930 crank case replacement needed!
 

Just got more bad news about my ever growing list of engine teardown discoveries. My car is a 1981 sc.

After removing 1,2 and 3 cylinder heads, it looks like the rebuild done in 1997 (I just bought this, my first Porsche) replaced the head studs but re-bored the threads crooked on a couple! Too much material missing adjacent to the cylinders too so a re-bore looks way too risky, in fact, one of the cylinders has a small perforation in its wall about 1" from top opening. The crooked studs were actually bent in order to fit the reinstalled heads! One of them is now pulled through completely.

Not exactly what I was hoping for when I finally pulled the trigger on a car like this, but that's what I got and I have to deal with it. Yes, I did a P.P.I by a reputable PCA mechanic too...

Question now for anyone out there is what should I do now? Used case? Used engine? two month bender?

I would really appreciate some insight. BTW, I am in So. Arizona...

Thanks all,
Bill

Bill,

I'm very sorry to hear of your misfortune here. Its tough to spot these issues in the average PPI due to time and customer budgetary constraints. I've seen this problem before and I simply cringe when seeing the result of "shade-tree mechaniking".

I think the best way forward here is to either source a GOOD used SC/Turbo case or perhaps a decent complete 3.0 core engine for parts and sell off what you won't need when the job is completed & running.

I'd postpone the bender until its all running well once again and give you good cause for celebration.

Thanks Steve,

The hard part will be sourcing either a "good" case or the engine I imagine. I am new to this forum as well as these cars so I am open to any and all suggestions as to how to go about this.

By the way.... care to cringe?http://forums.pelicanparts.com/uploa...1361341567.jpg

Ahh, hurts my eyes to see such a damage on otherwise good case.

I may be totally wrong here but wouldn't heli-coil or timesert work in this case? or is it too little meat there?

Thanks R.B..

While open to all second, third and fourth opinions, my mechanic is pretty adamant about your "not enough meat" assumption. I would love to be pleasantly surprised but I am not holding my breath.

Ok, my opinion was purely based on the fact that 2.7 mag cases have equally small amount of meat between head stud and spigot but case-savers, tim-serts really work on those and aluminium is stronger than magnesium.

http://i5.photobucket.com/albums/y17...x/DSC_0056.jpg

Can you TIG it and then have it drilled and tapped straight? Ollies is in Arizona, they might be able to give you a second opinion.

andy

You can see the area that "punched through" about an inch down in the cylinder "hole" . . . I, too, would look at getting that welded and machined (but Steve didn't mention that option so maybe it is not doable?) . . .

Like JimTweet, over in the 930 forum, would say: MFer, WTFer, SOB!!!!!!!!!!!!

Yes what about this steve? A combination of tig welding some additional material back and time cert or helicoil?

I didn't mention TIG welding (I've done that on rare, collectible cases such as RSR & 935) because the parent metal around the weld is changed and its not as reliable. I only do that for display engines such as the above. Remember, those are 1 million dollar cars with special cases that are NLA.

For anything you will USE, I'd strongly recommend getting another good used, unmolested case.

Thanks to all for responses. It really helps knowing there are folks out there who understand and want to help.

The tig thing was discussed and dismissed for the same reasons Steve pointed out. I want to restore and use this thing, then pass it on to another who will appreciate it... do NOT want to half-ass it once again (too much bad "car-ma" already... sorry).

I am still at a loss as to the best ways to seek out a good replacement case or even a core engine. Does anyone have any suggestions outside of this fine forum? PCA classifieds? Specialty machine shops?

Lastly, I know that the 911sc cases were changed slightly as the model ran it's course, mine is an 81 and the p/n's off the case (one side) reads 930.101.103.4R and the other is the same except a 104.4R. I understand this is simply a right and left side of case designation. I also understand that these same numbers can be seen on all sc cases throughout the years (78-83). My question: If they made changes to the cases, why did the p/n's stay the same? Should I look for a particular vintage case?

