Full Version: Crankwalk Explained
I've been hearing about 2g motors getting "crankwalk". what is it? how can i avoid it? can the 2g motor be modded so that this doesn't happen or do i have to swap a 1g? ....haha one more question....why don't the 6bolt 1g's get crankwalk compared to the 2g (what is it 7bolt? or 4?) whatever...help
wortdogg would probally be really good at explaining and answering all of your questions... as well as many others on this board...
i'll try and find a clinical definition for you, but there's not much if anything you can do to prevent crank walking... the 6 bolt swap is the about the only thing to do.
i'll try and find a clinical definition for you, but there's not much if anything you can do to prevent crank walking... the 6 bolt swap is the about the only thing to do.
The vfaq's is a great source of information: all information taken directly from the
vfaq's.
A 'walking' crankshaft is a crankshaft that moves too much inside the engine. This is also known as excessive thrust bearing play. The movement is usually due to the crankshaft not fitting inside its bearings correctly. While not bad for the crankshaft, the movement can place excessive or uneven loads on the bearings, causing premature failures.
Many 2G owners have suffered from walking crankshafts. It appears that Mitsubishi built many 2G engines using defective crankshafts, which were machined out of specification and are thus capable of moving around too much inside the block. All 2G model years appear to be affected to some degree.
To fix this problem, Mitsubishi has designed several versions of matching crankshaft bearings. This allows the defective motor to retain the crankshaft, yet matches the bearings correctly so as to eliminate the excessive crankshaft movement. Matching the bearings in this manner is tricky and requires exact information about when the crankshaft was manufactured, which may be determined by color markings on the crankshaft itself. The 2G factory manual includes information on how to match crankshafts to bearings.
1G owners do not generally need to worry, as there are no chronic problems with crankwalk in per-1995 cars. However, it is possible for any engine to experience crankwalk if there is a problem with the crankshaft bearings. It has been reported that 'small rod' / 7-bolt flywheel motors (manufactured from later 1992 through 1994 on 1Gs) are more prone to crankwalk than 'big rod' / 6-bolt flywheel engines (manufactured from 1989 to early 1992). However, there can be no guarantees, since big block V8s and all other engines can also suffer from crankwalk.
It can be difficult to tell if a particular car is experiencing crankwalk. Symptoms are usually indirect and difficult to diagnose until major damage occurs.
Since the clutch places pressure on the crankshaft, many owners have reported clutch or shifting problems associated with the walking crank. Having the clutch 'stick' down on left-hand turns is often a telltale sign of crankwalk. Other symptoms include inconsistent engagement height, poor or rough engagement, difficulty shifting, ticking noises and varying pedal height or pressure. Another possibility is having the engine RPM decrease significantly when the clutch pedal is down.
Another problem with crankwalk is that the crankshaft may move so much as to literally tear up and destroy the 2G crankshaft angle sensor. This problem usually manifests itself as a ticking noise coming from the timing belt area, as the sensor is literally and slowly ground away by the crankshaft. Any such noise should be investigated right away to prevent serious problems.
Unfortunately, cranshaft angle sensor failure usually leads to a replacement sensor, rather than a replacement crankshaft, as mechanics fail to diagnose the underlying problem. 2G owners who have experienced premature failure of the crankshaft angle sensor should investigate the possibility of a walking crankshaft immediately.
vfaq's.
A 'walking' crankshaft is a crankshaft that moves too much inside the engine. This is also known as excessive thrust bearing play. The movement is usually due to the crankshaft not fitting inside its bearings correctly. While not bad for the crankshaft, the movement can place excessive or uneven loads on the bearings, causing premature failures.
Many 2G owners have suffered from walking crankshafts. It appears that Mitsubishi built many 2G engines using defective crankshafts, which were machined out of specification and are thus capable of moving around too much inside the block. All 2G model years appear to be affected to some degree.
To fix this problem, Mitsubishi has designed several versions of matching crankshaft bearings. This allows the defective motor to retain the crankshaft, yet matches the bearings correctly so as to eliminate the excessive crankshaft movement. Matching the bearings in this manner is tricky and requires exact information about when the crankshaft was manufactured, which may be determined by color markings on the crankshaft itself. The 2G factory manual includes information on how to match crankshafts to bearings.
