SC engine won't hand turn after cylinder install
 

Hi all,
odd question at least from me as I have never done this before. A friend who has torn down a few water cooled (997/Cayman) engines asked for my help reinstalling pistons and cylinders on a basket case 84 911.

I came in for an extra set of steady hands reinstalling cylinders/pistons and wrist pins. All went back together pretty easily. now engine will not hand turn past 45-90 degrees in either direction without a solid metal clink at the end of travel. we did run into this a bit on piston install but it was always the rod shoulders hitting the case because we had a hard time keeping unladen rods centered in the bore as we rotated the crank. We'd simply back off a dight, recenter the piston and continue. Now with all cylinder and piston on the crank has very limited rotational movement.

I'm sure there is something, hopefully simple, that he/we missed.

thx
https://youtube.com/watch?v=X1zLxdMbXv4&feature=shared

https://i.imgur.com/MjAsD95m.jpg
https://i.imgur.com/mb6LgsUm.jpg
https://i.imgur.com/vaSWiKgm.jpg
https://i.imgur.com/Is4neuVm.jpg

Are just the cylinders on, no heads bolted down?

I am no expert, but I would say your timing chains are getting kinked-up and not letting you turn the crank. Just a guess on my part.
Hope this helps. Good luck.

Yes, seems like a chain kink but they are free and clear. When cranks "hits" limit, very metallic clunk from below the crank but hard to source side to side. Just pistons and cylinders thankfully, no heads yet so no blockage at top of pistons

Yes, seems like a chain kink but they are free and clear. When cranks "hits" limit, very metallic clunk from below the crank but hard to source side to side. Just pistons and cylinders thankfully, no heads yet so no blockage at top of pistons

Was the case split during this rebuild?

You aren't binding up on the engine stand? BTDT
Alan

Case was split and engine was taken totally apart, and cleaned at machine shop. All new crank bearings and rod bearings, rings, seals, cylinder studs.

Original rods, pistons, cylinders, wrist pins as they were in great shape. Piston, rod, cylinder placement, triple marked, checked and as original. Engine is on a stand. Not sure how you get this far any other way?

Are timing chains hanging with sprockets on them? I would double check timing chains they can sometimes fool you and what your describing sounds exactly like a kinked up timing chain.

yes, hard to see in the picks but both sprockets hanging from chains and turning. Agree that it seems like a chain kink. But anyone whose done this or been around chain drive motorcycles knows the sound of a metal chain kinking on an alu or similar case. This is a hard metal clunk. Of course volume dependent on how hard you rotate the crank. If not solved may try to get a vid this week, though time in the shop is at a premium for a while.

+1 on timing chain(s) kinked on the inside part of the gear. Feels hard metallic when it happens. Might want to get a borescope tool in there and take a peek.

Not in your case, but aftermarket rods will hit the oil pump, necessitating grinding some clearance in the oil pump.

It will sound hard and be a very abrupt stop, nothing like a cycle chain on an aluminum crankcase cover.

Video after removing one bank of cylinders. So, if chain how can we confirm/fix?

https://youtube.com/watch?v=X1zLxdMbXv4&feature=shared

That video is so short and cuts off so soon it's difficult to analyze.

It looks like 2/5 journal jumps at the clunk. Need to watch this in slo-mo...

Edit: in slo-mo the #2 rod moves much more than the others and seems to coincide with the knock sound.

measure from the chain housing surface on the case to the same point on each sprocket and whichever is shorter, that's the bound up chain.

I appreciate it is short, but the crank only rotates ~45 degrees. Nothing to see before that, or after as it's stuck. I can say on the vid, all the rods you can see are free in the case, i.e., the shoulders are not catching on the inner case.

You have rod bolts installed upside down.

Cylinder one you have the rod bolt upside down, nut goes on top.

well spotted!

Wow, so apparently I misspoke when I said everything was put back together as original!
That makes all the sense in the world (not only because I was not on the tear down team!) as the interference was both seeming minimal and very metal on metal, and the rod bolt "keepers" did not seem to engage their reliefs as well as i thought they should. All are installed incorrectly!

If so a very straight forward fix. Much appreciated all!

https://i.imgur.com/adVvOdQm.jpg

Thanks to Dpmulvan for catching the bolts being installed upside down. Great catch. I'm the builder working with mike 491.

Connecting Rods Orientation…………
 

Stunistu,

Did you install the connection rods with stamped # all facing the same direction when all are hanging down on the crankshaft? Did you use stretch bolts? Thanks.

Tony

Yes, all numbers are in properly. I'm using ARP bolts.

Lucky you can re-use the rod bolts, not so lucky that the cases have to be split to correct the issue. I would look carefully at the rod bolts and mating rod surface to ensure no damage has been done to either.

It’s an easy mistake to make, most connecting rods have the nuts on the bottom.

The connecting rods should be resized when installing ARP bolts. If they were rebuilt without the ARP bolts, they should be. If the were resized with the errant install they should be resized.

Reinstalled new rod bolts in the correct orientation and reinstalled case half. All turns nicely and pistons and cylinder hopefully next weekend. You can see, we should have seen, how well the anti rotation ears on the bolts seat perfectly in the recesses when on the correct side! Also can see what I think are gouge marks (north/south in the middle of the picture) in the case where the rod nut scraped the case when improperly oriented.

Doh! But not too expensive a lesson.
https://i.imgur.com/LT10Irkm.png
https://i.imgur.com/ksfnnnpm.png

Take the engine all apart again and start over with the specs in hand. Have a good study of the Bentley repair manual, check all clearances, every bearing you've had off. If this was missed, what about the other details? Spend the time now not later.

To be fair, the engine doesn't really get much more "all apart again" than down to the bare crank.

:)

Did you really just reverse the rod bolts without resizing the big end? I think as Henry said, that is a mistake that could cost you a spun rod bearing early during the break in period.

While I did have my rods resized with the ARP bolts (because in my 40 years of doing this stuff that’s what you do), I do wonder how necessary it really is in the OP’s case. Is the marginally higher torque value of the ARP bolts (5 ftlbs, maybe?) going to distort the cap to such a degree that it might shorten the life of the bearing? I’m skeptical- but have no data to support that. And I have never gambled on my hunch for any of my 5 or so various engine rebuilds, so it’s not a strongly held one.