my name is brian. I replaced the radiator , thermostat , water pump, flushed system,. water temp is perfect jeep runs good but very little heat comes out. the fan seams to work good. i'm stumped
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my used 4 cyl jeep radiator would only drain 1/2 of the fluid. jumped up and down on bumper and this dislodged the sludge in radiator and/or engine. flushed twice, then now notice low temp reading on gauge (out of specs) due to a low temp thermostat that someone installed due to previous over heating (sludge). Replace with factor spec thermostat and everything is fine.
If the pump isn't leaking or noisy, it's good. If the hose came off and the engine overheated you may have blown a head gasket (radiator hydrocarbon test is best to determine that) if you see steam from the tailpipe, coolant in the engine oil or oil in the coolant that also is a big clue. Jeep engines tend to rust internally. the rust packs into the bottom of radiator core, especially after an overheat. Therefore, don't trust that because the radiator looks good that it is good you cannot see what's actually inside it. (you could try back-flushing but should do that with the radiator removed to do it right). If you see any improvement after flushing, replacement would be a good idea.(unless it completely works). You can use plain water in the cooling system while testing. Just don't leave the water overnight so it can freeze.
Flushing a radiator at home is most often a waste of time. The chemicals used by a radiator shop are far stronger than anything you get at the parts supply house. What happens is that the flow you see is deceptive as the water tends to flow around a partial restriction and does nothing to remove it. Though your garden hose has a lot of pressure it doesn't have the volume necessary. A garden hose will usually be sufficient to flush out a heater core though as it's smaller. Have a radiator shop flush your radiator core and have a hydrocarbon test done on the cooling system to eliminate the possibility of head gasket problems. When re-filling the system, turn the engine off just before it reaches 210 degrees and let it sit for a few minutes so the thermostat can open, then continue filling. Always fill with the heat on high. Thermostat goes in with the spring end into the engine.Forget about the water pump...unless you got one made for a twin engine marine (CCW) application it has nothing to do with the problem though I've heard but never actually seen that the belt can be installed so it turns backwards. When the engine is at operating temp cover the grille and force it to nearly go into overheat...the electric fan should come on and the mechanical fan should lock up to try to counteract that. Don't open the system when it's hot (you found that out already). And, don't allow the engine to actually overheat. My bet without seeing it? Likely a partially obstructed radiator. 4.0 engines make a lot of rust residue even when maintained. If that's what you have in there, or even the 4cyl. It is more than likely.
It sounds like the heater coil needs flushing out or replacing or the heater valve. Look on the engine firewall and make sure the heater valve is opening. If not open it manually and check the heat level. If that produced heat check the condition of the heater vale cable (or vaccum hose).
It's not the water pump. pumps can leak and shaft bearings go bad, but even then it is pretty much impossible that the pump won't pump. I'd start by changing thermostat. When re-filling, add coolant slowly and just when it reaches operating temp, shut it off for about two minutes. re-start, turn heater on high and continue filling till electric fan comes on (if you have one) at that point turn off again as before. Re start and run with cap off for about 15min. If overheat continues, remove radiator and flush, and bring to a shop to determine if there are any hydrocarbons in the cooling system. If so, there is a problem with either head gasket or head. (likely you will have fixed it before you get this far.)
Make 100% sure before you go and spend more $$$ that (1) you have good coolant flow through the heater core; get engine to operating temp,then with heater fan on high and temp control on full hot carefully grasp heater in and out hoses(i use a in-fared heat gun to diagnose). They should be very close to same temp, if not, core is plugged or if equipped with a flow control valve, its not opening or there is an air lock in system.(2) If coolant flow is good, suspect the hot/cold blend door being stuck in cold position assuming you have good air flow. Its very rare for engine cooling to be ok and heater core coolant flow be bad , caused by a failed water pump! Hope this helps! Please rate me,Thanks!