TheSamba.com :: View topic - Catastrophic Failure in a rebuilt 1971 Super Beetle 1600?

Tue Jul 15, 2025 10:35 am

Only about 500 miles on a 1971 rebuilt 1600cc. While driving at a steady 50mph the engine suddenly shuts off and I easily coast to a safe spot on the side of the road. Maybe overheating since it is July? After waiting about 45 minutes I crank the engine but something doesn't sound right. Low compression?

I pop off the valve covers to have a look and as my friend is cranking the engine, the cylinders seem to move freely but there is no intake/exhaust valve movement on either side.

Did the cam shaft disengage from the crank shaft? If so, how is that possible since they are directly geared to each other? Did the cam just break between the gear teeth and the lobes?

Has anyone heard of this happening?? Any advice would be much appreciated. Thanks![/b]

Tue Jul 15, 2025 10:42 am

If none of the valves are moving when you rotate the engine it would seem that the camshaft gear is either stripped or broken. That would be my guess. Good luck-Bob

Tue Jul 15, 2025 10:58 am

Never heard of this happening but, I guess anything is possible.

Pistons moving and camshaft not moving may indicate a broken crankshaft.
It happens. I don't recall seeing a crank broken on the cam gear end. The ones I have seen usually break near the #2 main bearing.

OP, grab the crankshaft pulley and see it it turns rather freely, like it's not connected to anything inside the engine.

Tue Jul 15, 2025 11:02 am

Lemme guess. Empi cam gear. Its stripped. Seen that more times than I care to remember.

Tue Jul 15, 2025 11:29 am

Maybe somebody left out the Woodruff key on the camshaft drive gear on the crank and it took a bit of heat to let go and start spinning.

Tue Jul 15, 2025 11:41 am

I'm betting the oil has a silvery sheen.

Tue Jul 15, 2025 2:03 pm

Spowers wrote: Only about 500 miles on a 1971 rebuilt 1600cc.
Did a shop rebuild this?

Did you?

What's the experience level of the rebuilder?

Tue Jul 15, 2025 2:16 pm

It was rebuilt in a shop but the 12 month warranty is expired. I guess I'll tear it down to see what happened. This will be my first time into the crank case of a VW. First time for everything...Wish me luck...Thanks for the feedback...

Tue Jul 15, 2025 2:20 pm

Back in the late 70s or early 80s I had to go help a friend tow his bug back home that had suddenly quit running for no apparent reason. Similar to the op…no valve train movement while cranking engine over. When we opened the case we found the camshaft broken in 2 places. Cam was an AP2 which was produced by Resolit of Brazil back in the 70s.

Tue Jul 15, 2025 2:23 pm

I had a core engine that broke the cam right behind the flange for the gear.

Brian

Tue Jul 15, 2025 2:52 pm

I am betting the cam broke. I have had a cam gear on type 4 strip the teeth off from a nut that came loose from the oil pump.

No matter what strips all the teeth off, it will not be a silent stoppage when it happens.

Ray

Tue Jul 15, 2025 4:18 pm

Spowers wrote: …

I pop off the valve covers to have a look and as my friend is cranking the engine, the cylinders seem to move freely but there is no intake/exhaust valve movement on either side.

… Any advice would be much appreciated. Thanks![/b]

If the cylinders are moving , that there may be your problem.

Joking aside, and assuming you meant the pistons seem to move freely, how’d you determine that?

Tue Jul 15, 2025 4:50 pm

Spowers good luck on the teardown, tough break but you may be able to salvage some parts of your engine. If you do not already have a copy, I suggest you get How to rebuild your Volkswagen engine by Tom Wilson. It will help you with the proper sequence with the disassembly to try to salvage what you can. Good luck-Bob

Tue Jul 15, 2025 5:19 pm

BFB wrote: Spowers wrote: …

I pop off the valve covers to have a look and as my friend is cranking the engine, the cylinders seem to move freely but there is no intake/exhaust valve movement on either side.

… Any advice would be much appreciated. Thanks![/b]

If the cylinders are moving , that there may be your problem.

Joking aside, and assuming you meant the pistons seem to move freely, how’d you determine that?

Start with this

Tue Jul 15, 2025 5:46 pm

If it does turn out to be camshaft-related, I just want to throw in that I have stock VW camshafts and gear in both my 1835cc and 1600cc rebuilt engines. 1835cc was built by me in 1986, and the 1600cc in 2017.

Tue Jul 15, 2025 7:15 pm

Broken cam bolts? Please report what you find.

Mon Jul 21, 2025 3:38 pm

Did someone say " Catastrophic Failure"?

eQ

Thu Jul 24, 2025 6:21 am

Spowers wrote: It was rebuilt in a shop but the 12 month warranty is expired. I guess I'll tear it down to see what happened. This will be my first time into the crank case of a VW. First time for everything...Wish me luck...Thanks for the feedback...

Over 12 mos and only 500 miles?

well- time for you to learn the hard way. As I always say to people - if you will be w/ this VW have 2 motors. Always.

Enjoy.

Thu Jul 24, 2025 8:02 am

earthquake wrote: Did someone say " Catastrophic Failure"?

eQ

OMG! :shock: :shock: :shock:

Thu Jul 24, 2025 8:18 am

veedubcrazy wrote: earthquake wrote: Did someone say " Catastrophic Failure"?

eQ

OMG! :shock: :shock: :shock:

That should buff right out!

OP - camshaft snap. Gear strip. Especially on rebound units. You might want to ask if that was the case.