Hi,
Is anyone having this problem? 03 Navigator with 133,000 miles I put into the shop as it was running just alittle rough when you would stop. Put into shop for tune up. Shop called said after tune up still running rough. They checked and said that the #8 cyc lost compression. Son did compression check also and said it had to go into shop ( he only does diesal engines). Put into different shop they said yep lost cmpression with a burnt value, and they had had several navigators come in with this problem. They felt it was largly due to a design problem with exhust putting to much heat to the #8 causing it to overheat. So now I am having to have the heads redone to over 2,000 that is IF the machine shop can rework value. ANYONE else having this problem if so has there been a recall? thanks:


****Correction engine is a 5.4 3 valve

 

A recall is only for items that are a safety hazard. This would be considered normal wear even though it could be argued that it is too soon. They are not going to do anything for you on an engine with 133,000 miles.

 

I dont think its a real common issue. If it was you would find information here and on the internet. Google turns up nothing really on this type of problem. The guy who told you that was a Lincoln/Mercury/Ford tech? If he wasn't then I don't see how he could have experience with "allot" of those engines. They are fairly rare the 4v 5.4.. I think its likely you have a fairly unique problem. Good luck.

 

I agree with Jethat. I don't think it's a common problem at all. Not only that, for a long time now (since unleaded fuel) when they had to make the valves and seats MUCH harder because of the loss of the lubrication of the lead in the leaded fuel, burned valves are very uncommon. How often do you hear about having to do a valve job because of burned valves anymore. Whereas it used to be fairly common.

BEFORE they tear it down to do a valve job, I trust they make SURE it is actually burned valves and not something else causing the low compression. Low compression is not AUTOMATICALLY burned valves.

 

I'm wondering, something jarred my mind when he said hi temperatures around #8. I read awhile ago that modular motors have a 'hot spot' back by #8 in certain years of the 4.6 and 5.4 both SOHC and DOHC motors. There were years when the heater core emptied into the back side of the passenger side head, but there was no cool coolant that entered the back side of the drivers side head which in theory created a hot spot. There have been several write ups called 'The Coolant Mod', I personally have done the coolant mod to my 99 5.4 and I can't say if it helped or not but I have better piece of mind. Maybe his Navigator had this hot spot, but I somehow doubt it. Either blew the head gasket around there, or it could be a problem with the rings I'd think.

 

Before I tore the head off I would check the valve train for any issue not letting the valve seat. I.E. broken or bent arm... IF the valve train looks good then the issues might be the harden valve seat has came loose, scored valve stem, bent valve or damaged valve retainer, all require head removal and rebuild. Doing one means you should do both in my book.

 

Have them perform a leakdown test on the engine. This test will give you a better understanding of valve integrity. It would be very rare to burn a valve on these engines and not sure how a tech can just throw that diagnosis out there so quickly. I have examined and worked on thousands of these modulars and never seen a burnt valve, a few broken valve seats maybe but not burned valves. You say it lost compression, do you mean zero compression or low compression and how low? I would remove the cam cover and check for a follower off or broken valve spring. A hydrolock can bend a rod and give you a low compression, a intake valve follower off will give you zero compression as no air can enter the cyl to be compressed.

 

****Correction engine is a 5.4 3 valve cam shaft & lifters and rocker arms have been checked with no issues. mawmawdowling4

 

****Correction engine is a 5.4 3 valve cam shaft & lifters and rocker arms have been checked with no issues. mawmawdowling4

 

I think it's a four valve........http://en.wikipedia.org/wiki/Lincoln_Navigator

 

I think your right.

 

Mid year 99 - 2004 All Navigators had the DOHC 4v 5.4. 2005 is when the Navigator and the Expedition received the 3v 5.4