95 Pathfinder Tapping Noise - Please Advise!

[danelectro]

Hello all, thanks in advance for your advice on this one.

I've got a 95 Pathfinder XE, it is making a loud tapping noise when running. I'm hoping that based on its behavior, someone with more experience can recommend possibilities/most likely scenarios before I start spending time and money digging into it. The behavior is as follows:

a) When the engine is cold, the tapping noise is immediately present after start. What is odd, however, is that it seems to cycle: it gradually becomes louder and then disappears, becomes louder and disappears, etc. It quiets as the engine warms up, and then eventually ceases to be noticeable.

b) If I spend any amount of time cycling the engine above ~2800rpm, the tapping returns, loud and with a vengeance. It is much louder at this point. If I pull off to the side of the road and idle the truck, it continues for a while and eventually quiets and disappears.

c) The tapping is linked with RPM, and seems to be coming from inside the engine or head in the approximate area cyl 4 and 6.

I'm not an experienced mechanic, but can read the service manual and get the job done. Any advice on where to start would be very much appreciated. Cheers!

[yeldogt]

how many miles ..........sounds like the valves -- not uncommon. Try high mile oil -- worked on one of my 02's with 150k. Only fix is to go in and see what's the problem.

[danelectro]

The motor has got 130,000mi on it. I ran a BG detergent through with its last oil change and used high mileage synthetic - the noise didn't change at all.

If I open it up and find that one/some valves have excessive valve lash, is there any way to adjust it with hydraulic lifters? Unfortunately it looks like NICO had to remove the FSM, can anyone speak to the bleed or adjustment process on the VG30E? Additionally, are there any other things I should look for as possible causes aside from valve lash?

Most importantly, is there any harm that can be done in continued driving with this noise?

[macgiver]

mac, it will sound like I'm PUSHING Magnetic drain plugs , but I'm old shool , have messed up -learned the hard way ANd 30 years ago a " small block " was a RAPP'IN and aTAPP'N ,I knew it might be the END.I buy magnetic drain plug and in three miles I had a small "Brillo pad" of shavings , as much as you would get in 7000miles They are the BEST barometer to judge when to sell your car when it still runs , full disclosure to all interested parties of course

[macgiver]

mac,another kind of "barometer" of engine condition - "need to get rid of it" - is after like overnight , cold engine , not run for 18 hrs., go and turn key to "ON" (RUN) , and STARE at oil press. IDIOT LT. in dash - will be Lit , then as you crank-start motor watch if it QUICKLY DISAPPEARS & STAYS OUT ; If any flickering or delay to go out ,like even 2 sec.'s, is oil lubrication/pressure/ bearings/clearance/ and with that noise SELL the CAR! Now VERY late model cars ,like the ones thst have a 5 seconds timeout enabling starter will mess with that IDIOT Light and won't act like above where it IS significant (late models usually switch out Lt. "upon crank").
It's IF 'n you wanna remove valve cover to check out the"valve noise" - yet many times at that point you just find out IT ISN'T the VALVETRAIN !! :
p.s. Everyone AZZ-U-ME 's you checked dipshtik

[danelectro]

Yes, the oil level is correct, and the oil pressure light does not flicker or remain on at any point.

I guess my question still remains, if it turns out that "its the valvetrain", what does that actually mean? What are some of the things that could be malfunctioning to create a tapping noise (does a reciprocating tapping noise serve as a clue to any particular problem?), and what am I to look for if I take off my intake and open it up?

Does anyone have a downloaded copy of the EM section of the FSM for this engine that they could share?

[macgiver]

mac, supposed to be some of the "smallest " of oil passages up there , and sludge / blockage is therefore high on the list of possibilities - this the "what it could be" the whaddaya do is ? Try (I 'm kinda not a fan) a "Motorflush-in-a -can" I did say TRY right?