Firehawk068

It sorta does...........
When the heater is turned off, the butterfly valve inside closes off the heater core, and simply re-directs the flow of coolant back to the water pump.


The arrows in the picture are correct.

djb383

The factory FSM "sorta does" show the 2 flow different flow paths thru the HCV?......my FSM doesn't. Not the heater core, there's flow or no flow thru the heater core.

Again, the flow diagram for '97 up XJ's is wrong in '97 up FSM's. Top nipple is the inlet and bottom nipple is the outlet.

Firehawk068

Heat









No Heat

Firehawk068

I assumed your FSM showed the same diagrams that I posted?


Those diagrams were taken from Jeep Factory Service info.

djb383

My FSM shows the diagram without the HCV.....no HCV on '97 up. The diagram is just the opposite of how the hoses r actually routed from the factory.

The diagram in '97 up FSM's is WRONG.

The '97 up diagram is the same diagram u post, minus the HCV. The Factory hose connections at the firewall r opposite of the diagram on '97 up XJ's.

djb383

Have u looked at the '99 XJ yet?

djb383

With regard to that 2nd HCV pic (post #48), what do the blue lines/arrows represent?

adamj

Yes, interested to see if there was a shift and in what year that happened.

djb383

I'd bet it was '97 up.

Firehawk068

Just coolant that doesn't really go anywhere, that's why I drew arrows on both ends of the blue lines.

Firehawk068

Yes, I have pictures of a factory-original, untouched '99
The heater hoses still have the factory clamps on them, and the hoses still have the Mopar markings on them.


djb383 is correct...............(the FSM diagrams are backwards)
I admit, I was skeptical that they would change the heater core flow direction, but you were right!


Here is the factory original '99 hose routing.











So, I am going to assume it is safe to say that they changed the flow direction within the heater core for '97-up. Not sure why the design change, given that the heater cores are identical between the years?


So, for '91-'96 HO the flow goes in the smaller bottom tube, and out the larger top tube.
'97-'01 the flow goes in the larger top tube, and out the smaller bottom tube.
I have only worked on 2 Renix XJs, and never paid attention to heater core flow, so couldn't comment on those.

djb383

Same routing/flow as shown in pic, post #35.

cruiser54

Renix HCV fix.

Gene Delong

thats what i did yesterday but i don't have a radiator witha cap, so you can go to moroso.com and buy a radiator hose filler which is basically a radiator cap that fits into the upper radiator hose so you can fill it. i had to get a different coolant res also.