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Loud knocking coming from engine


deltantor
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Was driving my '90 pathfinder a couple of days ago and went to pass another vehicle...revved up to 5000rpm, passed them, and then the vehicle stalled. Pulled off to the side of the road, and tried to start it back up to no avail. Tried starting it at wide open throttle and was able to, then let off and it stalled again. Started it back up the same way and drove about a quarter mile to a parking lot so I could get a tow home. The tow was about 3 hours away, so I had my father come over and we started it up, and it had a really loud knocking sound and a good bit off smoke pouring out from the tailpipe and a small bit from the engine compartment. Let it run for a minute, and then drove it home like that. Right now it is starting normally, but I still have an extremely loud knocking and you can hear it really well at the oil pan, sounds like it is coming from the engine block. No smoke anymore as well. I'm thinking that it is a bad rod bearing, but wanted to get some input. Considering doing an engine rebuild, any info on that would be great as well.

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Does it sound like this?

 

 

The problem was this:

bearing.jpg

 

Yeah...Pretty spot on to what it sounds like. Oil levels were fine, and we had just recently done an oil change. Not sure what caused it, but I'm thinking there was a good bit of gunk and grime somewhere in the engine that starved certain parts of oil. This was an engine we had pulled from a '92 pathfinder and put in our '90, it had run perfectly for about a week and then this happened. Really wish I ran that can of seafoam through it now...

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I spun a main bearing on the crankshaft and that is how it sounded. The 'gap' in the bearing was now allowing the piston to hammer what remained and nearly destroyed the crankshaft.

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Engines spin bearings... it happens. I tore apart a 40K mile VG (different engine that the vid/pic) that was toast because some asshat stuck thick grease in the crank case to maybe "up" the oil pressure. All it did was quickly get sucked in to the sump when the engine warmed up and stop all oil flow. Didn't take long at all to destroy everything.

 

Any movement on a rod is going to knock pretty bad. My NO. 6 rod had about 1/8" of slop and it sounded like that.

Edited by Kingman
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Alaska doesnt have smog right? Replace that weeny engine with a gm one and you wont ever have a problem again, really I did it. If you want to rebuild this engine then by all means go ahead. How many miles are on your engine and what weight oil were you using just for laughs. vg's are gutless but are pretty hard too kill for a stock engine.

 

Best of luck patching your truck back togeather.

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Alaska doesnt have smog right? Replace that weeny engine with a gm one and you wont ever have a problem again, really I did it. If you want to rebuild this engine then by all means go ahead. How many miles are on your engine and what weight oil were you using just for laughs. vg's are gutless but are pretty hard too kill for a stock engine.

 

Best of luck patching your truck back togeather.

 

We had 5W30 in the engine and it had about 130,000 miles on it, had another engine start go bad and swapped this one in from a 92 pathfinder we bought to salvage off of. First engine had what sounded like a stuck lifter in it that just got a LOT worse, had a pretty bad metal on metal tapping sound coming from the head when it went bad, haven't pulled it apart yet to see what happened, but that will probably be the one we rebuild if thats the path we go.

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We had 5W30 in the engine and it had about 130,000 miles on it, had another engine start go bad and swapped this one in from a 92 pathfinder we bought to salvage off of. First engine had what sounded like a stuck lifter in it that just got a LOT worse, had a pretty bad metal on metal tapping sound coming from the head when it went bad, haven't pulled it apart yet to see what happened, but that will probably be the one we rebuild if thats the path we go.

dude that sucks. Pick up a vg33 rebuild it or at least give it a good inspection and go with that. Not much diff in the gas mileage.

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I think you should find a Hardbody with a KA24DE in it, get the wiring harness, motormounts and engine and swap that in there and document it really well so I have a clear idea of what I'm looking at getting myself into lol. I talked to a mechanic and he was telling me that the VGs are notorious for valve noise even on freshly rebuilt heads because they are shimmed or something. I hope that you can get the engine rebuilt fairly inexpensively and get your Pathfinder back on the road!! Good luck!

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The valve noise comes from the lifters. Most people screw those up because they don't know that the lifters need to be kept in oil and that they have a wear in procedure. Just check the FSM.

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Not shim the heads, shim the buckets that go over the valve springs. I don't know exactly, I have never taken a VG30 head apart. IIRC correctly even my DOHC Saturn had rocker arms. Like I said, that was just what the mechanic told me. I will probably build the VG30 for a sand rail or something after I pull it out of my Pathfinder. I had a 1985 300ZX several years ago and I have a love for the Nissan 6 cylinders from 240Zs to 300ZX Twin Turbos. I just don't like the VG30 in my Pathfinder because it takes up too much space to be easy to work on. I definitely need to download the FSM when I get back to the States! Sorry if I was misleading, I was trying to help out with what I heard from a reliable mechanic (seems like an oxymoron lol). Definitely didn't mean to tell someone else's lie.

