Sprag-O

Hey guys, I don't really post on the forum much, but I had a question.
I've been searching and not seeing a lot of guys run across this.

I have a 1999 4Runner, 3.4L Auto.

When the trucks warm, and has load on it (ie. Sitting at a stop light in Drive)
You can sometimes notice a "Tapping" noise. It becomes more prominent once the trucks completely warmed up, but again, only when you put load on the motor.

The thing that started to scare me about this entire ordeal was when I noticed the tapping was being carried through my drivetrain, and I could actually feel it through the t-case lever.

After some time with the stethoscope, it appears to be loudest at the pan, directly below no. 1 or 2 cylinder.


My question is, with these symptoms, would everyone agree this most likely is a spent bearing. Also, if so, the fact the noise hasn't really gotten worse in the last few months, what's the likelihood of not having to have the crank ground.

Final question is, dropping the pan on these trucks (4wd) is it as simple as pulling the diff (unbolting cv's and diff) and dropping the pan, or is there anything else to hang me up?

Thanks for any advice, truck has 108K miles on it, purchased a little over 6 months ago, and my warranties been gone for a while now.

Sprag-O

Guess I may dive into this tonight and see...

Before I tear into I'll try to get a clip of the noise as a reference for others.

peapicker

This is only a guess, very hard to diagnose something without hearing it. From what ive seen and been exposed to over the years that doesnt sound like a rod or crank bearing. If it was, it would have got extremely worse in a short amount of time. Sounds more like a wrist pin maybe, but the only way to really tell is to start pulling stuff apart sorry I couldnt be of any more help than that.

CTRJ

Mine has a knocking sound when I run 87 octane fuel. That is why I've been running premium fuel for the last year with great results. You might try that and see if it helps. BTW, I have 189k on my truck.

84truck

I had an 84 pickup i swapped a 22RE into and hydrolocked it after my brother had hydrolocked it in his truck and bent a rod. It sounded a lot like preignition or something but i couldn't ever feel it in the drivetrain. Unfortunately it never occured to me that i had a bent rod and about 3 months later on my way to school i threw a rod on I 25 outside of colorado springs.

Sprag-O

Ya, I'm fairly certain it's not preignition issues at this point, it was a little noticeable tap a while ago, then starting really hearing it and feeling it through the drivetrain in the last day or so, so I parked it.

I hope it's not the wrist pin, I can't hear it really any higher in the motor around the line where the pan meets the block.

mt_goat

Good luck, keep us posted.

stir_fry_boy

Does it get better when you change the oil?

Sprag-O

Well... it didn't appear to make a difference when it was a very light tap, but at that point it was hard to hear, with it getting increasingly louder, I don't want to monkey around running it more then I have to.

I've got about 1,200 on it since the last change. Purolator PureOne filter and Castrol GTX Dino oil.

aowRS

My '01 has exhibited a muted 'thumping' sound while sitting at a light in 'D' - for a few years now. I always click into 'N' and the sound completely disappears. I purchased the truck new, and now have 185,000 miles.

Auto tranny flexplate?


Andreas

Beto

EVAP canister solenoid has been known to make sounds mistaken for valve ticking, some people have gotten it really loud - maybe try pulling the wires off of that first if you think there is any chance that it could be external to the engine.

mt_goat

I had that ticking, it did sound like a valve tick except it wasn't rpm dependent.

2000t4rAKS

My 2000 Runner is starting to knock. I noticed it last week. I have been leaking oil but that is being taken care of next weekend. I am gonna check the oil levels and see if it is low oil that is causing the knock. If its the black box that is closest to the driver side firewall, it does tick. The other sound is more of a rhythmic thumping. Any ideas guys? Thanks.

aowRS

Just stumbled across this old thread. My truck still does this, and I still slip it into N at red lights. Only difference is that it now has 507,000 miles.
Original engine & tranny - never removed or messed with.



Andreas