Technical re-timing following cam belt failure

Colin Harrison · May 8, 2014

Hi All, My cambelt failed on my 1.9JTD mk2 Punto. I would like to put a new belt kit on and see if the car is okay. How do I set the timing when the belt has snapped in service and the crank has turned? Do I need to take out a glow plug and find top dead centre? How do I know which TDC it is (compression or exhaust)
Is it certain that the valves would have been damaged? Do I have a chance that just a belt swap will fix the problem?
Thanks.

Ziggy122 · May 8, 2014

Chances are no....
Iirc the 1.9 is an interferance engone

If the belt let go ibet its smashed a few valves

Ziggy

MikeSalt · May 8, 2014

Probably better to whip the head off and inspect the damage before going to the trouble of re-timing it up given the probability that there is damage.

oldhammer · May 8, 2014

id see what happens with anew cambelt on,
it will have to be changed any way ...so what is there to loose?

Did it snap on startup or did it let go at speed?

s and b · May 8, 2014

oldhammer said:
id see what happens with anew cambelt on,
it will have to be changed any way ...so what is there to loose?

Did it snap on startup or did it let go at speed?

SPOT ON ANSWER
after all a belts what £20?

Ziggy122 · May 8, 2014

*sits smug knowing that the 1.2 8v petrols are indestructable*

Ziggy

fingers99 · May 8, 2014

If a valve has bent, or has snapped off, you'll do a lot more damage putting a new belt on and trying to start it.

Needs head off, inspecting for damage.

s and b · May 8, 2014

fingers99 said:
If a valve has bent, or has snapped off, you'll do a lot more damage putting a new belt on and trying to start it.

Needs head off, inspecting for damage.

nothing to lose by belting it up
if damaged its already done and cars probably scrap if it is

oldhammer · May 8, 2014

fingers99 said:
If a valve has bent, or has snapped off, you'll do a lot more damage putting a new belt on and trying to start it.

Needs head off, inspecting for damage.

ive done loads of cambelt fails mate,

most have been saved with minimal damage,
if there is valve damage there will be war wounds on piston crowns anyway,as a norm,

FWIW. new cambelt on and disconect cranky sensor,
is what ido anyway,

oldhammer · May 8, 2014

Ziggy122 said:
*sits smug knowing that the 1.2 8v petrols are indestructable*

Ziggy

Thats something itake with pinch of salt, sorryto say,
as ive said's before, if they let go on motorway,

a safe engine dont make the shell safe,

varesecrazy · May 8, 2014

oldhammer said:
ive done loads of cambelt fails mate,

most have been saved with minimal damage,
if there is valve damage there will be war wounds on piston crowns anyway,as a norm,

FWIW. new cambelt on and disconect cranky sensor,
is what ido anyway,

from a quick SEARCH ;
https://www.fiatforum.com/tech-talk/282695-1-9-jtd-110-noisy-after-cam-belt-change-garage.html

s and b · May 8, 2014

varesecrazy said:
from a quick SEARCH ;
https://www.fiatforum.com/tech-talk/282695-1-9-jtd-110-noisy-after-cam-belt-change-garage.html

what you saying please?
dont understand

varesecrazy · May 8, 2014

belt fitted 1 tooth out , no damage done..,

I'm in agreement - for the cost of a belt.. may be worth a try.. as uneconomic to repair in reality..,

the FF search didn't find any great how to's on the Punto JTD, apart from it's a tight squeeze for access

This may give SOME idea though;

http://www.alfaworkshop.co.uk/alfa_jtd_cambelt.shtml

Have fun.

AndyRKett · May 8, 2014

If you're going to fit a new belt and see how it is turn it over by hand to begin with make sure nothing is going to do further damage, however it's pretty impossible on this engine to not do some damage, compression test will soon tell you that

oldhammer · May 8, 2014

varesecrazy said:
belt fitted 1 tooth out , no damage done..,

I'm in agreement - for the cost of a belt.. may be worth a try.. as uneconomic to repair in reality..,

the FF search didn't find any great how to's on the Punto JTD, apart from it's a tight squeeze for access

This may give SOME idea though;

http://www.alfaworkshop.co.uk/alfa_jtd_cambelt.shtml

Have fun.

(I'm in agreement - for the cost of a belt.. may be worth a try.. as uneconomic to repair in reality)

depends who does the work, if a garage then it might be cheaper just to
scrap the car, this is if valves are bent,

there is plenty of places that will take cylinder head in and sort it,
the place isend em too is a 2 day wait but they is good at there job and
cheap,

Colin Harrison · May 9, 2014

oldhammer said:
id see what happens with anew cambelt on,
it will have to be changed any way ...so what is there to loose?

Did it snap on startup or did it let go at speed?

It snapped in the fast lane of the A34 ! My wife was driving at about 50/60mph. She probably didn't know that it is a good idea to push the clutch pedal down.....

Colin Harrison · May 9, 2014

oldhammer said:
(I'm in agreement - for the cost of a belt.. may be worth a try.. as uneconomic to repair in reality)

depends who does the work, if a garage then it might be cheaper just to
scrap the car, this is if valves are bent,

there is plenty of places that will take cylinder head in and sort it,
the place isend em too is a 2 day wait but they is good at there job and
cheap,

I will pop the cylinder head off and take a look. My main unknown is how to do the timing of the engine if I get to that stage....I remember on older petrol engines with points you could establish which cycle the crank was on, i.e. when it was firing. No idea how to do this on the JTD though - I have a horrible feeling it will involve expensive electronic gadgets.

Ziggy122 · May 9, 2014

Right i had a quick scan on a timing diagram for you

Regarding crank
There is a Peg on the crank pulley - this needs to sit at 6 o'clock
It says to use a timing tool to hold this in place

The water pump - Guider and tensioner and Fuel Pump according to it are not required for timing

the Crank has a straight line cut on it - this in the timing mark for the crank - this needs to line up with a mark that is on the backing plate - about 1o'clock / 1:30

Remember todo 2 full engine crank revolutions by hand before doing ANYTHING with the starter

Ziggy

varesecrazy · May 9, 2014

Ziggy122 said:
Right i had a quick scan on a timing diagram for you

Regarding crank
There is a Peg on the crank pulley - this needs to sit at 6 o'clock
It says to use a timing tool to hold this in place

The water pump - Guider and tensioner and Fuel Pump according to it are not required for timing

the Crank has a straight line cut on it - this in the timing mark for the crank - this needs to line up with a mark that is on the backing plate - about 1o'clock / 1:30

Remember todo 2 full engine crank revolutions by hand before doing ANYTHING with the starter

Ziggy

isn't that pretty much waht the Alfa JTD link said..??

varesecrazy · May 9, 2014

Colin Harrison said:
It snapped in the fast lane of the A34 ! My wife was driving at about 50/60mph. She probably didn't know that it is a good idea to push the clutch pedal down.....

if you're near didcot, you are welcome to borrow my porter manual, that should cover it all,

Charlie

Technical re-timing following cam belt failure

Currently reading: Technical re-timing following cam belt failure

New member

Busy rebuilding pand'a

Distinguished member

Distinguished member

Busy rebuilding pand'a

Busy rebuilding pand'a

Distinguished member

Distinguished member

Busy rebuilding pand'a

New member

New member

Similar threads

Currently reading:
Technical re-timing following cam belt failure