ford 4.6L coolant refill procedure...

[crw]

On my 1993 Lincoln Mark VIII, I've changed out the water pump and the thermostat. Now that it is refilled, everything appears normal but I get no heat. I've tried various things and can't get the thing to put heat out the air vents...

On this model there is a metal pipe which the top hoses attach to. I've tried filling from there, from the overflow tank, I can also vent the system via that upper connection once hot, but nothing I try gets heat to come out. This really shouldn't be so hard... any thoughts?

 

[JamesBond]

Blend door problem? Crud in the heater core? Did you check that the heater hoses are getting hot? Squeeze all the hoses while it warms up, and park pointing up-hill. How long has it been? Sometimes it can take a few cycles to burp itself.

 

[Chris142]

Is this the engine with a pipe that goes across the entire front of the engine? If so those have 1 or possibly 2 bleeders that must be opened to bleed the air out.

One of the bleeders takes a large Allen wrench.

If it's not that engine then disregard my post and carry on.

 

[AdRock]

Pull the hoses off of the heater core and run some water through it. If it flows normally put on of the hoses back on and fill it through the access hole in the metal pipe at the front of the engine until it starts coming out of the heater core. Put the other connection back on, fill it up the rest of the way through the front pipe. Then start it up and let it run with the plug still out of the pipe. Also, run the heater the entire time. Once it's good and hot rev it up for 10 or 15 seconds. it'll speed the pump up and help it to push therough where an air pocket might be. It might take a couple times to get all the air out but this is the process I used last time I worked on one.

 

[TFB1]

Common for these to air lock, if the heater hoses are cold that's your problem(or it's plugged but I assume you had heat prior)...


If it's a air lock problem, opening the bleeders mentioned and having the front of the car up 8-10 inches usually corrects it....

 

[punisher]

Didn't work on a lot of MK VIIIs, but I do remember the tech videos and new model training we had to sit through on those.

They are very sensitive to coolant temps, sensitive in that things can warp if temp deltas get too large (hence the weird thermostat setup on the engine). Even detorquing the intake manifold incorrectly during R&R can cause parts to warp.

Fix the coolant situation sooner rather than later, bleed what you have to. Verify you have coolant flow through the heater core/bypass lines.

 

[RF Overlord]

If your motor is a 4V, and there's a separate round crossover tube in the front, there should be a bung in the top of it.

Raise the front of the car on ramps or other safe support structure. Remove the reservoir cap and the cap from the bung. Fill the coolant through that bung. When full, put the bung cap back on, but leave it loose. Start the car and let it idle until it warms up. When coolant stops fizzing and spitting from the bung, remove the cap and add more coolant. Tighten the cap. Refill the reservoir as necessary to the MAX line and replace the reservoir cap. Done.