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Rust is captured near the WP. I should have the heads off tonight. Then we will know why the crank turns less than a revolution in either direction. I am hoping for bent valves.
Pulled the heads and there are no bent valves after all. This is a very low mileage example from what I can tell. No visible wear on the cams. The bores are perfect. The underside of the cam cover looks brand new. The spark plug hole seals are as flexible as new ones I have on the shelf.
I believe the crank and cam(s) became out of time at time of impact. Through some twist of fate there was no enough inertia to drive the pistons into the valves.
I am no expert on this but if the valves are not bent I would surmise the accident causes the cams to jump timing after the crank stopped turning or vice versa.
What I need to do next is have the block welded.
Last edited by Kevin in Atlanta; 05-26-2017 at 07:35 PM.
I am no expert on this but if the valves are not bent I would surmise the accident causes the cams to jump timing after the crank stopped turning or vice versa.
What I need to do next is have the block welded.
Welding on the actual block sucks....very difficult.
Fortunately, what needs to be welded is the cradle. The cradle is made from a completely different aluminum material than the block section and welds adequately. (No German aluminum casting welds well.)
If done correctly. the warping can be kept to a minimum. However, it's going to warp no matter how it is done (or who does it) and this will have to be dealt with. You can usually have the cradle surfaced and then align bore the block back to a standard bearing size, if the warping is controlled.
By the time you are done with the welding, the surfacing, and the align boring, you might find that the repair simply isn't worth the cost and it might be cheaper to find another block. (Unless the engine is a GTS or something that needs to have matching numbers in a chassis, this is frequently the case.)
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Pull the plugs and put a borescope down the cylinders. For the go get hit so hard that the timing jumps, the damaged would be a lot more than the few chipped parts. Maybe someone dropped a bolt in there during engine removal.
Used it to repair the three broken pieces on the cradle. I used a bolt with the threads removed in the center of it and a bolt (pictured below next to the oil level sensor) to hold each broken piece in place of the course of two days while I built it up.
I am going to leave the alternator mount alone. Plenty of thread there.
I would make studs and JB weld them into the block it will be stronger than screwing bolts into the broken ends
NOTE fit check everything before you install the studs to verfiy they are long enough.
I dont see any way the timing jumped from an accident either in the timing belt or the timing chain.
The comment that the engine freezes up at a certain point leads me to believe the crank might be bent . check the flywheel for runout,
OR maybe you had a pin sticking out of the flywheel for the dealer timing sensor that was hitting your engine stand
Stan, I like the stud idea. I'd use loctite red rather than JB Weld in this situation. I'll check runout at the flywheel. I am not familiar with how the accident could bend the crank but I guess anything is possible.
JB welding the studs into the girdle will be much stronger than red loctite.
its a permanent repair
IE the studs will never have to be removed, I have done this a few times on stripped girdle bolts as long as you dont super torque the nuts the studs hold fine.
The drive shaft and TT can be bent by side forces to the chassis this force can be transferred to the crank. look carefully at the flange areas of the TT you might find a small bulge on one side
might help some to put a skinny nut on the new jb-welded stud into those holes with a little bit of torque on it to give it some more "bite" onto the block
if you did need to weld something you might contact Vitesse Racing in Atlanta who might be able to weld it for you or direct you to someone who can. they are big on the 944 side.
05-23-2017, 01:33 PM