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There's no shimming of anything on a VG head. They are hydraulic lifters, way different than the buckets on KAs and you can't adjust them. They tick when there's no oil in them or they're poorly installed.

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Ok, well thank you for clearing that up for me! I guess the mechanic I talked to had no idea what he was talking about when it came to VG heads. Sorry for the misinformation and thank you for enlightening me!!

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There's no shimming of anything on a VG head. They are hydraulic lifters, way different than the buckets on KAs and you can't adjust them. They tick when there's no oil in them or they're poorly installed.

 

Interesting, the first engine we had in our pathfinder had a ticking noise that we just guessed was a lifter, but didn't think it was anything too bad, so we drove it about 500-1000 miles until the ticking turned into a loud tapping in the head. Starting to pull that engine apart because it is the one we are going to rebuild, and noticed one of the rocker arms was pretty black while the others were a nice copper color. Interesting.

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old pathfinder lifter tick is just down to old, sticky lifters. BMW's have similar issues. If they tick, they're just not happy, you're low on oil, they're getting older and more sticky, or it's their time of the month, is all.

 

Mine always ticks loudly on a cold start for 4-5 seconds, and then just disappears. never been a problem.

Edited by Honeybadger
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old pathfinder lifter tick is just down to old, sticky lifters. BMW's have similar issues. If they tick, they're just not happy, you're low on oil, they're getting older and more sticky, or it's their time of the month, is all.

 

Mine always ticks loudly on a cold start for 4-5 seconds, and then just disappears. never been a problem.

 

Same thing mine does. If it's below 0*f overnight, it'll usually tick for a few seconds when I start it up. I'm running 10W30; it might go away with a thinner oil.

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Typical hydraulic lifters bleeding down overnight. The worst ones are in the Rodeos/Passports with the V6. Those things clatter like no other, always!

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Well, we have pulled apart the first engine that had noise in the head, looks like one of the heads was in pretty bad shape and the valves looked pretty beat up. We are currently considering using parts from both engines together to get one up and running until we can rebuild the other. Any input on this? Thinking the 92 engine with the rod knock will just need the bearings from the 90 engine and possibly the crankshaft if that got beat up. Pulling the rod knock engine out tomorrow and pulling it apart to figure out exactly what is happening.

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First engine had what sounded like a stuck lifter in it that just got a LOT worse, had a pretty bad metal on metal tapping sound coming from the head when it went bad

 

That sounds like either a bad rocker arm or a lifter that has fully collapsed and holds zero oil pressure to maintain valve lash.

 

shim the buckets that go over the valve springs. I don't know exactly, I have never taken a VG30 head apart.

 

This is true of the DOHC VG30s, the VG30DE, DET, & DETT. They use shims under the buckets to adjust valve lash. The bores the cam followers (buckets) slide in wear out turning the heads to garbage. The DOHC VGs are no where near as durable as the SOHC engines. They have many problems, though they're still better than 75% of the competition.

 

old pathfinder lifter tick is just down to old, sticky lifters. BMW's have similar issues. If they tick, they're just not happy, you're low on oil, they're getting older and more sticky, or it's their time of the month, is all.

 

Mine always ticks loudly on a cold start for 4-5 seconds, and then just disappears. never been a problem.

 

Use Chevron oil, it's the most detergent commonly available oil. Or run half a quart of Dexron ATF in place of half a quart of oil all the time. VG heads run really hot, and this causes sludge buildup. The heat also makes gunk build up inside the lifters causing them to stick and/or wear prematurely.

 

Well, we have pulled apart the first engine that had noise in the head, looks like one of the heads was in pretty bad shape and the valves looked pretty beat up. We are currently considering using parts from both engines together to get one up and running until we can rebuild the other. Any input on this? Thinking the 92 engine with the rod knock will just need the bearings from the 90 engine and possibly the crankshaft if that got beat up. Pulling the rod knock engine out tomorrow and pulling it apart to figure out exactly what is happening.

 

Why don't you use the bottom end from the 'old' engine and the heads off the 'new' engine? That would make the most sense, it'd only cost you a gasket set. VGs have very tight bearing clearances. The tightest of any production engine that I'm aware of. You can't go swapping bearings around between them and expect them to live more than a few minutes. These engines are known for their amazing longevity even when run hard and/or abused. They live so long because they were produced with extreme precision. Their only real weakness is oil starvation. They cannot tolerate it at all. If your oil pressure light ever blinks under braking or cornering loads stop and add oil IMMEDIATELY or you will kill your VG.

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