No compression after timing

[Number4]

So, recently did the timing on my 4.0 while the engine was out. I have the master timing tool kit and followed all the instructions. Nothing rotated while we did the job.

Didn’t have time, so dropped the engine off at a shop with the car. Just got a call today saying that one side of the engine has compression and the other doesn’t. No noise, just no compression.

WTF?

Engine had 150k on it and was running fine when pulled. The oe timing components were shot.

Thoughts?

 

[Mbrooks420]

Jumped time and ruined the valves on one head, or one cam is out of time.

 

[Number4]

Jumped time and ruined the valves on one head, or one cam is out of time.

Just not sure how that would happen. We had everything locked down while doing the timing.

The mechanic said there was no noise. How would timing be out to lose compression but not do damage? We rotated the engine after doing the timing and there was nothing preventing it from turning.

 

[Mbrooks420]

I don’t see what else could cause zero compression on one side, other than something stupid like forgetting the headgasket. Time to pull a valve cover and see if the valves are moving.

 

[Number4]

I don’t see what else could cause zero compression on one side, other than something stupid like forgetting the headgasket. Time to pull a valve cover and see if the valves are moving.

The engine was running when pulled. It sat on a trailer form a month covered. Someone uncovered it and it rained. Maybe two days with water?

We turned it over, drained all the water if there, and verified it still rotated.

Then we put it on a stand, removed all the covers to inspect it. Everything looked good.
Removed plug #1, set at TDC and did the thing according to all the instructions and using the proper tools.

Once done, rotated engine, had reasonable resistance due to compression.

Took to shop to have done. It sat there for a month before they did it. Once in it wouldn’t fire, they checked compression and none on left drivers side. They pulled a vacuum and there is none? So the valves aren’t sealing? And they say the engine freely rotated without resistance.

So I’m lost as to what it could be. Having it towed home and will have to look more into it.

Would the valve seats rust and prevent a seal?

 

[Mbrooks420]

I’ve seen valves stick in the guides and stay open, but only on things that have been sitting years. Rusty seats might give a poor leak down, but I can’t see them being the cause of no compression.

 

[Number4]

Looks like valve marks on the piston top. Piston top looks like crap too.

Not sure how much pressure would clause this?
Would rotating by hand so this?

#1 & 2 pistons have this.

 

[Fix4Dirt]

is motor out of time? looks to me like piston smacked valves... i am doubtful that rotation by hand would do that to that extent...

 

[Mbrooks420]

You can definitely bend valves by hand, but I really think you’d have felt that unless you were really cranking it with a long ratchet.

It’s possible it’s still in time, but the valves stuck in the guide and the piston hit the stationary valve.

 

[boominXplorer]

With the cam gear being press fit if not torqued correctly it can spin on you. The cam is the only thing common on one side of the engine. Plus if you got 2 orv3 cylinders on the same side with bent valves chances are it's the timing. Time to swap out some valves.

I recently had a dodge truck with a 4.7 come to me from a transmission shop. I was told they drove it in perfectly fine but after the transmission job it runs like crap and has no power. Sure enough the helper turned the engine backwards to put the torque converter nuts in and that made it jump time. Granted the guides were already weak in this situation, these chain timing guide setups do not like turning in reverse. Just a situation that came to mind that could be relevant.

 

[Mbrooks420]

I never considered spinning it backwards could case an issue. Excellent info.

 

[Number4]

Looking down the intake tubes, valves don’t appear to have bent. But it may not need bent much. This is the #1 cylinder and it’s on the compression stroke. Bubbles are coming out from at least one side of the valve.

Video wasn’t shot with the intent of uploading, so it has a moment of nothingness in the middle.

 

[Fix4Dirt]

valve couldve smacked piston, and now isnt seating properly and is leaking where it smacked piston

 

[Mbrooks420]

It doesn’t take much bend to make them stick in the guides.

 

[drdoom]

I never considered spinning it backwards could case an issue. Excellent info.

Never, ever turn an engine backwards. The slack side of the timing chain will wreck the guides when it comes taut.

 

[Mbrooks420]

Never, ever turn an engine backwards. The slack side of the timing chain will wreck the guides when it comes taut.

I probably wouldn’t have, but it wouldn’t have occurred to me about the timing chains. Outside of power sports all my rebuilds have been on pushrod motors.

 

[Number4]

Doing a leak down test, the air is coming out of the exhaust on cylinders 1 & 2. Haven’t done the rest yet.

That’s at top dead center, obviously. No air/noise from the intake valves (intake is off) and nothing from the oil pan. Pretty good sound out of the exhaust manifold.

 

[Number4]

When I did the timing, I brought cylinder one to TDC. Made sure the harmonic balancer timing mark matched.

Then, using the OTC timing kit, locked the engine down per each step.

I also took a sharpie and marked across each cam lobe and the head to verify position.

Just performed a leak down test on all cylinders. Confirmed that the exhaust valves on bank 1 aren’t holding. Brought cylinder 1 to TDC, balancer was at 0, and my sharpie marks were off.

If I align my sharpie marks, then the balancer timing mark is at 3 o’clock instead of 10 o’clock timed.

I have no sensation of valve contact while rotating the engine.

When looking in the plug hole, I can see the exhaust valve open as the cylinder approaches TDC, but this is normal, correct? As the engine pushes the spent compression out of the cylinder?

Also, as a note, when I did the front balance shaft connection, it’s wasn’t aligned as in the Cloyes timing video.

Now, the exhaust valve is open the entire compression stroke and closes right before TDC. Or is cylinder 1 not doing anything on this stroke.

The mechanic had said he was getting pressure on the intake and that it was odd. So is my issue, that bank 1 cam is off?

I’m lost on this.

 

[drdoom]

You locked at TDC compression or intake stroke? The asymetric lock grooves in the camshaft ends, were they facing down?

 

[Number4]

You locked at TDC compression or intake stroke? The asymetric lock grooves in the camshaft ends, were they facing down?

We used the OTC tools, so the cam was in whatever rotation it needed for that.

Here’s what I see, with the piston up, balancer at the timing mark, if I were to undo the rear cam bolt and rotate the cam back until my sharpie marks align, then the intake and exhaust valves would be closed at TDC. Heading toward an exhaust open down stroke.

Can I simply undo that top rear cam bolt and rotate the cam? The only valve spring being compressed current is the #1, which I want to rotate back.


Balancer at 0.

Cam not aligned.

My sharpie marks on cam, rotated too far

Vs sharpie marks on head

Where lobe point is, vs where it should be (finger tip)