Should I fix crankwalk this way

[_Madman_]

Ok, I had my diff blown, and while taking off the tranny I checked if my car has a crankwalk, and it seems it does. The crank walks around 0.5mm maybe 1mm, and I can hear that it hits against one end of the block or other when you physically move it. There is also sound like that on the crankwalk videos on youtube when I start the engine, but it's way quieter.

I'm offered a quick fix, take out the engine, polish the crank by 0.25mm, replace bearings with nonOEM stuff, all that for around +400$ to transmission fix.

I searched other threads, but I couldn't find the answer if this approach is OK?

As far as I understand, the walk is not too bad, so far, and it can be fixed without ill consequences, right? And if it walks again, I can just keep swapping those cranks?

What bugs me is, what is the average time before it walks again on average?

P.S.: The repair will be done by torquing all bolts by hand/air gun, no factory spec'd stuff.

 

[deviousgst]

i bought my car last year in march b4 that the owner had the car for about 6years and never suffered from crankwalk.. I also rebuilt it 7 months ago and still havent suffered from crankwalk

 

[JEFFREYCASTGSX]

Now how do you know that is crankwalk? For a brief background, all that happens is that the main bearing gives out. It can happen to any car(srt's are now known for it). Just replace all bearings, and if they do it the right then it wont happen again, ever. Think of it this way, CRANKWALK IS A MYTH.

 

[->PrOjEcTGS<-]

Depending on how bad it is determines how much work is needed to be done. If the Thrust bearing is totally trashed and the crank got damaged then you would have to get the crank's thrust surface welded up then recut down to the proper size. If the thrust bearing is worn but not to the point of doing damage to the crank then it should be just a matter of replacing bearings. Shoot, the 6-bolt that is in my car "walked". It tore the thrust bearing all up and ate up the crank's thrust surface. I had the machine shop fix the thrust surface and grind the main and rod journals down. Put in some undersized bearings and it's been good so far for 14,000 miles. I run 27psi on a daily basis and haven't had any problems from a "rebuilt" crank.

It's interesting that they are only going to charge you $400 on top of your trans rebuild for this service. The crank machining I had done cost $300 alone. I would beware and make sure they do the work. A lot of companies are just trying to make money right now and if they can screw someone out of a few bucks they will. Since, these are parts you can't visually see them replace unless you witness them tearing your motor apart or you tear it down and measure the bearings. Good luck I hope you trust the shop.

 

[->PrOjEcTGS<-]

Best way to fix crankwalk is to go get rid of the 7bolt and get a nice 6bolt motor.

Common Misconception. 7-bolts are just as strong as 6-bolters are. Plus they are generally cheaper to build since for some reason no one wants them. "Crankwalk" is just another way to say "Thrust Bearing Failure" Rebuild the motor before it happens and you won't have to worry about it. This can happen to any engine even 6-bolts as I stated happened to my 6-bolt.

 

[BulletShiftTSi]

they are right 6 bolts can crankwalk just like 7 bolts but the 6 bolts are less known for doing so. you have a 2nd gen therefore a 7 bolt. whats not true is when they said if you replace the bearings you will never get crank walk again. it's always going to be a bigger possibility with a 7 bolt because of there oil squirters. but crankwalking in 7 bolts doesn't happen as much as people like to make up don't worry if you replace your main bearings and cut the crank or replace it you should be fine for as long as you own the car.

good luck

 

[_Madman_]

Ok, so I understand it's not a bad idea to do this right now. And polishing crank down by 0.25mm is not that bad as well?

The thing is so cheap because it's not through company, it's through a mechanic I know well. And it's not in US

 

[knochgoon24]

One of the theories behind why crankwalk happens has to deal with the oil squirters that spray the bottoms of the pistons. 6-bolt oil squirters tap into the main oil gallery, while the 7-bolt oil squirters get oil from the feeds for the main bearings. At low pressures, if a 7-bolt oil squirter clogs open, the possible lack of oil pressure on the thrust bearing can cause premature wear, aka crankwalk.