1G owners do not generally need to worry, as there are no chronic problems with crankwalk in per-1995 cars. However, it is possible for any engine to experience crankwalk if there is a problem with the crankshaft bearings. It has been reported that 'small rod' / 7-bolt flywheel motors (manufactured from later 1992 through 1994 on 1Gs) are more prone to crankwalk than 'big rod' / 6-bolt flywheel engines (manufactured from 1989 to early 1992). However, there can be no guarantees, since big block V8s and all other engines can also suffer from crankwalk.
It can be difficult to tell if a particular car is experiencing crankwalk. Symptoms are usually indirect and difficult to diagnose until major damage occurs.
Since the clutch places pressure on the crankshaft, many owners have reported clutch or shifting problems associated with the walking crank. Having the clutch 'stick' down on left-hand turns is often a telltale sign of crankwalk. Other symptoms include inconsistent engagement height, poor or rough engagement, difficulty shifting, ticking noises and varying pedal height or pressure. Another possibility is having the engine RPM decrease significantly when the clutch pedal is down.
Another problem with crankwalk is that the crankshaft may move so much as to literally tear up and destroy the 2G crankshaft angle sensor. This problem usually manifests itself as a ticking noise coming from the timing belt area, as the sensor is literally and slowly ground away by the crankshaft. Any such noise should be investigated right away to prevent serious problems.
Unfortunately, cranshaft angle sensor failure usually leads to a replacement sensor, rather than a replacement crankshaft, as mechanics fail to diagnose the underlying problem. 2G owners who have experienced premature failure of the crankshaft angle sensor should investigate the possibility of a walking crankshaft immediately.
here is an article in the dsmorg.com/archives....
Many have emailed me requesting the technical service bulletin
information regarding the weakening of crankshaft bearings and the
subsequent shift of the crankshaft, as it applies to 1995-1998 turbo 2.0
liter DSMs.
The reason I can't find the TSB in the dealer's records is there has not
yet been a TSB written for this problem. The District service manager
for the southeast said they were in the process of writing the TSB for
the Eclipses and Talons. There is already a TSB in effect for certain
3000GT's, but I'm not sure which models specifically since I breezed
past the information sheets for them looking for DSM TSB's.
This problem is very real. If you have experienced a problem with your
crank angle sensor on your 2G, turbo, then you should be aware that the
problem may lay with the crankshaft "walking".
On a related note, I and several readers have always been confused when
someone with a 1G says we all have one all inclusive sensor that reads
camshaft angle as well as crankshaft angle, and that sensor is located
on the passsenger side of the intake camshaft. This is indeed the case
with 90-94 DSM's. However, 95-98 turbo DSM's have two separate sensors:
one to read cam angle, located on the driver's side of the intake
camshaft for the 95-96 models and located on the passenger side of the
intake camshaft (same as 1G) for 97 and maybe 98? (not sure about 98'),
and one to read crankshaft angle. 2G turbo DSMs have a completely
separate crankshaft angle sensor located adjacent to the crankshaft
sprocket reading its signal via a "trigger plate" or a "back plate"
depending on which shop manual you read.
When the crankshaft "walks", it pushes the backplate into the crank
sensor causing it to fail (literally, it tears through the sensor). The
approximate cost for a new crank angle sensor for a 2G turbo is between
$40-$70. The part number for the crank angle sensor for a 2G turbo is
MD 300101. If your crank sensor has suddenly failed, the chances that
the sensor has done so on its own, with no mechanical factors to effect
that failure in the first 60,000 miles, are low. If you have taken
apart your car to replace the crank sensor, look to see if there are
plastic shavings on the trigger plate, where the plate has actually
contacted the sensor itself. To replace the sensor alone is a short
term fix, if your crankshaft is walking. Getting to the crank sensor is
a lengthy process since the timing belt and all else has to come off.
You might even use the opportunity to change your timing belt.
