This is beyond my understanding why manufacturers decided to introduce this “friction based system” in first place?!?!
I agree. It’s a terrible idea, especially if the engine is an interference design. Having the crankshaft pulley (and camshaft sprockets) keyed to only go on in one specific position makes it easy to change the oil seals underneath, and makes it easier to install the timing belt/chain.
It has to be cheaper and harder for DIY, Both wins in the manufacturers eyes.
Is something left out? I don’t see how just removing tbe pulley and reinstalling it out of position stops the engine from rotating. It will affect starting because the CPS is out of time but how does this prevent full rotation of the rotating assembly?
There was a thread on here several months ago involving a Ford Focus in which an inexperienced mechanic removed the crankshaft pulley to replace the front main seal, not realizing that it was not keyed in any particular way. Once reinstalled (incorrectly) the engine was destroyed on startup. I found it very difficult to believe at the time that such a poor design exists, but apparently it does!
Explain how it happens? It just won’t fire up as the ignition timing will be off. The valve timing is unaffected by just removing the crank pulley.
In this case, it appears a used motor was installed prior to being fired up. The OP pulled the crank pulley to make it fit and after installation found it would not physically rotate 360 degrees. Now if the pulley is installed in the correct orientation with the crank, it is now free to turn. I missed something or it doesn’t add up…
I do remember that Ford Focus discussion here too…
It was that timing sprocket was shimmed by the pulley and it was a special “diamond coating” there to hold everything in place, but it was nothing preventing sprocket from getting timing shifted out once pulley is removed, the assembly procedure involves putting crankshaft and timing sprocket into some alignment before applying the torque/pressure.
For me it is totally insane, but this is how it was designed.
There is no key on the crankshaft sprocket. During assembly the cams are locked into place with a special tool, the crankshaft set to TDC, then the crank bolt and pulley are tightened. This allows for more precise valve timing, important for emission output.
Chrysler did a similar thing on the old 3.5 L engine, the camshaft sprockets are not keyed, they must be aligned during assembly.
There is little chance for disaster with the camshaft sprockets not having keys, if you are going to remove a cam sprocket the engine should be at TDC and the timing belt removed.
Omitting the key from the crankshaft sprocket is a dirty trick played on the general mechanic who may not be familiar with these engines.
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From what I’ve seen on German engines, they indeed have no key, but on the camshafts, not crankshaft, so apparently they are doing it to make timing a fraction of percent more precise… huh…
I remember that discussion
And we never did hear the final outcome from the op
I am imagining an “animated” conversation with the mechanic took place . . .
I wonder what the Ford engineers would say? There must be some other upside to omitting the key on the crankshaft than manufacturing expense. I can’t imagine there would be much incremental cost to machining the key into the crankshaft and timing sprocket. I wonder if a motivation is to reduce the chance of inadvertently damaging the crankshaft in the event of an improper sprocket install job.
I didn’t mention anything about cost savings but that is an economic method of being able to adjust the valve timing. Having the camshafts indexed properly is important for tail pipe emissions.
On the old V-8s off-set cam sprocket keys are available to adjust the camshaft center line to a preferred setting.
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The original Chrysler 3.5L V-6 was non-interference, so incorrect installation of the timing belt, or misalignment of the camshaft sprockets would not have been a problem (other than the effort needed to correct the mistake). However, once you have removed the camshaft sprockets, for example to replace the oil seals, how would you know to reinstall them correctly?
In the old days of the Cadillac big blocks (472, 500s, etc) the harmonic balancer was a press fit on the crankshaft nose. There was no retaining bolt but they stayed in place.
Yeah I forgot to put the crank pulley back on when I was putting the torque converter bolts on and after I turned the flywheel around a bit to put the first bolt on and my roommate saw it sitting on the floor and put it back on it locked it out of time.
Basically the timing gear isn’t engaged until you tighten that pulley down so if you happen to turn the crank with the pulley off then the cams didn’t move with it since it’s friction based and not keyed and because it’s an interference motor the Pistons were tapping the valves.
the motor has a pin that is installed to lock crank at TDC. but than you use another lock to hold flywheel so crank bolt can be torqued. suppose pin would shear off if you did not use flywheel lock? and there is a lock for the cam sprockets also. sounds like fun motor to time.
Ok, that’s the piece I was missing. If the crank gets turned, all bets off. Thanks for taking time to clarify. Bummer you had to learn hard way but at least no harm done!
Welp, she started today. Had to do a head job along the way because my roommates dad decided he knew how to time it better and tested the timing with the starter and busted the valves off. Thankfully the pistons and bearings are still okay. Got a bit of lifter ticking because I’m not sure how to do the valve lash on this motor but I think it’s about time I broke down and bought the repair manual for it anyways and there should be some info on it in there.
Measure valve lash and make notations of those that are out of spec
Remove the buckets for those valves that have lash out of spec
Turn it upside down and you’ll see a number, which indicates the bucket thickness
Make your calculations and determine which bucket you need to install instead
describe “busted” valves? you took heads apart and inspected valve guides for damage? busted and/or bent valves are 2 different things.