bent crankshaft nose on a b4?

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
crank tip/pulley/bolt oscillates about a 32nd to a 16th of an inch.
i have not taken the bolt and gear off yet because i don't have a new bolt.
plus, i'm not even sure what that would tell me.
bolt is tight. pullys are all tight. timing belt tracks fine. waterpump only lasted 30,000, but it was kinda suspicious from the beginning.
motor had 117,000 miles when i put it in, and was from a junkyard, so car was likely totaled.

it seems like my choices are to either 1, get a new crank, and do a lower end rebuild etc.
or 2, drive it, and just keep an eye on things, as it has been going for 30,000+ miles with no apparent problems.

any advice would be helpful.
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
thanks for the tip.
on a hunch, i checked the harmonic balancer/serpentine pulley on a flat surface. bent!
swapped it for a used one i had, and it cut the wobble in half. crank is bent though. i can see the crank bolt wobble ever so slightly. and i replaced the bolt when i put the motor in, so i know it was done right.
it must have taken a pretty good hit at some point.
i can't believe it has taken me this long to notice!
i think i will try to run it till next year. i'll just have to try and save up some repair funds.
 

94x

TDIClub Enthusiast, Vendor
Joined
Nov 16, 2006
Location
Westfield, Massachusetts
TDI
2002 CTD w/12 valve, 2003 GTI w/ALH
It is possible that the crank bolt came loose at some point and it was tightened down. The lower timing belt pulley mates with the crank bolt surface of the crank. If the crank bolt surface is not completely flat the tb pulley will wobble and can cause the crank bolt to come loose again. You may find the crank is wearing into the flat part of the pulley. I just fixed a similar problem on a customer's car. I'd suggest removing the lower timing belt pulley, file the crank bolt surface flat, and replace the crank pulley and bolt.
 
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TDIDaveNH

Left Lane Coal Roller at Large
Joined
Feb 17, 2009
Location
North Conway, NH
TDI
1997 Passat TDI x2 1984 Buick Century 4.3 diesel. 2012 X5d 2012 Passat 6-speed
and was from a junkyard
With that kind of damage, I would suspect the salvage yard, because that is their M.O. Chained in all the wrong places and getting handled roughly because the people at these places don't seem to care about minor details like how the handle an engine properly.
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
It is possible that the crank bolt came loose at some point and it was tightened down. The lower timing belt pulley mates with the crank bolt surface of the crank. If the crank bolt surface is not completely flat the tb pulley will wobble and can cause the crank bolt to come loose again. You may find the crank is wearing into the flat part of the pulley. I just fixed a similar problem on a customer's car. I'd suggest removing the lower timing belt pulley, file the crank bolt surface flat, and replace the crank pulley and bolt.
good thought, but in my case the bolt is tight, and i replaced it myself when i got the motor, so i know it's good.
also, the serp. pulley was bent, so i know it took a hit before i got it.
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
It is possible that the crank bolt came loose at some point and it was tightened down. The lower timing belt pulley mates with the crank bolt surface of the crank. If the crank bolt surface is not completely flat the tb pulley will wobble and can cause the crank bolt to come loose again. You may find the crank is wearing into the flat part of the pulley. I just fixed a similar problem on a customer's car. I'd suggest removing the lower timing belt pulley, file the crank bolt surface flat, and replace the crank pulley and bolt.
well, when i checked the bolt to see if it was tight i only set the torque wrench on 50lbs. i just wanted to confirm that it was still tight.
i just now turned it counter clockwise and guess what? it's loose!

i guess you were right after all:eek:
i guess it's time to take it all back off and check the crank gear and nose.
luckily i have a spare gear, just wish i had a spare bolt! this time i will order 2.
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
I might have one if you have a time crunch. PM me if you want me to look.
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
crank gear had about 1/2 to 3/4 of a tooth of play in it:eek:
when i put my other used one on it only has about 1/8 of a tooth in play.
so...what is the best way to tell if there was any valve to piston contact? without taking off the head that is.
would 1/2 to 1 tooth off be enough to worry about contact?
i just don't want to get this all back together and find out i need to do the head.
 

schultp

Veteran Member
Joined
Mar 11, 2008
Location
Michigan
TDI
2010 Jetta Sportwagen, 6sp manual
You take the valve cover off and see if there is any evidence of lifter damage. If one or more have cracks then you can suspect valve damage. However, normal appearing lifters don't give 100% assurance that there isn't any valve/piston contact. It is an easy option. Also, check your timing alignment at the cam, injection pump, and flywheel.
 

94x

TDIClub Enthusiast, Vendor
Joined
Nov 16, 2006
Location
Westfield, Massachusetts
TDI
2002 CTD w/12 valve, 2003 GTI w/ALH
I doubt there is any valve damage. The flat spot on the sprocket of the car I fixed was almost completely round. The engine sounded like it had bad lifters... very loud. It was the sprocket spinning around. The car started very hard. If there was no damage in this case, yours should be OK.

With the new crank sprocket in place you will notice it will rock up and down, side to side. Get a good file and plan on spending alot of time filing the end of the crank flat.
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
I doubt there is any valve damage. The flat spot on the sprocket of the car I fixed was almost completely round. The engine sounded like it had bad lifters... very loud. It was the sprocket spinning around. The car started very hard. If there was no damage in this case, yours should be OK.

With the new crank sprocket in place you will notice it will rock up and down, side to side. Get a good file and plan on spending alot of time filing the end of the crank flat.
that's encouraging. and yeah, the end of the crank was pretty ugly, so i did some careful filing. now it is flat, square, and ready to go!
 

jackgreen

Veteran Member
Joined
Nov 15, 2008
Location
lewiston, northern california
TDI
1998 jetta tdi
got it all back together today, runs great! no bent valves:D

at my last timing belt job i used an off brand of tensioner and waterpump(from egermanpartsdotcom)after only 30,000 miles the spring in the tensioner was about to fail! and the waterpump was toast!
there are some things you can get away with going cheap. never again for me! at least not where a failure could be so destructive.

thanks for all your help and input folks!
 
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