Yamaha 150hp 4 stroke, No Oil, Slipped Timing Belt, After Service

My buddy took his boat into a shop for yearly service, Motor is an 2008 F150 4 stroke with 250 hours. After Service, the boat was launched and ran on low idle (throttle position the entire time) in water canals for about 30 minutes when it died. After checking electronics we noticed the Oil dip stick showed no oil. The oil light never came on. We added 5 quarts of oil and the dip stick looked normal, however it still would not start.

I checked compression and each cylinder registered 30 to 34 psi.

The boat was taken back to shop and discovered the timing belt slipped. The shop said they replaced the belt and boat started right up. They ran it and the diagnostics on it came back clean. Temperature was good, and compression was between 180 - 190 psi on all cylinders. they also pulled the filter after the run and split it open to check for metal and non was found. The Shop did not charge him for fixing this.

My concern is that there could have been damaged caused to the CAM when motor stopped when timing slipped.

My question, should my buddy be concerned since the shop didn't pull the CAM journals to verify if there wasn't any galling to the CAM?

Is this a free wheeling motor or not ??

I made a mistake on the description, it's a 2011 model and not a 2008. I reviewed he owners manual for an F150 model and could not find that it was free wheeling.

The shop is possibly in heavy 'damage limitation mode'. I would recheck all the compression's myself. If you have bent a valve when the belt slipped you will probably see it in the compression readings. The lack of oil is possibly even more of a worry though. Do you believe that the shop forgot to put oil in the engine after draining it? If so, why did the oil pressure alarm not sound? Letting the shop check the filter for metal was potentially a risk as it may not be in their best interests to be absolutely truthful about any negative findings. I would put an external oil pressure gauge on the engine and check the pressure at idle on a hot engine to see if the pressure is consistent with an undamaged engine of that age and hours.

Good point. I'll check the compression on it myself. We still can't figure out why the alarm didn't sound. All the wiring looked intact and the fuses were good. My buddy did speak to another mechanic and he also questioned why the alarm didn't sound.