Thanks for sticking with me folks,
Bill

I'd start with the various Porsche dismantlers (aka junkyards). You could try "used Porsche parts" in a national search. You will find several who advertise in Panorama, the Porsche Club's magazine. Don't belong? Well, you should. Worth it. I don't know if Pano is available on line, at least to non-members. Any SC case will do fine. And you can post a want ad right here on Pelican on the for sale forum. Some of the guys who have a sort of sideline selling used parts read that.

Myself, I can't imagine why anyone would insert a 3.0 case. Unlike the magnesium cases, they don't need it. Maybe somehow threads were messed up removing the studs to replace them? But there you are.

I can't imagine a PPI catching this. Maybe if you used a borescope with a 90 degree mirror you might be able to examine these locations? But damaged studs and case spigots are simply not the kind of thing you expect on these motors. Leakdowns good, compression good, cams and rockers look good, all head studs are solid, what more can you expect?

Porsche 911 3 0 SC Engine Case Block | eBay

There are a few on there right now, and I see them pop up frequently here on the classifieds . All is not lost

Thanks FFR..

Saw that one yesterday. Want to do my best to find a good one this time.

What have you seen as far as pricing in your experience?

Bill

Thanks for the advice and insight Walt (as always).

I did just join the PCA, so maybe I will tap their resources as well. So far I am having some success finding some old cases out there but I am trying to be as careful as possible this time (pricing and condition) and want to do as best as I can to find a "good one". Once bitten....

Trouble is, how can I be sure I am buying a good one?

Cheers

I have a very different opinion.

Buy a good used 3L engine from an SC, and replace yours with it.
THen part out your engine to recover some of the cost.

Quick, and you are no worse than before. But if you are a stickler for the devil you know, then buy a used case, measure it out, clean it, line hone it, and put the guts back.

Thanks Yelcab..

Yes, a new motor is a possibility, but at what cost? how find a sound one?

Prevailing wisdom seems to be leaning toward the devil we know philosophy but in the end, a crap-shoot is the game being played. Plus, there is the "numbers matching" thing which may (or may not) come into play some day.

:confused:

I am dubious that numbers matching is ever going to mean much in the SC world. They are great cars, one of the best models ever (I have one, though it is a hermaphrodite which started as a 2.7, but is now full SC spec in all respects). But one which has been around the block many times is unlikely to fetch top $ 20 years from now, seems to me. Especially if you do what it was made to do - drive it, maybe autocross it, maybe DE it, and have a lot of fun.

And if your current damaged case has the requisite matching numbers, well you can keep it (won't fetch much as aluminum scrap), spend years talking with metalurgists about how best to repair it, and when you are getting the car into Amelia Island or Pebble Beach show condition, preparatory to Barrett-Jackson, you can build up an engine using the old case and on and on.

Some of the sellers of cases are people in the business and have reputations. Those with bad ones you can ferret out (check out MM if that comes your way). Those with good ones you can check, and they have something to protect. They can check the case out. Generally, it is believed that these cases, unless obviously damaged, should be fine. Are the bearing bores concentric and in spec? That's about all, really, because if they are, the case shouldn't be warped either.

You should be able to find a case which doesn't need line boring. If you do end up with one which does, you have Ollies nearby, and they can shave it and rebore to standard. You do not, repeat not, want to be dealing with oversize OD bearings - mucho dinero now, and when it is rebuilt again, and so on.

I hear you Walt, I would at least like to stay as original as possible if I have my druthers. You never know right?

Having said that, another member has offered to sell me a very nice 3.2 case that he states will work with all of my other engine parts (except the oil pump, which he can also provide.... its a turbo pump too, so better cooling as well?)

Any thoughts on this? I have been told that the end of the sc run (1983) saw the use of the 3.2 cases with the 3.0 motors before they updated the following year?

and the plot thickens....

:confused:

Porsche has a history of using what is on hand. So sometimes the last of a run gets parts from the start of a new run, as with the 3.0 cases. The dies were worn out, the new ones were made, the dimensions are all the same, so why not use the 3.2 style cases on the last 3.0s?

