flushed about every 2 years/
10k miles. The coolant level looks good and the coolant level looks
right. The exterior of the radiator looks clean and looks good. The
grille, which is quite small to begin with in a Corolla SR5, is
unobstructed. The water pump is original from 1989.
The car normally "likes" to run at 40% of max temp, which is what I
notice with other cars too. When I'm on the highway at 60-70mph
though, when it's between 2400-2800 rpm, the temp often creeps to
about 75% of max temp, and then either the cooling fan will kick in or
I'll get to a downhill area and the temp will fall. After it goes
back to 40% of max temp, it may reach 75% of max temp in about 5
minutes. Between 60-70 mph, the car doesn't have a lot of power,
understandably (2500 rpm in a 1.6-liter engine) but it doesn't feel
like it's lugging or struggling either. On purely level ground it
probably is usually at 50% of max temp.
NOW, if I turn overdrive off, say at 65 mph, then the RPMs rise by
1000 and the temp immediately falls to 40% of max operating temp
within 5 seconds. Likewise, if I drive at 75-80 mph, the car is at
3500-4000 RPMs and also will run at 40% of max operating temp. If I
floor the car for quick acceleration, it'll also downshift,
accelerate, and the engine temp drops quickly.

The thermostat and fan switch were all replaced in the past few years,
and the car operates at 40% of max temp under low-strain conditions
like local driving, so I don't believe either of these is faulty.

Unfortunately I didn't pay very close attention to engine temp before
so can't remember how long this has been happening. I don't remember
it was happening when I bought the car back in '99. It may have been
this way for a year or more, I just don't know.

Questions:
1. is it bad that the engine temp is reaching 75% of max temp if I
drive between 60-70mph in overdrive? Or is this normal? I worry that
the engine isn't supposed to be above 40% of max temp for too much
time. Also, I worry that cooling fans aren't meant to be kicking in
every 5-10 minutes, and that the fan could easily fail if it needs to
do so.
2. given that the engine temp is cooler when the engine's revving
higher, I'd have to conclude this is because the water pump is
spinning faster and therefore circulating more fluid when the engine's
RPMs are faster. When you see this situation, where the temp's high
in overdrive, does this mean:
a. don't worry about it?
b. get a new water pump? ($$$)
c. get the radiator "power flushed"? (don't object but am always a
little leery of places that want to sell "power flushes")
d. get a new radiator? ($$$)
e. add more coolant though the coolant level looks ok?

Please let me know what you think,
John

[email]johnyang97@yahoo.com[/email] wrote:[color=blue]
> Hi all,
> Happy Presidents' Day weekend!
> Hoping the gurus on this group can help me with another issue on my
> '89 Corolla SR5.
> It has 147k miles, carbureted 2AF, and 4-speed automatic with
> overdrive. It runs fine, gets 36mpg on the highway. It's on its
> original radiator and I do get the coolant flushed about every 2 years/
> 10k miles. The coolant level looks good and the coolant level looks
> right. The exterior of the radiator looks clean and looks good. The
> grille, which is quite small to begin with in a Corolla SR5, is
> unobstructed. The water pump is original from 1989.
> The car normally "likes" to run at 40% of max temp, which is what I
> notice with other cars too. When I'm on the highway at 60-70mph
> though, when it's between 2400-2800 rpm, the temp often creeps to
> about 75% of max temp, and then either the cooling fan will kick in or
> I'll get to a downhill area and the temp will fall. After it goes
> back to 40% of max temp, it may reach 75% of max temp in about 5
> minutes. Between 60-70 mph, the car doesn't have a lot of power,
> understandably (2500 rpm in a 1.6-liter engine) but it doesn't feel
> like it's lugging or struggling either. On purely level ground it
> probably is usually at 50% of max temp.
> NOW, if I turn overdrive off, say at 65 mph, then the RPMs rise by
> 1000 and the temp immediately falls to 40% of max operating temp
> within 5 seconds. Likewise, if I drive at 75-80 mph, the car is at
> 3500-4000 RPMs and also will run at 40% of max operating temp. If I
> floor the car for quick acceleration, it'll also downshift,
> accelerate, and the engine temp drops quickly.
>
> The thermostat and fan switch were all replaced in the past few years,
> and the car operates at 40% of max temp under low-strain conditions
> like local driving, so I don't believe either of these is faulty.
>
> Unfortunately I didn't pay very close attention to engine temp before
> so can't remember how long this has been happening. I don't remember
> it was happening when I bought the car back in '99. It may have been
> this way for a year or more, I just don't know.
>
> Questions:
> 1. is it bad that the engine temp is reaching 75% of max temp if I
> drive between 60-70mph in overdrive? Or is this normal? I worry that
> the engine isn't supposed to be above 40% of max temp for too much
> time. Also, I worry that cooling fans aren't meant to be kicking in
> every 5-10 minutes, and that the fan could easily fail if it needs to
> do so.
> 2. given that the engine temp is cooler when the engine's revving
> higher, I'd have to conclude this is because the water pump is
> spinning faster and therefore circulating more fluid when the engine's
> RPMs are faster. When you see this situation, where the temp's high
> in overdrive, does this mean:
> a. don't worry about it?
> b. get a new water pump? ($$$)
> c. get the radiator "power flushed"? (don't object but am always a
> little leery of places that want to sell "power flushes")
> d. get a new radiator? ($$$)
> e. add more coolant though the coolant level looks ok?
>
> Please let me know what you think,
> John
>[/color]
IMHO you are describing a coolant system flow problem. Increased RPM's
equate to a reduced temperature. I would say it's probably not the pump
since you are experiencing normal temperatures except for a low RPM,
high load condition, the fan cycling on and off. I would remove the
radiator and take it to a radiator shop and have it "boiled out". It is
a better method than just a "power flush". They will check the entire
radiator's function. A radiator that old may have many tubes blocked /
damaged, that will definitely reduce flow and cooling capacity, and you
may have to have it re-cored or replaced. The blockage can occur very
slowly and lead to your symptoms. Power flushing done at your local oil
change shop usually does not include a flow check. Your heater core may
be experiencing the same blockage as well. If you have an old or
original cap, I would replace it as well. Good luck.

