terminator

iTrader: (1)

OK, I have a strange sound that started very quietly about 2 weeks ago and now it's easy to hear once warmed up. I have a 96 4Runner Ltd. 3.4 4X4 automatic. It sounds like a rod knock but has been confirmed there's no engine noise at all, it goes away under throttle. You can hear the knock while at idle in P or N clear as day, accelerate to leave a stop and it's gone.

We did notice that when you engage the 4WD the sound goes away for a second then comes back and if you brake and throttle the noise goes away.

Has anybody heard of a similar issue? Perhaps loose torque converter bolts or something? I had a used engine installed about 4 years ago and I think it has about 85K on it now. Had all the normal stuff replaced, t-belt, water pump etc.

I'll try and post a sound clip for y'all.
Thanks
Jason

Texas_Ace

Basically you only hear knocking when the engine is under no load, add load and it goes away?

Your sure it is not in the engine?

michael0584

It could be loose converter bolts or a cracked flex plate. If you have access to a stethoscope, you may be able to tell better where the noise is coming from. I have on that I bought from harbor freight, works great.

terminator

iTrader: (1)

I had a mechanic also say it coulbe be loose converter bolts. My flexplate was cracked when I had the engine installed so it was replaced. I have a spare in case this one is cracked also.

As for the noise, pretty sure it's not engine related and it does go away under load.

MLiebal

Time to get under the truck and open the pia access panel. You can get to the converter bolts fairly easily, just have to bump the engine to get to a few at a time.

terminator

iTrader: (1)

The shop I work for is looking at it and of course it made the noise when they pulled it in and then went away. They're letting it cool down and will try it again but the tech is thinking it's a lifter noise.

The engine was put in about 3.5 years ago and had all new belts, water pump/t-belt and flexplate. The engine tag said it had 60K on it so now it should have @ 100K on it or so. I've used Castrol 5W30 the entire time every 3-3500K except for one oil change where I went with Castrol Syntec 5W30 and 6K, that was the previous oil change and I'm about 2K into the conventional switch back.

I can't afford any major engine repairs right now so I'm hoping for an inexpensive solution here.

terminator

iTrader: (1)

Update:
After the shop not looking at my 4Runner all week I finally had a tech look at it near the end of lunch. He is thinking either tranny or transfer case. The noise went away in 4 LO, strange.

Near the end of the day all of the techs got involved and the general consensus now is potential loose torque converter bolts. No longer lifter noise which I didn't think from the beginning but hey, I'm not a tech!

Friday I pulled the skid plates off and MAN the access bolts are tough to get to on the driver side. How in the world do you get to those bolts????? The passenger side bolts look easy but what's the trick on getting to the bolts on the driver side?

terminator

iTrader: (1)

In the shop today, they pulled the starter, rotated the engine and found one missing torque converter bolt and others that don't look good. Ordered new ones from Toyota and if all goes well it'll be back to quiet Tuesday. Crossing my fingers and hoping for the best.

mark3406e

Im not sure why they would go through the headache of pulling the starter when there is a access panel. Also our 5vz engines do not have lifters there overhead cams. The cam rides on a bucket and pushes the valve open. Granted there is a shim in there.

I curious to see if the bolts fix it.

terminator

iTrader: (1)

Easier to pull the starter than that access panel by far.

I'll know Tuesday if this fixes the noise or not.

mattbatson

so, do they know where the missing bolt went?

terminator

iTrader: (1)

Haven't found it yet. The engine was installed in Louisville, KY at a place called Advance Engine Exchange and since then I've had a couple of issues. I haven't put it past them that they forgot to put it in just yet. Who knows though but the mechanic is checking to see if there's a bolt inside the housing somewhere.

j2the-e

If it was me, I would pull the trans out and find that bolt, I would also likely replace the flex plate and all the bolts if I saw any signs of wear from them being loose. If that bolt is bouncing around in there, it could cause some serious damage if it wedges itself between the flex plate and the engine. I've seen it before. Dont shotcut this one, you will regret it later. And, btw, the inspection cover is very easy to remove with a gear wrench on the drivers side bolts. Dont forget that one of the converter bolts is different than the rest

terminator

iTrader: (1)

The new TC bolts are here, any idea as to why one is different? I read on AllData that it's to aid in aliging the TC to the flywheels but if you removed the bolts 1 by 1 wouldn't it still be aligned? Just curious

As for the missing bolt, not sure if one was ever installed with the engine. We haven't found it in the case yet.

j2the-e

What are you referring to? What case? The bellhousing? Did you pull the trans? If one was missing to begin with, why would the others come loose? They were all loose and 1 fell out. Its probably in there somewhere. I almost guarantee your bolt holes are worn from the bolts being loose. You really should replace that flex plate with the other one you have and then you'll be 100% sure the bolt is not in the bell housing. You also need to check for cracking on the torque converter around the bolt holes. I am a toyota master tech. I have seen this before. Sure, you might get lucky, but then someone eventually wins the powerball jackpot too.
The different bolt goes in first, it is tapered to align the converter properly. Doesnt matter which hole it goes into. (blue loctite and correct torque is your friend here)
If you dont pull the trans...best of luck to you, you'll need it...

j2the-e

If you do end up replacing the flex plate (and I hope you do) Be sure to clean the flexplate to crank bolts with a wire wheel and clean any oil out of the holes in the crank and install them with a little sealant on the threads. I prefer Toyota FIPG (form in place gasket), available at your local dealer. Rear main seal is a good idea at this time too...

terminator

iTrader: (1)

All back together and same noise so trans is coming out. I'll let you all know what we find.

mark3406e

Rather than pull the trans why not just unbolt the torque converter and run it and see if the noise is gone?

terminator

iTrader: (1)

Hmm, didn't cross my mind. It won't cause any other damage would it?

What's weird is when I drive home, about 20 miles and @ 65 degrees, it makes the noise just like before. When I drive to work in the morning (this morning it is about 45 out) it's much, much quieter and you can't hear it except in P and N. WTF???

We haven't pulled the trans yet, obviously.

mark3406e

I have don't it many times on many engines and it's never hurt a single one. Can you post a video of it?