Driving to get fuel this evening my Low Oil Pressure light came on, which is unusual because this Disco usually has great oil pressure.

Within 2 blocks the motor started vibrating fiercely, so I parked it. I checked the oil level. Full. Coolant temp was also normal.


I'm thinking oil pump and time to replace the main bearings plus rod bearings (just because I'll already be in there... even though the rod bearings are new).


...but some of y'all have owned these trucks for a lot longer than my few months. I could be way wrong.

Could it be a worn/warped crankshaft and/or bad harmonic balancer or something else?

 

Was it also making any kind of noise as it started vibrating,?
How long since you replaced rod bearing's?

 

No unusual noises. EDIT: wait, before the problem began this evening I thought that I heard a "vacuum leak" or similar sort of rasping sound under the hood.

Rod bearings done 2000 miles ago, so pretty new. Definitely not a rod knock sound. I remember how that sounded!

Strong vibrations. Struggle to make any power.

 

Do I need to do a compression test and leakdown test?

 

What else was done 2000 miles ago? Sounds like you may have wiped a couple cam lobes. Or broke a rocker.

 

Could the rasping sound that I heard have been a loose timing chain?

 

I kept it pretty simple. Dropped the oil pan, replaced the rod bearings, then replaced the water pump and fan clutch/blades. Buttoned her up, filled her with oil, and have been driving for 2,000 more miles since.


Yesterday I replaced an O2 sensor.

Today I put in a different ECM, but that triggered the Immobilizer, so I put my original ECM back in and she started up fine. Surely unrelated to low oil pressure later this evening though, right??

 

I haven't had either of those issues in my past so I don't know how to respond/proceed.

Do I do more than remove the valve covers to see the rockers?

Can I inspect the cam lobes with a borescope?

 

I would say your rod bearings are highly suspect but it's very odd that there isn't any clacking involved.


Personally Im not a fan of bearing changes with the engine in vehicle. Not a good situation for control and its hard to take the appropriate measurements accurately. Should just pull it and do it right one time.

 

Upper intake and valve covers have to come off to see the rockers, lower Intake needs to come off for cam inspection.