Tackled the big end bearings today - almost. The very last bearing that came out of the new set of bearings had a large gouge across the bearing surface, rendering it useless. Fortunately, I'll be getting another set Monday AM from WorldPac so I can wrap up the job. It's just frustrating, as I was hoping on completing the job today.

I found replacing them to be relatively straightforward, and the ones that came out exhibited moderate wear on the lower shells, and significant wear on the top shells - every top shell from the rear of the engine to the front was worn through the babbitt to the brass across about 1/3 of the bearing shell surface.

Otherwise, the interior of this 4.6 is very clean with almost no sludge, and I imagine it should run quite nicely once I can start it again.

 

Some pix would be nice. Also consider a before and after oil PSI measurement. The valve train, if also worn, can hold down oil PSI significantly. That oil pickup needs a new O ring and Locktite on the bolts that will hold it back in place. How many miles on this truck?

BTW, doing the oil pump gears?

 

Only have one pic that I took today of the back 7 top bearing shells - sorry! You can see a few of the bottom shells too. Crank journals were nice with no ridges.

The only pre oil pressure readings I have are as follows:

Cold: 50 psi at idle and 2000rpm (taken off my GlowShift electric gauge - and I just installed it today so who knows if it's right)
Warm: 15 psi at idle and 40psi at 2000rpm (taken by my mechanic's mechanical gauge a month ago)

Definitely renewing the oil pickup seal as well. What color Loctite for the oil pick up screws?

70K miles on the truck, oil pump has already been replaced.

Thanks!

 

Were there any low end knocks at idle?
Are those gone now??

How many miles on the engine??

I am sure my Discovery I needs to have mains and connecting rod bearings replaced at 166k miles.

The Discovery I has a slight knock.

And, I did have antifreeze in the oil and bronze looking bits in the oil around 139k

I am probably running on luck with the Discovery I now with respect to the main bearings.

Well, good you did not spin one and you caught it in time.

Great work.

 

Hi Jfall,

No knocks at idle. There was noise at cold start at both idle and load, which then disappeared when warm at idle and remained under load. We'll see if this has rectified that...on Monday.

The rods were relatively simple, and my friend's Snap On digital torque wrench with angle measurement made it a whole lot simpler than it would have been otherwise (as did his lift).

 

Can't wait to read about result. I have the same symptom and this is where I've been leaning toward.

 

I will also be interested in the overal improvement of your engine.

Buzz, how many miles were on the engine you pulled these pictures from?

 

I'll certainly report back.

Two quick questions:

1 - What color loctite for the oil pick up bolts?

2 - I have a theory about a new method for priming the oil pump. Tell me if this makes sense: once the oil pickup is reconnected, and before the sump is put back on, I stick the pick up in a bowl of fresh oil, and then turn the crank slowly by the pulley until I see oil coming out of the bearings. Then put the sump back on, refill with oil and start it up. What do you think?

 

I don't think you really need to go to those extremes, just fill your oil filter as much as you can and you will not experience any dry starts.

 

UPDATE: The job is done.

Prior to replacing the connecting rod bearings, the engine exhibited the following noises under the following circumstances:

Cold at idle: Moderate, constant "piston slap" type sound (ie, diesel-like sound with mild knock - the knock sounded like lightly hitting a hollow wood block)
Cold under load: More pronounced "piston slap" type sound with mild knock
Warm at idle: Little to no sound
Warm under load: Mild knock

After rod bearing replacement:

Cold at idle: Quieter, and "piston slap" sound is not always present.
Cold under load: Still some diesel-like noise, but no knock.
Warm at idle: Dead silent
Warm under load: No knock, still seems noisier than a typical V8 to me.

Oil pressure now:
Cold idle and 2000rpm is 50psi
Warm idle is 15psi
Warm 2000 rpm is 50psi

Overall, I'm pleased with the results. Clearly, the rod bearings needed replacement given the wear, and they were likely the cause of the mild knock that the engine exhibited. However, the diesel-like piston slap noise remains when cold. At this point, not sure if it is an issue with the engine or my mind.

One more thing to add: this engine was surprisingly clean inside. Very little sludge buildup, and everything else looked new. There was a label from "Land Rover Parts" with a serial number on the front driver's side of the engine, and the timing cover was painted. The previous owner was a Land Rover tech's daughter. I wonder if this might have a replacement engine in it? The truck itself only has 70K miles on it.