Attempted leak fix on 3.6 ends in disaster - need comlete teardown. ARGH !&#$@#
 

My #8 nose bearing was leaking a bit for quite some time. Nothing wild but more of a nuisance. At some point I picked up one of these kits where a machined ring gets epoxied to the case flange in an attempt to stop the leak. Since it's less than 100$ I thought I'd give it a try. This weekend engine and transmission came out to fix the 915, perfect opportunity to install the leak-fix kit.

The harmonic balancer has to come off the crank and we used the center bolt from a standard steering wheel puller. It threads right into the balancer to push it off. Unfortunately it doesn't reach far enough into the threaded part of the crank to exert pressure. So either a small socket or something of that nature as a spacer to make it work, right.

Instead of a small socket we picked a random 20mm M4 Allen bolt and put it thread-first into the center before threading in the steering wheel puller bolt. And that turned out to be a fatal mistake. Once the impact wrench had its way the balancer didn't pop right off. When we took the large puller bolt out the small Allan bolt seemed to have punched a hole into the crank. Oh SH|T. Well not quite but it found its way into the oil galley bore and pushed the aluminum plug ~20mm into the bore. We got the small bolt out but at that point we sensed doom. With digital calipers we checked on another crank and quickly confirmed the plug went so far in that it exposed the first cross-drill for the #8 bearing supply. We tried to get a small hole drilled into the plug to try and pull it out but in the process it disappeared even further into the bore beyond reach. GAME OVER

The engine has to be torn down for the crank to come out. It needs to have all oil galleys opened and cleaned out. On a high note I will end up with a fresh motor when this is all done. And I can fix the leak properly....

Dang!!!! Goood luck man

That sucks!!!

But like you said you will end up with a fresh motor.

Bloody hell. Thanks for nutting up to take the public hit; maybe some poor batard will learn from your pain.

A horrible lesson but one that WE can all benefit from. Thank you for sharing this episode and wish you a steady hand with what I'm sure will be a thorough and careful rebuild.

Ouch but if it's any consolation, kudos to you for sharing this with everyone.

holy moly. sounds like you have the technology, you can rebuild it. better, faster, stronger...


keep the camera shooting on this and the tranny. i have a similar set up and hope i don't need this info any time soon but i'll be glad to observe/learn for the future.

The transmission got done and is ready to go. I had to replace the early main shaft and put in the later style operating sleeves for added strength. See here: http://forums.pelicanparts.com/porsche-911-technical-forum/908427-today-day-much-needed-915-upgrades.html

The engine will come apart next week to swap another crank in. Painful but at least I then have piece of mind that main and rod bearings are good. When we did the rebuilt in 2003 we never split the case. We put ARP rod bolts and new rod bearings in. That is how I inherited the leaky #8. Stupid in hindsight.

It'll be interesting to see how the mains look (mileage unknown) and how the other stuff held up for the last ~50k.

Good luck. i shared different pains in my build, but i know the sting. The piece of mind later will be worth it.

Was it difficult to source a new crank? Would like to see a pic, if it's not too painful. I guess I was thinking these things were solid... :eek:

That is just hard to read. I cringed as the story unfolded. I wish you a speedy and perfect rebuild with no leaks at all and lots of HP and torque.

Ouch perhaps you can email the kit manufacturer to put that little warning in the instructions

Sorry to hear of your concerns. It's like doing a little plumbing at home. One thing leads to another.

On the rod bolts, how were you able to accomplish this?
Pull the rods out, put in new arp bolts, refurbished the rods, then reinstall them on crank in the case? Oh, how would you measure the crank- special tools?
I've thought about doing this in the past...just wondering. Thanks for your assistance.

Would this only be an issue on a 3.6, or are the earlier engines built the same way? I know there isn't a harmonic balancer, just the lower pulley to remove- same issue, or no sweat?

Sorry to hear about your "disaster," good luck.

When I read the words impact wrench I knew something bad was going to happen. I dont mean to sound like a Monday morning quarterback, but I would never under any circumstances use an impact wrench with a gear puller. I am almost certain that if you used the same bolt, but did it by hand it probably would have worked.

I think I will just put up with my leak, it isn't that bad.

BTW, the phooey word was heard in the OC and caused a rock slide. Good luck on the rebuild, Ingo. :D

That is exactly what we did. ARP recommends using a stretch gauge when tightening the rod bolds. That obviously isn't going to work unless you split the case. When we did it we actually not even reconditioned the rods or replaced bearings if memory serves. I was on a budget at the time and the "rebuilt" came as a surprise on what was promised to be a good used 3.6. However, it leaked like a sieve and all cylinders were out of round due to the leaks on top having caked up the cylinder cooling fins and preventing proper cooling, etc. In addition it was the old style 964 and the head to cylinder surfaces leaked.

We took one rod bolt at a time, replaced it with ARP and torqued to spec with assembly lube. That way I was able to save some money not doing the full case-split. The decision was made since oil pressure was healthy and no signs of poor maintenance on other wear surfaces. ARP was put in for additional piece of mind since stock 964 rod bolts are a known weak point and accumulate damage over time. Then at some point they let go.

I'm not an expert per-se but my assumption is on pre-3.6 you can use a traditional puller since the pulley is a solid piece. Just loosen the center bolt and push on it while pulling on the pulley. The reason you can't do this on 3.6 is the rubber isolator between inner pulley and outer mass.

Ingo

Nope, it wasn't the use of the impact wrench that spelled doom. It was the small bolt we used as a spacer. The correct way to do this is a special Porsche tool 9285/1/ It's essentially an M16 fine-pitch bolt with a 35mm long and 12mm diameter rod at the end. Our tool was an M16 bolt but the spacer was something we grabbed without thinking. Look at the stylized cross-section of the crank. The oil galley is about 6mm diameter and slightly off-center and at an angle. The small bolt went right in there and pushed the plug (red) some 20mm to the left past the cross-drilled passage for the oil feed. This blocks the oil feed to the crank's center bore. When we tried to get the plug out is went even further in.

The only difference between an impact and the factory method is that the factory method has you holding the pulley with another special tool (or lock the crank). With the impact wrench inertia is enough to exert the required force into the center bore. Without impact it would have been the exact same result. If we just had used a larger bolt for a spacer.....

Plug in correct position
http://ims.asuscomm.com:6000/pelican/crank.gif

Plug pushed into the galley bore - BAD
http://ims.asuscomm.com:6000/pelican/crank_bad.gif

Ingo,

I understand your pain but do you really need to replace the crank? Reason I ask is on account of what modifications i've seen to other cranks. My SC 70.4mm crank was cross-drilled by Marine crank. When David did the work, they also chose to remove all the plugs and replace them with set screws by tapping the plug holes. What I also found is he tapped the nose of the crank and the flywheel flange (in the dowel pin hole) with set screws as well. So it would appear that you could tap the snout of your crank to restore that location? I think Marine does this because it makes for easier cleaning by having the ends open to flush stuff out.

While you have it out, I would have the crank checked and if all is in order it wouldn't cost a bunch of money to have it cross drilled. Not saying it's a must-do. Just an increased oiling benefit to rod journals #2 and #5 since their oil supply comes from the ends of the crank.

Cross-drilling #2 and #5 and feeding them via the #4 main bearing location (you have to either groove the #4 bearing or the #4 main journal and enlarge the feed holes to ensure a path of lesser resistance into the crank here) provides a more direct path to those rods. In other words under normal circumstances #2 and #5 rods are the last to get oil & the cross-drill provides a more direct path.

Good luck with the fix.