Some 1974 2.7S cars came with the earlier S aluminum front caipers. Guess they had a bunch of those left over in the parts bin, so why not and leave the cast iron A calipers for later?

I like the Turbo oil pump - have one in one of my race motors. But in another motor, one I purchased, there sits just the standard SC/3.2 pump. I spun that motor up even higher (8,200), and it never had a lick of an oil pressure issue despite two 964 coolers through which all that oil had to be pumped by the scavange side. So for a street motor the Turbo pump is overkill. In fact, it will cost you some HP by increasing parasitic drag. But not enough to worry about as a practical matter. If the case is already clearanced for it, and comes with it and the shorter connecting tube to attach it to the intermediate shaft, go for it.

With cases, it used to be that guys looked for the casting numbers. The ultimate 2.4/2.7 case was the 7R case, which had better reinforcement than its predecessors. But that isn't true with the SC and 3.2 cases. All equally stout. Besides, no one purchases a case by part number. That is, unless you purchase one through a dealer brand new (does Porsche still have a stock of NOS 3.2 cases?). The part number cannot be found on the case, as is the case with most parts. All you get is the casting number. And a stamped serial number and model number.

Agree with Walt on the above. The 3.0 and 3.2 cases have proven to be very stout and pretty much never need line/align boring thru the mains.

That ebay link above is by a guy here on the forums. His name is Ed Baus (edbaus username) and he is a stand up guy. He's not selling crap that other people are going to get screwed on.

I think if you've got the wherewithall (sp?) to rebuild the engine, then a replacement case will get you pointed in the right direction. WAY cheaper than a complete engine. Plus, you NEVER know what surprises lurk inside an alleged "good, used" engine that someone is selling. Even a reputable seller can only know so much about an engine he is selling secondhand.

Thanks Kevin,

The search continues. Walt mentioned Ollies nearby, I know there is an Ollies in AZ. but also one in California. Are they affiliated? The AZ Ollies is also a Porsche specialist Machine Shop...

Another photo showing the worst of the past machining damage....:mad:http://forums.pelicanparts.com/uploa...1361487527.jpg

I believe Ollie emigrated from CA to AZ. Their loss, your gain.

I just got off the phone with a guy who says that while 10 years ago the "aluminum cases never need align boring" rule was more or less correct, they have had 10 more years of use, some of them hard (as in racing) use. He believes he can tell if this is needed by looking at the wear patterns on the main bearings.

You might consider sending a used case you purchase - even from a trusted source like Ed Baus - to Ollies to have them measure it and tell you if anything needs to be done. If Ed has a good history of this case, and it came from a street car, and had never blown up, and sat on a shelf for 10 years as a bare case, and so on - maybe having it checked is overkill. Maybe any good machine shop could check, but it takes more than just a bore gauge, as you are not only checking the bearing bores for ovality, but are really checking to see that each bore is absolutely concentric with all the rest. A place like Ollies is used to doing just that on those cases.

Me, I think I'd skip that step. But that's just my Alfred E. Neuman side.

Alfred -

That's the first piece of good news I have heard since the first bolt was loosened (Ollies local that is).

I believe I will be hauling my heads, replacement case and anything else (crank shaft? rockers? etc.) over to Ollies once I find a case I can live with. Any suggestions of what other parts to have checked and/or machined, well, I am all ears. The last thing I want to do after going through what I have so far, is do it again. I will admit though, that if it wasn't for the $, this process would be almost a pleasure for an old engineer like me.

Who was it that said: "This is the most fun I ever had without actually having any"

Thanks as always Walt!

Doesn't hurt to have a crankshaft checked to be sure it is straight. Check the journals to see if you can still use standard ID bearings (I think maybe 1st under rod bearings are less expensive than stnadard these days? So having crank ground if it needs it maybe not all bad). Have journals polished. Have rods checked and resized if needed, plus wrist pin bushings checked and rebushed as needed. Rockers can be checked, resurfaced, and rebushed as needed. Have them check pistons (including ring grooves) and cylinders (ovality).

