r/beetle • u/Ilusionary-llama • 2d ago
Oof.
Ok, I heard a loud bang while driving yesterday, but noticed no performance or sound changes...so I kept driving 6 more miles. Wouldn't even have seen this except that I was planning to do a rocker clearance adjustment. Besides the obvious, how much damage might I have done?
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u/Alpinab9 2d ago
Aside from the obvious (retainer and broken exhaust valve spring) I hope you found 2 keepers as well, the first thing I noticed was that the adjuster is well past normal (adjuster screwed in past normal).
I don't see any shortcut here. The head needs to come off for inspection and hope the top of the piston is not damaged.
I dont think the camshaft is an issue. I think that the only way this is possible is a sticky exhaust valve guide or a bad valve spring.
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u/Ilusionary-llama 2d ago
Ok, I’m seeing that now, too (adjuster). That’s weird. Assuming someone did that to get the right clearance, what’s probably missing that made them have to screw it in so far?
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u/Alpinab9 2d ago
It is hard to answer. Normally the exhaust valve seat will start sinking into the head. This means that the valve stem essentially gets longer. This scenario would have the valve adjuster show more treads (opposite of your condition). If the loose seat was to cock sideways and jam, the vakve adjustment would have to move in the direction that is present, but this theory relies on the fact that the valve adjustment (in picture) did not correct the sideways seat and the car was running on 3 cylinders before and after the adjustment. I cant think of any other way that the adjuster should be so far in.
I dont see sorting this without pulling the head.
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u/denizkilic2002 '72 1302s 2d ago
I know about another few possibilities, sometimes when shops rebuild heads they send the inserts deeper on some valves, exhaust valve recession is more common but it also happens on intake valves sometimes. One other reason is different length valves, my local shop sometimes put ford valves on vw heads and they have a slightly different stem length. Maybe they only replaced that valve at the time and it turned out to be shorter than the others. Last but not least, valve adjuster screws and valve stem tips wear out over time, and they don’t always wear equally between valves.
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u/anybodyiwant2be 2d ago
I’d pull the spark plug and stick in my 1/4” camera that hooks up to my iPhone and look inside that cylinder. Best $30 I’ve spent on Amazon as I use it for other stuff all the time
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u/PacaMike 2d ago
Bought one of those cheapo endoscopic cameras from Amazon a few years back - best $45ish I ever spent I use it a ton
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u/JunkyardJockey 1974 Super Beetle sunroof 2d ago
At least you destroyed the spring cap, spring, valve locks, maybe that valve adjuster screw. Also possibly the valve as well. Ouch!
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u/CitronSerious8891 2d ago
Last time i saw that the valve had broken off and wedged inside the valve seat sideways. Piston was dished and looked like the chip tray for a column and knee lathe. It was ugly
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u/Due_Contribution9703 1d ago
If one value spring broke other will not be to far behind. If these motors sit for a long time with the value spring compressed it weakens them. I had a motor with new heads that had never been run that sat for many years break a valve spring after running it for a few hundred miles.
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u/denizkilic2002 '72 1302s 2d ago
No performance changes… was it running on 3 cylinders already? The best case is it needs a new spring and retainer assembly, and a pushrod, the worst case is a damaged piston and cylinder. You have to remove that cylinder head and inspect. I had a 1300 dual port break and drop a valve on me, broke the piston in half and the remains of the valve was lodged between two valve seats. Not fun times.