I've given up on trying to come up with the money to pay someone to fix the Navigator for me. I don't have enough money for a reman or a bone yard motor. I can fix this one myself for 1/3 the cost of any other option.

I've rebuilt many pushrod motors in the past but I'm a bit nervous of the DOHC. Any tips/guides that could be suggested so that I don't do something stupid and destroy the engine. I'm not sure yet if I'm going to only pull the head and replace head gaskets or if I'm going to pull the block and go through that as well. The engine has 107k on it.

First, can the heads even be pulled without removing the entire engine. According to Chiltons, I believe they say it's possible. After the amount of time required to simply get at the plugs and remove them, I'm guessing it will be quite tight at best. It may be easier without that massive intake in the way, but the heads look to be quite large and the manifold bolts don't look like they are very easy to access either.

Thanks in advance for any help you can provide.

 

The heads can be removed with the engine in the truck. It's not easy, but they'll come out.

And check EBay, or Helms if you have to, get the factory service manual/DVD.

 

Before you do anything remove the damper and rotate the crankshaft keyway too 12:00. Now leave the crank in this position while you remove the heads, timing chains etc. In this postion all eight pistons are below the deck and you will not bend the valves when you rotate the cams with the chains removed and when you remove and replace the timing chains. Do not move the crank at all until you have the heads reinstalled, the timing chains installed and the chain tenisoners released. Just rotate the cams only when aligning the chain timing marks on the crank and cam timing marks.This is the easiest way to remove the heads and remove and reinstall the timing chains without bending any valves. Those heads are heavy by the way and you may want someone there to help lift them out of the engine compartment. You can reuse the head bolts ( some people may dispute this) but I worked with the head bolt supplier regarding this. You will need new head gaskets. Good luck.

 

I'll be one of those to dispute reusing head bolts, especially on this engine in that vehicle, as hard as the heads are to get in and out. Spend another hundred bucks or so and get new head bolts. This is one of those jobs you only want to do once.

 

I had already planned on new head bolts. When I was intending on rebuilding my 4.6 DOHC in my Cobra, I was under the impression I needed a kit that locked the cams in place so that they did not rotate once the chains were removed. I did purchase this kit but have yet to use it. Is this not required on the 5.4?

Also, stupid question, but I'm assuming there alignment dots/keyways to align on the cams as well as the crank?

Thanks again for your help.

 

You don't need the tools to hold the cams and crank in place, they just make life easier.

Leave the keyway at 12:00. The only other marks are the brass colored links on the timing chains.

 

anytime i ever mess with my dirtbike and are messing with the head, i use a sharpie and mark the tooth on the cam sprocket and the chain that goes on that sprocket.

 

You can dispute the reuse of the head bolts if you want. The facts are they can be reused with no ill effects. I worked in the Romeo Engine Dyno for 20 years testing/ building the Modulars. During durability testing we would reuse the head bolts up to three times when we were running special component tests etc.with never a failure. The head bolt supplier explained to us that all their testing proved the head bolts were reusable several times with no problems. Now I won't fault anyone for wanting to be safe and use new bolts. But again the facts are that you can reuse them with no problems expected and that is straight from the supplier and my years of experience. Take care.

 

That's fine.

But, Murphy being Murphy, with the engine in the truck outside of engineering, the second you reuse the head bolts is when they stretch a little too far and compromise the seal. Then you gotta take it alllllll back apart again.

New head bolts are cheap insurance.

 

Quintin, you're right about Murphy lol. However I have seen problems when people install new head bolts and don't prestretch them. These bolts when new have to be torqued down, loosened and then final torqued to spec. Failure to perform this step will allow the head bolts to stretch losing clamp load and allowing leaks. Even the automated torque process in the assembly plant performs this sequence. In the end whatever allows you to sleep better at night is the route to take.

 

I hear that Sean Hyland Motorsports has a dvd covering the rebuild. spend the extra $1000 on Comp cams 262's for that motor while you have it apart and degree the cams. Well worth it!

 

I have the SH DVD and it is worth the cost but I will say its lacking in details that would be critical in assembling a new Modular/Triton motor. All that said get the dvd.