There is a good chance both cylinder heads will need to be machined, most machine shops will just machine them a bit just to clean up the surface and keep removing material until they are flat.

 

I plan not to pull the passenger side head if possible.

Is it safe to drive this in? The dealer wants to confirm my diagnosis. It's about 25 miles. The CEL goes off during each upshift. I assume that it is sucking air during the shift, and throwing a false 'too lean' reading, and then throwing the mixture rich until the fault clears.

 

Depends how hot your cat is getting with all that extra fuel being burned. That is a tough call. My father is a premium AAA member cost likes $17 a year and you get free tows within 100 miles.

 

Is that what ruins a cat when running rich; the heat generated from burning fuel in the cat itself?

 

Hey Rob sorry I got thrown with the mention of RTV under the sensor safe line of info, my bad.
Anyway before you pull the head/s, I would also suggest that you do a compression check, this will give you a better idea of the condition of the other cylinders.
Also if you want go to NAPA, and get a Block Checker, ( about 50.00)this is a useful tool for finding hydrocarbons in the coolant.
You fill a tube with blue dye then suck fumes out of the coolant bottle with the engine running, if the fluid turns yellow then you have a leak in a head gasket a cracked head or a cracked cylinder.
The other thing you can check is remove the left manifold and put the ports on a flat surface to see if it is in fact warped or flush.
My 04 Disco was also leaking at the #5 port but it was due to a loose manifold bolt.

 

Yeah, pretty sure the head gasket is bad, and the manifold is good. If I end up doing the work myself, i'll be checking for flatness.

I'm hoping the exhaust has not infiltrated the oil or coolant. Both appear normal. I guess the exhaust leaking from between the head and block has relieved any pressure there.

I wish I just had a loose manifold bolt, lol.

I've driven the truck a whole 180 miles, and i'm into head gaskets already....

 

The good news is that if you inspect everything and dont find any other problems you should be good for another 50K..
FWIW, I was looking at an 03 with a blown motor ( oil pump failed) it had 180K on it and it was just about worn out,driven mostly in the mountains and salty roads, I passed , it was just too nasty

I think I will be searching for a truck with under 90K, prolly a 2001 or 2002, and I am reserved to the fact that headgaskets will need to be done, these Rover engines really could have been made to better tolerances

 

Just curious.

These LR engines are based on '59 Buick engines, no? How long did head gaskets last then?

If, as I suspect, 75k was the norm, then LR didn't do a lot of improving on the original design.

My only frame of reference in a 'Cuda that I once owned...big block, 383. I think I went through a set of head gaskets and two complete overhauls in 25,000 miles. Of course, I was also running nitrous and 12:1 pistons on regular pump gas.

 

yes and if you were smart enough to put a nitrous on your Disco you will promptly blow the heads off the motor.
That said I wish there was a way substitute a Chevy block and then go with the aluminum heads or cast iron even.............this would increase the usefulness of the trucks, as the engine wouldnt be a weak link in an otherwise nice package

 

I've seen adapter plates and motor mounts for a GM small block switch.

Problem is, even a tuned down 350 would be too much horsepower for the rest of the drivetrain.