Heater control valve (arrow)

[ChristopherASA]

3 days ago: My 1998 Explorer XLT (5L engine), Amy, was overheating so I took a look under the hood. The heater control valve (passenger side/top of the firewall) was broken so I replaced it. Question: I notice that the valve has an arrow on it. Should that arrow be pointing toward the radiator? (I believe that was the direction the arrow was pointing on the broken valve.)

2 days ago: I took her for a short to see what the temperature gauge would do. When I started off I had a horrible tappet (?) noise , but I kept going anyway: my 1st DUMB decision. As I drove, the temp went higher. And higher. And HIGHER. I should have just pulled to the side of road to let her cool down, but I was stupid--again--and just wanted to get her home. My 2nd DUMB decision.

Today: Have taken Amy for two short rides. The "tappet" noise is gone and she runs fine except for the overheating problem, thank The Supreme Being.

 

[1998Exp]

3 days ago: My 1998 Explorer XLT (5L engine), Amy, was overheating so I took a look under the hood. The heater control valve (passenger side/top of the firewall) was broken so I replaced it. Question: I notice that the valve has an arrow on it. Should that arrow be pointing toward the radiator? (I believe that was the direction the arrow was pointing on the broken valve.)

2 days ago: I took her for a short to see what the temperature gauge would do. When I started off I had a horrible tappet (?) noise , but I kept going anyway: my 1st DUMB decision. As I drove, the temp went higher. And higher. And HIGHER. I should have just pulled to the side of road to let her cool down, but I was stupid--again--and just wanted to get her home. My 2nd DUMB decision.

Today: Have taken Amy for two short rides. The "tappet" noise is gone and she runs fine except for the overheating problem, thank The Supreme Being.

Had the same dilemma after my heater valve broke, and was removed for an emergency bypass on the road. Not 100% sure, but turns out the arrow should point to the heater core. Pretty sure mine was originally installed the other way round; perhaps an error at the assembly plant -- stranger things have happened... I seriously doubt it matters much which way it's installed anyway. By the way, the other direction is to the water pump, not the radiator.
Sorry, can't help much with the overheating. Are you sure the system is correctly filled with coolant, without a significant air bubble? Not common on the 5.0, but you may need to "burp" it. If you think you heard tappet noise, it may be smart to test oil pressure with a mechanical gauge. Overheating may also indicate exhaust gas entering the coolant through a damaged head gasket. Won't hurt to buy the "magic sniffer" to check this.

 

[Mbrooks420]

Yeah, the arrow denotes flow.

Not having the valve noise might be moot if you’ve blown your headgaskets and warped your heads. Quit driving around an overheating vehicle to “see what happens“.