Engine Question

[Shinnymoon]

My 2003 Land Rover Disco se2 thermos stat stuck and it overheated. I replaced the thermos stat but still overheats within a mile. Still starts, no anti freeze in the oil, missing a little now. Had a guy pressure test the system via the reserve bottle he pumped it up to 80 on the gauge it look like it held but didn't do it for long. Little smoke when it first starts. When it gets hot the extra fan in front does not turn on.

So besides all that I found a 2000 Disco se2 but it has a 4.0L engine in it but the engine runs fine. Can the heads be used off of it or what is the difference between 4.0 and 4.6 in my rig.

 

[Hubacek]

I will bet that the 4.0 does not have the secondary air system. If you want a plug and play engine swap that will pass state emissions testing and not have your dashboard lit up with warning lights then you have to get another engine and cylinder heads plumbed for secondary air like you have from the factory, currently. You could start off by pulling your cylinder heads, check the cylinder heads for everything: valves, cracks/pressure test, warpage, etc. then you need to check the cylinder liners in the block for movement, pressure test it, and see what turns up. Hopefully the issue is just with the heads and not the block. The last thing you want to do is overheat one of these rover V8s; the result can be catastrophic failure. When you get everything sorted out you need to hook up an aftermarket temp gauge with audible warning programmed at about 210 or 220, buy yourself a 180 degree low-temp thermostat, or ditch the rover Tstat altogether and modify the system with an inline 180-degree thermostat.
Replace your aux fan, top and bottom coolant hose assemblies, radiator and fan/fan clutch. Maybe the water pump too. Getting your truck running at 200 deg or less should be your goal and every part of the cooling system has to be performing at optimal to achieve this. Every Rover at the recycler is there either because it was rolled-over or overheated. Hopefully you know that the dash gauge doesn't move when the engine begins to overheat. You will always see steam before the temp gauge starts to move up.

 

[ubuntu]

Major differences between 4.0 and 4.6 would be:
Heads if 4.6 has SAI - the 4.0 heads will not have the SAI ports. You can swap the 4.6 heads to the 4.0 engine and that solves the problem.
4.6 rotating bits: crank, pistons, connecting rods and cam are different. The rest is the same. You can shove the guts of a 4.6 into a 4.0 block and have an instant upgrade to 4.6. Some people claim 4.0 pistons (high compression) plus 4.6 crank and connecting rods give you 5.0 - I'm too dumb to figure that out though.
A bit of smoke on start up = valve stem seals shot, among other things.
If it overheats that fast then your cooling system ain't doing its job (among other things). Blocked/restricted radiator, water pump not pushing coolant. Blocked coolant passages in the block/heads. Duff thermostat - you say you replaced that. Check the coolant for combustion gasses. Check the serp belt routing - some people find a creative way to route it incorrectly and the water pump rotates the wrong direction.

 

[best4x4]

The 4.0L you found "could" be equipped with SAI if it was a CA Low Emissions Vehicle. Just gotta pop the hood and look for the stacks coming off each head, and the SAI piping and pump.

Also from what I've heard if you get yourself a NON SAI computer you can indeed turn an SAI equipped setup into a non SAI equipped setup with some work (Friend is going to do it on his P38 Rhino).