I'm still looking for a Discovery and I've found several 2004 models with over 100,000 miles on them and on the original head gaskets. Does anyone know if they last longer on the 4.6 liter motors than they did on the 4.0 liter motors from the earlier years?

 

also seach for posts on 4.6 and oil pump... (failures)

IMHO it is not the quality of the HGs, but the numerous problems that can happen with the cooling system, combined with a gauge system that makes a wide range of temperatures appear "normal" on the gauge. When temps slide up, people don't know that this is a very, very bad sign, and keep driving. Same with the nonsense of having just an oil light instead of a gauge on some models. Who, other than an ex-spouse, would drive around town with 10 PSI of oil pressure and think it normal?

The combination of very little information coming to the driver from instruments, and sky high dealership prices, and the skunk smell economy make for deferred maintenance.

 

I have an 04 and had to do them at 104K, so i would plan on it one way or another if it hasn't been done. Also, this is on a motor that was previously replaced by LR early in its life

 

They don't hold any better the any other D2 engine. That being said, if you have a new set installed properly, the chance of them ever needing to be replace is slim and none.
Also, 04's didn't have the oil pump issues some of the 03's had.
If and when you do buy one, make sure the front drive shaft has been rebuilt/replaced, must have 1 grease fitting on each of the 3 front u-joints.

 

There is nothing special about the 2004 head gaskets as far as I know. I'm pretty sure they are the same as the 96-2003. Now before 96, the 3.9L engines had metal head-gaskets, the the newer style composite head gaskets are supposed to be better.... but they also changed the heads, and removed some bolts.... so who knows.

I do remember seeing an early discovery once that had a head gasket so bad that it was leaking combustion gasses between the block and the head. It sounded just like an exhaust leak.

 

having recently bought A 2003 DISCO with a 4.6L I used car fax and it turned out that "my" disco had the head gaskets done by the dealership at 50,000. It has now got 90,000 on it but i do not have any ticking or 3 amigo's so driving with the fingers crossed. Personaly I like the 4.6 over the 4.0 but they can suffer from alot of problems.

 

That's exactly what my '02 was doing, gasket tore right open on Cyl. 6. Could feel the air and thought it was an exhaust leak on the lower exhaust manifold gasket.

 

Yeah, x2 what was said about the cooling system. I have never thought it was the actual head gasket that was the issue. It was the poorly maintained cooling system that turned into an overheating issue that ended up in a warped head or blown gasket issue. You let your engine float past 235 degrees and you will be doing head gaskets.

 

So, while we're on the topic...of FRONT DRIVE SHAFTS..what;s the hot tip for a reolacement, who makes it, sells it, how much, the usual...Appreciate it. Oh, also, as I am just about to start the tear down on a HEAD GASKET R&R, same Q's but for the plug wires...Do they have weird ends? If not, I be willing to bet I can build a set of MSD's 8.5's for less and get way better wire...like 45ohms/ft, If I remember, they're dbl spiral wrapped, suppression, the amount of wire per lineal ft is massive...they're not exactly cheap, but the only way to get more juice is solid core...
All input is appreciated.
Thanks

 

onewingman - look in tech sticky area of the D1 forum, there is a how to on propshaft DIY rebuild, about $21 per ujoint. Please have the RAVE tech manual on hand for head job, there is a separate section in there for "overhaul", has specs for flatness and machining, etc.