Cracked cam gear???
08-01-2010, 05:52 PM
#1
Team Owner
Thread Starter
Cracked cam gear???
One of my customers with an 82 928 called and said that the engine stopped running and the cam cover is bent forward. Anyone seen this happen before , I believe that the cam and crank and oil pump gear`s have been converted to the HTD system
08-01-2010, 06:02 PM
#3
Nordschleife Master
Brian's former car, Sexual Chocolate, had a '79 engine in it with a broken cam shaft...I think it was near the end where the cam gear is too... Maybe Sean will jump in here and talk about it...
08-01-2010, 06:03 PM
#4
Hope the cam didn't snap.
Replaced two that did that.
Replaced two that did that.
08-01-2010, 06:12 PM
#5
Race Director
whats VERY odd about this 16V 928 is the passenger side cam or cam gear broke...since most cam failures in 16V 928's is the longer drivers side cam that turns the distributor? Very odd....
08-01-2010, 06:29 PM
#6
Agreed, just got back on to post that. Hope it is just the cam gear. Get some pics for us Stan.
08-01-2010, 06:31 PM
#7
Team Owner
Thread Starter
Sean what cam did you replace the Driver side or Passenger side
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08-01-2010, 06:36 PM
#8
Team Owner
Thread Starter
More info.
Owner told me he was driving and heard a clunk then the engine dies so he coasts to a stop in front of his house,
then turns the key and it wont start just cranks, so he called me i hope that the valves didnt get bent or that the cam isnt in some way damaged .
the car is a USA 928 1982 5 speed
Owner told me he was driving and heard a clunk then the engine dies so he coasts to a stop in front of his house,
then turns the key and it wont start just cranks, so he called me i hope that the valves didnt get bent or that the cam isnt in some way damaged .
the car is a USA 928 1982 5 speed
08-01-2010, 08:29 PM
#9
Nordschleife Master
Valves should be fine.
Normally it is the 5-8 bank cam that fails.
It could be either the gear or the cam from that picture.
I have thrown out a number of early gears as I have seen hairline cracks.
Normally it is the 5-8 bank cam that fails.
It could be either the gear or the cam from that picture.
I have thrown out a number of early gears as I have seen hairline cracks.
08-01-2010, 08:49 PM
#10
Former Sponsor
Wow.
You'd have to think that something came loose...like the cam bolt. The gear will then "worK' on the end of the cam, until it wears down the key/key groove until there is enough play to allow enough inertia to split the cam gear.
Makes sense it cranks and won't catch. Stock '82 should not have valves and pistons touch. 1982 cams have pretty low lift, with the same valve reliefs.
You'd have to think that something came loose...like the cam bolt. The gear will then "worK' on the end of the cam, until it wears down the key/key groove until there is enough play to allow enough inertia to split the cam gear.
Makes sense it cranks and won't catch. Stock '82 should not have valves and pistons touch. 1982 cams have pretty low lift, with the same valve reliefs.
08-01-2010, 09:00 PM
#11
Team Owner
Thread Starter
Car got towed over to the shop,
got the cover and gear off (well the gear fell out rather),
the cam is toast, about a 1 1/2 years ago I worked on this car and checked the belt tension put a torque wrench on the cam bolt to see if was tight and it was 47ft/lb IIRC
I didnt notice any other weird things anyway the pulley looks like it was cracked for a while as one side is polished where the crack was.
note this is a HTD pulley and the teeth are quite worn.
I didnt swap out the pulleys this was done in 1994
got the cover and gear off (well the gear fell out rather),
the cam is toast, about a 1 1/2 years ago I worked on this car and checked the belt tension put a torque wrench on the cam bolt to see if was tight and it was 47ft/lb IIRC
I didnt notice any other weird things anyway the pulley looks like it was cracked for a while as one side is polished where the crack was.
note this is a HTD pulley and the teeth are quite worn.
I didnt swap out the pulleys this was done in 1994
08-01-2010, 09:48 PM
#12
Shameful Thread Killer
Rennlist Member
Rennlist Member
Cam gears are cast. A few minor casting defects, and bam, that's it. It's rare, but happens some times. Cam breakage is completely different failure mode.
08-01-2010, 10:12 PM
#14
Inventor
Rennlist Member
Rennlist Member
What are those two washers doing there?
