2000 frontier knocking

[luisrivera]

I have a 2ooo frontier with the 3.3 liter v6 with 260k on the odometer. Engine was rebuilt (because it overheated but car was fine in the bottom end) prior to me getting the vehicle. Crank shat was cut .25mm but i believe it was not machined properly. The engine knocks a bit past 4k rpm. I replaced oil pump with new OEM since it was not done when rebuilt, knocking was quieter but still there. I opened crankcase and revised every rod and retorqued and crankshaft and bearing were in great shape, not one scratch. I did not check the mains but I believe the problem is there. BTW I did not notice any metallic residue when i did this and I was running a 4k OCI. I have been adding a lucas oil treatment with every oil change with 10w 40 and it helps the noise but at $10 a pop for Lucas I am looking for options. I am planning on running 3qts 20w 50 and 1 10w 40 with no additive for 3k oci and want to see what happens with knocking. Also when oil temp is normal with no additive lifters start sounding off, I believe its due to the crankshaft not being machined properly and it has a pressure leak so its looses pressure up top. I wanted some opinions.

Thanks

 

[KB2008X]

Thicker oil is a good diagnostic tool for bottom end knocking noises. I think your plan is a good one, considering your location. Thicker oil, no additives, and then re-evaluate.

How did you wind up with a vehicle with these kinds of problems ?

What is the "pressure leak" you're referring to ?

If you're dead set on keeping it consider getting a good junkyard engine, assuming that is feasible there, or sell it on the other side of the island to someone you'll never see again. That may also require a name change.

Keith

 

[jjcom]

A heavy oil should be able to help mask the problem, but it's not going to be a good long term solution. I would hook an oil pressure gauge up to it, and see where it's at right now. The mix you've got in there should be pretty heavy, and if it's not anywhere near enough oil pressure, I doubt your new mix will be enough to help anything.

Also, since it was recently(?) rebuilt, it might be worth fixing the problem correctly. It's a good sign there's no metal floating around, but the extra wear and tear on the cam, lifters, and all the other bearings may show itself sooner than later.

I believe what he means by pressure leak is, with the crankshaft machined poorly, it's losing oil pressure in the bottom end. This leaves a "leak" for the oil that should be going to the top end. Normally when a car spins a main or rod bearing, the lifers start making a racket since they're no longer receiving good oil pressure.

 

[luisrivera]

The pressure leak I refer to is and again only my theory, I believe there is some clearance in one of the mains and that causes the drop in pressure for the top end. Now when I use heavier oil the lifters and additive they quiet down because the clearance is filled.

as far as why I got into this car, was a combo of my mistake and a need. I had a 08 Mitsubishi Lancer (non Evo) that was a lot of to drive but very unreliable and at the time I was building my home and needed a small pick up. I have a small child and one on the way so I figured a crewcab would be best for my situation. When I test drove it i didn't push it hard since it rode really nice and shifted properly. After speaking to guy who rebuilt it I felt very comfortable with the situation since the owner according to the mechanic the owner is a hippy (my abservation as well)and never really pushes the car. The car idles nice and quiet hot and cold no knocking. Crewcabs a very very expensive in PR and this guy gave me a very good deal for the Lnacer which I was dying to get rid off

What I most likely will do is buy a short block and locally and just rebuilt it with a new OEM crankshaft, bearings ect. I mostly use this car to go surf and fishing and the ocasional trip to the race track with my son. I mostly ride a scooter to work.

 

[luisrivera]

BTW as far as oil goes I use anything that's on sale with any filter but orange can fram