timing belt snapped while driving and a question

[eliterit]

i have a rwd ca18det and the timing belt recently snapped while driving. im trying to replace the belt right now hoping that no valves were bent, however, the exhaust cam seems to be more less in the area it needs to be, and the intake cam timing mark is way off and i cant seem to turn it to where it needs to be.

does this mean that the valves hit the pistons? or should i try harder to turn the intake cam clockwise to its designated position via fsm?

i can turn the intake cam almost 180 degrees but it gets to this one point where i start to overtighten the cam gear center bolts.

the crank pulley is set to 0 degrees and i made sure it was right as i pulled the pulley off.

any help is greatly appreciated

thanks
Modified by eliterit at 1:03 AM 6/14/2006

[c-rad]

If you were driving it and the belt snapped, your valves are bent dude. Head is most likely trashed from the guides getting all jacked up too. It's an unfortunate event and happened to me on my Z32.

[eliterit]

so buy a new head completely? or can i rebuild this one?

thanks for your response

[biosehnsucht]

would the valves have damaged the pistons? or are the valves the "weakest link" ?

how are you trying to line up the cams ? overtighten the cam gear center bolts? try putting a wrench on the cam (it has flat spits for this), even if everything is ok you'll have to force them into position because they're being forced against teh spings.. and I hope you're not ramming the valves into the pistons when you're trying to turn the cam..

[eliterit]

would the valves have damaged the pistons? or are the valves the "weakest link" ?

how are you trying to line up the cams ? overtighten the cam gear center bolts? try putting a wrench on the cam (it has flat spits for this), even if everything is ok you'll have to force them into position because they're being forced against teh spings.. and I hope you're not ramming the valves into the pistons when you're trying to turn the cam..

i am trying to line up the intake cam via one of the 4 11mm bolts on the center of the intake cam gear. by trying to tighten one of those bolts, the gear turns freely for almost a half a turn, but before it gets midway through the turn it stops and if i put more force on the ratchet, it begins to tighten the bolt more, rather than turning the gear.

how much force is required? and should i be turning the cam gear by another method rather than one of the inner four 11mm bolts?

also, if i am at 0deg tdc the valves shouldnt be hitting the pistons, but in this case according to C-rad since the car was driving when the belt snapped the valves are probably already bent.

[biosehnsucht]

take off the cam covers if you haven't already.

Look at the cams, they have flat sections you can get a large adjustable wrench on easily (or non adjustable, but then you'd have to figure out what size it is :P ) .. once you have it approximately in the right position you can turn it to the right position using this. I think the front and rear sections have offer 90 deg flat sections so you can use a pair of wrenchs to turn further.. but I'm not sure, been awhile. Just take off the covers and look, you should see what I mean. It's tricky to do by yourself, trying to hold both cams in the right place and fit the belt, get a buddy to help makes it much easier, you can line up the cams and one of you holds them there while the other fits the belt.. or some combination.

[boost_boy]

Don't waste your time trying to install a new belt because your intake valves are done, like c-rad says. Your head is probably salvageable, but you'll need new valves and guides. Don't worry about the valves taking out the pistons, this one's a bit tougher than the DSM scenarios. So again, start taking the head apart! You can't turn the cam gear to where you want because the valves are bent (end of discussion).

Dee

[capwred]

i agree with dee.this same thing happen to me on my '91 ford range.i had to have 3 valves replace but the head was fine.so i would start taking the head of the engine.sorry dude but your in for some work.

[eliterit]

ok cool. i guess its no big deal seeing as i got the car for 500 bucks anyway.

i guess ido have a bit of work lined up for me

[biosehnsucht]

So where in TX are you? There's several of us..

[eliterit]

im in san antonio

[dattodude]

A standard CA18DET will not bend valves from a broken timing belt unless you are valve bouncing on the redline when it happens.

I agree that many cars will bend valves if the timing belt breaks, especially high compression (low clearance) NA engines.

I have it from first hand authority from a fella whos rebuilt dozens of CA's that this isn't the case for a CA18det.

Re-align the cams and crank pulley to TDC cylinder one, and put another timing belt on it.

Chris

ps. not being able to turn the intake cam does sound rather ominous though...like the other boys say, use a wrench on the hex section of the cam with the cam covers off.

[fanta]

Leak-down and pull the head.

[dash]

interesting to hear the different points of view, but I'd make certain that the valves are bent *before* going thru all that work.Bring up #1 to TDC if you can... go 90 degrees before of after, so the pistons are halfway up the bore, then try rotate the cams by the hex on the shaft. If the cams spin ok, go ahead and set the timing. You gonna need a new timing belt anyway.I broke the timing belt on my escort 1.8 dohc while normal driving (n.a./ higher compression). I took a chance and put on a new belt that I already had (45minutes total, FWD). Motor ran with a slight miss and valve tap, as I suspected a 'minor' vavle bent. After ~30 minutes driving, it cleared right up - motor returned to silky smooth idle/driving/revving. Lucky, I guess

[eliterit]

interesting to hear the different points of view, but I'd make certain that the valves are bent *before* going thru all that work.Bring up #1 to TDC if you can... go 90 degrees before of after, so the pistons are halfway up the bore, then try rotate the cams by the hex on the shaft. If the cams spin ok, go ahead and set the timing. You gonna need a new timing belt anyway.I broke the timing belt on my escort 1.8 dohc while normal driving (n.a./ higher compression). I took a chance and put on a new belt that I already had (45minutes total, FWD). Motor ran with a slight miss and valve tap, as I suspected a 'minor' vavle bent. After ~30 minutes driving, it cleared right up - motor returned to silky smooth idle/driving/revving. Lucky, I guess

a friend of mine told me to do just that. turn the crank a little more than 0deg so i can turn the intake cam where it needed to be. so i did that got the belt on perfect and a manual compression test shows #1=55psi #2=25psi #3=55psi and #4=0psi.

i didnt mind putting the belt on for the heck of it. i just wanted to see what happened and it looks like i for sure have some bent valves.

oh well. thanks very much for everyones input i greatly appreciate it. looks like i will be looking for a head or just have a valve job done.

[dattodude]

Thanks for the update. Certainly settled any future arguments.

Good luck with a cheap solution, and getting back on the road asap.

Cheers,Chris

[boost_boy]

A standard CA18DET will not bend valves from a broken timing belt unless you are valve bouncing on the redline when it happens.

I agree that many cars will bend valves if the timing belt breaks, especially high compression (low clearance) NA engines.

I have it from first hand authority from a fella whos rebuilt dozens of CA's that this isn't the case for a CA18det.

Re-align the cams and crank pulley to TDC cylinder one, and put another timing belt on it.

Chris

ps. not being able to turn the intake cam does sound rather ominous though...like the other boys say, use a wrench on the hex section of the cam with the cam covers off.

Maybe all his customers were just coincidentally lucky because they do get bent at lower rpms, but they are not extreme interference-type engines like the mitsubishi 4G DOHC series. I've experienced bent valves at idle when a camshaft broke, so I guess one can safely assume that while under load, they are very much bendable; especially when the belt lets go. i've never had the displeasure of popping a belt before.

Dee