I have a backflushing kit I'll be using soon, I need to cut the heater inlet hose and 'splice' in a piece. The directions say use the hose running from the firewall to the top of engine, look here:

http://www.students.uwf.edu/lad2/enginebay3.jpg

There's three arrows, is what I want the green, red, or blue arrow (I'm thinking blue, the girth is throwing me off)? Thanks.

 

If im not mistaken the green one is the top one but im not sure. there is also the second heater hose under the blue arrow hose which is the second one. The blue arrow hose i belive is a radiator hose not a heater hose. Might want to go with the green arrow hose but dont quote me on that.

 

If you look on the firewall, the one hose attached on fender side (with alum. pipe to rubber) should be the inlet hose. The hose on the right (all rubber) is the outlet hose.

So I guess if you follow the hose on the left you will see which of your hoses is indeed the inlet hose.

I replaced the outlet hose cause it got burned by my headers.

Someone please correct me if I gave the wrong info.

 

The answer is none of the hoses you have arrows to. The green arrow is the heater outlet hose. The red goes to the remote reservoir and the blue to the throttle body.

See this diagram. So, Bubba, the hose with the more rubber at the firewall is the inlet hose.

 

Thanks. All this time I just assumed it was the outlet hose. Well, I guess I replaced the inlet hose then. And a bitch it was too.