On Sun, 18 Feb 2007 18:41:49 -0800, johnyang97 wrote:
[color=blue]
> Hey there!
>[color=green]
>> rock-solid on the temp gauge. Have you replaced the thermostat, and did
>> you use a Genuine Toyota? I noticed with my Mazda that the temp goes up
>> to halfway before settling back, and it didn't do this before I replaced
>> the thermostat.[/color]
>
> The thermostat was replaced by my mechanic about 3 years/15k miles ago,
> likely using a non-OEM part. The sense I get from the temp gauge is that
> the car does try to maintain 40% max temp, so the thermostat is probably
> working ok.
>
> About 5 years ago my buddy and I drove the Corolla up Mount Washington in
> New Hampshire (highest peak in the Northeast) and back then I remember the
> temp gauge would hit about 75% max before the cooling fan kicked in.
> Since we were climbing up extremely steep grades I didn't think anything
> of the temp. Unfortunately, I forget how the temp behaved when on the
> highway.
>[color=green]
>> It sounds like you've done a good job maintaining the cooling system.
>> But you didn't say if you have replaced the water pump. If you haven't
>> changed the timing belt at 120,000 or so, you may be due for a belt, and
>> the water pump is another 45 minutes labor and ~$100 for an OEM pump.
>> Also, power flushing the radiator isn't a bad thing like a tranny; it
>> can clear a lot of gunk out of the bottom of the radiator.[/color]
>
> The timing belt was replaced by the first owner in '97 when the car had
> 90k miles. He didn't replace the water pump. When I bought the car
> (1999, 94k miles), I fretted about the water pump for a long time,
> worrying it would fail soon. I called some local shops that told me
> something like $400 to do the timing belt, $400 extra to do the water
> pump-- they said it wasn't an overlapping job. Anyways I ended up doing
> nothing, not knowing how long the car would last. Right now I'm kind of
> trying to avoid sinking a lot more $$$ into the car since I just did so
> last year replacing a lot of worn-out parts to keep the car in perfect
> shape. For now I think I'll just flush the coolant myself since it's
> cheap to do this as a first step, and will see how the temp gauge behaves.
> In an IDEAL world I'd replace the waterpump myself, but unfortunately I
> don't have the skills or tools to do it.
>[color=green]
>> (Um, those are cool cars, BTW!)[/color]
>
> Took another 250 mile drive today-- temp still behaving the same-- drops
> instantly if I downshift (the automatic) and raise the engine RPM. With
> the heat on even just a bit the temp gauge is always 40% max, but I can't
> keep the heat on year-round obviously.
>
> The car ran and rode smooth, solid, beautifully as always. Has
> surprisingly good pull from 50-75mph in 3rd gear. The transmission is
> tight and flawless too. Cruises very quietly on the highway. It's one of
> the smoothest cars (of any size or age) I've ever driven. The car spent
> most of its life in Los Angeles, and afterwards garaged in the Northeast
> (now I live somewhere where it's too expensive to have it garaged, so it's
> been parked outside for a couple years unfortunately-- as per my other
> post re. that cracked windshield). The body and paint are great and better
> than some of the 2-year-old cars I see out there, and mechanics are
> shocked when they see what good shape it's in.
> Serious question-- would you or someone you know be interested in owning
> it someday? I may sell it within the next 4 months, or next year,
> depending upon my parking situation. My guess is book value is around
> $1000 and since it looks/runs great I might squeeze $1500 out of someone
> out there. The car is much, much too nice to be a beater, and I'm loathe
> to sell it to someone who's going to abuse it and drive it into the ground
> without maintaining it, but that is what people looking for $1000 cars do
> with $1000 cars. I'd rather sell it for less money to someone who would
> take care of it, but how do I accomplish this? There's no Toyota museum
> out there as far as I know, otherwise if they needed a Corolla SR5, I'd
> donate mine there so that it could live forever!
>
> Anyways, my goal is for the car to be well taken care of and well-used by
> whoever owns it next-- if anyone has ideas how I can do this, let me know.
> The problem with my keeping it indefinitely is that parking spaces cost
> big $$$ in Boston so keeping an extra car costs a ton.
>
> Take care!
> John[/color]


Well, you could ALWAYS leave it with me in Greenfield... ;)

This is an interesting problem and similar to one I had with a Plymouth
Grand Voyager.

When the engine was revving, I had heat...when it went into OD, I didn't.
I took out the waterpump, and it was fine (pump was outboard of the
engine).But I broke 3 bolts trying to get it out, and since the engine was
in sad shape anyway, I scrapped it...