They are not exactly identical and the Buick engines were made in the early 60's so parts are going to be hard to find anyways.

 

So they are different then the later buick and cadillac 4.6l engines from the late 90's and 2000's?

 

The Buick/Cadillac engines that you are talking about are not even aluminum. The Land Rover 4.0 and 4.6 engines come from the Buick 215 designed in the fifties and used in a few small Buicks and Oldsmobiles in the very early sixties. Rover bought the rights and has used the design for 40+ years.

 

ok. so there is no way around having to buy a used rover engine to put in this? If rover uses the same block as the buick's, does that mean the transmission bolts up the same as the buicks?

 

You are greatly mis understanding what people are telling you.
Originally the engine was a 215CID used in a Buick, it was aluminum and light.
That was the late '60's.
Buick sold the engine to Mercruiser, they used the engine as inboard motors for big boats.
Then Rover bought the engine in 1970 or so.
What these guys are saying that you are not understanding is that the engine block is the same basic design as the 1960's engine.
Rover started with it as a 3.2L engine, then it went to a 3.5. 4.0, 4.2, 4.6.
They are all the same engine block in basic form.
You can use any Land Rover engine that has the BOSCH engine management system.
That means a engine from a P-38 Range Rover (Google it) or any other year DII will bolt right in.
NOTHING ELSE WILL WORK, no Ford engine, no GM engine, NOTHING!
You cannot use a engine from a '08 Land Rover, you cannot use a engine from a '94 Discovery.
There is a place in the UK that will sell you a complete engine for under $5000 shipped to your door.
Honestly, if your brother held the title it is his problem and he needs to pay for the repairs.
Since he is a complete idiot for driving with the oil light on he needs to fork over the money or I'd take is *** to court.

 

ok. got it. I just went out and added 5 quarts of oil (that's how much it took to get up to the bottom of the "add oil" line) and started it up. It seems to run alright. The engine is a little loud and sounds like it isn't getting oil. I shut it off after about 3 seconds. I looked through the service history and the dealer and once replaced the oil pickup in the pan because it was "deformed and picking up air". I'm going to drop the pan and see what that looks like. Is that a common problem with these? If that isn't it, I'll pull the timing cover and get a new one from rover (after doing a compression test on the cylinders). They sell an updated timing cover and oil pump right?

 

You are greatly misunderstanding what is wrong with this truck as well.

Forget an oil pump problem. Your bottom end is toast. Running with no oil or oil pressure will wear out the rod and main bearings in no time, certainly less than 200 miles. No matter what shape the oil pump is in, you WILL NOT HAVE APPROPRIATE OIL PRESSURE with trashed bearings. Not to mention the other problems of having trashed bearings. And not to mention it only had a quart of oil in it. With that little gem, I'd say the shop was wrong about the pump anyway.

If what you are posting about the condition and history of this motor is accurate, the motor is trash, and your brother in law is pretty much as uninformed as one can be about vehicles. He also sounds like a loser for breaking it and then "giving it back to you." It needs a complete tear down, or another motor. Not a new band aid stapled to the front of the block.

 

At this point, I'm not sure what the other shop did to check it out or do. I'm going to drop the pan and check it for metal residue and check the main and rod bearings while I'm down there. I'm just going to ignore what he told me, and what his version of the mechanic told him was and start from scratch. Thanks for your help. If the bearings look good and the bottom of the oil pan isn't filled with metal sludge, then I'll move forward and figure out what the oil pressure problem is. If bearings are trash or there is metal in the pan, then I'll start hunting for a new engine. Thanks again for your help.

 

Go back out, start it back up and the go inside the house.
Before bed g remove the key from the ignition because the engine will be seized.
As it is right now it is a boat anchor, might as well finish it off.

Sounds like your brother in law drove it for 6 months without ever checking the oil and it ran out of oil hence the oil light coming on.
He is a tool, he needs to pay.
If we were neighbors and I borrowed your lawn mower and I broke it, I would pay for repairs or buy you a new one, he needs to do the same.

 

You can't evaluate main or rod bearings by a visual inspection without removing the bearing caps. Again, complete tear down.

No offense meant, but from this thread it sounds like you are in way over your head here. Worse than not knowing, you are making incorrect assumptions about things that will lead to nothing other than wasted time and money.