I have 02 explorer 4.0 136k on it, the other day the engine just died while driving it, when trying to turn it over the engine just didnt sound right. After getting it towed home I started troubleshooting long story short I did a compression test on two cylinders on each bank and had no compression, I am well aware of this model having BIG issues with the timing chain tensioners breaking and giving slack in one of the four chains. After taking valve covers off and turning the crank by hand both cams were turning so I new the primary chain was intact but suspected one of the chains jumped a tooth or two. After pulling the balancer off and the timing chain cover I seen the primary chain was tight, but what else I seen the key on the crankshaft for the primary chain was broke right at the gear for the chain, so with the balancer off and it not putting pressure against that gear, the gear just spun freely on the shaft. My question is without buying the expensive timing cam tool for this vehicle how can I first check how far the cams are out of time because I dont want to turn it the engine over anymore than I have to to avoid bending valves. I know this is a interference engine and the odds of the piston hitting a valve is good but when before the engine stopped I didnt hear any noise. One other thing when the keyway on the crank is at 12oclock the timing marks on the right cam shaft are at 3 and 9o clock and the left cam is at 12 and 6 oclock.