Ruh-roh!

Been talking on and off about my experience doing a timing belt change on an Accord. Tough wrenching! One of the hardest jobs ever.

Anyway, I have had a couple of mistakes along the way, mostly minor recoverable stuff. This one has me wondering...

I was working to get the cam sprocket off, after the belt was out.

Torquing the sprocket bolt loose just wants to spin the cam, so the Haynes book says "use a screwdriver to keep the sprocket from turning". They don't suggest any good places to PUT the screwdriver, probably because there aren't any.

I wedged one in anyway, then figured I should not do that trick. The screwdriver shaft was pressing down on the back belt cover, which is plastic, and I already cracked one cover on this job. Also, if the screwdriver takes a bite out of the valve cover gasket mating surface, the engine will leak for life.

Instead, I wedged an allen key in the sprocket farther down, bracing the end against the motor mount. That gave solid resistance, although I had to hold it with one hand.

Okay, carefully get a wrench on with the other hand, cheater bar over the wrench, start to torque... torque... nothing. Solid as Mount Rushmore. No give at all. Why do the Honda factory guys use so much threadlocker?

Torque, torque, torque, nothing, torque, whoa, aaaaah!

Allen key slips. Sprocket spins about twenty degrees counterclockwise. I hear a clicking sound, then fortunately the wrench runs out of radial travel and doesn't go any further.

Was that interference I heard? I pop the valve cover off and have a look. The #3 cylinder exhaust springs are compressed. I reverse the wrench and spin the sprocket about 10 degrees the other way. The springs uncompress. I work it back and forth a few times.

Seems okay, but I'm wondering if the valves got a piston kiss.

 

They might have, but the only time that something like that will cause serious damage is when the engine is running and has more force in the rotation of it all to bend things. A wrench on the cam sprocket shouldn't really cause you too much pain, even if you accidently spin the cam enough for the valves to touch the piston.

 

Like 1stGen said you should be fine.

If you're overtly paranoind about it just check to see if the valves on your #3 cylinder are level with all the other while in thier resting position. A bent valve will hold that valve slightly lower than the others in the valve train. It's not a very accurate way to check tho. Furthermore a compression test once your t-belt install is done should alliveate your concerns.

Also if you're having trouble getting that sproket off you can use the old timing belt and a pair of vice grips as a make shift strap wrench. Just wrap the old belt around the sproket. Take the vice grips and pinch the belt so that it makes a tight loop around the sproket. Use the vice grips as leverage against the direction you're trying to turn the bolt. HTH

~Steven

 

agreed with the other two guys.

and if you want to remove the cap sprocket, use an air impact wrench and an old timing belt to hold the sprocket in place.

 

Next time, before its too late...

That's a good reason to put the crank 90 degrees away from TDC. Then NONE of the pistons are up at the top of their stroke, so spinning the cam can't do any damage.

Then when its all together, put the cams at their TDC timing position, where none of the valve are really open. Then spin the crank to put #1 at TDC so you can put on the timing belt.

If you've got real clearance issues, like non-stock cams or whatever; you can back your tappets off enough to close your valves when the cams are set at TDC. Then rotate your crank, put on the belt, then adjust valves.