Fiat fire engines

Timing correctly...

Reading the valve timing here now the engine is in the set position and locked, it is clear to see to the persons that can read valve timing by sight that the Fiat designers have chosen not to use the engine setting position of TDC when timing these engines.

The onlooker can see this by reading the valve timing below...




Removing the old belt...

Timing correctly...

I then looked at the other side of the belt between the teeth area and found that the damage resulting in a hole was between the teeth area of the belt...



 

But what could cause this damage to the belt like this?

Moving on...

When I came to the part of the job to fit the new belt, this is when I realised why the old belt removed was damaged. It was damaged by the mechanic who fitted it! How do I know that?

Referring again to post on and the picture of the old belt fitted, the tension is incorrect, therefore to tension the belt round the pulleys moving anti-clockwise, the belt had to be secured to the water pump gear, and to do that the only method I know is to use some large body panel grips that will contact the gear teeth and the backwall of the timing belt, however, the mechanic who fitted the belt must have really layed on the compression force to hold the belt to the gear while fitting! A really unnecessary amount of force in my opinion had been applied. (On a side note, I also see this a lot with mechanics who clamp off brake hoses. It is absolutely unnecessary to use such force). 

Once the new belt has been gently clampped to the gear, moving anticlockwise, locate the belt around the camshaft gear and round the tension device, making sure ALL the slack of the belt is on the tension side. Release the tensioner and using the key provided in the tool kit apply FULL tension to the belt. Lock the tensioner in this position. 

Remove the crankshaft and camshaft setting tools and rotate the engine two complete revolutions and align back to the setting position for the crankshaft and camshaft. Refit the alignment tools. Release the tensioner and correctly tension so that the aligment tags are parallel, and then torque the tensioner to specifications. By feel it is possible now to understand that the belt is tensioned between each gear and no slack is present.

The key points being highlighted are...

1/ The manufacturers do not always use TDC as a setting position when changing timing belts,

2/ Paint and chalk marks are not really recommended. Camshafts such as this one which are not timed on TDC can and more than likely will move once the belt is removed.

3/ If the mechanic is lead to believe that the engine crank position is TDC when its not, then engine damage is most likely to occur.

4/ Some of these fire engines as single overhead camshaft designs are also VVT, which is recognised by the frontal area of the camshaft gear. There is another setting position for that when installed. 

The manufacturer Fiat are not using a new idea here, Ford used to do this a very long time ago when they recommended cylinder 1 intake valve fully open when renewing their timing belts, which probably not many with remember those days!

The point being made here is that it does not matter what the engine setting position is so long as the mechanic understands exactly what he is doing? However, I've seen a few over the last eighteen years where things have gone wrong because mechanics have done their own thing instead of following industry standards.

I maybe wrong but I think I remember it was a common problem for the crank/timing gear keyway to shear when the crank pulley was tightened.

seem to recall a lotta the later twin cam rover stuff was timed at about 90 degrees btdc or thereabouts also on summa the rover 800s one of the timing tools was 80 grit flatting paper or similar to stop the fooked up tensioner design from moving when you tightened it.bring back the pintos i say.quick,easy and if the worst happens then just slap another belt on.or why not use summat similar to the old family one gm lumps where the rockers would snap instead of the valves bending-at least on the diesels-again easy quick fix rather that the complete engine being toast like most of em now.the current wet belt fad is also a worry.anyone seen any manufacturer out there getting em to last to the service interval on a reliable basis?let alone the faff involved with the fitting on a lot of em.

I vaguely remember something at our place with a timing belt I fitted. The woodruf key was a slack fit in the crank journal groove, which I didn't think too much about at the time. I put the crank pulley back on and something must have alerted me to think it was not located or positioned correctly. I can't remember properly now but I removed the crank pulley and found that the woodruf key had caught on the edge of the crank pulley during fitting and caused the woodruf key to run up vertically into the timing cover housing. Had I not removed the pulley that could have been a disaster waiting to happen. Woodruf keys and their slots were never a good design to start with. Some keys were so small they were a disaster just waiting to happen.