oil pressure light & top end noise?

[Rover1]

1996 SD with 156K miles.
Had the oil light stay on after starting the engine this afternoon-about 40F outside and car was sitting for 5+hours. It finally went away before I started driving, but this is the first time in the cars 15yr history I have seen this. While researching this forum I was reading about a 'top end noise' and its possible association with the oil light...what exactly is this? I have been noticing the engine running rough above 55mph for the past week. I though it could be the rotoflex (which needs changing), but after reading some older posts I'm thinking this might be associated with the oil light? Any ideas?
I use synthetic Mobil1 10-30 (same oil for 10+years) and have never had the truck run rough like it has the last few weeks. Temperature is normal, even while driving in the mountains...
Thanks in advance!

 

[Lake_Bueller]

Sounds like a fairly common issue on the high milage Disco. There is probably sludge in the oil pan that is causing the pick-up to get pluged. As the oil "thins" with heat, the problem seems to disappear.

Drop the oil pan and do a good cleaning. That seems to be the best start. I've success on both my old DI and a friends truck.

 

[Ben]

I had a similar problem but it wasn't sludge. I had already cleaned the sludge out. What it was for mine was the oil pickup tube had come loose from the bottom of the block. As it loosened, it started losing pressure. At first it was a low-rpm tick. But warmed up and at speed it would still make enough pressure to run smooth. Over a couple weeks the tick got louder at idle and then the oil light started coming on at idle. If I brought the engine speed up, the oil light would go out.

I any event, the advice is to drop the pan and clean the sludge out of the bottom, check the pickup tube that it's tight against the block and the gasket is intact. Also thoroughly clean the pickup screen. It's probably full of crud, sludge, old gasket maker etc.

 

[Rover1]

Thank you! The ticking at idle is another symptom I have noticed over the past month. Never heard it before and never associated it to the oil sludge issue. It seems like this is indeed the problem. How do I drop the oil pan? Is this difficult to remove and put back together? Will check the oil pick up tube and screen as well...will check the Haynes manual for removing the pan.
Thanks again

 

[d1driver]

Removing the pan is easy. Just take all the bolts out. In order to get it all the way out though, it makes it easier if you jack the truck up by the frame to get the front axle out of the way.

Use "Right Stuff" when putting it back together.

 

[Rover1]

I was reading in the Haynes manual that I will also need to remove the steering damper as well as the panhard rod (or another rod, I can't remember which). Is this really necessary, or will I have enough clearance by supporting the vehicle from the chassis and allowing the axle to hang down?
Thanks!

 

[d1driver]

I didn't need to remove either on my truck to get my pan out. But I also have a 2" lift and my track rod mount is an aftermarket setup. If anything, you might have to take the track rod loose at the joint on the drivers side. No need to touch the panhard rod though. The pan goes in from the back of the axle.