I have a 2002 f150 supercrew with a 4.6 i posted some head problems that I was having it will no longer hold pressure in the radiator and I have to add water every day to go to work and come home...the truck still runs great I cant find a leak anywhere . I cant afford a rebuilt so I will most likely resort to getting one out of a wreaking yard but some people say get a 5.4 .what would I need to do or change if I did get a 5.4.Would it be worth it I really do like the 4.6 even thou I'm having the problems I'm having. Thank you I really do appreciate the help and advice

 

Your wild thinking may cost you a lot more money and hassle.
Find the coolant leak first.
If your losing it at that fast a rate it has to be seen at some point.
Pressurize the cooling system to find the leak.
The coolant just does not disappear into the air without a trace.
You have the hoses, the radiator, the heater and hoses, the line that runs through the block valley to the rear, and water pump shaft seal..
If you had a head gasket leak into a cylinder the motor would not run so well.
If it is going into the crank case you should see that evidence on the dip stick.
The radiator has rubber seals around the side tanks. They can be temperature sensitive and either seal with heat or open a leak with heat.
Look under the area for signs of a leak. Anti Freeze usually leaves a trail.
Shame to replace a motor for some lesser outside coolant leak.
Good luck.

 

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thanks for the response bluegrass two weeks ago I put a pressure test on it and it held 16 lbs for 20 minutes cold, at that time I would smell antifreeze at any time I would start it up but the next day I would open my radiater cap and it was holding pressure also cold .Now when I open to add water it looks like it leaves a rusted dirt looking substance all around the tank inlet when I add water. The only thing I haven't done was pull the intake to look at that hose under it and I don't see any water under the intake where you can see below it. Any full time mechanic whos looked at it can only assume its a so minimal warp that its only letting water by when I'm operating with my foot on the gas.

 

Do an exhaust gas check in the coolant to tell this story.
If you smell antifreeze there is a leak to the outside world for some reason..
Is it the heater core?
It may leak when hot and seal when doing a cold engine test. Things expand when heated and contract when cooled. This happens every time you use the truck.
You have to keep chasing until you pin it down.
Good luck.

 

Parts stores may have this, possibly even in the loaner tools, just buy the fluid.