what can cause a cam to break?
 

long story short, my buddy texted me asking how something like this could have happened and i was at a loss. it's an 02 rsx-s with ~116k miles. only mods are an intake and exhaust, otherwise internally stock. oil level was good. i'm not there with him so i dont have all the details of what happened but from i can gather he downshifted from 6th to 5th on the freeway and the car died. he and another friend did a compression test and got super low numbers so they popped the valve cover and found this:

https://sphotos-a.xx.fbcdn.net/hphot...87229520_n.jpg

https://sphotos-a.xx.fbcdn.net/hphot...49610582_n.jpg

https://sphotos-b.xx.fbcdn.net/hphot...21816847_n.jpg

there are deep scratches on the cam caps and probably some bent valves too

Re: what can cause a cam to break?
 

if you don't have them aligned properly and don't tighten them down little by little in the correct order, they will snap like a twig.

Re: what can cause a cam to break?
 

it's an internally stock motor. these are the stock cams. never had them removed prior in the time he's had the car.

Re: what can cause a cam to break?
 

Defective cam or possible driver abuse, is he an "aggresive" driver

Could be a valve bent that got stuck closed, how is the valve timing, did the timing belt skip some teeth? 94

Re: what can cause a cam to break?
 

he told me when they took off the valve cover the bolts holding cap #4 were loose. the cam snapped in cylinder 3. owned the car 3 years and never had a problem.

i wouldnt call him an aggressive driver. no more so than most honda drivers i guess. :shrug:

Re: what can cause a cam to break?
 

Holy shit man, that sucks! As stated above, if they aren't torqued down in sequence or per torque spec, they'll snap like twigs. Looks like the #4 cap being loose caused undesired stress on the cam. I watched a friend snap a $600 HKS cam in a 2JZ on an engine stand a few years ago because he thought he was a badass and didn't need to follow the sequence.

Additionally, I have never heard of a cam breaking because of "aggressive driving"...

Re: what can cause a cam to break?
 

i was thinking maybe the cam breaking caused the loose bolts but who knows? it's odd though that after 3 years of ownership and never once removing the cams those bolts would decide to work their way loose now.

Re: what can cause a cam to break?
 

I'm thinking the bolts on the cap backed out causing the cam to snap. I'd maybe search to see if any other DC5 owners have experienced this or maybe if there was even a recall?

Re: what can cause a cam to break?
 

It wouldn't surprise me if someone DID loosen those bolts. Sometimes we make mistakes without realizing it. Maybe someone loosened it by mistake and didnt tighten it down well enough. Point is that the cam breaking wouldn't have caused the bolt to come loose, and I don' believe the boys at Honda left 'em loose either. k20=timing chain

Re: what can cause a cam to break?
 

regardless, it happened. he replaced the cam and rocker assembly and the car started right up. i'm still telling him to do a leakdown to check for bent valves.

Re: what can cause a cam to break?
 

uneven torques on the screws. heat. etc. unbalanced rotation.

Re: what can cause a cam to break?
 

I saw something like this on a 97 Mazda Protege' 1.6. A buddy called me to ask if his timing belt should have broken at 81K, yet was due at 105K. He told me a few hours later that the oil LEVEL was good, the timing belt intact, but that the cams actually snapped, because they seized. Turns out he was beyond overdue for that oil change, and topped his oil after being sidelined (to throw his wife off the trail, I figured). Guess he didn't want to live up to being an ass.

That cam in this R- looks fairly worn in some places, (unless it's not a roller) as if something was brewing a while before she gave up the ghost.

Re: what can cause a cam to break?
 

A roller...interesting patterns...

Re: what can cause a cam to break?
 

You could take what's left of the camshaft to a metallurgist. He or she would probably be able to offer some insight. Seems weird that an OEM camshaft in a basically stock engine would snap.

Re: what can cause a cam to break?
 

lol i dont think he cares enough to take it that far

Re: what can cause a cam to break?
 

Take a close-up pic of the break and I can tell you a little better about what happened.

Re: what can cause a cam to break?
 

Just throwing it out there. Haha

Re: what can cause a cam to break?
 

Loose cam holder or not torque to specs