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I'm in a similar position to you, went through the pros and cons of welding, oversized bearings etc etc. My issue is with the thrust faces on the crankshaft. I'm approx 20 thou over, magnafluxed ok, polished and looked like new. But still seems like the consensus is to replace the crank. I think Jake Raby chimed in as much. I was tempted by welding etc, but shipping to California and reimporting is a PITA from Canada. (As I found out with my LN Nickies).
Eventually found a crankshaft available from these guys, their service has been very good so far. I paid $1200 US for the replacement plus shipping etc (to Canada).
Regards 3.4>3.6 as I understand the crankshaft dimensions are the same. Bore size went up for the extra capacity and switch over to cam drive for IMS rather than Chain.
I'd prefer to have this one ground/polised and refitted. Some of the related threads I looked at here are a few years old and I'm hoping things may have changed a bit for the positive in that time... Is it really true that oversized bearings are not available for these?
What's available isn't proven. It was haphazardly created, and thrown on the market without in depth evaluation.
In every instance where I have tried to regrind these cranks, I have experienced a compromise. The heat treat is not deep enough for the surface to be ground effectively.
Usually wear like what I see in these pics will also lead to a crankshaft that fails the magnaflux test for cracks.
For many years I've been working with this challenge. We've even fitted Chevrolet rod bearings to these engines, and tried to make others work as well. I have a couple of test engines still going with these, but to date the longest we've had positive results was 14,000 miles.
Thats about 10X less than I'd be willing to accept at minimum.
I had a similar failure. I spun number 1 and popped out my thrust washers.
I was lucky enough to find a partial motor that had suffered a cracked head. It yielded a good crank and some other parts I added to my rebuild or sold.
I struggled the whole time I had it apart with the "sell it immediately" mentality. You know what? At the end of the day it's just another motor. If you take your time and pay attention to the details it will run just fine. I have 1500 miles on my budget rebuild and my 996 is NOT FOR SALE.
My crank, block-halves, heads and all related short-block guts were delivered to Engine Lab of Tampa today, and a meaningful decision as to how we move forward will be made after the crank has been magnafluxed and measured.
The block halves were already in a tank getting cleaned up for a proper eval as we were on our way out the door. http://enginelaboftampa.com/
Schnell Gelb will appreciate that when we spoke about the availability and repairablity of cranks, the owner of the shop mentioned Marine Crankshaft in California as a resource. Apparently they have done business with them several times.
Feeling optimistic of good things to come, even if the crank is beyond use... Thanks to you all for your info and positive vibes!
I had my crank welded and regrinded in 2011, have done 57k miles after that.
So it can be done. Company that did the repair has good reputation for these kind of repairs.
That's a pretty good test of endurance for this repair, are you easy on the motor? or do you track the car / redline frequently? If you could mention the name of the shop I would be interested if they did any nitrideing or any other hardening procedure after the weld and regrind.
AFWIW if you have a 3.4 engine, the crank from a 2.7 or 3.2 from 2000-2003 Boxster will work as long as the IMS drive is the same, ie both dual row chain or both toothed chain.
Last edited by Porschetech3; 07-31-2017 at 08:14 PM.
Just passing on some hard-won knowledge.
As these engines age, we are going to have to pool our contacts to keep the best M96 repair shops in business.With Boxsters becoming so cheap ,they are getting a throw-away-when-broken reputation .That causes the best Indies and repair shops to look elsewhere for business. The "I bought it because it was as cheap as a Miata" guys will be the death knell of the older 2.5 Boxsters. So let's help keep the best guys in business.
Originally Posted by jaetee
My crank, block-halves, heads and all related short-block guts were delivered to Engine Lab of Tampa today, and a meaningful decision as to how we move forward will be made after the crank has been magnafluxed and measured.
The block halves were already in a tank getting cleaned up for a proper eval as we were on our way out the door. http://enginelaboftampa.com/
Schnell Gelb will appreciate that when we spoke about the availability and repairablity of cranks, the owner of the shop mentioned Marine Crankshaft in California as a resource. Apparently they have done business with them several times.
Feeling optimistic of good things to come, even if the crank is beyond use... Thanks to you all for your info and positive vibes!
If you want to weld, I'd highly recommend Shaftech. If you have one journal, about $750 plus you shipping to them. More journals, more cost. Crank will be checked, welded, ground, balanced, and nitrided. They do business for a reputable Porsche builder in CA and are used by one of he best machine shops in the DC area.
Do a search. The two places in CA have done good work, but there are complaints. If you are getting work done for yourself, a little different than through an engine builder that does lots of business with said shop. Everything is a gamble and there are a lot of opportunity for gotchas if you gamble wrong.
So..... I found out my crank had 0.002" of rollout, which basically means its bent. That explains the horrendous clearances that can be seen in the photo below. My engine must have been fighting itself with every RPM!
Due to this discovery, the rebuild shop I'm dealing with does not trust the old crankcase/basket either... Luckily, I was able to source a replacement crank & basket that came from the same car, with only 24k miles on it from QualityPorscheParts out of New Mexico. There's no visible pitting on the journal and the crank looks practically new. The pricing was very competitive and I've bought parts from them with much success in the past.
So, while those parts are en route, I'm awaiting rebuild quotes for either a standard build staying at 3.4L using the original pistons and just new rings, or a 3.6 rebuild that involves steel sleeves and new pistons. I know all about nickies and what a great reputation that product has, but they would push this build well beyond my budget and they are not an option for me at this point.
AFWIW if you have a 3.4 engine, the crank from a 2.7 or 3.2 from 2000-2003 Boxster will work as long as the IMS drive is the same, ie both dual row chain or both toothed chain.
I sold my Cabriolet on BaT back in March/April timeframe after the full engine-out refresh and 99k miles on it. I replaced that car with a 2000 Millennium Edition coupe with 90k.
This is an interesting example to justify why I let my Machinist deal with the crankshaft restorer(Marine Crankshaft in Santa Ana). That way the Machinist examines the work and he does lots of business with them.If I had gone direct and there was a problem ..... not good. This si a subject that requires huge amounts of skill and experience to be proficient and to develop a reputation in.Well worth the extra $ imho.
Originally Posted by jaetee
So..... I found out my crank had 0.002" of rollout, which basically means its bent. That explains the horrendous clearances that can be seen in the photo below. My engine must have been fighting itself with every RPM!
Due to this discovery, the rebuild shop I'm dealing with does not trust the old crankcase/basket either... Luckily, I was able to source a replacement crank & basket that came from the same car, with only 24k miles on it from QualityPorscheParts out of New Mexico. There's no visible pitting on the journal and the crank looks practically new. The pricing was very competitive and I've bought parts from them with much success in the past.
So, while those parts are en route, I'm awaiting rebuild quotes for either a standard build staying at 3.4L using the original pistons and just new rings, or a 3.6 rebuild that involves steel sleeves and new pistons. I know all about nickies and what a great reputation that product has, but they would push this build well beyond my budget and they are not an option for me at this point.
07-28-2017 | 12:18 PM
