Sounds like injection timing is jumping. Valve trains don't
appreciate it when injection happens into the hot, compressed air
while cams are trying to open valves. The explosion will easily bend
valve stems.....and make that backfiring sound as the valve is
partially open. Of course, once bent, the valve can't fully close so
there's lots of blast-by if it has enough heat and compression left to
fire the injection....which it probably does with the pre-heaters
setting it off....



On 29 Oct 2003 20:18:44 GMT, (Spamfreedom) wrote:

thanks for reading. I am seeking some feedback on a problem I have had twice
this year on my Volvo Penta MD17C diesel. the engine is in good shape with
under 1500 total hours. it has been overhauled and serviced etc. well this
year In early june I had a pushrod (on the intake valve) fail on cylinder #2
and the exhaust valve pushrod was bent. New pushrods were installed and valve
clearance and timing checked etc. Well, today I started the engine and it was
sounding like backfiring and I checked and exhaust was belching out the intake
of cylinder #2. turns out the pushrods are bent again!?!?! my mechanics are
stratching their heads. I am puzzled as to why this is happening ( timing?,
fuel?, ). BTW, it seems to happen after the engine has sat for awhile
(months) and during cold weather starts....

please post reply here, this is a no email address.....thanks...


Larry W4CSC

"Very funny, Scotty! Now, BEAM ME MY CLOTHES! KIRK OUT!"