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Discussion Starter · #1 · (Edited)
I've got a 1990 Corolla that has been running warmer than usual for the past couple of months. I'm gonna dive into her this weekend so thought I'd seek some advice first.

Normally the temp guage is at roughly 1/3 but lately it runs consistently at 1/2 or slightly above that. No coolant leaks - radiator is always full - no fan trouble - runs warm at freeway speeds as well as in city traffic. Radiator was replaced a couple of years ago due to a leak in the old one. Radiator cap was replaced a few months ago after wife noticed it getting warm and we discovered the coolant was leaking out past the cap.

Second symptom: Pinging. It pings when accelerating, which it only used to do in summer running 87 octane with the a/c on. Now it does it all the time. I'm suspecting it's running lean which is also causing the overheating. Either that or the timing is too far advanced. But aren't the timing and the fuel mixture controlled by the computer? How are those things adjusted? No manual - I know, I know.....I need one.

Water pump - anyone know if the impeller has metal fins, or are they rubber? I'm wondering if some fins could have broken resulting in less efficient circulation of the coolant. Or maybe the thermostat stuck partially open?

The old girl's been a great vehicle so this kind of trouble is unusual. She's got 232k on her, always starts, still has plenty of power, and doesn't smoke at all.
 

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The impeller fins on the OEM pump are metal. On my 1990, the timing is not controlled by the computer but is adjusted by moving the distributor, the old fashioned way.
 

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tashirosgt said:
The impeller fins on the OEM pump are metal. On my 1990, the timing is not controlled by the computer but is adjusted by moving the distributor, the old fashioned way.
that's to get base timing when jumpered....... the ecu & ignitor still advance and retard the timing

try changing the t-stat for the running warm issue.....
 

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ae101 levin&trueno
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Even if you are running lean it won't overheat a healthy cooling system, I've seen quite a few melted pistons which didn't move the temp gauge at all.

Replace your thermostat, remove your radiator and flush it. Put in new coolant.
 

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Discussion Starter · #7 ·
Thanks for the replies. Gives me an idea on which way to go.

retiredat44 - best I can remember, the radiator is about 3 years old. It's a two-row that previously worked great - in fact the car almost seemed to run too cold this time of year. Also - if your handle is true, I'm very jealous!

punter - When I replaced the radiator cap a few months ago I also drained the radiator and put fresh coolant in it, however I did not flush the system. I think I'll start with the following this weekend:

- Remove radiator, check for dirt blocking airflow on rad and a/c condenser.
- Flush system
- Replace thermostat
- Might as well replace the hoses while I'm at it
- Check timing

I'll try that first. If it still runs warm I'll look at the water pump.

We've put 110k miles on this car since we've owned it and have never replaced the thermostat or any of the hoses, so I guess it's due.
 

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Discussion Starter · #9 ·
Success!

punter said:
Replace your thermostat, remove your radiator and flush it. Put in new coolant.
Bingo! Thanks punter, that did the trick.

I pulled the radiator, flushed it out, pressure sprayed the fins on both the radiator and a/c condenser (both were somewhat dirty), flushed the head, installed new thermostat and hoses, and refilled with fresh coolant. It was getting dark outside (no garage) so I didn't have a chance to check the timing. Decided to take it for a test drive to see if there was any improvement, and the ol girl's back to her old self! Temp guage is at 1/3, and the pinging is gone! I guess it had been running warm enough to affect combustion. Glad that's fixed, sure wouldn't want to hurt that engine. At 232k, it's just barely broke in. :)
 

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ghost_ryder35 said:
glad to hear it man. maybe I'll flush my coolant again sometime this next weekend or so :) can never flush too much :) :) :):D
As long as your radiator fan is working you will be fine. :lol: :lol:
 
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