Timing belt snapped

[all_accord]

ive been hoping and prayingfor the best all day this has got me all messed up its my daily and im alreadymissing work tomorrow because of it

[ProSouth]

eeek, sorry bro. pull the plugs ASAP. also like ender said align the pistons up. it may be hard to do with the head on. but turn the crank over a little, try turning the cam, turn the crank over a little, try turning the cam.

[Straight Success]

I could be wrong here, but I popped my timing belt about a month and half ago. I'm certain that I bent a few valves, and that's why my car is sitting; at least for now! I also popped the TB on my 1990 Honda Prelude Si (first car) back in 2001. Sure enough, bent valves.

I hate to say this, but almost 10 times out of 10, our interference engines bend valves when we snap a TB. Bent valves stuck in place is one culprit that wouldn't allow the cam to move. Hope everything works out.

[dysfunk]

My timing belt snapped a couple weeks ago. I'm one of the very fiew that didn't have any valve damage. Good luck, bro.

[Straight Success]

I stand corrected.

[JDMDriver]

There could be a chance you have not bent your valves but it's a slim chance. From experience an interference engine can survive a snapped timimg belt, so thats something, and someone above echoes that experience.

My experience was from a b16a twin cam jdm engine which is still an interference engine that is notorious for almost always resulting in bent valves, however when my belt snapped it survived.

It would depend on the condition at the time it broke if the probability of the valves surviving is high or not. in my case my belt broke in a down hill coast with slow gradual accelerator pedal application on approach to the bottom an start of ascent. I am not a lead foot nor an aggressive driver (police here in Australia have changed the landscape of drivers and have removed many if not all drivers that drive, tend to drive spiritedly and even some. Seriously all that are left are drivers with self control made of steel and sterner stuff)

Back on topic - if the belt broke on heavy throttle such as high speed freeway conditions, uphill, towing a heavy load or under heavy acceleration via aggressive spirited driving then the probability is greater it will result in bent valves.

For me my belt broke due to neglect. I failed my car. I knew it had to be done but always reasoned to delay it as I didnt have the cash. Well my cheapness almost cost me 4 to 5 times just paying for preventative maintenance for just a normak timimg belt service.

GoodLuck hope it's ok.

[dysfunk]

I was going down hill and slowed down to a roll, due to going over a speed bump. My belt snapped at idle.

[bassrock234]

Mine snapped about a month ago now I guess. I was in 5th gear about 40-45mph, pretty low rpm. My cam was about the same, would turn maybe 1/4in and no further either direction. I used a compression tester hose to put pressure to the cylinders with all the cam towers loose so the valves would be closed. Not a single cylinder would hold any pressure at all. Pulled the head and found about 8 bent valves. Good luck.

[Straight Success]

Think about it in simple terms. Your cam is moved by the rotating motion of your crank. The timing belt is what connects those two together. If the TB snaps/pops, the crank will continue to rotate due to the momentum that it already has until it comes to a rest position due to friction. Even at idle, each piston is moving up and down ~11 times per second. You cam is probably 1/6 - 1/8 (estimate) the weight of the crank which means it has much less inertia than your crank. There's a difference in frictional forces that act on both the cam and the crank. This means that the cam and crank will slow at different rates causing them to rotate or stop at a different time/position/velocity. Hence, one cylinder will have at least one valve past the clearance point of the piston's TDC during this non-unison rotation. While the crank is coming to a rest position, the pistons will continue to move up and down. It's a good chance that the cylinder with the open valve will have a piston come meet it in those few seconds of the crank coming to a halt. It's a long shot, but there's hope that you will be one of the lucky ones.

[oyajicool]

Before you attempted to time the crank shaft and cam shaft for timing belt installation, you need to loosen all of valve adjusters in order to prevent valve damage, provided that none of valves were damaged in the first place.

Or, you could loosen bolts for cam shaft caps, pop the shaft off of bearing surfaces and rotate into position. Torque down the bolts after wards.

----------------------------------------------------

On your car, does the cam shaft turn in either direction? Even a little? If it doesn't move at all, you have seized cam shaft. If it turns in one direction but not the other, you have a stuck valve.

[all_accord]

Well I did what was suggested yesterday and the cam turned over just fine once I lined up all the pistons. oyajicool the cam was turning about a 4th an inch both way then stopping and would not turn. I actually loosened the cam bolt trying to turn it left. I put a magnet in the spark plug holes and didnt pick up anything so im guessing they arent broke but might be bent.. However I was sitting at a stop sign when it happend I had just taken left turn when the car started to bog. hadnt even left 1st gear no more then 2k rpms. LOL now Im just trying to get the braket off the mount so I can put the belt on but the 14mm bolt is rounded off.

[dj_ender]

Do you have access to a leak down tester? If not, get one, otherwise, I suggest pulling the head and inspecting for damage.

[oyajicool]

If he wants, he can loosen all of valve adjusters so that all of valves are seated. With one spark plug in one cylinder, remove the rest, then hand crank the crank shaft. If there's resistance in turning as like building compression, that cylinder is good, then move onto other cylinders to check. You can do this before installing new timing belt.

[dj_ender]

I never thought about that, good idea.

[oyajicool]

Something similar thing was on this form some place else. It was new to me at the time.