2003 Disco 2, 120,000 miles on it.

Never had any issues overheating or anything, but I'm doing preventative work. I just finished a top-end reseal with new valve cover gaskets, all new cooling hoses, coils, plugs, wires, etc.

Now I'm off to the bottom end, where I have a pan gasket leak.

I'll be replacing the timing chain, gears, & oil pump. Since I already have the pan dropped should I at least do the big-end bearings, if not the mains?

 

If there's no knock and you have decent oil pressure then I would say leave them alone. If they were wiped out they would let you know. From what I've read, with regular oil changes the bearings on these engines will hold up pretty well. The cam and lifters are a different story.

The waterpump should be changed while you have it off if it has some miles on it. And if you're buying parts now, Atlantic British has a 20% off deal going this weekend. Might want to pick up one of the expensive pieces from them. They carry the waterpump with the bronze impeller by the way.

 

i would agree; if you do not have an oil pressure problem now. I would just replace the pump & timing chain .

 

Yup...don't worry about the bearings in the bottom end unless you've got issues there. Oil pump yes - bearings no.

Oil pressure gauge should be mandatory for anyone that cares about the longevity of their Disco.

That's my .02

 

An old rover mechanic once said he'd never seen a rover crank that didn't need to be turned. So if you do pull the caps to look at the bearings, you'll probably see that the crank needs to go to the machine shop....to be ground or at least polished.

I guess they all wear at different rates depending on how they were maintained but, on the two engines I have here, one with 110K and the other unknown mileage, both have main bearings that are pretty worn and scratched and big end bearings even worse with copper showing on all.

One crank needs turning and the other needs at least polishing and probably tuning as well.

They may have made it for a good while longer but, I just wanted to put new bearings in anyway, since I have the engines out and am putting most everything new.

If I were in a hurry and needed the trucks I probably wouldn't have even looked at the bearings.

So... unless you are planning to go all the way, don't even look.

m2c

 

your rods and mains bolts are also STY bolts, so once you open it to peak you will need to replace them. leave the lower end until 200k

 

Do the rod and main bearings. Or at the least, do the main bearings. You wont need to polish or cut the crank. Check out my write up. I have done 4 sets so far and have not had any bad wear on the cranks, but every one had totally wiped out main bearings. The rod bearings seem to hold up much better, but for an extra hour and 50 bucks, why wouldnt you replace them?

 

I guess I've been hanging out with perfectionist types who would polish the crank if it had a scratch the size of a human hair and both of these I have here are way past that.
Maybe the siliconized aluminum bearings they make for backyard builders will polish out scratches that builders used to have polished out by a machine shop???

 

When you look at fixing things, you have to think a lot about about why and how, and not so much as what the book says, or what is the "official" way to do it. If you replace your crank bearings, you will increase your oil pressure and keep wear on other parts to a minimum (rocker shafts, cam bearings). You're not going to touch the crank because you MAYBE lost .0005 (if that) off the metal of the crank, but you lost most of the babbitt off of the bearings. If you have gouges in the crankshaft that go all the way around the surface of the crank journal, they will just fill with oil and not make any difference at all. The crank floats on the oil being pressed between the bearings and itself, all you are doing when you replace the bearings is putting the metal closer to the metal making it harder for oil to escape. Grinding the crank and undersizing the bearings is big diesel engine/racecar/1938 rolls royce stuff, where your big diesel crank costs 4000 dollars and has 1.2 million miles on it, or your forged 350 crank that has been spinning at 8500 rpm for 4 seasons is missing a lot of meat. Or that 1938 Rolls barn find crank is rusted solid. You can reuse all the bolts in the bottom end, I have and do all the time.

 

Well there you go. I've only worked on one of these, he's worked on 100's. My P38 4.6 had great oil pressure and was smooth and silent with 130k on it when I sold it, and my current D2 has great oil pressure too but there's only 53k on the mains and rods.

Just out of curiosity, when should replacing the bearings be considered? I know low oil pressure is a good reason but if you pull the pan for a gasket change at 100k would you replace the bearing too?