HELP!!! What Did I Break??!

[Wide77]

Hello, I am new to the forum and it's unfortunate I had to post my first thread on a negative note. I am in the process of restoring a 1977 911s.. Long story short, while replacing the points and adjusting the gap I used a large wrench to turn the motor from the crankshaft pulley (to get it right at the highest point of the lobe on the hexagonal shaft of the distributor)... after setting the gap I put the cap and rotor back on and tried to start the engine and what I heard whas a loud CLUNK!! but the engine ran for a few seconds, with LOUD CLUNKING NOISES!... I realized I had left the wrench on the pulley and as the engine turned over it made it hit the side and loosen up the center bolt holding the pulley to the crank..

.. I put everything back in order and re tightened the pulley, but now the pulley rubs against the alternator housing.. and not only that, but it became "frozen" for a few tries, and after turning it some more by hand it will now start back up but there are strange clinking noises while idleing..

MY QUESTION: What could I have broken internally??.. I am thinking the worst, but is it possible for the sprocket that runs the cams to have jumped a tooth??... am I over reacting and could it just be the pulley got bent??.. I have come to this forum countless times and recieved GREAT technical advice, and given that this is my first Porsche, any and all replies will be deeply appreciated.. Thanks!

-Alex

[lindy 911]

Loosen the crank pulley bolt back up and check to make sure the orientation pin from pulley to crank is properly aligned. Tighten it all back up and you should be good unless the pulley was bent by your fubar. You can tell easily if its bent.

[jsveb]

Hi

I think I know how you feel. I once had a piece of cloth catch the belt, and it snapped.

I would remove the pulley nut and inspect the alternator bearing etc. for damage. To see if that is what causes the fan to hit the casing.
I would also inspect the pulley; shaft, shims and halfs.

The alternator should be able to spin freely when the belt is removed.

Remember to use all of the shims. I think it is six total.

Good luck and report back.

[Henry Schmidt]

Lindy's advise sounds good. You probably have the pulley and crank dowel misaligned.
Good luck.

[Wide77]

Thanks for the great advise guys!..

UPDATE: I removed the crank pulley and started the car to see if the sound would go away but it is STILL THERE!!.. now this means it is something more besides the crank pulley rubbing against the fan shroud.. It almost sounds like a bad connecting rod, or a valve??.. So I did a partial drop of the motor and removed all valve covers to inspect the rockers and I BELIEVE to have found the source of the noise.. The rocker arm for the exhaust valve on cylinder #6 seems to not be returning??!!.. The rocker arm has play of about 1/4" if I rock it back and forth.. So this is leading me to believe to be the cause of the loud chatter noise..

What can cause the valve not to return? or Close???!!.. any Ideas?.. broken spring? Bent valve?? :/

[Flat6pac]

Your ideas are working. If its a broken spring, you can see it. I have read that the spring can be replaced in the car but have never done it, if it bent youve got a top end to do.
Bruce

[Wide77]

In the case of it being a bent valve, could I get away with rebuilding just that one head with the affected valve? (possibly the guide as well).. This would, of course, be after finding the real reason for the bent valve in the first place..

-Alex

[Walt Fricke]

Alex

Yes, you can deal just with that one head. If you have a bent valve, you should also check the guide, to see if it was damaged as well. A bent valve can sort of saw its way into a guide (engines can run a surprisingly long time this way, though you are tempting fate to do so on purpose).

Yes, you are on exactly the right track with your mechanic thinking. As with blown fuses, one question always is why did this happen, and will it just happen again.

A bent valve stem does sound like a likely cause of the sudden appearance of a quarter of an inch of play. The stem has yet to abrade its way into the guide so it can fully retract. And the clunking sound could be the piston hitting this bent valve because it protrudes beyond the clearance available.

Absent the clunking, one possible cause of failure of full return could be installing the rocker shafts wrong. The shaft should be roughly flush with the thiinner of the two cam carrier ends. If you have it flush with the thicker end, the expansion of the ends when you torque the rocker shaft hardware will expand the shaft into the rocker bushing. This introduces a tremendous amount of friction into what should be something which moves freely. But that is easy to check for - if the rocker moves freely at the proper TDC (through the full 1/4" you report), then that is not part of this equation.

It is hard to imagine the "left the wrench on" blunder is connected to the stuck valve.

In order for valve spring breakage to be involved, both would have to be broken. These engines will run fine up to some RPM (at least 5,000 rpm, and more like 7,000 if my experience is any guide) with one broken spring of the two.

It is exceedingly unlikely that both springs broke at the same time. Did you have a valve job done as part of the rebuild? (actually, I see you didn't say you had rebullt the motor). Even if the spring height were set way way off I'd not expect broken springs right off the bat. On the other hand, if this motor has lots of miles on it, maybe it ran with a broken spring for a long time, and just now has had the second spring break. Coincidence confounds diasnostics all the time.

Only if both are broken is it easy to see that things are broken. And you should be able to pull the retainer and with it the valve) up with your fingers to close that 1/4" gap. If you can't, more evidence the valve is bent.

That still leaves the question of why the piston would hit the valve (and, by the way, with the head off you should be able to see if and where piston hit valve.

You might check the cam timing, just to be sure about skipped teeth and so on.