Quick theory question for those who know more about old vehicles than I do. (My 1988 truck is older than I am!)

I was poking around on my truck, and saw the pipe that goes from the intake side of the timing cover to the bottom rear of the manifold. I know the manifold is heated (I guess to help the fuel mix), but why have that pipe and hose out there when it could have been done through the block? It seems like it's just an opportunity for leaks and added expense.

What baffles me even more is the fitting on the middle of the intake side of the head, with the BVSV for the AAP and choke opener, but also the heater? Would that not screw with the BVSV depending on if the heater was open or not? I'm pretty sure I get the theory behind that BVSV. (once up to temp, suck the choke wide open, until then, activate the AAP when vacuum drops to compensate for poor mixing) However, I'm stumped by the heater being run off that same fitting. Would it not get poor flow when the heater is off? Does it even make a difference? Just wondering if anyone knows the "theory" behind the design.

 

Revenge for the USA winning the war !!

It could be it was cheaper !!

Might be added after the block and head designs were final.

More options going that route rather then internal

Might just be" I think we forgot something here Guys "

 

Those are all valid! My favorite is the engineer who caught his wife sleeping with a mechanic!

I have a thing for trying to understand the why of everything, I believe that it really helps out when it comes to understanding anything, be it trucks or sports or politics. Plus, I'm in the middle of demogging my truck, and I like to know 100% what Toyota was thinking before I go and change it!