I have a mysterious coolant leak, I have bled the system several times, but after a day or two, no more heat, I have replaced the thermostat and radiator cap, pressure tested the system and it holds pressure and no leaks, I have noticed dried coolant on the air filter box,as if the cooling fans are slinging it up there perhaps 🤔, but I don't see dried coolant anywhere else, like once a month I have to refill the overflow container, any advice welcome

 

You obviously have a leak somewhere and if you cant locate it on the outside, it could be internal, like a bad head gasket. I hope not for your sake. Check the oil for obvious signs. If external, the engine heat is drying out the coolant before it hits the ground. Other than the heater cire coolant hoses, there may be hoses to the throttle plate, if I recall correctly on our 07 ES350. Also, check the water pump weep hole, it will be at the bottom. Remove all plastic panels, top and bottom, to help ID leaks a little better.

 

Chuyrobles is correct, the throttle body is heated by coolant on the bottom of it, and it is within a few inches of the air box. However, I would expect to see drips at the connectors on a pressure test, if you can see under there with all the stuff, unless it is internal someplace. Pic from air box looking at TB, air hose removed:

 

[QUOTE=Mesquite77;11301977]Chuyrobles is correct, the throttle body is heated by coolant on the bottom of it, and it is within a few inches of the air box. However, I would expect to see drips at the connectors on a pressure test, if you can see under there with all the stuff, unless it is internal someplace. Pic from air box looking at TB, air hose removed:

This^^^ I'd also check the overflow jug & the hose as well.......I'd pass on thinking its a H/G......

 

BTW, there is also a metal pipe in the valley of the V6, with an o-ring on the water pump side, and connected to hoses on transmission side. It could be very hard to determine if that o-ring is leaking (someone on this forum found one there), but on tranny side should be able to get a stalk camera to the pipe connectors.

 

I'm definitely going to check around the throttle plate for any signs of coolant residue, Thx

 

The thought of a coolant leak in the valley plate has entered my mind, I really hope it's just a hose or O-Ring that is where the coolant leak is and hopefully it's fairly accessable, but I'm definitely going to check the hose and surrounding area of the throttle plate,

 

Only one thing bothers me about this... If you have a coolant leak, how could it pass a pressure test?

 

Thx what I don't understand, I pressure tested the cooling system at the proper pressure, I think it's 15psi, I didn't go higher than the recommended PSI because I didn't want to create a Leak, but I didn't lose any pressure after a half an hour and couldn't find a leak
I suppose I could add some Leak detector dye and see if that May pinpoint the area

 

Alumaseal will stop small leak say 0 rings

 

If the leak is small enough, a short term pressure test will not reveal it.

 

You guys have a valley plate on the 2GRFE?

I know the valley plate 3MZFE on the RX330's can leak very slow.
This leak is almost undetectable for a long time due to only leaking cooolant slowly when engine heats up and valley plate seal expands.
Of course the drips are evaporated off the engine leaving only a pink crusty cake growing in the valley plate that is elusive unless shining a flashlight at perfect angle up in there to see.

 

On 2GR-FE once the intake manifold is removed, the coolant cross pipe is in the valley:

 

Actually, you’ve removed the intake plenum; the manifold is still intact.

 

Lol, you are correct! Here is another pic without the manifold, valley pipe still there though.