I am changing the intake gaskets out on my 99 F150 5.4L and also want to replace the o-ring in the by-pass water pump line but can not get the line loose. It appears to be welded to a bracket on the back of the motor on the passenger side. Has anyone removed this line before. I can't see what is holding it in place, can't get a good look at it with a mirror either. All I can feel is two bolts holding the bracket down. I backed off the nuts to this bracket and I figured this would loosen up the bracket but the line is still solid in place. Any help would be appreciated. I really need to get this thing put back together tomorrow. It would also help if anyone might know the size of that o-ring. I could go ahead a get that today instead of hoping to find it on a Sunday.

Thanks

 

I guess not many people have changed the o-rings in the by-pass water line. Well, for future reference for anybody that decides to take this line out, here is how it's done. This assumes you have taken out your intake manifold and are changing the gaskets. The line is anchored down by a bracket on the backside of the passenger side valve cover. You won't be able to see the nuts, all you can do is feel for them. This bracket has another bracket over it that holds a wiring harness down and I assume also serves to keep the harness off the engine. You have to take two nuts of one bolt and one nut off the other bolt. These nuts are 10mm. Then remove the first bracket that holds the wiring harness. Then loosen the upper left stud that holds the water line. It takes a 13mm wrench. Remove the lower right stud completely. The water line bracket slips off the upper left stud. Once the heater hose is removed from the by-pass line, you can twist and pull the line away from the fitting that is behind the water pump casing. There are two o-rings that must be replaced. I am not certain of the exact size since I could not find any reference to them at the parts house. I matched them up to 1/2" X 5/8" X 1/16". I hope that's the right size. I'll know in a couple of hours when I get everything back together.

 

I know for a fact, there's an actual kit made for this fix, I can't find it at this point - still looking, I'll find it.