Technical Punto HGT cambelt change musings

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Technical Punto HGT cambelt change musings


Established member
May 19, 2006
Tonbridge, Kent
Hi folks

Don't often come to this bit of the forum but I find myself doing a cambelt and variator change on an '02 Punto 1.8 HGT.

The procedure seems all OK (I've done quite a few other Fiats now, generally 500s, Pandas, older Lampredi-based engines (e.g. Bravo/Brava 1600), and Alfa 1750 TBi - Pratola engine so similar architecture). It's a bit tight in there but I like the way that these older Fiats are designed so you don't have to mess around with undoing engine mounts... I've got the official workshop manual info.

Having done many newer Fire engines with the Marelli engine management I am paranoid about cam/crank correlation and phonic wheels (!) though I now have a procedure off pat.

On the HGT engine though (Pratola Serra "modular" engine with the Hitachi engine management), there is a phonic wheel fixed to the exhaust cam pulley. The latter is movable (within certain limits) and indeed one is recommended to slacken the exhaust pulley when doing the belt change.

The phonic wheel is bound to end up in a different position post change, but there is no facility in the ECU software to relearn it....

No-one however seems to raise an issue with I can only assume that the phonic wheel signal is not used for precise timing info, just to determine which "half" of its cycle the cam is in when the crank reaches TDC, within the tolerance of the cam pulley movement.

Does that sound right or am I missing something?

More musing than actual problem (though have not started it up yet)....maybe I should not look for problems that perhaps don't exist ;). Interested though if anyone knows the technicalities...