Re: Chain tensioner adjustment, turned in to major failure
Posted: Tue May 07, 2019 8:19 pm
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Stefan2000 wrote: ↑Sun Aug 19, 2018 10:11 pm Dan,
I was there by coincidence last Friday and they were just opening up your engine when i walked in. Really sad to see the damage that occured.
But what i heard from them and what i could conclude myself was well was the following.
The studs from the camshaft bearing caps are made of 5.6 grade steel. The torque spec. for the nuts that torque down these bearings are actually to high for a 5.6 grade steel stud. Therefore if you torque these bearing down to the specified torque these studs stretch up. I have seen and measured these studs at their facility and they really are stretched, all of them at every cilinderhead from every engine. You will notice that because the tread is stretched and the nut will not get on it without resistance. So what they do over there with every Dino cilinderhead is replace all the studs with 10.9 grade studs and special notched nuts that can not come loose.
What happened in this case is that one of the studs was so stretched that the nut came completely loose, it feel off at some point and ended up falling between the teeth of the drive gears for the camshafts. This damaged the gears and because of the high force needed to sqeeze that nut between the gear it also ruined the bearing from that shaft.
This got worse rapidly until it really broke down. Probably by tensioning the chain to try to get rid of some unwanted noised the forces on the gears and the broken bearing got even higher and death penalty was declared...
Well it's in good hands now. Keep us updated because this can be informative to everyone over here.