New heater core doesn't seem hot enough
 

I just replaced the heater core in my '02 F-150 and the heater doesn't seem to put out a lot of heat. Don't get me wrong it is hot air, just not as hot as I remember it getting. Enough suggestions? Thank you in advance.

Measure it so you're not guessing.

your heater core only works as well as your engine's cooling system. check your engine temp it should be running around 190-200*f if its not you probably have a thermostat that is stuck open. also make sure you have no kinks in your heater lines going to the heater core and no water pump issues

why did you replace your heater core?? leaking?? plugged?? or just low heat??

also have you verified your blend air door (hot/cold door) is working correctly??

The heater core was bad. I think I was just trippin'. It is plenty hot. One thing I know I am NOT trippin' about is that 3 weeks after I replaced the heater core I am now leaking coolant. It seems to be at the back of the engine. Is it a water pump?

your water pump in at the front of the engine , check your hoses going from your engine to your heater core. you may pressure test the cooling system to find out exactly where its leaking.

Is there a way to do that myself? Thanks for all the info, I appreciate it.

yes its not hard to pressure test the cooling system, if you don't have a cooling system pressure tester, go to your local autozone or similar parts store and rent one. then on your radiator cap is has a psi reading probably around 15 or 16 psi. just pump it up to that pressure then look for the leak. you may have to pressure test it with the engine cold, then if you don't see it dripping, get it hot and re pressure test it. do not run the engine with the pressure tester on it, you could over pressurize the system.

heater hose leak
 

I found the leak. It is on the heater hose that runs to the back of the engine. There is a smaller diameter hose that attaches to the plastic(or whatever it is made of) tube that connects to the heater hose. I can see it leaking right below where the smaller diameter hose hooks on. Do I need to pull the intake manifold and replace the whole tube assembly? Or is there any easier fix. Thanks for all your help.