lets say 1.2 16v engine snaps timing belt

i was wondering how much stuff gets damaged after timing belt snaps while driving, do higher speed/revs equal more damage?

my thinking- two pistons go up at same time, belt snaps, so 8 valves will bend 100%?, does that mean that those two pistons and 8 valves took whole force of the impact and engine stops, or does it continue banging and bending every valve until it slowly stops

so required parts needed for engine to run are

timing belt
valves
headgasket

water pump?
tensioner?
spark plugs?
skimming necessary?

is there anything else?

Higher speed will generally mean more damage but you never know until you open up. Very unlikely the crank will go from 3000 rpm to zero in one revolution.
I would be looking for a used head before taking on new valves, worn guides, seat grinding, etc etc.

Generally if the belt lets go at speed the top of the engine will stop pretty quickly less than a rotation as there is no weight to carry on the revolutions meanwhile the bottom carries on, and depending where you are in the rotation of the engine dictates how much gets damaged. If the belt tensioner lets go then it's a different story and you can wreck every valve and piston as everything rattles out of time.

I had a friend many years ago who's 2litre Zetec did this at 100mph+ and he bent everything and fractured a cam shaft. The fracture was slight so when he put the new bare head with new valves in, he reinserted his old cam shafts and when he first started the car the camshaft then broke (between 1 and 2) leaving a quarter spinning and the other 3 quarters stationary and it wrecked all those nice new valves.

flisko said:

timing belt
valves
headgasket

water pump?
tensioner?
spark plugs?
skimming necessary?

is there anything else?

Click to expand...

on the TS alfa's ,
it's common for the big ends to knock after a ( belt failure) top-end rebuild,
often after @2000 miles

so you'd also want to factor in new shells

that zetec stuff is brutal, all that work went to waste

so camshafts can get damaged too

what about pistons as they hit valves, do they need to be replaced

pistons - YES

flisko said:

that zetec stuff is brutal, all that work went to waste

so camshafts can get damaged too

Click to expand...

Not only camshafts but their bearings can get cracked or punched off the head.

Brendan W said:

Not only camshafts but their bearings can get cracked or punched off the head.

Click to expand...

which bearings?

It's actually possible to bend the con rods, crack Pistons, snap off the valve head and have it rattle about in the cylinder and score the bore, or even embed itself in to the piston, or even the valve seat, meaning your engine is fairly toast. Not saying that's what's happened though ;-)

Tbh most people fit a 2nd hand engine therr and then
Often getting a head rebuilt is too expensive....

Trouble is 2nd hand engine could have issues of its own


Ziggy