Can You Help Me Understand This?

[Fitz98]

98 Expedition 5.4
There is a hose that comes off the return line pipe that runs from the heater core to the back of the water pump.
See where the yellow arrow is.

It goes into a the back of a 3 way fitting on the side of the throttle body

The hose that comes off the side of that fitting goes to the PCV system and the hose that comes off the front of that fitting goes to a nipple on the fitting at the front of the intake. What is this sensor?

I am not understanding how coolant is not getting sucked into the intake system, assuming that 3 way on the side of the throttle body is part of the intake system.

 

[mk378]

It's an isolated circuit. The "three way fitting" doesn't actually tee all three hoses together.

Under certain circumstances (cool humid weather) a throttle body can ice up. This coolant circuit heats it up.

 

[Lolvoguy]

Originally Posted by mk378
It's an isolated circuit. The "three way fitting" doesn't actually tee all three hoses together.

Under certain circumstances (cool humid weather) a throttle body can ice up. This coolant circuit heats it up.

+1
First time I saw this was on my 86 BMW.
On older cars, there was hot air that was routed from around the exhaust manifold.

 

[bdcardinal]

According to the catalog, that fitting p/n is F85Z-12A671-AA with a note of "Water temp sender with threaded adaptor that has water tube on side" which was part of the F85Z6A603BB r/b F85Z6A603FA PCV kit which are both obsolete.

 

[Fitz98]

So if I am understanding correctly, the hole that goes through the throttle body as shown in the picture below, would be part of the PCV system and the water temperature sender hose and hose from the heater core tube would be isolated internally from that and just be routed around it to keep the throttle body warmed up?

Makes sense to me, just didn't look that way from the outside which was my initial confusion. At first, I thought I was putting the wrong hose to the fitting, I thought why would I be hooking a cooling hose up to an intake port?

 

[Imp4]

Threads like this is why BITOG is great.
I'm glad you found your answer.

 

[Linctex]

That coolant flow circuit should NOT be hooked to a vacuum source!

 

[Imp4]

Originally Posted by Linctex
That coolant flow circuit should NOT be hooked to a vacuum source!

You're right and it isn't.

Originally Posted by mk378
It's an isolated circuit. The "three way fitting" doesn't actually tee all three hoses together.

Under certain circumstances (cool humid weather) a throttle body can ice up. This coolant circuit heats it up.