both cam sprockets broke bolts

[UndrdaSHO]

OK so I had an engine failure and put a new one in, I started tearing down the old one for parts and diagnostics and found something weird...
The rear cam broke all three bolts dropping them down into the timing covers and damaged any pulleys in their path. I went to remove front cam Sprocket and bam, one bolt broken one almost gone and one still intact. I haven't dug into the heads yet cause I'll have to remove the cams to get to the Allen torqued bolts so not sure what's up down there yet.
Has anyone ever had this issue? What should I look for cause this is all kinda new to me. Just trying to figure out why this all happened, when the car died it flashed all of its dash lights and shut down so I coasted to a safe place and stopped the car. I tried to start the car and it tried to turn over once, then the second and third time I tried to start it there was a grinding sound so maybe that caused the damage to the cams? This whole thing is just weird lol :banghd:

 

[SHOtimer]

When the old motor died did it have any oil in it?

Also, IIRC you should be able to pull the heads without taking off the cams. It's been awhile so i don't remember for sure.

Doug

 

[UndrdaSHO]

Yep good on oil for sure I'm really "religious" about that for sure it did have an oil leak from the valve cover gasket not being re-torqued down after it was put on but it only burned about 1 quart every 3,000 miles. Just trying to figure it out everything still rotates fine goes to tdc and cams turn fine.........just weird altogether

 

[yamahaSHO]

Scott (strings1732) had this happen under boost. It melted 2 pistons and cracked another.

 

[Irish Pride]

Had any work been done to the old motor before it died? 60K, timing belt?

The only way that could have happened is if the cam sprockets were not tighten/torqued after the last time they were off. The bolts were put in but not tightened, started to work their way loose and then from that point it was only a matter of time before they snapped. It would be my guess that whomever worked on the motor last skipped a step.

 

[UndrdaSHO]

Im not running any kind of boost those I wish I could lol that be nice I'll dig into the heads and block tomorrow to see what's up down there but everything seems to move fine. I guess its just my bad luck lol I must have broke a mirror I guess cause I'm in my third year of nothing but bad luck. I'll update tomorrow
When I find some more input about the condition of the lower half of the motor. Its just crazy lol

 

[kevinspann]

Seems like the motor isn't blown, just someone messed up.

 

[Toolman]

Yeah, there should be no damage to anything internal, assuming you had stock cams/pistons.

 

[jimtash]

There's no reason for the cam bolts to snap like that unless the tensioner seized or something foreign got into the belt system and locked a sprocket up.

I will say that I won't use Dayco timing belts anymore and exclusively use Cloyes because they work better and are much quieter.

 

[rubydist]

I have only seen that if the cam sprocket bolts were not tight, or if the dowels were missing.

you can pull the heads without pulling the cams - there are small reliefs cut into the cams so that you can pull the head bolts past them if you are careful.

 

[jimtash]

Think the belt was on too tight?

These Dayco belts suck majorly. I could never set the tension right with them and either it would be too tight from releasing the tensioner or too loose from having to back if off manually. And this was common in two different belts. With the Cloyes there's no issues and haven't had to adjust out any whine from being too tight. It functions perfectly.

 

[UndrdaSHO]

That's what I thought too tight timing belt cause it was a ***** to put on. I originally thought the bolts to the sprockets were loose but I know I was last to touch the front cam, husband last touched rear. So I knew that they both couldn't be loose. Its really all good though I found a 3.2 with a engine that had 100k in a junkyard 300 bucks runs like a dream. Found a lot of weird shit though like electric connections leading nowhere, four bolts missing the low rpm butterfly canister (thanks Fred) wasn't even on my old motor.

 

[Irish Pride]

If the tensioner had siezed it would have generated enough heat and wear to cause the belt to snap, or the pulley on the tensioner would have come off before either of the cam pulleys would fail. The ATX tensioner sets itself automatically. It cannot overtighten to the point of putting too much pressure on the belt. There is nothing internal that would cause a cam to lock up with enough force to snap those bolts on one cam yet alone 2. The only way this could have happened is the bolts were loose, they started to back out, the sprocket started to wobble, and they eventually failed. Without the sprocket coming loose there is no way to put enough pressure on those bolts to cause them to snap like that.

 

[rubydist]

well it is possible for the timing chain to fail in such a way as to cause the cams to lock and shear those bolts, but that is very unlikely on these engines and the evidence would remain to be seen if it did happen.

if the bolts are loose in the cam sprocket, it will rattle like heck (don't ask me how I know...), so one should have heard that and been searching for the cause of the racket....