so my heater does not want to work when its cold outside any suggestion on what i should be looking at to get it working properly

flush your heater core

Unhook both hose at the thermostat houseing . take the water hose and run water through one hose for a while then switch hoses and run throught that one. Do this for a while switching sides. till you think it is cleaned out enough.

what he said.

take the inlet tubes off at the firewall, and run a hose through (both ways) until it's clean.

also, remove the valve from those two lines, and connect them directly to the heater core...you don't want that thing anymore. they never work.
it closes and opens via vacuum to allow the coolant to bypass the heater core when heat is not being used. however, there is no reason for this since putting warm coolant through the heater core isn't going to give you heat in the cab.

remove that, plug the vacuum line with a screw and some silicon, call it a day. should get heat back.

I too am having the same issue on a 87 xj i picked up. So far I have removed the heater valve, replaced the thermosat, fixed a small leak in the radiator, flushed the whole system, removed most of the hoses to check for blockage. Still no heat. I also checked the cable and it seems fine. I get flow through the heater core. What else am I missing.

wheres the valve yall are talking about so i can remove that while i'm changing the head on my jeep

did you flush backwards and forwards at the firewall where the heater core is, with the hoses disconnected?



you have to get that cleaned out.


also, when you move your heater control, what do your vents do? does it change where the air comes out when you change positions?

next to the firewall, inline with the heater tubes.

those the metal T's that run up to the remote bottle

yeah. the goal is to get rid of that valve in there, and at the same time to flush the heater core with a garden hose.




BTW while you're doing anything with coolant, you need to properly bleed out the system. this requires parking it facing slightly downhill, and unscrewing the temp. sensor from the driver's side rear top of the head to let the air out.

do you hook the top hose to the heater core and the the out to the heater core to the top of the botle and the bottom to the thermostate

Yes. I flushed it right at the core both ways. And yes the vents are working properly. The only thing I can think of at this point is that the blend door is not closing all the way. Like I said the cable looks fine and the arm it is attached to moves freely and is all the way against the plastic stop.

bleed the air out of the system

i was wondering i seen in your signiture where you had an ho motor in your 87 did you change motors or just the head

the only thing that's 87 on my truck is the body. everything else is 95