Overheating - 2 mechanics failed to resolve - Toyota Nation Forum : Toyota Car and Truck Forums

steve4king · 11-16-2010, 10:52 PM

Some history: 1994 Celica GT
So, after going to a couple of mechanics out of laziness, I've decided to figure this one out myself.

Last year my water pump started leaking, I took it to a mechanic who replaced the pump.
Not long after my car started overheating again. It no longer retains any pressure when it's hot.

I took it to another mechanic who said I needed to replace the rad cap.. and flush would probably fix it.. I was skeptical, but he replaced the thermostat as well and suggested I replace the radiator soon.

The car seemed OK for a while(2months) but then the radiator developed a crack in the upper plastic section and started leaking.

I replaced the radiator last night. I drove the car to work and after I parked I noticed that although the top hose and top of the radiator was hot, the radiator fins, bottom of the radiator and bottom hose were still cold.

I'm guessing this situation existed before I replaced the radiator.. but since I didn't check I can't be sure.

The heater DOES work.. (that means the water pump is working right?)

Any ideas?

Bitter · 11-17-2010, 07:22 AM

air pocket is probable, bleed the cooling system of air. google how.

steve4king · 11-17-2010, 04:00 PM

Thanks Bitter,
I read up on that a bit ago (need to buy some wheel ramps or jack-stands for the front I guess), but I thought it improbable that both mechanics would have failed to bleed it properly. Is there no air bleed on the 94 Celica GT near the water pump as some cars have?

Bitter · 11-17-2010, 07:21 PM

no air bleed I'm aware of, you don't need ramps really. just run the car with the cap off adding coolant as needed till the thermostat opens (heat turned on), top radiator up, put cap on, top reservoir, wait for fans to come on, let it cool overnight, add coolant as needed and test drive.

its possible both missed an air pocket, depends how good they are.

steve4king · 11-17-2010, 08:43 PM

I've done that several times now.

Open the Rad Cap while the car is idling, squeezing the two hoses to force some movement of fluid.

Yesterday I parked on a slight hill (to put the radiator higher than the engine) and let it idle for a good 25 minutes.

The top of the radiator was quite hot, the thermometer in the car showed at the center line. (I expect the thermostat would open a little below center)

Fans were spinning, bottom of the radiator was cold and I could see no flow occurring below the rad cap.

***MR2Jedi*** · 11-18-2010, 02:17 PM

Quote:

Originally Posted by steve4king

I've done that several times now.

Open the Rad Cap while the car is idling, squeezing the two hoses to force some movement of fluid.

Yesterday I parked on a slight hill (to put the radiator higher than the engine) and let it idle for a good 25 minutes.

The top of the radiator was quite hot, the thermometer in the car showed at the center line. (I expect the thermostat would open a little below center)

Fans were spinning, bottom of the radiator was cold and I could see no flow occurring below the rad cap.

Sounds like a blockage somewhere then.

Ace2424 · 11-18-2010, 02:53 PM

Are you getting hot air? I am almost thinking there may be a blockage in the heater core or near that area. Any smells or leaks?

steve4king · 11-18-2010, 05:23 PM

Yeah, I'm kinda worried about a blockage.. but not in the heater core.. heater works fine. I assumed I had a blockage in the radiator but replacing that did not resolve.

I'm planning to drain the system tonight, remove the thermostat and refill and try running without that to see if it circulates..

If not then maybe I should try pushing water through with a garden hose.. Is there any risk to that?

No leaks currently other than than around the overflow tube which was mis-shapen out of the box. I'll need to hit it with some sand paper and that will be resolved.

***MR2Jedi*** · 11-18-2010, 05:45 PM

No, hose won't hurt anything.
Open the drain **** at the bottom of rad, and see if you get flow from there as you fill with hose.

Ace2424 · 11-18-2010, 08:37 PM

Flushing everything with a hose is what they recommend too. Just make sure it's not below freezing out.

fkamp · 11-20-2010, 05:39 AM

Quote:

Originally Posted by steve4king

Thanks Bitter,
I read up on that a bit ago (need to buy some wheel ramps or jack-stands for the front I guess), but I thought it improbable that both mechanics would have failed to bleed it properly. Is there no air bleed on the 94 Celica GT near the water pump as some cars have?

On both my 4afe's (maybe also on your 5sfe) The thermostat from toyota has a "jiggle valve" to help release trapped air. See http://www.toyotavanpeople.com/forum...php?f=2&t=5052 I was never able to find one at the local parts stores. I didn't want to pay the premium for one from the dealer so I drilled a small hole in the flange of the thermostat and installed it per the shop manual. Never had any trouble with bleeding them.

Hope this helps

Don

Bitter · 11-20-2010, 08:18 AM

the toyota one isn't really any more than a stant super-stat which has a jiggle valve usually. heck, I think I paid $11 for my dealer t-stat.

steve4king · 11-22-2010, 12:35 PM

After flushing with the hose and replacing the TS, the car appears to be running fine.
I still hear a sloshing noise when I take off.. so I dunno if that means I've still got air trapped in the engine somewhere.

Also, I must have hooked something up incorrectly because both rad fans come on the moment I turn off my car and appear to run as long as the car is on. (Rather than waiting for the car to get warm first, then staying on 30 seconds after I turn off the car)

Bitter · 11-22-2010, 09:09 PM

is the engine coolant temp sensor plugged in? what is the OHM reading? when thats bad it can cause the fans to run on and on...or the fan switch. I can't remember. I think there may be 3 things...sender, sensor, and switch.

steve4king · 11-23-2010, 03:19 PM

I'll check that. (wouldn't that cause the needle in the car to stay cold or hot all the time though? That seems fine)

The Jiggle Valve.. I'm guessing that was the problem from the get-go.

The guy that replaced my pump also replaced the Thermostat and didn't use a thermostat with such a valve.

Theory:
The guy that replaced my pump did not replace the Thermostat which left me with a stuck thermostat. The guy that replaced the cap and thermostat didn't use a thermostat with such a valve. There was air trapped causing an incorrect temp reading.(I could hear sloshing when accelerating from a stop sometimes) The top of the rad got too hot causing the rad to crack. I replaced the Rad and thermostat.. but didn't know about the jiggle valve and used OEM without.

Solution:
I'm considering popping out the thermostat and just drilling a tiny hole in it.. do any of you think a 1/16" hole could cause any negative side-effects? Shouldn't be enough flow to keep the car from warming up.. (I'll check to see if the local parts store has one with a jiggle valve first)

Ideas? critiques?