snb13

So last week I spun the cam sprocket. I haven't had a chance to pull the sprocket yet, but I'm hoping I got lucky. In the attached picture, the yellow arrow shows the position of the cam keyway. The red arrow points to the keyway in the sprocket. You can see it didn't actually go too far. In this case it looks like the sprocket keyway got messed up, possibly instead of the cam keyway. On the tip of the cam shaft, I can see no damage to the keyway. I'll know more when I get the sprocket off, hopefully tomorrow.

I had a 4* cam key in there. It looks like it's made from a softer metal than the original. It's toast.

Should I set the engine to TDC first? Will I be able to tell if the valves and pistons crash when turning by hand?

Chunkerz

The engine will stop rotating when the pistons meet the valves. Don't force it or else you might damage the valves. Remove the spark plugs so the engine is easier to rotate. That way you can tell if you're fighting a piston on the compression stroke or smashing your valves/pistons together. Watch out when you are fighting against a compression stroke. After the piston finishes squishing the air it likes to spring down and spin the engine, which can rip the wench out of your hand and hit you with it. Ask me how I know...

Seeing that picture makes me think twice about using my 4* key...

snb13

I don't blame the cam key. In fact, I have another to put in. When I installed the sprocket bolt, it didn't feel right, but the torque wrench broke, so...

New procedure. Always a new sprocket bolt. Everytime it comes out, a new one goes in with anti-sieze compound on it.

Live and learn. I just hope I got super lucky. I have a another sprocket and 4* key.

Chunkerz

You're supposed to replace it every time. It's a one time use stretch bolt. I wouldn't put anti-sieze on it if I were you because the bolt may back out and cause expensive problems.

snb13

Hmmm, first I've heard that. 2 dollars and freaking 95 cents.

Darwantae951

I highly doubt it's a stretch bolt...

Factory torque is not even as high as the aluminum lug nuts. Pretty sure that the steel bolt is not stretching at 65-70Nm (48-52ft/lbs).

So long as the socket is not damaged, I have reused them. You have to ensure the bit is fully seated to avoid stripping the head. Replace the bolt if you want, but I have yet to find anything official or see/experience any significant reason why the cam bolt would be a one time use fastener.

Chunkerz

I was told it was a one time use bolt. If you want to reuse it then be my guest. Which version of the bolt do you have? The triple square or the cheese head?

Darwantae951

You can find relevant information in regards to fasteners in the FSMs. Search and you can download them for free.

You can also research elastic vs. plastic deformation.

snb13

Cam keyway is toast, too. I can't rotate the engine too far in either direction without the valves touching the pistons.

I firmly believe in doing as many "while you're in there"'s as possible. I wanted to build my other head and swap them. It's difficult for me to just swap them without doing some improvements. My issue now is time & money. This is my DD.

william_b_noble

do not rotate the engine. remove cam shaft in the usual way. Check that all valves close by pressurizing each cylinder with air - if you have any leaks, pull the head and do a valve job. I don't know what a 4* cam key is, but why the heck would you use anything except the original key? You will want to replace the sprocket and if damaged replace the cam too. In an emergency you can probably build up the groove with Moglice or weld it and machine it back, but the sprockets are cheap from junk yards so replace it.

It is clear that the "improvement" wasn't much of an improvement - these cars are pretty carefully designed, make it run as the factory intended and they are reliable - I have well over 250K on one I bought new, it's fine.

Dougs951

The 4º key isn't the issue.

snb13

Exactly. You missed the point of the thread. It was the cam bolt.

Darwantae951

So I'm assuming the bolt backed out?

snb13

That or the threads bound and it wasn't torqued properly. It felt wrong going in, but when the torque wrench broke, I thought I was mistaken about the bolt. I only had about 100 miles on it after changing the belts when this happened

I won't do that again.