Timing Belt & Crank Shaft Pulley Bolt/Key



I have a 1996 Honda Civic. Timing belt was replaced in June 2006 by my regular mechanic. In August on 2007, I was driving when a loud (and terrible) noise came from the engine and the power steering went out. I immediately took it to a nearby mechanic. The first question he asked was if there had been work recently done on the timing belt. His diagnosis- crank shaft pulley bolt was very loose, which caused the crank shaft pulley key to break = $850 in damages to the engine of my car. He said that usually the only time the crank shaft bolt is touched is when work is done on the timing belt. Is this true? I would like to file a complaint for negligence against the original mechanic (the one who installed the timing belt).

Thank you.

Ps. When I spoke to the mechanic who had done the original work, he told me the warranty had expired and he then hung up the phone. Great customer service.


Exactly what are the damages? Seems to me it needs the crank keyway replaced and maybee a crank pulley.


yes, crank shaft gear, key, pulley, timing belt, upper and lower timing belt cover, drive belts, and valve cover gasket were replaced.


Seems to me you got taken by both mechanics. I have seen a few Hondas that have suffered from shadetree timing belt replacements. If the crankshaft bolt is not tightened to specs it will back out. I have seen them go so far as to fall off, followed by the crank pulley and shredding the drive belts. These repairs only required changing exterior components. I can think of absolutely no reason for replacement of the timing belt again, the crank gear, or the timing covers.


Was the mechanic an independent mechanic and did he have the proper documentation and torque values for this procedure?


You never mentioned the water pump. Maybe it was just an oversight. It is common practice to replace the water pump at the same time as the timing belt. In your vehicle, the water pump is driven by the timing belt. However, if for some reason the water pump wasn’t replaced at the same time as the timing belt, another reason to remove the crankshaft bolt would be to replace the water pump. You didn’t have this done after the timing belt job did you?


I agree with Dartman. JMHO, but I always use Loc-Tite on things like this along with proper torque and that’s always on top of visually inspecting the threads. It’s cheap insurance.

One thing here. What about any damage to the crankshaft nose or keyway (slot)? Any wallowed nose (out of round) or looseness in the keyway means that any repair is not going to last. ???


I was given the option of replacing the timing belt – I opted to change it given the possible “trauma” it may have experienced. The cover and gear pulley were replaced because they were totally worn down by the loose bolt. I have all of the old car parts and the mechanic who did the current work explained evertyhing while showing me the damaged parts – the metal of the gear was worn, the key was broken, the timing cover was thrashed–. I actually trust him and believe that he is telling me the truth (he has an incredible reputation).

The question that remains: Is it possible the bolt was not tightened properly when the timing belt and water pump were installed last year? Would there be any other reason for the crank shaft pulley bolt to be touched??? I am trying to determine the reason for the broken key. Could it possibly be related to something else? Or is it pretty clear it is directly related to the timing belt installation?

Thank you for your advice.


Instead of anyone trying to list all possible reasons to touch the crankshaft bolt, it would be more to the point if you listed what other work you actually had performed on the car after the timing belt job. Then we could say whether or not the crankshaft bolt would likely have been removed.


To answer your question I can think of no reasonable explanation for removing the crank bolt other then to change the timing belt, timing belt tensior, cam seal, crank seal, timing belt idler, and water pump. It sounds to me like the first mechanic failed to properly torque the crank bolt after changing the water pump and timing belt. As OK4450 mentioned earlier inspection of the threads on the bolt and in the crank are imperative along with thread locker and proper torque.


There’s not much I can add except that if the threads are good and the bolt is properly torqued then it should not come loose at all, even without Loc-Tite.
Loc-Tite is just an extra “insurance policy” IMHO.

It seems to me the fault here falls back on the guy who did the timing belt last year.
As to what to do about it, that may get sticky since he hung up on you.
Good luck anyway.


Even after after replacing many timing belts, and many on Hondas, I find myself unsure of where to stand on this issue. Long ago I learned to use a common shop chemical as a thread locker and it has been so successfull that a pulley bolt has never loosened itself after I replaced it as far as I know. If this situation were to face me I would likely repair the car as necessary unless there were indications of repairs subsequent to mine,as it certainly would appear to be the result of poor workmanship.


The only other work done on the car since the timing belt in June 2006 was to have the emergency break tightened (September '06 by the same mechanic) and the oil changed. Would the crank shaft bolt be involved?


The only other work done on the car since the timing belt in June 2006 was to have the emergency break tightened (September '06 by the same mechanic) and the oil changed. Would the crank shaft bolt be involved?


The oil change and park brake adjustment would not be related to this problem at all.
It all falls back on the guy who did the timing belt.