Hey guys I'm new to the forums and just want to say thank you for your insight in advance. I just began the process today of doing some minor TLC to my 1997 F150 5.4 L to get ready sell it. I noticed the Coolant reservoir was low so I added so more water to it before cranking it and noticed it was leaking out just as fast as I could pour it in. On further inspection I noticed the leak looked like it was coming from in-between the motor and transmission. Surely there isn't a freeze plug in there? Has anybody ever seen this or have any idea what this might be?

Thanks!

 

it's either a heater core hose leaking (two lines going into the firewall) or the fitting in the valley under the intake.

this is the first post i found explaining the various leaks. funny, it was a thread started by me lol.

 

It may well be one of the other leaks mentioned, but a lot of engines DO have freeze plugs on the back of the engine. I'm not sure if yours does or not.

 

Well I checked in the valley where the hose should be and didn't notice any water. Also if it helps the leak seems to be coming from the drivers side. I checked the oil and it was very milky...may be an unrelated problem? If it is a freeze plug on the back side of the motor it looks like I'd have to pull the engine to replace it or drop the transmission, anybody done this?. It's a 1997 4x4 lariat with 203,000 miles on it. Not really sure if it would be worth my time to fix or to just sell it as is.

 

was the oil on the dipstick milky or just the bottom of the filler cap? if it's just on the filler cap then you're most likely good.

check the coolant level and make sure it's not turning dark.

milky oil is usually never a good sign.

 

Did the engine freeze? Not enough antifreeze at some point?Thats what it sounds like.. if it did who knows what damage you have.

 

In back, lower head -



There's also a bypass line on the 97's. Connects to a stem integrated with the heater core hard line just behind the passenger side head. A 1/4" or 3/8" heater hose connects to it (bypass) and runs to a tree (3 finger)/ passenger side of the throttle body elbow. That small heater hose line could be compromised.

How much coolant does the degas bottle hold before it starts leaking ? Well, that would the system level of your leak. As mentioned, it's possible you blew the o-rings right behind the water pump. ark2bama, your going to have to determine where the leak is. See how much coolant is standing on top of the block cavity. If you have coolant in the cavity, chance are, it's not freeze plug. As the cavity fills, coolant will divert and over flow out the passenger side of the engine, - right on top of the starter.

BTW- The coolant bypass line is pictured above. Not the line itself, but the bypass stem is shown. If you look closely it has a white cap on it, about 6" down from the top of the heater core hard line. That's where they can leak.

The pick above is of the 2000 -2003 5.4L's. But works for this explanation.