With regard to warranties. As I have come to understand the meaning of
"TSB", there is no obligation to pay for the failure of a factory
component if you have exceeded your powertrain warranty or an extended
powertrain warranty that applies. So, if you didn't buy an extended
warranty and you are over 60k, and your crankshaft is walking, you'll be
replacing the crank, bearings, and sensor on your own nickel. If you
are under 60k, find a dealer whose service manager has heard of the
problem and is actually WILLING to fix the problem if you have it.
If you are doing the work yourself, remember to order the crankshaft
first, then read the color marks on the crank to identify which SPECIFIC
bearings should be used with that particular crankshaft. There are
several iterations of crankshafts, and the color marks identify which
specific bearing sizes will fit correctly.
Paul Estevez
95 GST
Many have emailed me requesting the technical service bulletin
information regarding the weakening of crankshaft bearings and the
subsequent shift of the crankshaft, as it applies to 1995-1998 turbo 2.0
liter DSMs.
The reason I can't find the TSB in the dealer's records is there has not
yet been a TSB written for this problem. The District service manager
for the southeast said they were in the process of writing the TSB for
the Eclipses and Talons. There is already a TSB in effect for certain
3000GT's, but I'm not sure which models specifically since I breezed
past the information sheets for them looking for DSM TSB's.
This problem is very real. If you have experienced a problem with your
crank angle sensor on your 2G, turbo, then you should be aware that the
problem may lay with the crankshaft "walking".
On a related note, I and several readers have always been confused when
someone with a 1G says we all have one all inclusive sensor that reads
camshaft angle as well as crankshaft angle, and that sensor is located
on the passsenger side of the intake camshaft. This is indeed the case
with 90-94 DSM's. However, 95-98 turbo DSM's have two separate sensors:
one to read cam angle, located on the driver's side of the intake
camshaft for the 95-96 models and located on the passenger side of the
intake camshaft (same as 1G) for 97 and maybe 98? (not sure about 98'),
and one to read crankshaft angle. 2G turbo DSMs have a completely
separate crankshaft angle sensor located adjacent to the crankshaft
sprocket reading its signal via a "trigger plate" or a "back plate"
depending on which shop manual you read.
When the crankshaft "walks", it pushes the backplate into the crank
sensor causing it to fail (literally, it tears through the sensor). The
approximate cost for a new crank angle sensor for a 2G turbo is between
$40-$70. The part number for the crank angle sensor for a 2G turbo is
MD 300101. If your crank sensor has suddenly failed, the chances that
the sensor has done so on its own, with no mechanical factors to effect
that failure in the first 60,000 miles, are low. If you have taken
apart your car to replace the crank sensor, look to see if there are
plastic shavings on the trigger plate, where the plate has actually
contacted the sensor itself. To replace the sensor alone is a short
term fix, if your crankshaft is walking. Getting to the crank sensor is
a lengthy process since the timing belt and all else has to come off.
You might even use the opportunity to change your timing belt.
With regard to warranties. As I have come to understand the meaning of
"TSB", there is no obligation to pay for the failure of a factory
component if you have exceeded your powertrain warranty or an extended
powertrain warranty that applies. So, if you didn't buy an extended
warranty and you are over 60k, and your crankshaft is walking, you'll be
replacing the crank, bearings, and sensor on your own nickel. If you
are under 60k, find a dealer whose service manager has heard of the
problem and is actually WILLING to fix the problem if you have it.
If you are doing the work yourself, remember to order the crankshaft
first, then read the color marks on the crank to identify which SPECIFIC
bearings should be used with that particular crankshaft. There are
several iterations of crankshafts, and the color marks identify which
specific bearing sizes will fit correctly.
Paul Estevez
95 GST
thank you very much xian. that helps a whole lot
The link that 94laser posted is the real reason behind crankwalk and is by far the best explanation for it. A true cure still hasn't been found beyond swapping in a 6-bolt.
thanks for the clarification... i can't believe the vfaqs let me down. I'm going home in shock....
a damn good link, and nice pics too!
a damn good link, and nice pics too!
Thank Nate for that actually, i remember him posting that on another thread, i just went and found it for ya. 
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