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Sometimes yes and sometimes no. Depends on how long it ran after the chain broke. Most times the first thing to go after the TC is the valves Because they are no longer firing in order and will hit the pistons and bend them. (bend the valves that is)
This is from Mr service
A broken timing chain will cause an engine to not start or fail while driving. If the belt is already broken, the engine won't have enough compression to start. If it breaks or jumps while driving, the pistons will be damaged from contact with the valves. The valves themselves will bend and potentially ruin the engine.
So my advice to you is dont try to start the engine. Take the valve covers off and see if any of the valves are bent, if they are your only choice as I see it is to take off the heads and go from there seeing just how deep the damage is. My philosophy is When you are that deep in the engine go ahead and replace the parts that need replacing plus the ones that fail often enough like the water pump, Timing chain (of course) but as well as the TC do the tensioner and plastic guide rail too.
At the very least you are looking at 60.00 ish dollars for the head gasket set without the bolts (106 with them)
Head Gasket set with bolts
Timing set with sprockets
As a worst case scenario if your pistons are damaged heres what you are looking at for the master rebuild set
Master rebuild set
Good Luck
 

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2003 RT (5.9)
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i think the timing chain broke, ran noisy, will it ruin the engine?
If you actually did break the primary chain it wouldn't even be running; if you broke either the right or left chain, if it was running at all it should be running like absolute shit, and barely running at that, as half of your cylinders would be dead. From everything I've read, those 4.7 valve trains are rather complicated to work on and the gen2 OHCs sound as if they can be prone to problems. If it is running but noisy, it could be something else going on; for example, from what I've read, it's not a super uncommon event for a rocker to fall off on a 4.7 of that vintage, and I suspect that would make some noise.

But if it is running & rattling & making a lot of noise--no, I wouldn't run it. It can only get worse.
 

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A broken timing chain will cause an engine to not start or fail while driving. If the belt is already broken, the engine won't have enough compression to start. If it breaks or jumps while driving, the pistons will be damaged from contact with the valves.
 

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Although its not Impossible… a broken the timing chain itself is not the first thing I would suspect for nasty internal noise; esp if its running at all. Other posters are correct about the timing chain design on the 4.7 being more complicated (there are 3 chains), but still, its pretty rare for a timing chain to just break for no reason, unless there are other factors that CAUSED it to break. there are lots of 4.7’s out there with 250k-300k+ miles on them with their original chains.

If your certain this is not something in the vale train or the bottom end, and your certain its timing chain related, id first suspect a timing chain guide or tensioner failure. The tensioners are oil pressure controlled, so for example; if you ran it low on oil, old jellied oil, or the pickup tube was clogged, or the oil pump failed… its a trickle down effect; you would loose oil psi to the tensioner, the chain gets loose and under higher rpm the chain would “float” off the cam sprockets, jump time or break. Also, The chain guides are made from a polyethylene plastic and could be worn out, again, a loose chain, same issues. But if you did loose oil pressure you’d tear up camshaft journals, score piston walls, have burnt rings, and possibly ruin crank shaft bearings.

you dont have enough information to really know; all you know is you had a nasty noise in the motor the last time you ran it.

no matter what the cause, if its making a bad noise, running it more will be bad, if you plan to fix it. I’m 90% sure the 4.7 IS an “interference engine” meaning if the valves are out of time with the pistons, the valves and pistons can make contact. Bad day for the motor when that happens.
 
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