3.0sc - split case or not?
 

Gentlemen,

Quick run down…I started out just wanting to clean up a 3.0 that is going into my 76s. After pulling the lower valve covers I discovered one barrel nut. Not Good.

Now I’m in deeper ($$$) than I want to go at this point. I wanted to save the money for the full rebuild on the 2.7 that is in the car now. I know things change – while you are in there do this and do that. So, I have a few questions and need your input on. Do I split the case and do a full rebuild on an engine that has 80K+ ran very good before pulling out of a 83sc?

I've pulled the camshaft housing/heads and all the cylinders look great.
I’m thinking that I’ll send them and the pistons into German Precision just for a second opinion with a good cleaning and what ever they suggest I do. I will be replacing all of the bottom studs with steel ones (?). Beside all of the other seals and gaskets, O rings, oil tubes, oil cooler ultrasonically cleaned, etc, etc... that go with rebuild any other suggestions?

Here are a couple pixs to see what I have;

http://forums.pelicanparts.com/uploa...1253157770.jpg

http://forums.pelicanparts.com/uploa...1253157847.jpg

http://forums.pelicanparts.com/uploa...1253157889.jpg

http://forums.pelicanparts.com/uploa...1253157956.jpg

http://forums.pelicanparts.com/uploa...1253158004.jpg

Thanks for the help,

I just split my 3.0 yesterday. All I had was one broken head stud to lead me to this point. I had gotten tired of contemplating if I should or shouldn't, so I figured With the Winter season approaching I might as well. This way I could check everything out, Reseal case, clean case ( in case I contaminated it upon tear down), Replace #eight o-ring and main and intermediate bearings.
Then my 3.0 ,107,000 mile engine shall be leak free.
Everything looks like new within the case except perhaps the intermediatee bearings.
The one frightening thing was hammering the case to split it. Think next time a block of wood is in order.

Anyhow, best of luck to you.

Leakproof.

I just split my 2.7 case because that seems to be the encouragement (and because I got some dirt/debri in the case during tear down - the engine was a complete dirty mess). Inside the bearings look smooth, the crank was within specs, etc. In hindsight, I wish I was better about keeping dirt out of the case and then I would not have split it. Split it can lead to another $600-$800 cost. Of course if you listen to everyone, that cost will go up to about $1,000 to $1,200. Just a thought.

Also,
I unfortunately or fortunately discovered I have Alusils. Two machinist told me within seconds without measuring, just to go ahead and re-ring without plateau honing, as discussed in great detail on this site. However the owner did mention to my surprise this type of honing to bring the silicon crystals back to the surface.
Also cleaned off all the carbon from the piston domes.
Had my heads completely re-done and had engine tin powder coated.
Also planning on having trans rebuilt.
Boy, did I get my self in deep on a perfectly running car. To late to turn back now. I am getting quite an education and a cool collection of tools.

Leakproof.

You can pull a rod bearing without splitting the case. See what it looks like, then decide if you want to go any further.

But there is a certain confidence in knowing what is inside the case and new sealant on the halves.
Bruce

its next to impossible to keep it clean for any period of time. i put a plastic bag over mine after removing the pistons, i was not going to split the case. i pulled the bag off to check something and found sand where the cylinders slide in. i thought at first about removing the sump pan and washing it out, but my porsche guru advised me to split the case and check everything and reuse if good, he did not know about the sand, but he too also mentioned how he hates to have one partially apart/toghter and sitting because of dirt.

Thanks for the reply
 

Leakproof – I’m sitting on the fence also with the winter coming up, what the heck is an extra $1500 at this point to split the case and put it all back together. Plus I think by splitting the case… with a block of wood, knowing once I had it back together everything is good for another 100,000+ that’s for Bruce (Thanks!). As for the tools – yes I’m collecting a good set to.

tadel001 – In the time I have everything apart I’m sure I’ll have some kind of foreign objects in there, thanks for the input.

BK911 – how difficult is pulling a rod bearing without splitting the case?

Thanks guys!

It's always tough to make these decisions, but with 80K miles, I wouldn't split the case. These motors are very strong. Opening it up will only take you in deeper money wise and in disassembly/reassembly time. Put it back together ASAP and use it. Ask the same question in this forum after another 100k miles are added.

That's sorta what I am thinking, as long as it was kept clean. Look in the cylinder hole. See the two nuts holding the rod together? Remove them and pull the rod apart. Check the bearings. If good, put 2 new rod bolts in and torque it back up. If no good, split the case.

KR8, It's funny, about a month ago I was asking the same question about removing the rod without splitting the case. Anyhow it takes about five minutes to remove a rod if that. Very simple indeed.

