Has anyone heard of Crank walk?

[DevonD]

I have had the same noise for a while now and everyone has thought it would either be the throw out bearing or a wheel bearing. after replacing both the car still makes the noise. I thought I would just have to live with it and basically just started ignoring it. In this months popular mechanics though I guy asks about a similar noise coming from his Chevy sanoma. (its on page 116 if anyone has it). after writing in about the noise popular mechanics mechanic or whoever he is suggests that it is very likely the crankshaft walking back and forth. It is a result of worn out thrust bearings and those worn out bearings will cause to much crankshaft slop, allowing the crank to move around in the engine more than the regular five thousandths of an inch.

As I have described before the noise only happens when the clutch pedal is out, so the clutch is not engaged. It is loudest when I just speed up to maybe 15 mph in 1st gear then let off the gas. It is a very loud almost grinding noise. even when the car is stopped and just idling it makes the noise, not as loud but still makes it.

what this popular mechanics guy is saying is that pushing in the clutch pedal it forces the crankshaft to the front of the engine block quieting the noise. so my question is has anyone heard of this? and if the crank is my problem do I need to rebuild the entire engine to replace the thrust bearings?

Thanks!

[PBfrEAk]

I've heard of crank walk in DSM's but NEVER in Nissan's...

IF this is your problem, you may have to rebuild the whole engine depending on the extent of the damage, but you won't know until you tear her down.

As far as it actually being crank walk, I can't say for sure, but I've never heard of this being a problem before...

(Of course, I haven't dealt with 4th gens at all...)

GL, I'm sure a 4th gen'er will chime in soon.

[allensteiner]

the thrust bearings are in the transmission not engine http://www.courtesyparts.com/m....htmlso it shouldn't be too bad to fix. might want to make sure thats the problem though.

[PBfrEAk]

the thrust bearings are in the transmission not engine http://www.courtesyparts.com/m....htmlso it shouldn't be too bad to fix. might want to make sure thats the problem though.

My bad, I didn't notice thrust...just bearings...oh well.

[DevonD]

yeah before I got tearing anything apart im going to make sure this is actually what it is. But I was just looking at the 96 Maxima FSM and I didn't see any bearings labeled "thrust bearing" specifically. so am I either just reading past it or what is it called?

And just on a quick side note, allensteiner. Im looking for some cheap ways to improve my cars performance and if you remember I was asking you about the ks and the resistors a while ago. the resistors worked great! So my question is what is the valve cover breather(15HP) thing you mention in your signature?
Modified by DevonD at 1:16 AM 11/21/2008

[PBfrEAk]

So my question is what is the valve cover breather(15HP) thing you mention in your signature?

That is definitely a sarcastic poke at the fact that it adds nothing lol (I hope )

[DevonD]

Haha well thats what I thought. just making sure. there is no reason to not keep looking for that miracle little thing that adds tons of HP for no cost. haha a Mechanic I knew was convinced his exhaust system on his pontiac grand am added 30HP over stock, and all he did was throw in a high flow cat. haha

[allensteiner]

That is definitely a sarcastic poke at the fact that it adds nothing lol (I hope )

DD: it's called a thrust needle-bearing...or thrust bearing needle one of the two.

i never heard of those but courtesy parts catalog shows them...and no needle looking stuff

[DevonD]

I just keep finding thrust washer. where is it located in the transmission? im guessing its on the input shaft right? There is a bearing right neer the end of the input shaft. it just doesnt say thrust bearing.

[allensteiner]

idk...i'm not that knowledgeable the part number is 31438x where x stands for a letter (or two) like N, NE and a few more. check out the link i gave you and you'll see what i'm talking about. there's 7 of them total and i think they're all a part of the planetary gear - don't ask me what that is

[PBfrEAk]

The planetary gear is a gear that runs along the ring gear...in an "orbit" like a planet...hence the name...

hold on...

Read this:

http://en.wikipedia.org/wiki/Epicyclic_gearing

And this (second section 1st page):

http://science.howstuffworks.com/gear-ratio4.htm

[95MaxOH]

What is everyone talking about??? There IS a thrust bearing in the engine lol.What do you think controls the crankshaft end play??? it is one of the crankshaft main bearings.

Also a tell-tale sign in the DSMs that the crank was "walking" was to make a sharp left turn and if your clutch pedal becomes really sloppy and easily goes to the floor then the crank was walking.