Question1983 Celica GT (no S). 22R-E 4 cyl, 2.4 liter, fuel injection, manual trans. 109k miles if one were to believe the odometer. I do. I have replaced the following in order to resolve this ongoing problem:
*water pump
*t-stat (twice, 1st one was tested the other day in boiling water w/ thermometer. At 200 degrees Farenheit, it was just barely opening.)
*temperature sending unit
*both rad hoses
*coolant (currently 60/40 mix coolant/H2O)
*fan clutch
None of the repairs above (or diagnosis below) have changed the nature of the problem at all.
In addition to the replacement of these components, I also ran a compression test today. Results of each Cylinder:
1) 150psi
2) 120psi
3) 150psi
4) 165psi
Standard is 178 or so. Minimum is 142. Maximum difference is 14psi. Per Hayes manual, I added a squirt of oil and tested again, this time getting higher psi readings. This indicates bad piston rings, said the manual. It did not say that it indicates a warped head which, I've heard, may cause overheating.
Also worth noting are the conditions under which the overheating occurs. I drive about 40-45 minutes to work and about 50 min back. There are no numbers on my temp gauge at the dashboard but let's pretend that it's numbered 1-10, 1=cold, 10=RED. I live 3 miles (at 45-55mph) from the interstate. By the time I hit the on-ramp, I'm at 5 (ideal). 15 minutes later at 60-65mph, I am typically at 7.5. I can stay there if I don't push it to go any faster. If I do go faster (70-80) the needle will go closer to the red.
When I come home in the evening, it gets up to 7.5/8, but when I hit the off-ramp and start driving at lower speeds (45-55), the temp will lower slightly to 6.5 or 7. If I have errands to run I can expect the temp to stay in this range throughout the trek.
One more thing, I haven't replaced or flushed the radiator yet. I don't have the funds to replace it and my dad, who is helping me with these repairs, doesn't believe that the radiator would benefit from replacing the coolant with water & dishwasher detergent and running to operating temperature to flush it out. I am in favor of doing this if only to eliminate the radiator as suspect. We did run tap water from the garden hose through it and it seemed to flow without restriction. But when I last drove it, I got it a bit hotter than usual (8.5) because I went a little faster than usual and when I checked the overflow jug, there were black particles sitting in the bottom with the coolant. They did not float. I probably need more diagnosis but I am hoping you can take these clues and point me in the right direction. Should I pursue the "warped head" lead, or should I replace/flush the radiator? In any case, my dad wants to remove the t-stat tomorrow & replace with a paper gasket. I live in Florida. It shouldn't cause any problems to not have a t-stat in this climate, right?
AnswerThere are just about only two more possible problems ,the radiator and the headgasket, there is a simple chemical test that can be done to check for the headgasket leak, most repair shops can do this to eliminate the headgasket as the problem before replacing anymore parts, you may be able to get the test kit at one of the larger auto supply stores, just follow the instructions. If you want to address the radiator issue first I suggest removing the radiator and taking it to a radiator shop and have it rodded out, this means that the radiator is taken apart and the core cleaned out, and if necessary replaced, removing the thermostat is not a solution it will still overheat but maybe just take a little longer. Running a water hose through the radiator and checking the flow is inconclusive because if the radiator was partially clogged the flow will still look the same, the water will not circulate through the entire core and this may very well be the problem.
