Hello.

My newly bought mates Fiat JTD 105 8V diesel -
Cambelt snapped on way to get it changed, 400m from my garage!
Is there any point in trying a new belt first before removing head?
I presume bent valves or cups. But is this always the case?
The comp ratio is 19:1 on these.
It snapped due to overtight cambelt tensioner, we knew when bought car, and why we were changing belt that day. So water pump ok.
Will guides be bent, of can I just slide new valves in and reassemble?
Also how do I line up the out of sync cam pulley now with crank pulley when I either try a new belt or indeed replace the sorted head?

Lee.

Check in here for some details on cambelt replacement...it may help?

https://sites.google.com/site/fiatmultipla/Home/repairs

Bummer ! To be honest i think if you dont re shell the bottom end as well as re build the head it will only last a couple of months.
Something to do with the way the cranks fit in the fiat / alfa range, seen many engines fail after a couple of months but you could be lucky.
I think you could allways just try it with a new belt you have nothing to loose, but expect bent valves mate.

i may be thick but petrol 8 valve engines dont bend valves when the belt snaps as they are non interfernce am i missing summit or are diesel 8 valve engines indeed different.

Yep, you're missing summat! It's all to do with clearances - with most modern engines, both petrol and diesel, the piston crowns will collide with the open valves if the camshaft stops rotating while the crankshaft continues to turn.

Some (not many!) engines have sufficient clearance to avoid damage, but I've seen valves broken off and embedded in the top of the piston, and occasionally a snapped off valve will make a hole right through the piston crown.