FourStroke

I just picked up a '98 4Runner Ltd. with 220k on it for $2900. Great condition all around except for a strange noise I didn't notice at the time.

When idle in drive or reverse there is a weird sound that sounds like something like a loose nut or pebble or something is bouncing around in the torque converter. We opened up the cover and let it run to see if anything would pop out and of course nothing did - never that simple. All of the teeth on the visible gear seem to be present. The sound is even more audible with the cover off so I'm fairly certain that's where it's coming from.

Performance wise there doesn't seem to be anything wrong with the way it drives. Always shifts smooth, and predictably. No weird noises while in park or neutral. Only when idle in gear and right when I shut off the truck you can hear the same noise of something that sounds like a grinding/bouncing metallic object/gurgling sound of sorts that kind of dies down as the engine shuts off.

Anyone else ran into this or have any suggestions in diagnosing or fixing this? Looks somewhat difficult to come by a used TQ Converter without buying up the transmission as well and I know I might as well just hack off an arm if I need to have it rebuilt.

Thanks in advance.

aowRS

Cracked flex plate?


Andreas

Texas_Ace

There was another case of a cracked flexplate not too long ago that complained of the same issues. In his case the plate was holding on by a thread.

FourStroke

I just checked out my flex plate and it's sound. I'm looking at prices on torque converters and it looks like it's only $150 for a new one from autozone.

Automatic transmissions run off magic as far as I can tell. Don't know anything about them, is this something I can just do a direct swap with the new one? Are there any other parts I should replace while I'm in there?

Texas_Ace

Might look around to see if there is a local converter rebuilder around you. There is one here that will rebuild it and upgrade the stall speed for $200 IIRC.

Although not sure why it would be clanking, everything inside of it is filled with fluid so it is unlikely it would have a clanking sound like you describe.

The other flex plate that was cracked could not be seen from the cover either, it was cracked way up near the center of it.

FourStroke

Well I've been reading into how all this auto tranny stuff works and trying to come up with a game plan on how to tackle this.

I found a full transmission with 125k miles on it at a local salvage yard for $350. I'm going to dismount mine first to see if the flex plate is cracked at all. If it is problem solved, swap the plate, if not since technically the torque converter shouldn't be able to make sounds like I'm hearing would it be worth just swapping the whole tranny at that price?

Texas_Ace

If the transmission is from the same year/model truck as yours that is the best idea if it is not the flexplate.

FourStroke

After reading some strawberry milkshake threads it just dawned on me that while my tranny fluid is normal colored my hoses and radiator look like they are relatively new.

My best Sherlock Holmes now is that the radiator took a dump, strawberry milkshake occurred, radiator and hoses were replaced, tranny was flushed, and the truck was sold. If that's the case new transmission is probably the best bet huh?

Texas_Ace

I kinda doubt it would have lasted this long if that was the case also you said it sounded like a nut was rattling around?

Everything inside the transmission is also covered in fluid so it is unlikely that it would have a sound like a nut rattling internally. Possible but unlikely.

FourStroke

Damn these automagic things. They're confusing.

So if everything is sealed with fluid and it's a rattling noise it's got to be something related to the flex plate right? If not cracked possibly a bolt backing out or something?

Texas_Ace

Something like that, it could be internal but much more likely that it is external.

FourStroke

Any tips on getting to the flex plate? Been searching around for a writeup can't find anything.

Texas_Ace

Only way to get to it is to drop the transmission, not a small job so make sure you are ready for it.

ncsugrad2006

How'd it turn out? Flex plate cracked?

Eurofreak

Another year or two later, I'm also curious. lol Same sounds here.

donomite49

weak point is between the bolts on the crankshaft and the bolts on the torque converter.

there is a thread with a picture of the broken flexplate cracked between the two sets of bolt holes on YT.

dan-senior

I had the exact same problem and at first assumed it was the flex plate. It turned out that one or more fins in the torque converter broke off and were making the metal sound during rotation. It didn't take long for shiny metal parts to start appearing in the transmission oil.

ZUK

iTrader: (1)

That is what I was thinking as the cause too.