Spoke to a machinist today and he said splitting the case is the only way. In fact he's the second machinist to say this.

Definitely not trying to pursuad you either way. Theres really not that much left to disassemble, just more money, education and decisions once in.

I think I'm actually glad I did it. Kind of a relief in a way.

Leakproof.

I would say the decision to split is different for a 3.0 case than a 2.7. Aluminum vs magnesium I should say. For a 3.0 with a broken stud that otherwise runs ok, just fix the stud and go on for another 30-40K miles, and IF, no other problems are showing such as leaks, oil pumping and burning, knocking. Spend your money updating the chain tensioners. Now, if you are looking for a long, expensive, interesting project ... go ahead.

Still open but more on the side of not splitting
 

Thanks All, I've talked to a lot of porsche people in the last couple weeks; at this point everything looks good - no need to split. Even in Wayne's book he mentions that if nothing is wrong accept a broken head stud I should get another 100,000 additional miles or more out of the rings, cylinders and pistons. I'll send some pixs when I get back into it.

Alusil Cylinders
 

Need help, at this point I'm going to take my camshalf housings - head assembly for inspection and evaluation to German Precision. At the same time I would like to take my Alusil cylinders and pistons for the same thing plus cleaning. Again, I'm trying to stay away from splitting the case. In our host book he recommends not to pull the pistons out of the cylinders and do not dislodge or disturb the rings. OK how the heck do you do that?

Sure I can set the piston as high a possible - pull the cylinder up as high but not past the first ring to expose the outside wrist pin but how do you get the inside one? The next cylinder is in the way. Help??

You can't measure the pistons and rings if you don't remove them from the cylinders. Personally I would take them out and just keep the same pistons and rings with each cylinder. Mark them so you don't get them mixed up. If you use the old rings it will not matter that you've "disturbed" them. I suspect that with the miles you have they will measure up just fine. Whenever I've bought new rings they measure as bad or worse than the old rings.

The wrist pins will come out easier if you heat the pistons with a propane torch.

-Andy

3.0sc - split case or not? Alusil Cylinders
 

Hey Andy, thanks for the input. I'll get back to this next week, take a couple pixs for the page to keep it running. I'm sure I'll need more help down the road.

I couldn't remove my pistons & cylinders as a set either.
Those piston pins did not come out as easily, as Wayne said in his book.
After separating them I finally discovered (on my own) to heat the piston with my torch (I am a plumber) Not kidding, the pins basically fell out at that point.
Then I discovered in one of my books that it's S.O.P to always use heat when installing pins! What a shock.

Leakproof.

Also, I just finished removing all my rods from the crank and there are defiantly two rod bearings that are scratched and worn, glad I did this.
The crank also has some scratches to match where the worn rod bearings sat. Hopefully this can be ignored.
I was thinking of re-using my old rings too. A Friend is advising me against that.
A Porsche expert told me to pull the #5 rod at the very least, to inspect bearings, because this is the last one to receive oil,
And by the way, my main bearings looked perfect (to me) But was advised by P-people to replace anyway. Intermediate bearings understandably questionable.
Always happy to share info learned,

Leak Proof.

KR8,
It's always hard to know what to do with opinions pro and con. IMHO I'd balance out the amount of hours vs the money spent. I'm of the school where if you have the engine down to the point you do, it's wise to get it done from the crank out. You've put hours into it, invested. Split the case for saving time and money. My point is....you put it back together without the split, who's to say it won't do something unexpected just 100 miles down the road..... then you'll think to yourself...all that work I just did cutting corners and time just went down the drain....(40-50hrs depending on your expertise)...and now I have to do it twice another 50 hours or more. Bearings are not that much and the intermediate shaft bearings?...just a few dollars. Rebuild the engine completely and have the confidence of knowing what's in there while you are driving along and not fear the next stud bolt will come back to haunt you. In addition, the 2.7 gets a bad rap but is a good motor if done correctly, but moreso a 3.0 SC is notibly one of the more dependably built by porsche of the air cooled.
Rebuild it and have peace about it...not worry. Good luck to you bud.

German Precision
 

Thanks Guys, I dropped off my heads, piston, etc. at German Precision yesterday. Ted seems to be a great guy and really easy to talk to. After his initial inspection all's good. Once he has preformed a good cleaning he'll know more. He suggested that I do not touch the ring with the LS unless after cleaning something looks bad. I hope not things are starting to add up. I've order 12 new steal head studs through our host for the bottom row. I'll try to get started on this in the next couple weekends. I don't think I'll really have an issue with them except for the broken one.

I'll up load some pix the next time I chime in.

