Hi everyone, this is my first post here(and yes I did try a search first). I just purchased a 1991 cruiser that has 197k on it. When I purchased it I replaced the radiator and all the main hoses. I made sure that all the air was out of the system when it was refilled, and not leaking anywhere. I let it idle for almost 20 minutes and temp guage stayed at the halfway mark. The problem starts when I start driving. After just a short time of driving the needle shoots into the red right away. It also will overheat if I just keep it in park and put some revs into the engine. Other than that at idle she just stays normal. Anyways, thanks for listening and hopefully someone can help.
weird overheating problem
- Thread starter sccchiii
- Start date
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If it overheats at highway speeds, look into your water flow. Start with the thermostat- replace it if you haven't, and use a genuine Toyota part. Normally I'd suggest making sure the radiator isn't clogged with crap, but you say yours was replaced. Did you do a thorough flush of the system? Often 'green' coolant and Toyota 'red' don't play well together.
If it only overheats when you're moving relatively slowly or stopping often, look into the fan clutch and air flow. Check the obvious- is the front of the radiator blocked by debris? Maybe a plastic bag caught in the grill? Did you re-install the shroud? When the engine is hot, tapping the gas should produce a fair amount of noise from the fan pushing a lot of air. If you don't hear that with a hot-running truck, you probably need to replace or rebuild it. There are quite a few threads on the subject, do a search on it.
-Spike
If it only overheats when you're moving relatively slowly or stopping often, look into the fan clutch and air flow. Check the obvious- is the front of the radiator blocked by debris? Maybe a plastic bag caught in the grill? Did you re-install the shroud? When the engine is hot, tapping the gas should produce a fair amount of noise from the fan pushing a lot of air. If you don't hear that with a hot-running truck, you probably need to replace or rebuild it. There are quite a few threads on the subject, do a search on it.
-Spike
Scchhhlll,
Clarify what "fan" you're talking about and what you did to verify it. I'm thinking you're hearing the powerful electric fan that I think the 4.0L has to prevent vapor lock. WE're asking about the engine's primary fan and you should clarify what you did to verify that's operating correctly.
DougM
Clarify what "fan" you're talking about and what you did to verify it. I'm thinking you're hearing the powerful electric fan that I think the 4.0L has to prevent vapor lock. WE're asking about the engine's primary fan and you should clarify what you did to verify that's operating correctly.
DougM
- Thread starter
- #6
I'm talking about the main fan. It has a strong sound at start up. When I open the hood at normal operating temp it is pulling a lot of air through it. Is there any other way to test it? When the fan clutch went out in my pickup truck it did the opposite, started getting hot at traffic lights(idle) and would go back to normal temp once I started driving. I'm not saying that it's not the clutch, I just have never experienced a truck going 65mph on the freeway, stay really hot and need the primary fan to keep it cooled down. I would think that the airflow through the radiator at that speed would be able to keep it at normal temp, that's why I was looking for maybe another problem but maybe I should take another look.
Why did you replace the cooling sys components (radiator and hoses). Were you having heating problems or was it a pm? If it was hot to begin with, you did not fix your problem.
Check your thermostat or replace if you did not w the radiator/hoses. And stay w/ the green coolant for the 91, that is what it came with... Do not rely on your overfill bottle to determine coolant level. Open up the radiator and make sure she is full, and run the heat on full to make sure you have no air lock....
Check your thermostat or replace if you did not w the radiator/hoses. And stay w/ the green coolant for the 91, that is what it came with... Do not rely on your overfill bottle to determine coolant level. Open up the radiator and make sure she is full, and run the heat on full to make sure you have no air lock....
- Thread starter
- #8
I replaced the radiator as pm. The only concern I have now is that the Toyota dealership parts guys told me I could only use the red Toyota antifreeze with my engine!? Do I need to flush the red stuff out and change to green or is the damage already done?
Back to the original problem, would a stuck closed thermostat lead to the overheating condition I have now?
Back to the original problem, would a stuck closed thermostat lead to the overheating condition I have now?
You can stick w/ the red, I don't think it will damage it. I just hoped you flushed the system well as the two do not like to be mixed. It will eventually form a brown funk in the cooling system when mixed.
If you are certain your cooling fan is in good shape, the thermostat, stuck partially or fully, or blocked w/ trash could certainly be part of your overheating problem, and check your coolant levels...My experience is it always took a few good drives after flushes, running the heat, to get rid of all the air in the system...
If you are certain your cooling fan is in good shape, the thermostat, stuck partially or fully, or blocked w/ trash could certainly be part of your overheating problem, and check your coolant levels...My experience is it always took a few good drives after flushes, running the heat, to get rid of all the air in the system...
The 3FE t-stat is easy to get to and test. I would start there if you are sure the rad and fan are working properly.
It takes very little effort to pop a new one on in there, just be sure to seal it properly when you reassemble...little bugger likes to leak unless you torque it properly with the right gasket.
It takes very little effort to pop a new one on in there, just be sure to seal it properly when you reassemble...little bugger likes to leak unless you torque it properly with the right gasket.
You are correct, the symptoms you describe suggest a water flow problem, not air flow. T-stat is the most likely culprit.
-Spike
Replace the thermostat.
its easy its cheap and most likely the issue,
if your new radiator did not come with a new cap buy one of those too. the cap is cheap and will lead to fluid loss at speed and at idle, once your low on juice doesnt matter how much air you flow it will overheat..
Dave
its easy its cheap and most likely the issue,
if your new radiator did not come with a new cap buy one of those too. the cap is cheap and will lead to fluid loss at speed and at idle, once your low on juice doesnt matter how much air you flow it will overheat..
Dave
- Thread starter
- #14
Thanks for everyone's help. It was the thermostat. My friend had a infared temp guage (neat tool) that we used to scope the temp of the thermostat housing and it was a lot hotter than the rest of the system(hoses, radiator, etc) so it was pretty clear it was stuck closed. I was an idiot for not changing such a simple part when I had the system apart for the new radiator. Oh well, live and learn.
