Broken down won't started suspected timing chain

[marc1234567]

the timing chain has broken and the rocker cover has been removed and no cradle damage is observable.

the mechanic is not sure and asked me to ask here.

the camshafts can be turned and the mechanic says that could be a bad or good thing. he is unsure as to whether the valves may be bent or whatever.

is there any way there may be no damage to valves etc.

Strange for the chain to actually break..?? If so it will be as Karl mentioned, it's unlikely to bend valves as they're straight on to the pistons and quite robust.... they usually pull the rocker shaft bolts or break the rocker ladder...or both.

If "both cams" can be turned 360 degrees with cyl #1 at TDC and without turning the crank...there's problems, valves should be touching #1 & #4 pistons.

Lord Knobrot

Many Thanks. the turning of the camshafts was done with no particular attention paid to position of crankshaft. Are there parts of the cycle where it would be ok to have the camshafts 360? should we check with cyl 1 at TDC. i think the mechanic said something similar. what are symptoms of rocker shaft bolt damage?

[karl]

the timing chain has broken and the rocker cover has been removed and no cradle damage is observable.

the mechanic is not sure and asked me to ask here.

the camshafts can be turned and the mechanic says that could be a bad or good thing. he is unsure as to whether the valves may be bent or whatever.

is there any way there may be no damage to valves etc.

if your mechanic is unsure then find a new one

[marc1234567]

the timing chain has broken and the rocker cover has been removed and no cradle damage is observable.

the mechanic is not sure and asked me to ask here.

the camshafts can be turned and the mechanic says that could be a bad or good thing. he is unsure as to whether the valves may be bent or whatever.

is there any way there may be no damage to valves etc.

if your mechanic is unsure then find a new one

he is doing me a favour and helping me. he asked me to ask on this forum but maybe he knows already

[karl]

the valve dont bend

[knobby1]

Many Thanks. the turning of the camshafts was done with no particular attention paid to position of crankshaft. Are there parts of the cycle where it would be ok to have the camshafts 360? should we check with cyl 1 at TDC. i think the mechanic said something similar. what are symptoms of rocker shaft bolt damage?

The cams should be able to be turned and valves moved if the pistons are half way up/down the bores...only when at TDC or very close to TDC will they hit. Symptoms of rocker ladder/bolt damage will be obvious, bolts will be loose/pulled and/or rocker ladder will be cracked or broken.

If the chain broke at anything above idle, the engine/crankshaft will spin quite a few revolutions before it stops...and pistons will almost certainly hit valves....but as Karl says, they don't bend, they tend to pull the bolts threads, break bolts and/or lift the rockers & ladder bits off the head.

Lord Knobrot

[marc1234567]

Many Thanks. the turning of the camshafts was done with no particular attention paid to position of crankshaft. Are there parts of the cycle where it would be ok to have the camshafts 360? should we check with cyl 1 at TDC. i think the mechanic said something similar. what are symptoms of rocker shaft bolt damage?

The cams should be able to be turned and valves moved if the pistons are half way up/down the bores...only when at TDC or very close to TDC will they hit. Symptoms of rocker ladder/bolt damage will be obvious, bolts will be loose/pulled and/or rocker ladder will be cracked or broken.

If the chain broke at anything above idle, the engine/crankshaft will spin quite a few revolutions before it stops...and pistons will almost certainly hit valves....but as Karl says, they don't bend, they tend to pull the bolts threads, break bolts and/or lift the rockers & ladder bits off the head.

Lord Knobrot

Thanks Again Knobby1, the engine was turned over many times by starter motor as recovery tried restarting with easystart etc. the chain broke whilst pulling away up hill and so revs could have been low. i guess there is nothing more to say other than show my mechanic friend this thread. i think he knows what he is doing but what are symptoms of broken bolts and or lifted rockers. should that damage be visible or evident in any way ?

[marc1234567]

the valve dont bend

ok many thanks. also my further question to knobby1?

what are symptoms of broken bolts and or lifted rockers. Should that damage be visible or evident in any way ?

[shortymk6]

the damage can be hard to spot mine was just a little crack there is a pic in this thread viewtopic.php?f=5&t=169610

[marc1234567]

We checked for damage and stripped bolts but didn't seem to be any. Fitted timing chain but turning over by hand meets with resistance before completing a revolution. Mechanic says must be valve bent after all. There is no other explanation right?

[Jim Archer]

Timing is wrong?
Coming up on compression?

It will not have bent a valve unless something has got trapped between seat and valve head as they are sat at 0° angle to the cylinder. It that has happened, then it is likely to have cracked the cylinder head.

Jim

[bambi mk 1]

Timing is wrong?
Coming up on compression?

It will not have bent a valve unless something has got trapped between seat and valve head as they are sat at 0° angle to the cylinder. It that has happened, then it is likely to have cracked the cylinder head.

Jim

Or a piston shaped like a ski slope Jim

[marc1234567]

Timing is wrong?
Coming up on compression?

It will not have bent a valve unless something has got trapped between seat and valve head as they are sat at 0° angle to the cylinder. It that has happened, then it is likely to have cracked the cylinder head.

Jim

What might have gotten trapped? If all the timing marks were lined up with the chain and pin in crankshaft censor etc could the timing be wrong still?

[knobby1]

What might have gotten trapped? If all the timing marks were lined up with the chain and pin in crankshaft censor etc could the timing be wrong still?

Glow plugs and injectors still in..??

Lord Knobrot

[marc1234567]

What might have gotten trapped? If all the timing marks were lined up with the chain and pin in crankshaft censor etc could the timing be wrong still?

Glow plugs and injectors still in..??

Lord Knobrot

Ate you saying that is what might be trapped? Would pistons hit those? Isn't if just the valves that would make contact with the piston?

[knobby1]

Ate you saying that is what might be trapped? Would pistons hit those? Isn't if just the valves that would make contact with the piston?

No...but if the injectors and glow plugs are still in there, it will have quite a bit of compression, we're talking ~18 or 19:1 compression ratio compared to ~9:1 for a garden variety petrol powered engine.

If the cam timing is correct they can still be quit difficult to turn over by hand.

Lord Knobrot