Crankshaft Pulley Came Off

[Ajbent86]

Two weekends ago I changed the timing belt on my 89 Accord DX. The job went successfully and i have put about 200 miles on the car since.

Today, when i went to start the car, i heard a terrible "THUNK" so i turned off the key. (Total runtime of about 2 seconds).

I looked under the hood to find the Crankshaft Pulley had come off. I have all of the parts (Crank Bolt, Crank Washer, Pulley, etc) except for the keyway; I cannot find it after this. I will purchase a new one from Honda, no big deal.

ANYWAYS, my question is........How is this possible?!?! I tightened the bolt down when reassembling the car.

Also, I was under the impression that the crankbolt constantly tightened with the counterclockwise rotation of the engine. (It took several hours to get the bolt loose to change the timing belt.) And why would it take 2 weeks and 200 miles to come off?


I intend on fixing it all tomorrow, but wanted to post here to get an idea of what might have went wrong. This is my 2nd DIY timing belt change on this car, so i felt quite confident i did a good job.


Thanks in advance for any advice.

[car6289]

Did you torque the pulley bolt to 108 lb ft?

I have never in my life heard of a constantly tightened bolt. There are things like lock washers, Loctite thread locker and safety wire (widely used in aviation) that reduce significantly the possibility of a bolt or nut from backing off.

Check to make sure the threads on the bolt and internally in the end of the crankshaft are good.

Use a torque wrench to tighten the bolt to spec, in this case 108 lb ft.

Check the torque on the bolt every 50 miles or so. Do this check 3 or 4 times (50 mi., 100 mi., 150 mi. and at 200 mi.) to be sure the bolt is not backing off.

[lostforawhile]

Did you torque the pulley bolt to 108 lb ft?

I have never in my life heard of a constantly tightened bolt. There are things like lock washers, Loctite thread locker and safety wire (widely used in aviation) that reduce significantly the possibility of a bolt or nut from backing off.

Check to make sure the threads on the bolt and internally in the end of the crankshaft are good.

Use a torque wrench to tighten the bolt to spec, in this case 108 lb ft.

Check the torque on the bolt every 50 miles or so. Do this check 3 or 4 times (50 mi., 100 mi., 150 mi. and at 200 mi.) to be sure the bolt is not backing off.
he's talking about a left hand thread bolt, the engine turns opposite the bolt threads so it can't loosen, you are really supposed to replace these crank bolts when you remove them,

[Dr_Snooz]

I thought the crank pulley bolt was regular thread. Never heard of replacing it. What do you know that I don't?

[lostforawhile]

I thought the crank pulley bolt was regular thread. Never heard of replacing it. What do you know that I don't?

Honda is recommending replacing the bolt every time it's removed now, I think the bolt stretches under that much torque, the bolt is cheap, good insurance

[car6289]

Honda is recommending replacing the bolt every time it's removed now, I think the bolt stretches under that much torque, the bolt is cheap, good insurance

Bolt replacement sounds like a good recommendation. I've changed my timing belt three times on my present 3G and have yet to have the bolt back out (touch wood). Sure it puts a few bucks in Honda's coffers but could prevent potential damage and downtime should the bolt loosen or back out altogether at an inoppertune time. Next belt change I'm buying a new bolt.

http://www.3geez.com/forum/showthread.php?t=75187 Another member's recent experience with the crank pulley. The bolt did not come out in this case. Bolt stretch? Improper bolt torque? Perhaps.

[Ajbent86]

well, I put it all back together today. Got a new crank key from Honda for 4 dollars.

Properly torqued it down this time as well. Hopefully it will go years without issue. She cranked right up with the turn of the key!

I plan on checking the bolt in 50 miles.

[lostforawhile]

I may put an extra key and bolt in the car for emergencies. does anyone know if the pulley is balanced independently ,or the engine is balanced with the pulley?

[car6289]

I may put an extra key and bolt in the car for emergencies. does anyone know if the pulley is balanced independently ,or the engine is balanced with the pulley?

Is anyone that built these engines back in the 80's still alive to answer your question Lost?

I'll guess they are balanced independently. I can't see a failed pulley causing someone to have to remove the crankshaft for balancing as an assembly with the pulley. A race team with deep pockets would probably go to that extreme. For we denizens of the road, slap on a new pulley and motor on.

[lostforawhile]

Is anyone that built these engines back in the 80's still alive to answer your question Lost?

