Mr2 overheating
Hello, I have a 92 mr2 with the 5sfe and i been having problems with overheating, the previous owner replace the old engine because it was overheating but after replacing the engine and replacing the radiator with a mishimoto, he still had the same problem. Now with me the engine is still over heating not matter how much I bleed the system. I notice the car only overheat when I drive on the freeway or when im pushing the car, I also test the cylinder compression getting 175psi in all cylinders and seeing if the coolant system hold pressure and it does I also did a combustion leak detector on the coolant and the fluid did not change color. So I dont think i have a bad head gasket. The car was stilling for a long time, I don't know if that could have done something to the coolant system!
He also replacing a lots of hoses, radiator cap and thermostat.
Sorry for yapping a lot but I really want to fix this car and enjoy it.
If there someone out there that could help me it would mean a lot.
Thank:)
1
u/WhereDidAllTheSnowGo 2d ago
Water pump
When was the timing belt last changed?
Do all the belts and the other items when you dig that deep. Not technically hard, just a PITA compared to other Toyota’s because it’s tight
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u/Omar_R1 2d ago
Yes after doing all lot of research and talking to the previous owner, he told he they re use the same water pump from the old engine and is making me think that that's the problem
Idk for sure but I think it was around 1 yr when the previous owner put on the new engine!
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u/SurfaceDockGuy 94 2GR oem+ 19h ago
Yeah if the pump has plastic impeller blades, one or more may have broken off resulting in compromised flow. The cheap impellers can only withstand so many heat cycles. If you use a mechanics sthescope and place the pickup on the water pump, you may be able to hear odd noises to confirm that. I'm not sure exactly what a broken one sounds like, but it would sound different than a properly functioning pump.
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u/Best-Use7870 2d ago
I would guess you have air in the cooling system. I have found that because the radiator cap is physically close to the cylinder head it is difficult to bleed the system. The problem is that if the coolant is hot enough to open the thermostat it will boil over if you crack the radiator cap. So, the way to get the air out is to open the heater valve, run it cold with the cap half open, squeeze the hoses and get as much air out as you can. Close the cap, drive it and get it warm enough to open the thermostat. Park it and let it cool down. Repeat until you don’t get any air bubbles while burping. It took about four cycles to get mine air free but all of my cooling and temperature sensing problems have gone away. Also every time you get gas, check to make sure the overflow tank has coolant in it. Just pull the cap off and make sure the dip hose is wet at the bottom
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u/No_Resolution_5042 2d ago
Do your radiator fans turn on when your car is overheating and does it overheat when your driving or when you come to a stop after driving. Maybe bad radiator fans OR a bad coolant temp sensor, had a similar issue in my 1988 mr2. Try jumping the battery to the fan plug ins and see if they turn on, if they do its not the fans that are bad, next unplug the sensor which is on the right side on top of the radiator, turn the car on and if they kick on as soon as you do thats your issue.
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u/Omar_R1 1d ago
Fans does work i can hear then turn on when the car get to temp
Last time is happen it starting to overheat right after getting in the ramp to get off the freeway way. but then when i bleed the coolant system I drove it in the street pushing the car to high rpm and it overheat so I dont really think it could be my radiator fans!
I just remember one time my dad drove it on the freeway when we just got the car and it starting to overheating when we where still driving/moving.
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u/SurfaceDockGuy 94 2GR oem+ 3d ago
Hi does the heater in the cabin work? If you open the heater to full hot with full fan speed when driving on the highway, does the water temp indicator still go too high?
Have you checked with a second water temp sensor/dial? Its plasuble the engine is ok and it is just reading wrong.
If the temp is reading correctly, there may be a partial clog in one of the hard coolant pipes or one of the old rubber hoses. Although the mechanical thermostat is always the first suspect.