Later...

Much of the times the broken stud causes the head to warp and the sealing surfaces need to be flycut.
Bruce

I hate Dilavar
 

Thanks Bruce for the information. Got everything back from Ted all look good except for #5. It had some marks on the top of the cylinder. Here is the before pix.
http://forums.pelicanparts.com/uploa...1259028656.jpg

http://forums.pelicanparts.com/uploa...1259028742.jpg

I forgot to take an after pix, before I wrapped them up in a box for storage. I’ll get that out soon. A few marks but really not that bad and all ready to go.

http://forums.pelicanparts.com/uploa...1259028797.jpg


I started on the bottom row head studs with the Snap-On tool, really easy on the first six. No need to add heat or any power tools. #4 first stud and #5 first stud didn’t move so I passed. #6 first stud (the reason I went down this road broken came off with a pliers – simple. Went back to other two that didn’t come off and two weekends later they are off. Minus a couple tanks of gas – a whole lot of heat and couple new extraction tools. I’ve read so many threads about problem studs and what everyone has to go through - Now I know all about head studs.

http://forums.pelicanparts.com/uploa...1259028846.jpg

http://forums.pelicanparts.com/uploa...1259028879.jpg

I’ll start installing the 12 new steal studs in a couple weeks – holidays and travel are eating up my time.

Report back later, with pixs.

im in the same boat...broken head studs on my 78. 4 of them, to be exact. I also had a cylinder-head gasket disentigrate which kinda messed up the head but can be fixed at the machinist. I also found a broken piston,hairline- between the rings. Fortunately, I have MAHLE cylinders that are still in spec so im waiting on a new set of JE pistons to go along with the head work. thanks for posting, this looks oh-so-familiar ;)

Piston damage
 

Once I recieved my parts back from Ted it really showed more damage than I thought I had on the top of #5 piston. Question - should I clean (grind down) this up or just leave it?

http://forums.pelicanparts.com/uploa...1266200965.jpg

strange - looks like impressions of bolt threads on the piston - any ideas on what caused it?

No, I bought this engine last year off of a local P-Car guy. Yes, it must have been a small bolt and there is no sign of it anywhere now.

KR8

I'd take a feeler gauge to the top ring on that damaged piston. See if the bolt dented things enough to cause a pinched spot above the ring. If it did not, you could clean up the damage with a file or something similar. Your goal would be to remove any sharp edges and generally smooth things out, rather than to try to recreate an unbroken surface like the rest of the top of the piston. And do the same with the #5 cylinder head. I think I can see pecker marks in the combustion chamber in your photos.

If you worry about such things, you could rebalance your pistons. Buy a digital postal scale at an office supply store - maybe $30 or so, which will weigh 2.2 kg or so at a 1 gram resolution. Then use a die grinder to make them all match the one which is lightest.

An alternative would be to find a good used piston for the '78-9 motors. Should be plenty around, but be careful about Nikasil vs Alusil. You would want to try to get one in the same weight class, or one a bit heavier so you can balance it down.

I once had the machine screws which held Weber air horns shake loose and get swallowed. Did this kind of superficial damage. One of three pistons had to be replaced, the other two have worked fine for years thereafter (Mahle 10.3/1 race 90mms, hard to come by and expensive). One had ring groove damage. But surface irregularities soon get carboned over.

I would carefully inspect the #5 cylinder for scratches, though.

Sharp Edges
 

Walt,

Thanks for the info, and I'll check the weight and evaluate from there. The only damage on the cylinder wall is the small marks in the pix above.

Right - I later saw those scratch marks.

You might post that picture on the 911 engine rebuilding forum and see if any of the professional engine builders there think they are important. Me, for a budget rebuild, I'd be inclined to let them be if they don't stick out. Your finger nail ought to tell. But I can't say I have used something like that. My disaster didn't affect the cylinders.

Used but in spec cylinders can be found, but it is always nice to have things in pairs.

Weight the same on all six
 

Even the damaged piston weighs (392g with rings) the same as the rest. Maybe I could grind down the #5 just a small bit, weigh it again and if there is a big difference I could just take a little of the rest to match?

Consulting a spec book I find Porsche saying the maximum weight difference should be no more than 6 grams for 2.7 and 3.0 liter pistons. But you could lighten the #6 a shade to match (after weighing a smoothed off #5) and call it very good. This isn't an 8,000 rpm engine anyway, is it?

Weight?
 

Hey Walt,

My conversation was completely wrong, the pistons all weigh between 561.31g - 564.15g , these are with the rings. They are all within the 6g's of each other. You are correct this will not be running 8000 rpm just stock.