cam gear is 180 degrees off

[nando]

nowhere here says its a 325...

M10s don't have timing belts, and his location is in the USA so it's not a hard conclusion to make. :)

[E30MACK]

I do indeed have a bently manual....so whats the recommendation at this point then? as long as the marks are lined up I should be back on time right?

[nando]

yes

[E30MACK]

you should have left it alone. it would have been fine.

there are 2 "top dead centers". One on the intake stroke, and one on the exhaust. the cam and crank will line up on the intake stroke. only the crank lines up on the exhaust stroke. you lined it up on the exhaust stroke, misunderstood the 180* off at the cam, then turned the cam, and now it's all messed up..

essentially, even if it were 180 degrees off, it wouldn't matter at all. It wouldn't be possible to damage the valves that way (since it's still in the same position relative to the crank) and it fires based off where the head is located, not (just) the crank.

Nando, no it wouldn't have been fine because if i left it in the time it was in then there would be no reason for me to have taken it apart to start with. as i previously mentioned I put everything on, tried to start it and no start. I was getting fuel and spark but it wouldnt start so I came to the conclusion it was most likely a timing issue.

[nando]

I'm telling you, it doesn't matter. Fuel is untimed and is only based off the crank reference signal. It doesn't matter where the crank or cam are for fuel. spark is based off the crank reference signal, but it can only fire based on the location of the cap and rotor. So matter where the crank is in reference to the cam, it will still fire based of of TDC after the intake stroke of the cam. The crank passes by TDC twice.

whatever caused your no start was unrelated to the cam.

[E30MACK]

ok......so at this point, what do I do to ensure everything is in time and will start and run?

[nando]

line up the marks. that's it. if it's still 180 degrees "out", rotate the engine one revolution and make sure they both match on the intake stroke.

[billybobjoseph]

+1, what Nando said . The idea of having the thing 180 out isn't correct. The pistons and crank don't know if they are on the compression stroke or the exhaust stroke. They move the same height with each rotation of the crank. The sensor wheel moves around the same way with each turn as well. The brain knows where the valves are because of the inductive spark sensor on the #6 spark plug wire.

[StereoInstaller1]

ok......so at this point, what do I do to ensure everything is in time and will start and run?

Look, as Nando said, you clearly aren't understanding here.

First, look at this: http://auto.howstuffworks.com/engine1.htm, pay special attention to the speed at which the cam rotates compared to the crank.

Basically, think of it like this: the crankshaft has only 360 degrees of rotation while the cam has 720. The cam rotates at 1/2 the speed of the crank, thus the 2 pulley sizes.

IF the crank mark lines up (do NOT use the diagram from the Bentley, it is wrong. Use the notch on the timing belt casting, NOT the ignition timing marks on the belt cover) and the cam mark is in the correct place, it is correct. Wiggle things around until you reach that status, or get a bus pass.

You might have to use a wrench on the crank and turn the cam wheel by hand to get things lined up. Using your old timing belt as a tool will make the cam turning easier: wrap it around the gear and hold it like you are pulling a girls hair out of the view, it is much easier.

BTW: you will not bend a valve turning the motor over with a wrench, unless you apply incredible levels of stupid. Again, your option is a bus pass.

Now, go pull the plugs, pull enough crap off to get to the belt, set the damn timing and get the car running.

BTW: easily the most common issue with an "M20 timing belt no start" thread is the 2 plugs you took off earlier: CPS and CID. They can be interchanged and are not marked. I put a zip tie around each side of the plug on one of them BEFORE I take them apart, since they are so easy to get wrong.

Luke

[E30MACK]

cool thanks, put the belt back on on lined stuff up, did 3 rotations with the belt on everything matches up. Im gonna throw it back together tonight. thanks guys

[StereoInstaller1]

Kick its ass.

[E30MACK]

started it up, everything runs flawlessly!

[Fidhle007]

So which plug did you miss?

[Mossman]

wrap it around the gear and hold it like you are pulling a girls hair out of the view, it is much easier.

Luke Rules!

[E30MACK]

wasnt a plug....just needed to get both gears lined back up.