4.0 SOHC Cooling Diagram

[cpumatt]

Hey guys,

I have a small leak in my heater core. It's my beater with 185k miles, so I threw in some stop leak about a year ago and its been working great.

One mistake I made though was I didn't flush my cooling system before I added it. It's been about 75,000 miles since my last flush, and my coolant looks like coffee, so I figure it's time for a flush.

I don't want my heater core to start leaking again when I flush it, so I want to add in a bypass valve to the core inlet, so when I need heat I can flip the valve and just refill what leaked out on cold days.

Does anyone have a cooling diagram so I can tell if I need a simple in-series valve or a whole three-way set up if its in a series loop with the heater core?

Thanks!

 

[koda2000]

Hey guys,

I have a small leak in my heater core. It's my beater with 185k miles, so I threw in some stop leak about a year ago and its been working great.

One mistake I made though was I didn't flush my cooling system before I added it. It's been about 75,000 miles since my last flush, and my coolant looks like coffee, so I figure it's time for a flush.

I don't want my heater core to start leaking again when I flush it, so I want to add in a bypass valve to the core inlet, so when I need heat I can flip the valve and just refill what leaked out on cold days.

Does anyone have a cooling diagram so I can tell if I need a simple in-series valve or a whole three-way set up if its in a series loop with the heater core?

Thanks!

I would add a loop to the two heater lines where they attach to the heater core at the firewall. Get a foot or so of rubber hose, a couple of plastic unions in the appropriate size (5/8's or 3/4's?) and some hose clamps from the auto parts store.

 

[cpumatt]

I would add a loop to the two heater lines where they attach to the heater core at the firewall. Get a foot or so of rubber hose, a couple of plastic unions in the appropriate size (5/8's or 3/4's?) and some hose clamps from the auto parts store.

I think they're 1" ID hoses.
Why did ford have to make replacing the HC on this truck an absolute god awful nightmare

 

[koda2000]

I think they're 1" ID hoses.
Why did ford have to make replacing the HC on this truck an absolute god awful nightmare

Maybe, I wasn't sure, though I have a complete set of heater hoses I just removed from my SOHC sitting on my work bench if you'd like me to measure the ID.

Replacing the heater core on any vehicle from the 80's forward is a PITA. The newer the vehicle the harder the job is.

 

[cpumatt]

Maybe, I wasn't sure, though I have a complete set of heater hoses I just removed from my SOHC sitting on my work bench if you'd like me to measure the ID.

Replacing the heater core on any vehicle from the 80's forward is a PITA. The newer the vehicle the harder the job is.

That'd be great! Grab me a measurement when you have time, thanks

 

[koda2000]

That'd be great! Grab me a measurement when you have time, thanks

Just measured. 5/8" ID 3/4" OD on mine. So 5/8" hose and unions. Even though you're not going to flush for heater core you may still end up with a leak once the fresh coolant dilutes whatever sealant remains in the system.

 

[cpumatt]

Just measured. 5/8" ID 3/4" OD on mine. So 5/8" hose and unions. Even though you're not going to flush for heater core you may still end up with a leak once the fresh coolant dilutes whatever sealant remains in the system.

I figured. It's such a small leak it's almost like its just burning off wherever the leak is.

I only need this thing to last me a year before I graduate engineering school
I've already put 75k on it.

 

[koda2000]

I figured. It's such a small leak it's almost like its just burning off wherever the leak is.

I only need this thing to last me a year before I graduate engineering school
I've already put 75k on it.

No guarantees, but I'm a big fan of using K-Seal on cooling system leaks. The only place it hasn't worked for me is on plastic tank radiator leaks. It's good stuff and wont clog anything.