I've been searching the forum and can't seem to find a good detailed write up on how to back flush both front and rear heater cores in a 2000 5.4l.

Heat is not quite hot in the front and luke warm in the back. Both core lines in front are pretty dang hot. My son and i removed the rear panel and removed/checked actuator it moves fine. manually moved the blend door and it moves freely with no binding when put in the heat position not much heat. The inlet hose getts good and hot but the outlet doesnt. =plugged core

Just replaced the intake manifold not to long ago and did a pretty good drain and fill of the system then. Heat didn't work to great then either. coolant was clean and is now also.

Is there a good way to back flush both the front and the back at the same time or should it be done seperatley? I want to back flush to prevent pushing clog further into cores. Any advice or link to a good write up would be greatly appreciated. Thanks

 

I got about 10 feet of heater hose (I don't recall the ID off hand, maybe 5/8), cut it in half to 5' pieces, removed the cover on the rear, attached the hoses to each tube on the core and used the garden hose flushing each direction with the ends in a bucket. Make sure you drain the coolant first so you don't contaminate the ground with over spill.

Each time I switched hoses, the pressure got better. A lot of crap came out at first and it took some pressure to push it out. I flushed it until there was no pressure and the water flowed clear.

 

Thanks buddy. That was going to be my plan of attack unless some one has come up with a way to fulsh both front and back at the same time. I figure if i tie in under the hood, before the T conectors, and try to flush both at the same time, with the rear being clogged the flow would just be diverted through the front core only and the back core would stay clogged.
Does anyone know if I could just cut out the factory T fittings under the hood and repalce them with a regular T and hose clamps? I have read rumors of some sort of reducer that diverts some of the flow from the front core to the rear. If this is true and it is located in the T fitting, then I dont want to remove them. If not then a regular T and clamps would make future flushes so much easier! Just a thought
I guess ill give the rear core a flush here in a few. I plan on taking pics and posting them in a seperate DIY thread, if I can figure out how, for the next guy who comes along and tries to search first like I did.
As always, any tips or advice would be greatly appriciated!!