Not mentioned is the matter of the cylinder and piston type you have - the desireable Nikasil, or the less desireable Alusil. There is a whole evening's Pelican searching's worth to get an idea what that is all about.

I'd guess that most of the parts - crank, rods, pistons, flywheel, pressure plate - which need balancing are still reasonably in balance for a street motor, where you won't run it up over 6,250 or so (and that not often) because your optimum shift point won't be higher than that anyway.

But that is one of those while I am doing this things to ponder once you learn what you are spending and what the extras might cost.

Well..... here's a wrinkle..

I contacted the boys at Ollie's and sent along the same pictures I previously posted on this forum. They say that they have seen AND REPAIRED worse than that on MAGNESIUM cases!

While they will reserve final judgement until they have the case in their hands, they are quite optimistic that they can give me my case back as good or better than new. They also mentioned that if needed, they can re-drill the threads a couple of thousandths outside away from the cylinders and that once the studs are flexed a bit to clear the threads, the heads will slide on fine.

So... original case (devil I know) back for a few hundred bucks vs. continuing my search for a more expensive and potentially iffy replacement...... I am thinking of driving everything over to Ollie's next week unless someone can chime in here!

Thoughts?

Gee, and just when things were going so well....

so, in addition to the case repair/replace question (see previous post), I should now beware of the dreaded Alusil P&C's? Like the case, I was planning on taking them over to Ollie's for a check (honing?) before re-ringing. One of the rings was found to have a tear in it on inspection, and though my pre teardown leak downs showed all cylinders at 2% or lower, I thought it was prudent to replace them all.

I still have to verify that mine are Alusils (10 fins vs. 11 for Nikasils?), before I add this new fish to fry, but as I am finding out, luck is not exactly on my side so far!

Anyone?.... Bueller?

Contact me if you are considering a used SC crankcase.

I have several available.

Alusil vs Nikasil easy to differentiate. The Nikasils are magnetic on the inside surface. Not strongly, but demonstrably.

Alusils not. The Alusil pistons have some sort of ferrous coating, too, per what I have read, so perhaps the piston sides are magnetic? I've got some Alusil pistons in my basement, and maybe I'll check them.

If you had 2% leakdown, perhaps you just save $ and put them all back in as you found them. Perhaps replace just that one ring. As you have noted, one of the strategies for Alusils is to do just that. 2% is about as good as it gets.

I once had a mag case welded up. It has suffered a whole lot more damage (engine blowed up, as they say) than this little stuff on your case. Worked fine, though other issues caused me to replace it.

I know Ollies says it has been able to do extensive welding successfully on the early sand cast aluminum cases - they can even cut out a damaged section, and weld in a replacement harvested from a similar case which was damaged somewhere else (blowed up motors often have a slot from a spigot all the way up to the case parting line cut in by an errant connecting rod).

I have a sand cast case which was created by mating two unmatched case halves and doing suitable machining to make this work. It has a couple of places where some welding was done (nothing really dramatic, though) to repair miscellaneous damage. Worked fine for the previous owner as a 2.8 race motor, and has for me too.

I have no personal experience with welding the later style pressure cast aluminum cases. And claim no expertise with the effects of welding on aluminum, far less how important this might be in particular parts of a case (some must be more critical than others).

Crazy...

As adamant as Ollie's is about being able to fix my case (based on the photos only), there are those who are just as sure that it's a bad idea...

On the pistons, based solely on the leakdown numbers and NO smoke, I am leaning toward using what I have as long as Ollie's checks and gives the thumbs up on all tolerances. I will most likely replace only those rings that are damaged (so far just the one) and move on. Of course, I am only assuming (based on my current luck) that mine are A-loser-sil;) at this time. I may also entertain changing them if I can find a good used replacement Nikasil set (looking as we speak).

