So I had the timing belt, water pump, hoses, radiator, and thermostat replaced. On the short drive home the lower radiator hose came off the radiator. Luckily the car did not overheat. The mechanic came to the house and reattached the hose and refiled and bleed the cooling system. I had ordered new lexus hose clamps to rule out the possibility of it being the problem. The car was left running for 20 minutes with no issues. Today I started the car and left it running to make sure that it wouldn't happen again before I left the house and after 10 min the hose came off and I had to shut the car off. Luckily I never left the house. The timing belt water pump kit is Aisin. The hoses, thermostat, and clamps are Toyota/Lexus and the radiator is Denso. Any thoughts on what could be causing this issue. This is becoming quite frustrating and worrisome. 😒

 

that is a weird issue. perhaps the lower radiator hose is worn out and has gotten a little larger and more loose-fitting w/ age. I would replace with new OEM hose and OEM clamps as a first measure.

 

Thanks for your reply. The hoses and clamps were also replaced with new ones.

 

Never heard of lower radiator hose coming off. Was it an oem hose and clamps? I have heard not to use the screw clamps. Maybe if wrong hose and length wrong it is pulling off.

 

To play it safe, I'd try and replace for the second time the lower hose with an OEM hose. You never know, it could have been defective. It's worth a try considering the risk of overheating. Of course keep the test drive close to home.

 

The thermostat, hoses, and hose clamps are Toyota/Lexus. The timing belt kit is Aisin. The radiator is Denso. I have a spare oem thermostat that I was going to use on the lx470 when the timing belt was due, its uses the same thermostat. I might give that a try before I start the parts cannon.

 

If the thermostat was bad you would see your temp gauge rise. Wonder if bad motor mount and engine jerking hose off. What did the mechanic say. Another thought maybe air in the system as these cars are not the easiest to get air out. Was the heater putting out hot air? If not then still air in system.

 

The motor mounts are good, can't even feel the engine when it's idling and doesn't have any movement or vibration. The heater blows hot. The mechanic is dumbfounded.

 

Same here. Try using the screw clamp so it can be tightened more past the lip of male input to hose.

Another thought here is if the Lexus hose is new old stock and possible the rubber has lost some of its moisture and pliability. Think I would try heating hose end with hair dryer to soften and use screw clamp.

 

I'd simply check the radiator cap first. I worry that the pressure of the cooling line builds up too high due to the failing radiator cap.

 

Thanks for everyone's help and suggestions. I changed the radiator cap and hose clamps with new toyota/lexus ones the second time around and still had the same issue with the lower radiator hose coming off the radiator.

 

The lower hose should be a very snug fit on the lower rad fitting and the clamp should put a noticeable indentation under its circumference when installed. When the clamp is installed it should be hard to rotate the hose by hand, if you don't have that then from what you've said I would guess the rad or the hose is wrong.

 

Sounds like you throughly vetted the hoses and clamps. Even though the radiator is Denso, it may be the problem. You should throughly examine the radiator. Best of luck with this issue.