crankshaft repair 996 3.4l

[tjonesmn]

the rod on piston 5 is loose (has play).

After opening the bearing case and removing the rod I noticed it was installed without a bearing.

There is still a small amount of play when I use an undamaged rod and new bearing as the crankshaft is worn slightly on the piston 5 connection.

Is this something that can be fixed?

Is there a certain amount of tolerance that is acceptable?

thank you.

[DRACO A5OG]

WTF? no bearing, really?

What does it measure out to? Yes, there is minimum wear tolerances, you may need to mix and match standard to thicker bearings to make sure.

Wow, I wodner who did the prior build, wow.

[tjonesmn]

Originally Posted by DRACO A5OG

WTF? no bearing, really?

What does it measure out to? Yes, there is minimum wear tolerances, you may need to mix and match standard to thicker bearings to make sure.

Wow, I wodner who did the prior build, wow.

I could not really believe it either. I need a digital micrometer to get an accurate reading (or a lease a higher resolution mechanical micrometer). thank you. I will try and post the diameter once I have it.

[boosted79]

I would be surprised if that rod journal is usable w/o a grind. It must have made a nice noise. I can't believe the crap some people are capable of.

[Tippy]

The bearing was more than likely there, it simply wore down until it was paper thin liberating from the journal.

Seen this many times on other makes.

[Mark Henry]

^^^ this would be my guess, the only oversize ID bearing is about $750 set, PM me and I can tell you where to get them.

But first thing is get the crank magnifluxed, then see if it can even be reground. If it has a burnt journal I personally won't use it.

The rods can not be resized on the big end as Porsche used cracked rods on the 996.

My bet is you will be on the hunt for a good used crank and rods. Not an easy (or cheap) search.
Other option is to find a used running engine or if you're sitting down our host sell reman engines.

[Jeff Alton]

I think the jury is out on repairing 996 cranks. We source good used in spec ones. EBS recently sent us a 3.4 crank, so it should not be too hard to find.

Cheers

[prschmn]

I wasn't even aware that undersized bearings were now available but--
I just did a rebuild and spent $1400 for a good used crank.
But have it Magd for sure

[Mark Henry]

The problem with grinding to .010 under is on the 996 crank is I heard the harden depth is very thin, so likely you would have to have the crank green ground slightly oversize, have it hardened and then finish ground to size. Then I'd have it nitrated.
All that work, plus the huge cost of the bearings, you are likely getting to the same cost as finding a good std crank.

I have to say I haven't done this, checked the quality of these bearings (aftermarket) and
this is 3rd party info on the crank hardness issues.

I've also talked to my crank grinder about welding cranks, he said he can do it, but it comes with a two part guarantee.
If it breaks you get two parts.

[JFairman]

you can make a heavy lamp out of it.