I took my 1991 civic in to have the timing belt and related seals replaced. I picked it up and drove 40 freeway miles and the engine stalled, the "check engine" light came on and as I tried to get it out of traffic lanes, it started and stalled a couple more times before refusing to start.

When it was looked at, the timing gear was not attached to the cam and the tip of the cam, which had broken off, was with it. The woodruff key was broken.

What probably caused this? Could the failure be related to the work performed?

 

Could be an over tightened belt.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by akandok &raquo;</TD></TR><TR><TD CLASS="quote">Could be an over tightened belt.</TD></TR></TABLE>

If an overtightened belt did this, then it was most certainly the straw that broke the camel's back. Let's face it. Even that particular part of the cam is pretty damn strong. Rather, the cam was probably 'faulty' to begin with, and succumbed to fatigue. I guess you can't really say that Honda made a bad cam here, as they probably never intended for it to last 17 years anyway.

 

im sure the cam was designed to last much longer than 17 years. i guarantee the cam bolt was put on with an impact wrench, more than likely 3/8" as thats what most shop mechanics like to use for friggin' everything nowadays. "torque wrench? we dont need no stinkin torque wrench. BRRRRAPPP!!!"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt &raquo;</TD></TR><TR><TD CLASS="quote">

If an overtightened belt did this, then it was most certainly the straw that broke the camel's back. Let's face it. Even that particular part of the cam is pretty damn strong. Rather, the cam was probably 'faulty' to begin with, and succumbed to fatigue. I guess you can't really say that Honda made a bad cam here, as they probably never intended for it to last 17 years anyway.</TD></TR></TABLE>

Im not saying that the belt was strong enough to break the cam, but strong enough to put excessive stress on the end of the cam. That might of caused poor lubrication in the journal, over heat, and break off. Pics would help though

 

I would have to go with the overtightened bolt. I too have seen way too many mech's use an impact gun to put things together...Idiots!!

 

Pictures! I just took my fatigue test and I'd like to take a peak.

 

Pics can be seen at http://www.msnusers.com/docsownstuff

 

Great pictures, will comment later.

 

Maybe cam bolt not tight enough?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by akandok &raquo;</TD></TR><TR><TD CLASS="quote">Could be an over tightened belt.</TD></TR></TABLE>

Wouldn't overtensioning the timing belt cause bad performance immediately?

 

Notice how it split along the line of the key way which is a section of high stress concentration due to the sharp angle. If the bolt was too tight (and I mean way too tight) it could have started the crack that ended the cams life. Also, if the belt was too tight it would have added to the crack, and last its rotating.

Or it could have been a casting flaw that was exasperated by everything I just listed.

 

After playing around with the broken pieces, I kind of put together a theory. The bolt was not fully tightened allowing the gear to migrate outward until the keyway and key broke, about halfway out. The remaining key then settled against the broken edge allowing the engine to continue running, but very poorly. The cam end then broke from the violent wobbles and the then engine shut down completely.

How's that sound?

 

sure sounds like a reasonable possibility. have you tried going back to the place you had the work done. i imagine youd have a pretty good case saying you had a timing belt changed there and 40 miles after you got the car back the damn cam gear broke clean off. they should compensate you. cams generally dont just fall apart ya know

 

My thoughts exactly. Let me guess that the bolt just unscrewed from the part that broke off. They either didn't tighten it or they didn't seat the cam gear all the way and tightened it.

If it lasted this long something took it out. Cannot be poor casting. It could be a worn woodruff key that let the camgear slip a bit everytime you got on and off the gas, which inturn loosened the bolt. I would still blame the mechanic that didn't inspect the $2 part if that was it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by D16SiHatch &raquo;</TD></TR><TR><TD CLASS="quote">sure sounds like a reasonable possibility. have you tried going back to the place you had the work done. i imagine youd have a pretty good case saying you had a timing belt changed there and 40 miles after you got the car back the damn cam gear broke clean off. they should compensate you. cams generally dont just fall apart ya know</TD></TR></TABLE>

Went back to them and they basically said, "**** Happens!", and its just coincidence it happened exactly where we just worked 40 miles earlier. It couldn't possibly be our 27 year experienced mechanic. Then they blamed it on cam seizure caused by low oil pressure and poor vehicle maintenance by me. So I filed a better business bureau complaint against them and its in process. I just wanted to hear from people who don't have anything to do with my situation and who see civic mechanical problems every day.

 

If the cam seized, wouldn't there be marks/scores on the cam journals/seats in the head and caps?

 

Contact the bureau of Automotive Repair as well.
http://www.autorepair.ca.gov/stdhome.asp

Specifically, http://www.autorepair.ca.gov/S...t.htm

Your camshaft didn't fail from an casting flaw or a old crack. There is no sign of any kind of cyclic stresses over a period of time. This break is all castrophic failure. If it were cyclic failure leading to castrophic failure you would see an initial area where the break is different. This is not the case.

This was not caused by camshaft seizure either. The journals are not scuffed or damaged indicating that the camshaft had seized. Theres only normal wear on the journals.

Besides from the picture, it does look like the camshaft key and the groove has uneven damage indicating that the key was not fully contacting the camshaft along it's sides which means the bolt came loose and it backed off until the pressure caused the metal to deform the key, placing uneven stress and increased loading on the camshaft snout and caused the whole thing to fail.

In short, it's their fault. They dont want to own up to it.

Janos