[Shazaam41]

Ok. So I was doing a leakdown check, and after 6 cylinder, the engine stopped cranking. It still turns over, just isn't catching. I've checked the starter, solenoid, and relay. All are functioning fine. No clue what else this could be. Anyone have an idea? Thanks!

Video posted to YouTube here:

 

[Shazaam41]

Forgot to add that while it turns over, no pressure is building at all.

 

[Elwenil]

"Not catching" sounds to me like the starter isn't engaging.  If the engine isn't spinning when the starter is making noise, then the starter is not engaging.  Could be a few teeth missing from the flywheel/torque converter, or more commonly, a starter that is not engaging correctly.

 

[KurtfromLaQuinta]

"Not catching" sounds to me like the starter isn't engaging. If the engine isn't spinning when the starter is making noise, then the starter is not engaging. Could be a few teeth missing from the flywheel/torque converter, or more commonly, a starter that is not engaging correctly.

Well the video clearly shows the engine turning while cranking.

I'm confused (which happens frequently). It's turning over, but not building pressure for the leakdown test?
With all the plugs removed, your not getting any compression. So it won't "catch". It'll spin freely.

 

[Elwenil]

Hmm, I didn't see the link for a vid when I read the thread.  Of course that was at 5am and I was probably still half asleep. 

 

[KurtfromLaQuinta]

Hmm, I didn't see the link for a vid when I read the thread. Of course that was at 5am and I was probably still half asleep.

Confusion reigns!

 

[712edf]

Not sure what we're looking for here, but if a certain cylinder or cylinders don't have compression then I would check the valvetrain. Start by removing the valve cover(s) for a looksey.

Bucky

 

[Shazaam41]

Well the video clearly shows the engine turning while cranking.

I'm confused (which happens frequently). It's turning over, but not building pressure for the leakdown test?
With all the plugs removed, your not getting any compression. So it won't "catch". It'll spin freely.

It should still catch, and compress the cylinder with the guage in the spark plug well. That's not happening. This vid shows what I'm doing. If you scroll to about the 3:30-3:50 mark, you'll see the guy doing the 5 sec bump and hear the catch. Mine is just spinning. I've done these before, and I've never seen anything like this.

I'm new to the SCC system, and thought that might be the culprit? From what I've read here it seems to be the "root of all evil!"

 

[Shazaam41]

Not sure what we're looking for here, but if a certain cylinder or cylinders don't have compression then I would check the valvetrain. Start by removing the valve cover(s) for a looksey.

Bucky

Hi Bucky,
I was just doing a standard compression test. Instead of compressing the cylinder that I had the guage hooked into, it just "spins." Having a hard time explaining this. The normal "whir chuck, whir chuck" you hear when trying turn over an engine is just nonstop the "whir" part. Hope that makes more sense?

 

[712edf]

Does this just occur with that 1 cylinder?

Bucky

 

[KurtfromLaQuinta]

Does this just occur with that 1 cylinder?

Bucky

If it is that cylinder... I would say there is little or no compression there.

 

[Shazaam41]

If it is that cylinder... I would say there is little or no compression there.

Nope. None are now showing compression.

 

[dodge82273]

  .... timing chain , all valves go up/down , yet there is little to no compression on all cylinders .... timing chain .
I drove a L/A 360 home , parked it after work , next day am it farted , then spun free like I had the plugs out , no compression , so don't thing that couldn't be it WAS just running , so was mine ... I lucked out and got home , good chrysler pat pat .....

 

[712edf]

Easiest way to see if timing chain has broke is too pop the distributor cap, crank engine & see if rotor turns.

Bucky

 

[dodge82273]

they usually don't break , the chain jumps a tooth or more on its sprocket , rotor still turns ... doing a compression test , finding motor cranking round and round , but no compression tells ya , chain jumped   

 

[712edf]

That's true. I've seen broke cams too. Any thing that throws off valve timing or actuation will alter compression.

I guess something happened during the leakdown test? I assume the engine was in working order beforehand.

Bucky

 

[Shazaam41]

That's true. I've seen broke cams too. Any thing that throws off valve timing or actuation will alter compression.

I guess something happened during the leakdown test? I assume the engine was in working order beforehand.

Bucky

It was working, but I was getting blow by. Man I hope I didn't break the chain. Might be all she wrote for the engine.

 

[712edf]

Whether the chain has actually broken or just jumped a tooth, the procedure to fix is just the same.

Bucky

 

[SuperBurban]

If you suspect the chain has jumped a tooth, I would not mess around turning the engine over. When the valves meet the piston, bad things can happen. I had a 318 self destruct that way. My feeling is if in doubt, change it. A new timing set, water pump, fuel pump, belts, hoses, thermostat, can give great peace of mind, and not awfully expensive.

Not a great way, but you can get an idea of the chains condition by removing the fuel pump, and poking a finger in, and pulling on the chain.

 

[dodge82273]

Been messing with small block mopars since my '66 barracuda in 1970 ,( big blocks before that) never had a bad chain bend valves , been lucky ? newer (80's-90's) low compression ones don't reach a piston ? and never had a chain break , I would NOT discount a truck or its motor just because of a chain, not that difficult to replace , nor that expensive , buy another used truck have the same thing , or a new one and pay upfront ..  the oem style chain is just fine , no need for more expensive "roller chains"  even on a slightly hot rodded motor .... IMO