Outer Limits 4x4 Board

looks like im going with a 4.6 as i can get one with 106ks long motor for $3500. But are there any known probs with these motors.

Head Gaskets, maybe worn cam although probably not that early on.

One cooking and it ususally busts it.

Put a drinking glass upside down over the oil filler and run the engine if poss and see if it fogs up, sure fire sign - check the other ususal suspects
milk oil, oil in the header tank.

Apart from that they are pretty good , it can cost $3K for a head rebuild on them if you get it done. The can also kill coil packs if they run too long with stuffed head gasket - they retail for $2k a set and secondhand from $500 ish for 4 IIRC (could be 500 for 2 can't remember)

Tom

These motors have steel liners in the alloy block. The liners can move in the block, allowing exhaust gas into the coolant galleries, which pressurizes the cooling system & drives coolant out. When the motor cools down after use, coolant is drawn back into the affected cylinder- which cleans it up nicely, but can make for bad starts. Eventually, the motor overheats within a few minutes & is unusable, or sustains damage. The cure? A new short motor. Liners can be refitted, but it's a heat process that usually loosens adjacent liners.
How common is this problem?
Check out how many 100k plus 4.6 rangies are advertised as having a new motor fitted...

The other problem is porous blocks. I've no idea how common it is, but it does seem to be more common the larger the bore, i.e. 3.5 motors fairly rare, 3.9 & 4.0's a little more so, 4.6's the most affected. Dittto the liner problem.

BE CAREFUL buying a 100k+ 4.6 motor. The liner fault can be difficult to diagnose, & is sometimes thought to be cured by a new head gasket, but it's only a temporary fix.

Finally (just in case you were wondering), yes it's happened to me. 4.0 motor though. LR were VERY good about it.

They are also hard on cams. I had a 3.5 with a noisy cam once. When we pulled it, the lobe closest to the firewall was completely rounded off. I suspect poor oil feed- these motors are a low-pressure type oil system.