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1995 Nissan Pathfinder 4wd never ending tapping noise.


Merzed62
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My son just told my wife to put full synthetic engine oil and the usual oil filter and air filter for the usual oil change. After the the process, we started the engine and viola the tapping noise came out. They research and found out that the synthetic oil loosened the protective coating the engine parts(bearings and pistons) and went loose. So I came home to see the problem. We tried changing the oil to conventional oil of 5w-30 but it didn't take the noise away in spite of adding oil treatment. I looked at the forum and tried changing the connecting rod bearings(which was really a pain in the butt,removed the front differentials and oil pan just to get the crankshaft and replace the bearings)). Reinstalled everything back but the noise is still there. Is the connecting rod bad?I need really a good advice or I will just sell it.

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Try running some ATF in the oil for the next oil change. Put a quart in with the old oil, run it on idle for 10 - 15 mins then drain. The atf should get rid of the lifter tap.

 

I have not heard of doing this before but I do have the same issue going on as well. How safe is it to put ATF in with the oil though just curious since I haven't heard of anybody doing this before.

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I have not heard of doing this before but I do have the same issue going on as well. How safe is it to put ATF in with the oil though just curious since I haven't heard of anybody doing this before.

It's very safe. Atf is high in detergents and will clean out most of deposits in the engine.
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Most of the time it isn't that they are worn, it is that previous owners (likely your average suburban idiot) did not change the oil on time, if at all, drove mainly short trips, or just plain treated it like @!*%, which causes them not to pump up with oil. The ATF cleans the @!*% out and allows them to work properly again. Mine has 438,000km and the lifters make no noise at all. Maybe on a cold start in -30 but that is it. Once and a while I will dump a quart of ATF in and drive it hard for 30 minutes, then change the oil. I only use mobil1 synthetic in mine.

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It's very safe. Atf is high in detergents and will clean out most of deposits in the engine.

 

Awesome, that is good to know & I will have to give it a go this weekend & see if that helps out with this thanks.

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In extreme cases where it was blow or go I've put a quart of diesel in the oil and let it run through a full heat cycle, shut it off did it again and revved until ticking cleared (with no load) then changed the oil drove it a hundred miles or so and changed it again.

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I would be really careful running diesel fuel in the oil. I was talking to a diesel mechanic and he said flushing a motor with diesel requires two people. After the engine is switched off, the properties in the diesel will cause 'run on' and the engine will not cut out and will redline if a second person doesn't block off the air intake with an old towel. It's a dangerous thing to do unless you know what you are doing.

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^That's a concern for diesel engines. A naturally aspirated gas engine with a throttle is not going to run away on crank case vapors.

 

I did the ATF trick on my '95 once or twice just to clean out whatever crud I could. The oil came out black, but then, it always came out black. Didn't seem to change anything but it didn't seem to hurt anything either. Hopefully it gets the crud out of your lifter, and hopefully that crud doesn't find anything else to stick to on its way to the filter.

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The lifters were the first suspect and we remove the valve covers on both sides and all are good-no late rise or slides or something to make a loud tapping noise. I changed all the connecting rod bearings with new OEM ones. But nothing sounds like this one.

 

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Wow! You went straight to main engine bearings, that's crazy! If that's a knocking it's too late. even if you change them. Gotta inspect and polish the crank ya know!

 

 

As far as your tippy tappy. It's almost guaranteed a lifter or a broken exhaust stud/manifold. As far as your inspection of the lifters, you're not wrong, I bet they all looked perfect. they're more than likely all good, even with the annoying tap. a collapsed lifter won't show any of that on visual inspection. They're hydraulic, they need oil pressure. With the engine in a running state, use a mechanics stethascope to pinpoint the bad one, or... Take all of them out and soak them in a nice clean Mobil1 bath (or your preferred oil). I'm sure the nice detergenty synthetic knocked some conventional oil crude loose. Not a big deal, just annoying.

 

Holy cow! I just gotta say it again.... right to the engine bearings. Extreeeeeeme!

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