Also, while I imagine that true engine combustion is at higher pressure than a leakdown test produces, how is it that the bad ring did not reveal itself with my 2% numbers???

like I said, crazy..

Another indicator of cylinder/piston type is the name on the cylinders. Almost all Mahle are Nikasil. Only very rarely were there Alusil cylinders made by Mahle. So if your cyls don't say Mahle, they're definitely Alusil.

Also, you can have Alusil cylinders bored and plated to your desired spec with Nikasil.

But if you're planning on reusing your rings, you can just stick the pistons back in their respective cylinders and you're good to go. By the way, which ring do you have to replace? Is it one of the two upper compression rings or the lower oil control ring?

Agreed it's good to check the crank for straightness and see if it's still in spec. The bearings themselves can give you an indication of what kind of wear the crank has seen. But it's still prudent to check because, obviously, you never know what decisions the previous wrencher made. Often times the crank can just be flushed out with solvent and put back in as-is, so long as the journals look good and measure within spec.

Appreciate the response Kevin. Turns out my rings were fine after all... I misunderstood the info I received and it was only the seal between the head and spigot that was "torn". I am happy to play the fool on this one! :D

Now I am back to seriously considering running what I have, after all, the thing was re-ringed 35k miles ago and all cylinders are at 2% or less leakdowns.

I have the rockers and camshafts on my mind now. Pretty sloppy shaft/bushing interface and no record of any work being done on them with the previous re-build.
Faces look pretty good and the shafts also show little or no obvious wear.

I want to at least send them out for re-bushing. Is it also a must to re-face them and if so, re-face the cam lobes as well? Lastly, for any and all this work, who might out there recommend to do the work. Anyone out there with a core exchange program? what kind of pricing might I be looking at?

Thanks again for the interest and all of the great responses SmileWavy

Bill

Yes those cylinder shims are typically a discard item when you rebuild the engine. Often you'll have to adjust your shim thickness choice from what was original, if you had work done on the cylinder head surfaces. The shim thickness is what sets the final deck height.

I'd go with what you have if it was recently re-ringed and has good leakdown numbers. How were the compression numbers, if a compression test was done?

Rocker bushings seem to be an increasingly common wear item. Take a close look at the bushings inside the rocker to see if they're really worn. Shafts also help you determine wear by the fingernail test. If you can feel any ridges, they are worn. The wear spec on the shaft is VERY tight. So only the slightly worn shafts can be polished and re-used.

There are quite a few shops that do the rocker work in no particular order

Supertec (Henry Schmidt here on the forums)
Steve @ Rennsport Systems (Steve@Rennsport here on the forums)
John Dougherty at DR Camshafts (camgrinder here on the forums)
WebCam- webcamshafts.com
Elgin Cams-
Craig & Denny at G2 Performance (cgarr here on the forums)

Any time you rebush the rockers you must square up the rocker contact pad. Kicker is that reconditioned rockers are all nice & new, but your cams are not if you haven't reground them or bought new. So sometimes you're better off sticking with what you've got if the wear is not bad. Existing rockers and cams have worn-in and fit nicely with each other. That's why its advisable to keep your rockers labeled where they came from upon disassembly.

Great info. Kevin,

No compression test was done, just L.D.

With regard to the shafts you mention. I assume you are talking about the rocker shafts and not the cam shafts? I suppose I was considering the 180 degree turn technique as they seem in reasonable condition.... No?

As far as the Machinist you mentioned, I contacted John already. Seems like a good, qualified guy. I am committed to re-bushing and re-facing the rockers, and the decision I have to make now is should I get the cams done while I am at it. They look pretty good, but am I taking a risk? John believes that with my 9.3-1 comp. ratio, it is a worthwhile upgrade to move to a 964 profile. He also has a less aggressive profile as well. The car will be street (with a track wannabe personality), so I want a set-up that will be long-lived and reliable.

Thoughts?

Thanks allot for sticking with me here...