Magnus Motorsports - Crankwalk Tech for more on this idea.

 

[Locke]

See here to check for crankwalk: http://www.dsmtuners.com/forums/newbie-forum/270553-measured-my-crank-endplay-today-cw-fear.html

Crankwalk can happen to any engine, but it does seem to be more prone to the 7bolt 4g63 blocks, of the early 2g design specifically. Nobody knows for sure why, but the oiling system changes, poor bearing and journal design, and very heavy pressure plates, have all been blamed as causes.

7bolt engines, even those from the early 2g years, have reliably made a lot of power. People seem to swap in a 6bolt block for reassurance, mostly.

Most people who have a couple of crankwalk symptoms scream "CRANKWALK!" and swap it out (or give up on DSM's altogether) without actually testing it to determine crankwalk. Those of us who have been around awhile all tend to agree that crankwalk is overrated, and doesn't actually happen as often as newer member would have us believe.

 

[sschambers]

I wrote this thread up earlier, you and along with everyone else should at least take a look at it. I tried explaining crankwalk (although I like to call it premature thrust bearing failiure) and the advantage of using the MBCAD kit.
http://www.dsmtuners.com/forums/new...ure-thrust-bearing-failure.html#post151782660

 

[BulletShiftTSi]

One of the theories behind why crankwalk happens has to deal with the oil squirters that spray the bottoms of the pistons. 6-bolt oil squirters tap into the main oil gallery, while the 7-bolt oil squirters get oil from the feeds for the main bearings. At low pressures, if a 7-bolt oil squirter clogs open, the possible lack of oil pressure on the thrust bearing can cause premature wear, aka crankwalk.

Magnus Motorsports - Crankwalk Tech for more on this idea.

I second this statement 100%

Stole the words out of my mouth!

This theroy makes perfect sense by people I can trust and I believe this to be thee main cause of CrankWalk. But everyone has there own opinion.

If you own a 7 bolt and are worried don't be. drive and race and upgrade your car like any other dsm'er would and if the day ever comes (this happens to less then 20% of 7 bolts) then worry about either fixing the crank or swapping to a 6 bolt motor.

For those of you who don't know the 2 main differences between a 6 bolt and 7 bolt is the number of bolts connecting the flywheel to the crank and where the oil squiters get there oil from.

The rumor mill is turning and I heard that magnus motorsports are devloping a fix for this problem so they can prevent it in every 7 bolt motor they build.




To the OP measure your crankwalk to be sure its crank walk and see if its still in spec.

Good luck

 

[->PrOjEcTGS<-]

For those of you who don't know the 2 main differences between a 6 bolt and 7 bolt is the number of bolts connecting the flywheel to the crank and where the oil squiters get there oil from.

Also the 7 bolt uses a girdle rather than the main caps that the 6 bolt uses. This alone beefs up the bottom end of a 7 bolt.

This alone almost makes me want to find a 92.5-94 7-bolt and build it up!

 

[Defiant]

I've always wondered if having the thrust bearing cap tied to the others is part of the "cause" for premature thrust bearing failure, but I've not heard of anyone betting the few thousand dollars to cut it free and find out.

 

[_Madman_]

So what do I need for this MBCAD kit? Only ARP main studs? And where are those inserts going to? Will all forces remain the same for torquing?

 

[MidShipCivic]

So what do I need for this MBCAD kit? Only ARP main studs? And where are those inserts going to? Will all forces remain the same for torquing?

Before you go on how is your oil pump, how old is it? I recommend you use OEM bearings.

How did you figure out 1mm?


This engine I'm using came out of a 94 Galant SOHC with 106k, it only had .002'' 3/4ths of end play. The limit is .009''

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The best revision Mitsubishi has done are those split thrust washers in 97-99.




I've walked a 6 bolt before all engines have a control amount of end play.

However I find that 40ft lbs on the oil pump gear bolt is too much preload and causes premature failure, so I give it less torque and use loctite since engine vibration from harder mount shake things loose.

When this happens (like below) do not use the same crankshaft again.

Clutch side.

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Oil pump side.

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