Antemortem

Posted in a sub-forum, but got no responses, so I'm reposting here.

When I started my car yesterday morning the engine sounded really bad--like metal being slapped around. I shut the car off and inspected the engine bay---nothing looked unusual...oil level fine, etc....started it up again and looked under the hood and saw that the crank pulley was going from side to side all wobbly. Pulled the passenger tire and the cover to find that one of the four 10mm bolts holding the pulley on had sheared off and the other bolts were loose as well.

Questions I have are:

1) has any damage been done to my engine w/the crank pulley out of balance? (It was idling only when the issue happened, but I imagine it was slightly out of whack the day before during a freeway drive.)
2) what does the center bolt do vs. the outer bolts and how do I loosen/tighten it without the crank spinning?
3) why would this happen in the first place? Neither I nor anyone else has ever touched the belts or the pulleys.


Thanks in advance

Steve_P

iTrader: (5)

the center bolt holds on the lower timing belt sprocket. I always tighten it with an impact wrench. Maybe the bolts weren't tightened properly at the factory? I would put on some new bolts and give it a try- it should be fine.

lbcevo

iTrader: (12)

I had my CP come loose too, and it damaged the crank angle sensor and my car died until it was diagnosed and repaired. Check the crank angle sensor for damage.

sonicnofadz

iTrader: (4)

Nothing is wrong with your engine. The center bolt that olds the crank timing belt sprocket DID not loosen (trust me) it is bolted on with 80 ft-lbs of torque and it is not even connected to the harmonic balancer. The four smaller bolts holding the harmonic balancer pulley just came loose, you should just unbolt it and remove the broken bolt and re-tighten everything. Did anyone do any work recently that would require removing the harmonic balancer?

Antemortem

Thanks for the replies, guys. No work has been done anywhere near the harmonic balancer. The closest I've come to the crank pulley is when I change the oil filter!

How can I tell if the crank angle sensor was damaged?

sonicnofadz

iTrader: (4)

If it throws service engine soon light, or if your car doesn't start anymore. Trust me, nothing was damaged, DSM's used to have the problem of the balancer actually falling apart (the rubber would crack and seperate). Just get a 1/2 drive socket wrench to hold the crank in place (the center bolt) and tight the 4 surrounding 12 mm bolts (I think they are 12 mm) with your other hand. You should do this with a torque wrench but you can guesstimate if you're cheap and lazy =)

Antemortem

Ok, the bolts from the dealer came in. I released the tension on the belt and removed the three remaining screws that held the crankshaft pulley on. More bad news...the inside of the crank pulley (where it attaches to the crank sprocket things) is chewed up a bit and the three holes where the remaining screws are are now slotted from the whole thing being loose and vibrating around. The threads on the crankshaft seem ok, but the old bolts I pulled out are pretty chewed up. I could put the new bolts in, but it'd be only a matter of time before the looser tolerances caused more problems.

Looks like I just bite the bullet and take it into the dealer. Damn--I hate giving anyone else the keys to my car! Think a Works Stage I tune and exhaust will end up causing the dealer to give me some BS about the mods causing the problem (even though there's no way in hell they did)?

sonicnofadz

iTrader: (4)

If you really want to pay the extra money to get it fixed at the dealership, go ahead. If you just buy some new bolts and slap them in there it should be fine, unless I misunderstood your description of the damage involved. At the very worst you will need a new crank pulley (harmonic balancer).

94AWDcoupe

iTrader: (125)

There should be a sticky on this event. Stock harmonic pulley is made of aluminum. With time the normal engine vibration is causing the alumnum pulley to compress under the bolts. People need to check those bolts for tightness at every oil change. From your description, if the four bolts will still thread in okay than you just need to make sure there are no high spots on the faces. Then bolt that sucker back on.

Antemortem

I've got the new bolts, but yeah....94AWD I think hit the nail on the aluminum head. That makes a lot of sense....Hardened steel bolt/washer compresses the AL. AL pulley compresses slightly under all that stress and pretty soon the tolerances/torque of the bolts loosens, weakest bolt shears, and the added stress to the other bolts eventually throws the whole thing out of balance. Only ? is--is the pulley AL?

Aside from that, the pulley is all ****ed up now due to the fact that it had room to shudder back and forth against the crank itself. So I'll need to replace that, too. Not so sure if the crank itself is damaged---that's something beyond my mechanical abilities to even diagnose!

DRFTKNGG

iTrader: (8)

Throw some loc tight on the bolts retighten and your good.

Steve_P

iTrader: (5)

the balancer/damper/pulley doesn't touch the crank- it only connects to the lower timing belt sprocket. On the DSM 4G63 there is a pin in the sprocket that aligns the damper- so it will only go on one way. I'm not sure if the Evo has this but assume so; if so that is something else that probably needs to be replaced if broken off and you might have problems getting it out w/o removing the sprocket.