97 Disco, 4.0, 90,000miles;
About a month ago I was driving on the interstate when I heard a knocking sound coming from the engine. It only took a few minutes at 70 miles per hour for it to go from a knocking sound to sounding like someone shaking a tin can of nuts and bolts. About that time the oil pressure indicator light came on. I pulled over as quickly as possible. I checked the oil level and it was fine.
After towing it home, I pulled the oil pump/timing cover off and checked it out. It looked fine. I pulled the oil pan off and other than a minimal amount of sludge in the bottom, it looked fine. I pulled of the oil pick up tube and it wasn't clogged either. I put it back together. When I started it up it quieted right down after a few seconds. When I test drove it, it ran good for about four to five miles then the sound came back. I let it sit for a day and went back to get it. About the time I got back home, it started again.
I decided to get a new oil pump/timing cover. After installing it, I test drove it about four to five miles and it started again. I then changed the oil from 10w30 full synthetic to 20w50 dino juice. Again after four to five miles it did it again.
I admit I haven't taken the valve covers off yet, but except for an unexplained red tint, it was very clean in the crank area and the timing chain area. I can understand how flakes of burnt oil can clog the oil pick up tube, but it is a coincidence that it does it evey time after four to five miles? Any ideas that I am missing? I thought about driving it four miles at a time until I got to a dealer to trade it in, just kidding.

 

possibly a spun bearing. Oil can be seeping into the bearings eliminating the friction temporarily until they dry out and start banging around.

I had a spun bearing on my 98 Cobra with only 6k miles on it and I even changed the oil every 3k miles. Ford dropped a new engine in and it was fine till I sold it.

 

If it was me I'd hook up a mechanical pressure gage to the front timing cover oil galley (remove the pressure sensor), and then start the engine and let it come up to normal temp. Then bring the engine speed up (2-3K is plenty)--and down-- and look for needle flucuations (actually quick "flutters" of the needle) as you are loading and unloading the bearings. This is a dead giveaway that the mains and/or rod bearings are not maintaining the clearance to keep steady oil pressure. This is only a test. If you have this condition do not drive the vehicle any more or you risk spinning a bearing and possibly breaking a rod!

Regards,
Geoman

www.eurotekapg.com

 

I agree, do a pressure test ang get a better idea what is going on.
I have a friend that just went thru a similiar issue with 150,000 miles on his Disco and after doing all you did and more, he removed the oil pressure regulator and but 2 washers behind the spring. Pressure popped right back to where it belonged and we are going to be giving it a good run early next week to verify.
Mike

 

Thanks for the info. I will give it a try and let you know what I find out. You would think with a vehicle like these, Land Rover would put in oil pressure guages instead of idiot lights.

 

Why, most people don't know how to read them or what the pressure should be at anyway. So few people even read their owners manual, the manufactures know that so they just throw in some idiot lights.
Take care,
Mike

 

Mike,
I was curious, how did your friends test drive turn out?

 

Not like we were hopping, pressure started dropping again, took it home pulled the pan again and while looking around found that one of the cam bearing was slipping out and dropping the oil pressure. Now he is not sure if he is going to chance replaceing the bearing and probably the cam and lifters or buy another used engine.
Mike

 

That's common Mike. Remember 30 year old equipment machined that block. The bushing slid for a reason, probably incorrectly line bored. If your friend tries to to just replace the bushing have him center punch the slipped bearing bore to increase the interference fit. Also need to line up the oil feed holes if it is a feed bush.
Very few if any good used engines out there. If in warranty it would get a short block. Hope that helps

 

Thanks Bait.
Yes we have talked about it, he hasn't made a decision yet. His biggest problem right now is time, he is supposed to be leading a couple of runs in Moab this month at the yearly get together.
Take care,
Mike