Technical timing the 1242 16v without locked cams

[arc]

hi all.

mate of mine has a brava and the timing belt has slipped. i dont know why yet - i've not looked at it, but it happened at low engine speed so as the cheapest and easiest solution am going to fit a new belt and then compression test the engine.

Last time i worked on one of these engines we just made sure that the bottom or top end just didnt move when the belt was off - but obiously now its all out of time.

Sooo what landmarks can i use to time it up?

 

[arc]

nm, the engine is totally goosed. got spare?

 

[dave]

was one on ebay for 100 quid the other day. always use the tools on this engine, because it has to be timed with all pistons in middle of stroke and cam pulley loose. you cant do it no other way with out it fcuking up

 

[jug]

nm, the engine is totally goosed. got spare?

1242 16v is an easy enough engine to come by. mk2 punto sporting or elx for example.

is it really buggered beyond repair? surely the worse case scenario is a few bent valves. go on, get your hands dirty

 

[arc]

it has overheated, shredded the timing belt.. i'm not sure how. the inlet is full of emulsified oil / water mix. there is visible debris in the cylidners when viewed through the spark plug holes.

i'll get my hands dirty enough removing it and fitting a new 'en!

 

[arc]

well here are some pics, anyone take a guess at what went wrong to kill the engine cos i don't know.

It happened at low speed, approaching a junction, car stalled, PAS was lost (suggests bottom end was stationary to me)

Teeth stripped, that must've been the crank pulley?

Belt is only half width, and has a groove in the back of it

that groove matches the damage on edge of the tensioner;

looks like it had been rubbing on something, but there was nothing there for it to hit. i couldnt get the tensioner to go anywhere near close enough to the head.

inlet manifold was full of water / oil

as was the pipework from the airbox to TB.

All 8 inlet valves are bent;

had been driven for about 15mins before this happened and after the car stopped, it blew its coolant out the cap.

So what caused it, and what are the results of that. I can't work out which is which! (i know bent valves is cos the belt stripped, it didnt snap though)

 

[jug]

water entered a cylinder (or cylinders) locking the engine so quickly that the timing belt buckled and stipped, bending the valves. head gasket leaks are common on the 1.2 so i would assume that was the initial cause.

 

[arc]

what caused the damage to the tensioner though, it was metled as if catching something - the cam belt cover?

 

[jug]

what caused the damage to the tensioner though, it was metled as if catching something - the cam belt cover?

the same force that killed the belt also pulled on every pulley on the belt just as hard. that can make the tensioner catch on the head. you can tell it caught on the head by the position of the wear (on the side of the wheel rather than on the belt running face).

check all the pulleys for signs of catching or any cracks or weakening where they are bolted on, or any sign that they are sitting off centre. timing belt is the weakest link but it can bugger other things before it lets go.

you have to imagine a cylinder full of water. the piston hits it and stops, jamming the crank pulley VERY quickly. all the other pulleys are still trying to go round and the parts they drive have a lot of momentum stored in their movement. the timing belt acts as the brake to stop them all very quickly, the force required to do that is huge!

 

[arc]

i understand the huge forces involved, but the tensioner is worn away rather than suddently impacted, it looks like it has been run next to a belt sander - and has a burr of melted plastic sticking up on it (that matches the damage on the belt)

the tesnioner has run out, if it has failed, hit the belt cover and then forced the belt off the waterpump puelly - could it take the slack long enough to keep the engine running,till it boiled the head and popped the gasket, hyrdolocking the engine? that would explain all the damage.

It def overheated as the coolant cap popped, and also all the HT leads were melted to the plugs (leads were new 12month ago if that). If the engine had died in one big bang then it wouldnt have had time, but it wouldnt have worn the tensioner down either

 

[dave]

is the tensioner seized?

 

[arc]

no, its not - nothing is.

 

[jug]

could it take the slack long enough to keep the engine running,till it boiled the head and popped the gasket, hyrdolocking the engine?

when it slipped off the waterpump it would cut out within a few secs (timing is lost instantly)

It def overheated as the coolant cap popped, and also all the HT leads were melted to the plugs (leads were new 12month ago if that). If the engine had died in one big bang then it wouldnt have had time, but it wouldnt have worn the tensioner down either

yes i agree. in that case overheating was definately the initial problem that caused the head gasket leak. what caused the overheating? you need to find out.

is water pump pulley turning freely and without any play?

 

[arc]

it is turning freely now, but it may have jammed if there was fod in the cooling system.

hows about this for a sceneiro, car is running nicely - something hits the waterpump, yanks sharply on the cam belt, pulls the tensioner out of shape which then hits cam belt cover - shredding the outter edges of the belt car runs for a bit with clobbered water pump and begins overheating, whislt shredding the belt also on the now damaged cam belt tensioner, it gets halfway through and the waterpump jams again, stripping the teeth.

Gimme a few hours and il have the engine in bits and a chat with my mate about where the belt was and wasn't when the engine finally died.

 

[stylers]

Ahh - nothing like a good post mortem to keep the brain in gear

 

[jug]

hows about this for a sceneiro, car is running nicely - something hits the waterpump, yanks sharply on the cam belt, pulls the tensioner out of shape which then hits cam belt cover - shredding the outter edges of the belt car runs for a bit with clobbered water pump and begins overheating, whislt shredding the belt also on the now damaged cam belt tensioner, it gets halfway through and the waterpump jams again, stripping the teeth.

yes thats definately possible. if there was already a head gasket leak, its possible that mayo clogged up the cooling system, and caused the pump to jam. mayo gunk is thicker than coolant, a lot thicker, so pumping it will suddently put the water pump under a lot more pressure, greatly increasing the force required to turn its pulley.

 

[arc]

the cam belt cover has melted bits on it. every valve is bent and jammed open, each piston is decked.

not stripped the pump out yet. will get photos later tonight.

 

[jug]

the cam belt cover has melted bits on it.

my AX GT set its cambelt cover on fire, along with a few other bits of engine bay plastic. in a moment of madness i hosed it down to stop the fire. i got that engine working good as new so dont fret, you'll sort it out.

every valve is bent and jammed open, each piston is decked.

that shows engine continued to rotate afte timing was lost on both cams. nice! crank shells would definately be on my parts list. actually in this situation it definately will be cheaper and quicker and easier to replace the entire engine.

as far as engine failure goes, this one is a beauty.

 

[arc]

there is a new engine sat next to it, ready to go in when the hoist turns up on friday

 

[arc]

so the cam belt cover is damaged and has melted bits on it;

crank pulley

spot where the other half of the timing belt ended up!!

cams are off, but all valves jammed open;

pistons..

and finally, the new engine built up (nearly) ready to be dropped in;

the water pump was fine and un damaged.