Jumping timing

[highmiles]

With a new fuel pump installed, my "free" project 2003 S60 started for the first time this weekend. It went into gear and moved out of the garage under its own power.
Unfortunately after 3-4 minutes of idling there was a hard noise and the motor cut of immediately. Cranking again produced one of those "that is not right" sounds, it turned freely but with no compression.
Checked the timing, sure enough, it had jumped. I noted that the tensioner was set more to "cold" so I figured that could be the issue. I reset the timing, adjusted the tensioner, turned the motor through a few revolutions, and restarted. I started and ran fine.
However, later in the day as I was continuing to move the car around (still just idling basically,) the same happened, noise, engine cut off, timing has jumped.
I realize that I may now have a bent valve or other issue, I will address that later. Any thoughts on what is causing the timing to jump? The tensioner appears to be correct and in good condition. The motor seems to turn freely and when timed correctly runs smoothly.
Background information, this car came to me with the motor completely torn down, so all my work is suspect!
Any guesses would be appreciated.

[RickHaleParker]

Any thoughts on what is causing the timing to jump?

Look at the tensioner, is the tab that goes into the block broken off?
Did you get the tab in the block?
Did you torque the bolt down after you adjusted the tensioner?
Belt condition?
Idler condition?

Belt, tensioner and idler should of been replaced when it was apart.

[highmiles]

Good thoughts and questions Rick. As a matter of fact when I looked at the tensioner after the first skip the tabs that fit around the engine casting were bent. I will check for that same condition now and report back. My guess is that would point to the tensioner. A new belt came with the project, but I don't know the age of the tensioner or idler. They both turned freely and smoothly so I used them, probably figuring getting it to run was the first step (was not sure I would get this far... first engine rebuild for me...) then I could review which parts to replace for longevity.
Tensioner install procedure was followed and torqued.

[RickHaleParker]

You might also check the threads on the bolt and in the block. They could be damaged.

[highmiles]

I checked the tensioner, no new damage to the tabs. I removed it, was still under proper torque, seems like bolt and boss in the block are OK.

Water pump and idler turn freely and smoothly.

I can't see any issue with the tensioner or idler but that is the simplest and most cost effective route to go. It seems the only other possibility would be some sort of intermittent internal issue. I would not guess that the VVT on the exhaust being activated could cause the skipping? Do I need to review and re-do the VVT set up? I feel like I did that correctly and that once you tightened up the pulley to the hub the task was completed. I spun the motor over numerous times when still out of the car though I realize something could be happening under load.

Thanks!

[tardcart]

The belt has to be loose. otherwise it would rip the teeth off the belt if say a cam seized up. did the belt look like the teeth were correct for the cogs? If you run it again,(retime) leave the cover off and observe.

[highmiles]

Thanks for the response. I agree with you. I ordered a new timing belt package. The belt came with the car, it certainly appears to be the right one, I think I saved the box, I will see if the part number is a good match.
I like your idea of observing it, but I already feel like I am gambling with bent valves. It ran just fine after the first restart, so my guess is that the jump is enough to shut the motor down but not enough to create piston/valve contact. I also sent the gauge cluster out for repair so will be leaving the battery disconnected until I get that hooked back up.
With any luck I will get both back this week and can get it running (having the gauges to be able to observe warning lights will also boost confidence...) again over the weekend.
Then I will move on to why the strange smelling white smoke... which dawned on me today is likely brake fluid, the pedal is soft and I bet leaking into the vacuum booster. This will be like a new car when I am done...

[cn90]

Was the old belt Gates?

For TB kit, use only Volvo OEM ($110) or Conti. Do not use Gates, the Gates TB is known to walk around.

[highmiles]

Good tip. The belt is a Conti, and that is the kit I ordered from FCP to replace tensioner and idler.