Heater core inlet/outlet

[robertbutera]

I did some work on my coolant system today (primarily to replace water pump).

I have observed many threads online that all do the following:

1. Someone asks which is the inflow and which is the outflow of the heater core
2. Respondents post a pic from the factory service manual, which shows:
   • the T-stat is the inflow to the core and the bottom connector to the heater core, it is also the larger diameter hose
   • the line to the water pump is the outflow of the heater core and is the top connector to the heater core
3. The original poster says "wow, mine is backward"
4. Ensuing conversation on whether or not this matters

I agree this is what the FSM shows.

And I too am one of those who has observed their heater core hoses to be backwards from the FSM diagram.

BUT now some fuel to the fire ...

I considered swapping the hoses while replacing my water pump and t-stat today. But when I pulled the hoses off, I was surprised to find this — the plastic pipe to the connect the hoses is a larger diameter on the top one vs. the bottom one. I really didn't want to connect the large hose to the smaller diameter connector, and vice versa. They are close enough that it would fit, but it felt wrong ... I decided to leave it as it was plumbed when I found it.

So maybe the FSM is wrong, at least on some models? 2006 LJ manual.

(I've found a few places the FSM is vague or missing info or says to do things that don't seem necessary (like removing the power steering to change the water pump, but wrong?)

 

[pagrey]

Hook it up how it fits. The direction doesn't matter.