PradoTDI
Veteran Member
I have been daily driving my ALH swapped Toyota LJ78 for the past few months and the cooling system has been just fine, but recently I had to replace a couple of bypass caps, one of which is on the little nipple on the back of the cylinder head. I was informed that rather than being capped off that should be plumbed back into the cooling system to bleed off any trapped air in the cylinder head. I teed it into the return line from the heater core and oil cooler, and have since been experiencing erratic and high coolant temps, probably due to air trapped in the system.
I am not using the VW expansion tank because there wasn't a good place to mount it in the engine bay that was high enough up, so I am using an inline radiator cap and the factory Toyota expansion tank. My coolant temperature sensor is in the coolant outlet pipe coming off the back of the cylinder head. I disconnected the hose at the heater core valve and found it empty, but the radiator fill cap is full to the brim. I still get good heat from the heater core. When I first filled the system it bled out just fine.
My question is: is it necessary to have that small return line plumbed in, and if so how should I go about bleeding the air out of the system? I realized after I made all of the radiator piping that I have the inlet and outlet to the radiator switched, but until now I haven't had any issues with it. Are there any other glaring issues with my cooling system? I have attached a rough diagram of my cooling system and some photos.
I am not using the VW expansion tank because there wasn't a good place to mount it in the engine bay that was high enough up, so I am using an inline radiator cap and the factory Toyota expansion tank. My coolant temperature sensor is in the coolant outlet pipe coming off the back of the cylinder head. I disconnected the hose at the heater core valve and found it empty, but the radiator fill cap is full to the brim. I still get good heat from the heater core. When I first filled the system it bled out just fine.
My question is: is it necessary to have that small return line plumbed in, and if so how should I go about bleeding the air out of the system? I realized after I made all of the radiator piping that I have the inlet and outlet to the radiator switched, but until now I haven't had any issues with it. Are there any other glaring issues with my cooling system? I have attached a rough diagram of my cooling system and some photos.