03 PATHY complete engine rebuild Q'S

A forum for the legendary Nissan Pathfinder and Infiniti QX4.
850pathfinder
Posts: 26
Joined: Tue Jun 14, 2016 7:44 am
Car: 03 pathfinder SE

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My timing chain install went very wrong. The exhaust cam 24mm hex built into the cam to hold it still rounded off. The exhaust sprocket is permanently stuck to both exhaust cams. I was using my 1" impact and needless to say the cam hex head gave before the the exhaust cam sprocke bolt. I spun the cam around before i could pull the socket off and broke the #1 exhaust valve in half. Great now add another 8 hours to remove the engine due to how hard the the transmission bolts are to get. Along with the passenger side manifold to convertor connection, it was not an easy task. Well i get the engine out and flex plate off and get the engine mounted to the stand. Here i start finding problems. i find black exhaust soot around the back of the block starting from the back rear portion of the exhaust manifold. no cracks so im guessing bad gasket. Leaking rear main seal. severely torn motor mounts. and the drivers side catalytic converter has what looks like a perfect ice cream scoop out of the center of the catalyst. All 6 soark plugs were covered in soot except for #4, which was white and severely degraded which i attribute to detonation.

While im still at tdc and the cams removed i run a leak down test on cylinder 4 and its at 60% loss and all the air is escaping into the oil pan... Now i know my one quart every 500 miles is due to bad rings. so i begin to remove the cylinder head knowing im going for a full engine tear down. I knew the combustion chambers were going to be dirty but i still wasnt ready for what came out. when i removed the passenger head.
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It was worse on the other side. SO i get the heads off and then work on the oil pan. Get the oil pan off and the tarnish was absolutely disheartening.
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with the pistons removed there was light scratching on the main and rod bearings. the piston rings were completely frozen in the pistons with carbon. I had the timing covers, block, rods, and pistons sent to be hot tanked and and inspected. Although the ring ridge wouldnt catch on my finger, the machinist said that if he has to ream the ridge he'd bore it .020" over. I told him no, to ridge ream it and hone it and check the clearances

So heres the question should i stick with oem nissan rings for almost 170$ or go with another brand like npr or ???


barnaclebob
Posts: 249
Joined: Tue Feb 10, 2015 2:55 pm
Car: 2001 Pathfinder LE
2011 Altima SR

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I think you are way over the heads of most people here including me. Good luck.

850pathfinder
Posts: 26
Joined: Tue Jun 14, 2016 7:44 am
Car: 03 pathfinder SE

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ehhh it was worht a try.

For a little update. I picked up the block today from the machine shop and was told everything was perfect. Cylinders, rods, and crank were all well below wear limits with cylinder out of round was off by .0008". Thats pretty much amazing for a block with 160K on it. There was no taper on any crankshaft journal and with a micropolish, it completely removed and fine scratches in the journals. My machinist didnt have to remove and ridge ream because they were non existent and the new crosshatch he put in was nothing short of perfect 60 degrees.

Heads are still being worked on and i still have some parts to order. One of the upgrades is the 2006 vq35de revup oil pump. Same price and a much better pump. OEM rings and head gaskets, rear main seal, OEM timing chains, tensioners, guides, and all orings. Fuel injectors are being ultrasonic cleaned and new O2 sensors. Should run like a kitten

With the block and crank codes my main bearings are going to be 3, 5, 34, 45. and rod bearings are 1, 1, 2, 2, 2, 2.

MisterH
Posts: 305
Joined: Thu Mar 03, 2016 5:04 pm
Car: 1999 Infiniti QX4

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When you're all finished with it I wonder if you could provide the total $ in parts and machine shop work you spent doing it yourself. Thanks!

850pathfinder
Posts: 26
Joined: Tue Jun 14, 2016 7:44 am
Car: 03 pathfinder SE

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i sure can. ill provide a list of part, manufacturer and price.

850pathfinder
Posts: 26
Joined: Tue Jun 14, 2016 7:44 am
Car: 03 pathfinder SE

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Heres the cross hatch and journal micro polish the machine shop did.
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EdBwoy
Moderator
Posts: 3352
Joined: Tue Dec 25, 2012 12:47 am
Location: Indiana, USA
Contact:

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Well, I've replaced engines and done quite a lot of assembly, but with regards to designing rebuilds, you've got more to teach me than I can offer you, heh.
All I can advise is to remember to threadlock your power valve screws if that isn't done already.
850pathfinder wrote: 1... One of the upgrades is the 2006 vq35de revup oil pump. Same price and a much better pump.

2.. With the block and crank codes my main bearings are going to be 3, 5, 34, 45. and rod bearings are 1, 1, 2, 2, 2, 2.
Some questions for curious minds, why is the revup pump better? Flow/pressure?
Also, what are those numbers for the bearings referring to?

850pathfinder
Posts: 26
Joined: Tue Jun 14, 2016 7:44 am
Car: 03 pathfinder SE

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So no real new updates except DONT EVER BUY VICTOR REINZ HEAD BOLTS. !4 out of 16 were curved brand new out of box. some couldnt even be turned 5-8 turns before seizing.

Upgrade to the 350z VQ35HR head bolt. SAme everything except 3mm longer and 3 extra threads for grip.

Got all bearings in and plastigauge. mains ranged from .0014-.0016 which is right in the .0014-.0018" clearances. Rods were between .0015-.0017 which is well within the .0013-.0021" range.

The vq35de REV UP oil pump also went on without a hitch.

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