Timing Belt Snapped.

[AwakenNoMore]

Been here as well, happened at low speed, but more importantly, low rpm, still mashed 3 valves and it ejected chunks of the aluminum casting that holds the rocker shafts, had to build another head. With the Bentley Manual it went just fine.

Here's a pic, if this didn't happen you can re-use your head most likely:

[AndrewBird]

24V swap time!

But really, find a used head in decent shape, have it surfaced and replace the valve stem seals and swap it on. You could probably find one at a u-pull-it for cheap and have it checked out by a machine shop.

Either that or check out www.BimmerHeads.com if you want to go all out.

[usualdeviant]

I'm certain I bent a valve or valves when installing my last timing belt. I forgot that the vibration damper has to be on the crank in order to check TDC. So, drinking boxed wine, I slammed valves into pistons while searching for TDC. The engine still runs and pulls hard, especially since timing the cam correctly and adjusting the valve clearance. However, there is a nasty ticking and a nasty scraping sound, pretty sure that's the valves hitting the guides.

The question is... Will it live? Will the noise get less noisy? Or do I need to get new valves and guides ASAP?

Edit: There is more to the story. After the new belt went on, valve timing was off by one tooth and valve clearance remained unchanged. There was a kind of a rattling sound in the low RPM range. Otherwise everything was fine. This was about a year ago and the car was more or less driven since then with no other related issues. Then I corrected the cam timing and adjusted the valve clearance. That's when this new noise happened. As if the valves got more bent somehow. I strongly doubt that actually happened, but that's what it sounds like. Got a funny look from the guy at the drive through.

[Madhatter]

The dampener doesn't have to be on to find tdc. The crank bolt will hold the hub in position and there is a notch on the crank sprocket.

The rattling noise you heard was probably pinging.

Nasty noises and ticking sounds could be a number of things. In my experience, unless they are well bent and stuck, normally a bent valve means the engine feels a little flat and the rockers get noisy because the valve doesn't fully shut. If you keep driving it like that it ends up burning exhaust valves and you have to pull the head anyway to fix.

So id be finding the cause of your problem rather than driving it.

[usualdeviant]

Didn't know that. But in any case I timed it with the VD on (insert joke here). If it was pinging, it passed emissions better than last time. My engine has killer power, no flatness. More than 200k miles on the clock, by how much I'm not sure. Probably just slightly bent valves hitting the guides in my guestimation. It's a lot of work to pull the head so I'm just going to keep driving it and checking the oil for metal flakes. Eventually I'll rebuild the engine anyway when I have a second vehicle.

[Madhatter]

They can't hit the guides. The valves bottom out in the seats before going anywhere near the guides.

[usualdeviant]

Are you sure? I mean the valve stems go right down the middle of the valve guides. Couldn't I have bent a stem or two? But either way, now I'm thinking the noise is either that or the head of the valve hitting its seat wrong. Before adjusting the clearance I noticed it was less, like maybe .008 or .009. Might just have to go back and see what happens.

[tonyloban]

Pulled the head off today. Two exhaust valves are bent and the pistons were nicked but my uncle says they should be fine.

Comfirming that it WAS the timing belt snapping indeed as presumed. Also, there's a metal roller the that timing belt doesn't actually spin but just slides along it, like a bearing. It was pretty bent and touching the timing cover. Any know what could cause that?

[Madhatter]

Are you sure? I mean the valve stems go right down the middle of the valve guides. Couldn't I have bent a stem or two? But either way, now I'm thinking the noise is either that or the head of the valve hitting its seat wrong. Before adjusting the clearance I noticed it was less, like maybe .008 or .009. Might just have to go back and see what happens.

Positive. If you take out a valve you'll see they wear a little ring nearly an inch from the valve. The valve is curved on the back side and flares out much larger than the (slightly less) 7mm of the stem. The guide is driven hard into the head and doesn't flex/move. If you bend a valve it is because you hit a piston.

Pulled the head off today. Two exhaust valves are bent and the pistons were nicked but my uncle says they should be fine.

Comfirming that it WAS the timing belt snapping indeed as presumed. Also, there's a metal roller the that timing belt doesn't actually spin but just slides along it, like a bearing. It was pretty bent and touching the timing cover. Any know what could cause that?

The roller thing is the timing belt tensioner. When its set in place properly it keeps tension on your timing belt. If it was all sorts of bent and/or moving around, there is a good chance something failed with the tensioner. Its kind of tucked to the right of the water pump, there is no way it should touch the front timing cover if the tensioner was in place properly and in working condition. Did you find the spring and pin that sit between the water pump and the tensioner?

[tonyloban]

Positive. If you take out a valve you'll see they wear a little ring nearly an inch from the valve. The valve is curved on the back side and flares out much larger than the (slightly less) 7mm of the stem. The guide is driven hard into the head and doesn't flex/move. If you bend a valve it is because you hit a piston.



The roller thing is the timing belt tensioner. When its set in place properly it keeps tension on your timing belt. If it was all sorts of bent and/or moving around, there is a good chance something failed with the tensioner. Its kind of tucked to the right of the water pump, there is no way it should touch the front timing cover if the tensioner was in place properly and in working condition. Did you find the spring and pin that sit between the water pump and the tensioner?

This piece

tensioner?

[dnguyen1963]

Yes.

[akorcovelos]

The guy I bought my 325is from snapped the belt and threw a new one on. Car actually ran decent in normal driving conditions. It had ZERO balls when you tried to flog it. It literally wouldn't spin the tires if you dropped the clutch. When it hit around 4500RPM it would "wake up" and take off, probably because the internal forces were enough to pull the 6 bent exhaust valves tight enough to seal. I drove it for a few thousand miles like that before rebuilding the engine.

[usualdeviant]

Update: dialed it down to .009" eccentric-to-valve and the noise is less now. No more sqeaking, just a bit of random ticking. I'll try and keep you posted.

[goldenbb]

Just pull the head now. My retrospective experience on the E30 goes something like: Pull the whole drivetrain as soon as you buy and just fix everything at once. That advice might extend to any used BMW.

[Madhatter]

This piece

tensioner?

Thats the tensioner all right. It's also the cheap one. It looks like the bolt holding the tensioner in place is doing it's job because the spring is still nice and straight where it should be. So it looks like the bearing probably collapsed or failed in the tensioner which is why it is on an angle. It will most likely be the cause of all your trouble.