Bill

Flipping the rocker shafts is indeed acceptable practice! The shafts used to be cheap and was easier to just buy new vs. polish/recondition. Now the shafts are $20 each....

Well if you're going to do the rocker reconditioning, you should have your cams reground to have both working on each other's fresh surfaces. Just doing the rockers alone is similar to replacing chains w/out doing sprockets- accelerates wear on the new chains.

As long as you are doing a cam grind, yes the 964 is a worthwhile change. No ill effects with the 964 profile. It's a common modification that the tuners discovered works quite well years ago.

Thanks again Kevin,

964 it is. Already have the SSI's, B.B muffler, cat-delete tip and an Electromotive HPV-1 on the thing so.....

Just had a sit down with the Machine shop on my heads. While he will measure everything out, he thinks they look pretty good (they were re-done 35k mi ago).
The mystery on them is that there seemed to be a bit much build-up which would seem to indicate an oil-burner. This was not the case while it was running although several of the exhaust valve seals were "torn" as opposed to dis-integrated. The guides look just a bit long, but upon measuring, do not look to be the culprit as far as interfering with the seals. Springs look good too but will be tested.

Current theory on the ripped seals is that they were not properly fitted when installed during last head job and got banged around at first? Anyway, this may or may not explain the excess oil buildup around the valve seats. I guess we will know more once the heads are disassembled and measured.

Speaking of valve seals... I am being told that I should look for the Viton seals instead of the teflon type????

Much appreciated,
Bill

What color are the valve stem seals? The white are teflon and some have said they seal too well and don't allow lubrication of the guide. Also seem to be a bit harder to install. So that may be why yours are damaged- faulty install method.

The Viton ones seem to be the preferred type. Do a search and you'll see varying experiences

http://forums.pelicanparts.com/911-engine-rebuilding-forum/528811-valve-stem-seal-teflon-og-rubber-viton.html

Show us a picture of the oil buildup. Could be valve guide leakage or could be carbon buildup. Carbon buildup is fuel related and often occurs on engines that are "babied." Need to keep port velocities up and blow that stuff out. Engines that are rarely taken to high rpms often have a considerable amount of carbon on the exhaust valves. That said, often times the super duper carbon buildup in the exhaust guide(s) is a combo of valve guide leakage and fuel.

So that's what they mean by "spirited" driving ehh?

Heads are at Machine shop right now for disassembley and measuring. The seals are the white teflons. I have read more than my feeble mind can handle on the teflon/viton debate but it does seem that the prevailing wisdom out there (as well as my machinist) is that Viton is preferred these days.

I am posting the photos I have at this time that might give you an indication of the buildup issue. The fuel theory is interesting.... I know that the car had an un-diagnosed blown airbox and had been running quite rich for a while before we got in there so there's that too...

Not sure if things are clear enough but here goes -
http://forums.pelicanparts.com/uploa...1362000622.jpg
http://forums.pelicanparts.com/uploa...1362000665.jpg
http://forums.pelicanparts.com/uploa...1362000719.jpg

How do the exhaust valves look on the inside as they currently sit in the head's exhaust port (where you bolt on the heat exchanger)? That's where a lot of carbon buildup occurs- on the end of the valve guide sticking into the exhaust port.

I recently got a set of pistons and cylinders from an '85 3.2 that were said to have only 16K miles on it. 16K seemed reasonable based on how nice the cylinders looked. But I was surprised how much carbon was on the piston tops. Also found that at some point early in the carbon buildup process that someone slightly over-revved the engine because the pistons all had tiny little smiles on them where the exhaust valves had contacted the pistons....... :mad: But nothing a little bit of grinding and mirror polishing couldn't fix.

They actually looked quite nice, clean and shiny (at least on the ones we looked at yesterday).

So by the photos, does this look like carbon buildup (fuel) as opposed to oil?

Also, as I am considering re-using my P&C's as they are, am I foolish not to clean all that crap up and if so, how best do it. Everyone warns about messing with the Alusils once they seat :confused:

By the way.... you want to part with those 3.2's ? :)