I have a 2004 Toyota Corolla, which currently has 101,xxx miles on it. I want to replace the radiator hoses, which are original and now feel old and squishy. I also want to replace the thermostat at this time, since it’s never been changed.
According to my Haynes book, it is necessary to remove the alternator in order to change the lower hose, though I fail to see how that provides any advantage unless I was to also discharge the A/C and remove the compressor (which I’d rather not do). It appears that I can remove the splash shield in that area, though I’d probably have to remove the cooling fan in order to have enough space to work.
The directions for removing the upper hose and thermostat body are even weaker, as they skip from draining the coolant and removing the accessory belt and alternator to removing the bolts on the thermostat body. Obviously, I need to get access to this area in order to do that. Am I supposed to remove the throttle body and associated wiring harnesses?
I am sure that someone here has either done this procedure on their own (similar) car, or done it for a customer, and I’m sure there’s an easier way. Any ideas?
No offense… but maybe taking it to a shop might be the trick here?
For a long time I’ve enjoyrd working on my cars… but I avoid messing with anything involving fluids. Meaning oil,coolant, etc. If you’re already going to have to disassemble these various things, do you also have a plan for both capturing and disposing of the coolant?
I’ll let Corolla owners add their comments, but I just want to say- do NOT mess with the a/c. Don’t disconnect anything, don’t move the compressor, nothing. There’s gotta be a way to do it without that.
Never had to replace hoses and thermostat in my 20 year old Corolla.I just do a basic flush of the cooling system and replace the long life coolant when its required.
I was going to do mine in my Pontiac. It had access issues with the lower hose. I put it off so long that I finally just had the shop do it all-hoses, thermostat, fluid change. I don’t remember the cost anymore but it was quite reasonable. So I have a brand new hose clamp tool that I have never used.
I would rather not take the car to a shop if I can avoid it. I generally only pay a professional mechanic to work on my cars if the work to be done requires special tools that I don’t have, such as a lift, factory scan tool, etc., or if diagnostic expertise is required.
I already bought the parts, and would like to do this myself over the weekend. The issue is not that I can’t remove the throttle body, cooling fan, or even the A/C compressor–it’s that I’d rather not.
I am an HVAC repairman, so I understand how to properly recover the refrigerant into a disposal tank, pressure-test, evacuate, and recharge the system, however that adds some additional cost: a new accumulator-drier, a new O-ring set, and the cost of refrigerant. Similarly, if I have to remove the throttle body, that adds the cost of a new gasket.
I was hoping somebody here knew the manufacturer-recommended procedure for replacing the radiator hoses and thermostat, which surely must be easier than what I have mentioned, but even if not, adding the cost of an accumulator-drier, O-ring set, R134a, and a throttle body gasket still is a bargain compared to paying a shop several hundred to do this job.
I seem to recall that any work on the front of the engine required removing the motor mount and fender liner and once those were out of the way everything seemed kind of obvious. And. I have replaced water pumps, etc on late model Corollas with timing chains but it’s been a year or two.
You may want to take another look at your Haynes Manual. Rather than repeating a specific task (i.e. removing belts or alternator) several times for different repairs, you may want to go to the section that describes replacing an alternator, or replacing a belt or… whatever you need to remove. You may have to jump between several sections of the manual to replace the hoses.
I did the job today. I removed the cooling fan assy, throttle body to replace the upper radiator hose, and removed the front passenger wheel and splash shield, and alternator to replace the lower radiator hose and thermostat.
Now, I have a problem. I put everything back together, refilled the coolant, and let the engine idle with the heat on, to purge any air from the system. The temperature gauge never reached the halfway point, and the upper radiator hose got very hot, but the lower hose never even got warm, and the cooling fan was running full blast. I turned it off at this point.
I think I have air trapped in the system. I noticed that the OEM thermostat had a little air removal valve, and the new one does not. Is there a way to purge the air out of this thing without taking everything apart? I need this car to be usable by Monday, so if I do have to take this apart again, am I better off to reuse the OEM thermostat which is now 14 years old, or just drill a small orifice in the new one to assist with air removal?
To remove any air in the cooling system, start the engine and let it get up to operating temperature.
While the engine idles, loosen the upper radiator hose clamp and slip a small flat bladed screwdriver between the upper radiator hose and the radiator hose neck.
Allow the engine to idle til all the air is purged and nothing but coolant comes out.
Remove the screwdriver and tighten the hose clamp.
This is a “reverse flow” system. The thermostat is between the water pump and the lower radiator hose. When I started the engine with the radiator cap removed, coolant began overflowing, but no air was released. I put the cap back on.
That is not unusual, with the engine off wait for the heat from the engine to open the thermostat, there is cool coolant on one side of the thermostat and hot air on the other. After the thermostat opens the coolant level in the radiator will drop so you can add more. You may need to run the engine for a few minutes more for the thermostat to open.
