r/beetle • u/vintagestereolover99 70's + Standard • 8h ago
What is this knocking noise on a 1970 beetle?
It isn't in gear, and it's on jacks. I think it's the jacks knocking on the frame but it might be the engine mounts. When I get it above 1k rpms it smoothens out a lot.
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u/Visible_Document_376 7h ago
Check to see if two of your plug wires aren't reversed on one side of the motor
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u/BigBlue175 8h ago
On top of the misfire issue (which I think is probably the problem) check your timing. If it’s out of timing bad enough it’ll cause your engine to rock like that
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u/382Whistles 7h ago
Check timing closely. Make sure you're aren't 180° off or have two wires crossed. If correct, swap wires and plugs looking for carbon, two at a time and see if the problem moves. I got locks for my lids because some idiots think it's funny to move ignition wires around or unplug the coils on Bugs in parking lots.
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u/vintagestereolover99 70's + Standard 7h ago
The plug wires are in the right order, how do I check timing? When I took the old plugs out, people said it was running rich and the new ones were already blackening after a few hours of being in.
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u/nrg8 7h ago
Distributor goes in one way no chance of 180out
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u/Send_bitcoins_here 5h ago
The distributor can go in only one way correct, but the little socket doohickey it fits into can be installed 180° out.
I spent months trying to figure out a misfiring issue after I pulled and rebuilt my ignition.
Then I came across this page..
It explained all, and I don't know how many times I've shared this and helped out others.
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u/Routine-Amphibian450 6h ago
Simplest check is with 12v test light, point stuck in ground, lead clipped to coil (-) low impedence, engine sitting about 15 deg btdc.
Turn ignition to on, gently move engine clockwise until test light comes on.
What does pully read?
For SVDA should be 7-1/2 btdc static.
Now turn ignition off or you'll burn your points.
Join The Samba, read stickies.2
u/AKA_Squanchy '55, '58, '62, '62 (ragtop), '64 Bugs and a '69 Square 7h ago
Seriously people do that?!!
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u/PD-Jetta 6h ago
Sounds like your engine is completely missing on a cylinder. Maybe something is amis in the valvetrain or it's a compression leak. Pull each sparkplug wire in turn until you get to the cylinder that doesn't change without the plug wire and you will have isolated the missing cylinder. Remove the valve cover on that side and inspect the rocker arms and valve lash. Does the engine make a banging sound when accelerating? If so, one of the cylinder heads may be loose. If this is the case you need a valve job. What happens is the valve guides get worn and the valves do not land in their seats squarely and over time it shakes the head loose. You risk dropping an exhaust valve as well.
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u/imprl59 6h ago
I would start by doing a compression test on all four cylinders. That way you know whether you have a healthy engine or if somethings majorly wrong. From the way it sounds and is shaking it seems like you have at least one cylinder that's completely misfiring. That could be ignition but it could also be valves or something worse.
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u/vintagestereolover99 70's + Standard 5h ago
Cylinder 3 tested 81 psi, I didn't have time to test the others
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u/imprl59 5h ago
90 is the absolute minimum. 120 to 140 is healthy with not more than 10% difference between. I'd check the rest of them and do a leak down test while you're at it so you can see whats wrong.
Have you adjusted the valves?
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u/vintagestereolover99 70's + Standard 4h ago
No, I am working out of my driveway, it's usually very cold when I have time to work. I am also balancing this project with high school. My parents are getting a proper shop built, should be finished around February.
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u/vintagestereolover99 70's + Standard 4h ago
Once I have summer break and a finished shop, I plan to drop the engine and rebuild it.
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u/Substantial_Wall_480 3h ago
Your firing 180 degrees off or your running on zero oil and at least one bent pushrod.
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u/Top_Independence2676 6h ago
Timing, firing order, put some cardboard down and pop valve covers.
Last resort. Stethoscope, wooden dowel, thin piece of wood(1x2). you will hear where it's coming from.
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u/Historical-Knee4704 8h ago
Sounds like a major misfire situation with the engine . She’s rocking bad. Troubleshoot the misfire