I'll guess they are balanced independently. I can't see a failed pulley causing someone to have to remove the crankshaft for balancing as an assembly with the pulley. A race team with deep pockets would probably go to that extreme. For we denizens of the road, slap on a new pulley and motor on.

my book says externally balanced, crap,that means the pulley is balanced as an assembly with the crank

[cygnus x-1]

my book says externally balanced, crap,that means the pulley is balanced as an assembly with the crank


What book says that? My 'lude service manual says nothing about balancing that I can find. And I haven't heard of an inline 4 being externally balanced. When I had my engine parts in the shop they only balanced the crank and flywheel, and they were done separately. I even asked them specifically about balancing the whole assembly and they said no, not on an inline 4.

I suppose you could do the whole assembly but the parts are all essentially symmetrical so it shouldn't be necessary.


C|

[lostforawhile]

What book says that? My 'lude service manual says nothing about balancing that I can find. And I haven't heard of an inline 4 being externally balanced. When I had my engine parts in the shop they only balanced the crank and flywheel, and they were done separately. I even asked them specifically about balancing the whole assembly and they said no, not on an inline 4.

I suppose you could do the whole assembly but the parts are all essentially symmetrical so it shouldn't be necessary.


C|one of my service books says this, I really need a new crank pulley,as I discovered a large chip out of mine,it's going to get worse if it's not fixed

[YK86]

I've had to replace the crank bolt on quite a few F and H motors. Backing out seems more common on the H22 as I've had to repair 3 5th gen Ludes with wobbly crank pulleys. I don't know if it's just install error/wasn't torqued properly at the previous shop, or an actual problem with the bolt.

Most of the time, both the key and pulley are no longer square after wobbling around on the crank. Luckily, the crank has never been damaged on any of the cars as we caught it before it flew off or got really bad. For the H only, I order new crank bolts now.

For pulley replacement, just speaking from experience, I have never had an issue with using a pulley from a different motor. I've used an f22 pulley on an h22 motor, f22 pulley from another f22, h22 pulley from another h22. I always assumed they were balanced independently from the factory so it didn't matter what motor/crank they went on. :dunno:

I think anything is better than a chipped pulley so I'd just replace it.

[lostforawhile]

I've had to replace the crank bolt on quite a few F and H motors. Backing out seems more common on the H22 as I've had to repair 3 5th gen Ludes with wobbly crank pulleys. I don't know if it's just install error/wasn't torqued properly at the previous shop, or an actual problem with the bolt.

Most of the time, both the key and pulley are no longer square after wobbling around on the crank. Luckily, the crank has never been damaged on any of the cars as we caught it before it flew off or got really bad. For the H only, I order new crank bolts now.

For pulley replacement, just speaking from experience, I have never had an issue with using a pulley from a different motor. I've used an f22 pulley on an h22 motor, f22 pulley from another f22, h22 pulley from another h22. I always assumed they were balanced independently from the factory so it didn't matter what motor/crank they went on. :dunno:

I think anything is better than a chipped pulley so I'd just replace it.
on a lot of the later model honda's there's a new bolt design and new torque procedure, I ran into this on the 98, the bolt had to be torqued something like 30 pounds, then rotated 45 degrees, ran for 15 minutes, then rotated another 45 degrees for a total of 90 degrees, the bolts are disposable

[car6289]

on a lot of the later model honda's there's a new bolt design and new torque procedure, I ran into this on the 98, the bolt had to be torqued something like 30 pounds, then rotated 45 degrees, ran for 15 minutes, then rotated another 45 degrees for a total of 90 degrees, the bolts are disposable

My 09 Ridgeline and 05 Civic use the torque plus so many °'s of bolt rotation tightening procedure.

I was reading through the 1986 -89 Accord Master Manual that has the torque of the pulley bolt as 83 lb ft. The 1989 Accord Service Manual and 1989 Accord Supplement Manual have the higher torque 108 lb ft.

[Dr_Snooz]

Lost, I've been running a junkyard pulley on my car for years now. I busted a chip out of mine pretty early in the game. It's not been a problem.

[88Accord-DX]

I had a nightmare removing the crank bolt almost 10 years ago. I had to use some 3/4" industrial size sockets & impacts cause it broke half inch sockets! (impact driver at that time was weak) Had like a 5 foot cheater bar on the end of a 3/4" industrial breaker bar..
The bolt does tighten up with the motor spinning. Maybe put some red threadlocker on the threads & torque it again to specs after a day.