Peter here in Alaska. I've been reading the forum for years, and this is my first post.

My 2003 disco II was purchased in 2013 with 64,000 miles. I paid $4,000., buying it from a diesel mechanic. He loved the truck, his wife hated it, he felt the ticking was undoubtedly just a lifter.

And yes, the Disco had a notable tick, had many of the other annoying problems. The usuals like bad switches, leaky sunroof and plenty more. With aggressive oil changes and many small general repairs, I got the truck to run well, was a daily driver and dependably made numerous trips into the Alaska bush. I came to love the truck and its off-road and snow performance. Last April with 142,000 miles, the tick became impressively consistent, and just before I talked a local mechanic into helping me pin the cylinders, the oil pressure light came on.

So... we pinned the cylinders, replaced the oil pump (it was cracked in two), new timing chain, and new rod bearings. Put her back together. She sounded great, ran her 75 miles, and the oil pressure light returned. We check the sender, then installed a gauge. The truck starts with 50lbs cold and in about 5min after reaching operating temp it drops to below 7-5 pounds. Oh yes...she still ticks although quieter, my guy also believes its a lifter.

In a last-ditch effort, I found a 2001 4.0 with 110,000 miles in Fairbanks from a yard for $500. We thought that we just drop it in, get the truck back on the road and possibly rebuild the engine later. When I arrived in Fairbanks (250 miles each way), the guy said the motor's compression test was from a sold engine. This 4.0 had inconsistent compression ranging from 145-111. He offered it to me for $200.00, and I hauled it home. We have not touched the 4.0. By June I had to replace the truck and almost bought an LR3, but ended up with a 2008 Mercedes 350 CDI diesel. FYI, the average 25 miles to gallon has been sweet.

I have decided that the 2003 Disco really suites my summer business as a wilderness fly fishing guide. There are off-road places where I have to launch my jetboat, and very few other trucks would work. Also, my clients just loved being hauled around in the Disco, so I am about to rebuild the 2003.

Next week we will pull the 4.6, pressure test both engines, decide and order the parts. I am ready to work with either engine, or parts of both, but I'm leaning on rebuilding the original. Both have secondaries on the heads, and my 4.6 never ran hot or leaked coolant. Also when we pulled the 4.6 pan, we found plenty of sludge and what we believe are two small fragments from the rings.

The goal is to have an excellent running engine for a 100,000 miles.

I'm sure you guys have some thoughts??

Just a note: Shipping to Alaska is a nightmare, so must use what I have.

 

I'm confused, which 4.6? I thought you had 2 4.0's. Choose the 2001 4.0 over your orig. 2003 4.0.

 

Lisa, the 03 would have a 4.6 from the factory.

AK, when you replaced the oil pump did you also replace the front cover? If not, pull the front cover off the 4.0. If the oil pump is in good condition and the front cover is not scarred, try putting that front cover on the 4.6 to see if that fixes your issue.

 

^^^ Yup!

With new rod bearings and oil pump you should have good oil pressure, especially with a new front cover (presuming oil pickup tube is clean).

Of course, a simple thing to try first might be a better oil filter.

If you do a new front cover then also clean/check/repair the emergency oil bypass?

 

I would like more info on what method you used to pin the cylinders, please.

 

[QUOTE=Alex_M;626040]Lisa, the 03 would have a 4.6 from the factory.

I knew there was a change to the engine in 03, didn't know it was a 4.6 change. Wow.

 

Walked cam bearing is probably your oil pressure issue.

 

Agreed the cam bearings have to be the culprit at this point. When we take it apart, we will also replace the mains and the rod bearings once more. One note, the rod bearings were well into the copper, not the worst he had seen but definitely in bad shape.

Transfering the front oil cover is a really good idea. Thanks!!!

We did check the pickup tube and the bypass. The oil was changed twice after the repair, the second time with 40w racing oil just to see if it made any difference. It didn't.

I drove this truck nearly 80,000 miles with meticulous oil changes, and the inside of the engine was nasty. The pan was full of sludge and just filthy everywhere. Just goes to show how important those first 60,000 miles of care can be. After checking bearings and a cracked oil pump we were sure we had nailed the low pressure issue. No so much.

 

Davis regarding the pinning, I'll post a few pics below. We installed one pin in each cylinder, not two. We also removed more ancillary stuff to improve access. Once the pan was off, the starter (a real pain) and the manifolds, it only took about six hours to insert the pins.

We sat on milk crates for three hours talking about the process and rechecking the engine before the first hole. After the first one, it went pretty fast. First hole set, second one drilled. Note the blue towel inside the hole.
The stud was locked in place with one nylon lock nut and backed up with a second nut. Both stainless.
We rounded off the end with a concave finish. The installed stud rests just under the surface of the cylinder wall.
Three cylinders installed.

 

Abran, wouldn't a walked can bearings also show low pressure when cold? That's just my speculation; I haven't had that problem yet so I don't know.