Cole

I had a new belt shed about 9-10 teeth and the head survived.

My guess is that your "breakdown guy" is a bit of an idiot. It's REALLY hard to bend a valve on EVERY cyl. To get "no compression on any cyl" typically you bang one valve on maybe two cyl.

Not saying its not possible. It could have kept spinning valves for a few seconds since it's a slip and not a break. But usually once it slips it quits opening valves, which means they don't end up getting hit by the pistons.

I'd use a leak down tester and manually test each cyl. The nice thing about a leak down tester is that you can supply your own air source and don't need a timing belt hooked up to test it. Just applie pressure and rotate the camshaft to open and close the valves. You can watch the pressure hold and release on the leak down test gauge.

Good luck.

(also, FWIW. You don't "have" to replace everything in a head to rebuild it. You can replace just the bent valve as long as it slides freely in the guide. Just use valve grinding compoound to grind the new valve to the head and you will have a good seat. New valve is about $50 + a gasket set of your choice)

zogster

thanks Cole (and others), that's all helpful and quite encouraging...

Guess I'll reset timing tomorrow and see how she runs.

To be more accurate about what Mr Breakdown looked at, he only checked compression on one of the cylinders - the at the front of the engine. Apologies if I suggested he'd checked them all. But turning on the starter, the sound of the engine was very even, suggesting (I think) that all the cylinders are in the same state... I'm guessing that if I had damaged valves in only one or two cylinders then it would show itself in some kind of unevenness in the sound of the spinning-but-not firing engine. So maybe they're all good... fingers crossed.

Cole

I bought my car with a broken timing belt. One valve was bent.

It takes a lot of force to bend them, but it only takes a little bend to make them not work. So for the most part it could sound fine until it fires over and then the cyl with the bent valve just won't fire right since its not sealing.

Here is a picture of the bent valve my car had when I got it. See how close it is to sealing?

zogster

So I've put the flywheel lock on, engine TDC on cylinder 1, and just tried to turn the camshaft those pesky few teeth back into sync... and it seems very hard to turn. I can only turn it 1-2 teeth, with difficulty, before I'm unhappy with how much torque I'm having to apply via the mole grips I have clamped on.

Do I just need to apply more torque here? I just don't want to cause any damage if I've been lucky enough to escape it so far...

[Just to clarify, though this may be stating the bleeding' obvious - the camshaft is 9 teeth behind where it should be, so I'm assuming that the right thing to do is rotate it the 9 teeth clockwise back into sync. While I was able to crank the camshaft along with the rest of the engine when I set it to TDC, I don't want to try using that technique to get the cam sprocket back to its mark, then unhook the belt and rotate the rest of the engine the long way around to get cal 1 to TDC]

zogster

Anyone have an idea re. how hard it should be turn the camshaft? Do I just need to get a big 32mm spanner and apply more force?

Cole

It takes a fair bit of leverage. I used a 12" wrench when I did mine and I'm not a small guy.

This is without the belt on right?


If there is something mechanical in the way you should feel it.

cruise98

With the belt off, I would leave the crank at 45 degrees or so BTDC on number 1, rotate the cam CW and align the cam marks and then rotate the crank CW into position. The cam has lots of resistance, but the crank should turn easily. If the pistons are out of the way while the cam is rotated, you are free to turn it without fear.

I hope none of your valves are bent.

zogster

Yup, belt off ;-)

Sounds like it's one of those spots where I just have to use more force. I guess in turning at least one of the cams is always having to open a valve against the spring, so it needs a fair bit of torque

tod84944

Take the flywheel lock off while trying to set the timing, or like stated above, turn the engine 45 off TDC, so the pistons wont be in the way. Taking the flywheel lock off, if you are pushing a valve against a piston, the engine will be free to move.

zogster

OK, sooooo...

Used the 45 degrees BTDC trick, which made things a whole lot easier, to get the timing back, and the engine still won't fire.

It sounds like this: https://files.me.com/pireson/x8ecv7.mov

Which I guess that means valves are probably damaged, and I need to get the head off to have a proper look

Cole

Doh.....can't watch the video on my iPad. Can you load it to YouTube?

cruise98

I cannot see it either.

theiceman

just reading this casually and a couple of things came to mind..

are you sure you are not 180 out with your cam ?
belts dont " slip" especialy new ones .. did you find out your root cause ? did a tensioner back off ? they can however jump if way to loose and the cause has to be fixed, or your ripped eeth off your new belt .. either way has to be fixed
.
Did you just rush through and try to fire it up or did you do as suggested and do a compresion check ?

zogster

It's an audio-only .MOV, but I'll see if I can upload it to YouTube or put up an .MP3

Good thought re. 180 degrees out Iceman, but yes I'm sure about that. And I think the reason the timing went was that I didn't tighten the tensioner properly... not a mistake I'll make again

I haven't been able to do a compression test myself, as I don't have a tester...

spanky

Pls follow my advice and either borrow a compression test guage or buy one and confirm your engine compression. Are you dead sure you had the engine crank locked a TDC when you set the cam into position. recheck by relocating the cranck into TDC and crawl under the car, look at the bell housung engine point of connection and you will see a small window notched into the bell housing casing at 6 oclock. Look inside this casing window and you will see the flywheel and it to has a notch that is slightly smaller than the casing window, this flywheel notch will be visable and centered inside the casing window when you are at TDC. then recheck the cam TDC position and both bal shafts. The upper bal shaft will be at the 1 oclock position and the lower bal shaft will be at the 7 oclock position if you are really at TDC. All of these must line up