ok then, well considering you can barely hear the noise, how long could something like this go before needing immediate repair?

 

Most likely for quite a while. It will get worse over time but I wouldn't hesitate to drive it.

 

I agree with Geotrash, put the oil pan back on and drive it, when it gets so bad that you have to shut it off at the McDonalds drivethru then do something about it.
Hell, it might go another 100k before you need to do anything.

 

just so everyone knows, i am going to attempt to change out the rod bearings. The bearing material is lead bronze, so hopefully, it is soft enough that the crank has survived. like i said, it is in its very initial stages, so we will see. I am going to post many pics so that everyone can see the results of my atf flush, and Dave "okdisco guy", that report was very informative you posted a link to. I wish I had read it beforehand!

 

ok well i pulled fuel injectors 1 by 1 and there was no difference in the sound. could it still be a rod bearing? the only remaining bearing seems to be the center shaft bearing. any thoughts?

 

I dont know man, I am at a loss.
Sorry.

 

I don't know that pulling an injector would prevent it from happening completely. A loose bearing may still be heard as the con rod changes direction.

You could also be hearing piston slap in a single cylinder. My 4.6 has plenty of it. My advice is to drive for another couple of months and see if it worsens at all. Nothing to lose at this point.

Dave

 

well i have replaced the rod bearings. They were worn, but no pieces missing. some were worn pretty bad. i put 10w40 in it and no knocking so far. everything seems good....tonight! we will see how it does over the next week or so. thanks everybody that has helped me.

 

Change the oil and filter again in 500 miles.

 

I just wanted to clarify some points in this thread in case anyone else needs to replace their rod bearings (big end bearings) in a Disco 1.

1. You do need to remove the steering stabilizer to get the oil pan out. In fact I had to also remove the oil pickup also, with the pan pushed aside as far as it will go, you can get to the bolts with a ratchet.

2. The big end bearings torque is 15 ft. pounds, then turn an additional 80 degrees. The other torque specs in this thread are for the main bearings.

3. The main bearings are made of the exact same material as the rod bearings. They are not roller bearings, and they are non ferrous. I just wanted to clarify this in this thread.

4. For anyone that wants to know, the con rods are machined, not cracked, so be sure to place the bearing caps back exactly as they came off.

5. I coated each bearing generously in oil when I installed. After I torqued, I rotated the crank shaft one rotation to ensure the bearing rotated smoothly.

6. I am not that strong, I needed a breaker bar with my ratchet to get the bearing caps loose.

Specs in case any one wants to know.

oil pan bolts: 1/2"
oil pickup bolts: 7/16" and put new o ring on!
bearing cap bolts: 10mm

everything went smoothly for me after a lot of reading and with talking to others here, I hope it goes as well for you. By the way, the bearing caps are extremely sharp from machining, I have a pretty hefty cut on the thumb, my wife thought I changed the tranny fluid also with all the red on my shirt.