Are they interchangeable?

The '02 has the infamous plug blowing 4 thread heads. The '04s have 8 thread heads. So is an '04 head a direct fit onto the '02 engine? (4vDOHC 5.4L)

JB

 

if they are both dohc then yes

 

Thank you.

JB

 

Next step, my head supplier has to have a casting number in order for his man to even check stock.

Can someone give me the casting number for the '04 Navi 5.4L DOHC 4valve left (Port side) driver's (US) side cylinder head?

If I can get that I think I should stand a pretty good chance of being able to get a good reman 8 thread head for around $400 out of Florida.

Can somebody help me out with this please?

JB

 

New info. Ford's current part number for the replacement head is:YL7Z6049EA. That should be an 8 thread head and I think that one should be pretty safe. My head, in cylinder #6, blew out the spark plug and dropped both exhaust valve seats out, cracking one of them. I'm very lucky it didn't hole the piston.

Casting number for this bad head is: RFYL7E6C064AC.

Thank you,
JB

 

Nick at Modular Head Shop dot calm is an expert, nice guy as well. He would likely verify for you.

 

I sent him an email. Guess I won't be ordering that head today though, unless I want a new one from Ford.

JB

 

More info. Nick thinks the 4 thread heads ran into the '04 year. That may be, as Ford has a habit of using up defective parts before switching to the good ones. This is the second major repair I've suffered because of this bad habit, and they are 2 for 2 with me on later model vehicles. Not a good record. As much as I like this truck, if I am forced to use the earlier head casting to repair it my next move will have to be to sell it and buy something made by a more reliable company. I simply cannot take a chance on dropping more exhaust valve seats.

I understand the problem is rare. But the clinical definition of insanity is to do the same thing over and over and expect different results. Ford says the problem is caused by hot spots. Although no root cause is ever identified, they claimed to have redesigned the casting for better cooling. An 8 thread head would be clear evidence of a different casting, but so far they seem to be very rare, or perhaps even nonexistent. Vaporware maybe. Regardless, the most likely scenario to me seems to be a random alignment which results in the valve problem. This alignment likely involves more than just the particular head, and includes the entire cooling system, the rest of the engine, and perhaps the entire vehicle itself, along with use patterns, fuel, and any number of other variables. Note that the same casting is used for both heads but the problem only occurs on the left side.

It would be extremely foolhardy in my opinion to replace the offending head with an identical part, leave the entire alignment intact, and expect different results. Insane in fact. That being the case, I have no choice but to find a different head casting if I am to keep the truck. The only other choice that presents itself is to modify the cooling system externally. That is a band-aid, and band-aids are not dependable.

JB