Jacob's rebuild thread

[e170drvr]

Jacob,
Lookin good! I plan to start mine next month. Just going to enjoy her a little longer before I tear it apart. My rebuild is based on high milage. Have you decided who will do the machine work yet? And have you come up with a ballpark budget for all this? I have not yet researched the machine shop expense yet. Good luck! I should be right behind you with a similar build.

Eric

[jwasbury]

Originally Posted by e170drvr

Jacob,
Lookin good! I plan to start mine next month. Just going to enjoy her a little longer before I tear it apart. My rebuild is based on high milage. Have you decided who will do the machine work yet? And have you come up with a ballpark budget for all this? I have not yet researched the machine shop expense yet. Good luck! I should be right behind you with a similar build.

Eric

Budget? What's that? I don't have a firm number figured out, but I expect its going to come in at 10-15k. Some possible choices that will push it to the higher end of this spectrum will be if I bite the bullet and do twin plug ignition (I'm going to have the heads prepped no matter what, so why not just go all the way...hello slippery slope!)

for head work, I'm planning to use Anchor Atlantic. This guy is in my home state of jerzee and comes highly recommended http://www.anchoratlantic.com/aaenter.html

For other machine work, I was looking into another jerzee place: Verden Tool & Manufacturing...they seem to be highly recommended in my area.

I still need to look into cams

[9dreizig]

Originally Posted by juicersr

Great work Jake. Taking apart your motor is a fascinating journey into it's inner workings and a truly great learning experience.

Keep the pix coming.

Pretty cool coming from a surgeon!! LOL,, dude did I miss you on your west coast trip??

[krasuskyp]

Originally Posted by juicersr

Great work Jake. Taking apart your motor is a fascinating journey into it's inner workings and a truly great learning experience.

Keep the pix coming.

...'twas thinking the same!

I hope to someday grow sac enough to endeavor. Fear (respect!) me Fecal Touch for time being.

Just feel that dropping the motor on your 930 is just some sorta carazy Right of Passage one that I must Heed To.

Rock on Jacob.

[IDGAF27]

If you need some help, let me know.... I can wrench, can do nothing, can consume beer while you wrench........................etc.

[Ed_]

Alright, since I seem to be unable to get my ass over to your garage as often as I'd like, I've had to resort to subscribing to this thread, instead. Pitiful, I know.

[jwasbury]

The "engine room"



Top looks reasonably clean:



Bottom:



Most of the exhaust ports look like this...whitish soot. I think this is normal.



#2 looks slimey...valve guide bad maybe?



Stowed away for the next round of wrenching:

[mark '87 930]

subscribed. I plan to do the same in the next year or so. I need to save my cashola though. Great job thus far, and like you, I plan on doing much myself. It's as much fun as driving it i find.

[jwasbury]

Yesterday I got in pretty deep. Found some things I expected (like the cause of my bad leakdown # on 6), and had a surprise or two. The biggest surprise is that the top-end has been apart before. I found cylinder numbers etched on the pistons. I'm not sure why it was apart before...my guess is broken studs sometime in the past. Currently all the studs are good, but they are the factory spec dilavar's (and will be replaced with ARP).

Chain housings, heads and cam towers were removed revealing the following view:



My car has the old style idler arms. Both arms are showing signs of wear inside the pivot bore. The left side was the worst, and the idler arm was actually binding on the pivot shaft. You can see the nasty wear on the shaft in the next picture. I'll ask the machine shop about polishing this out, or else I'll be looking for a new left side chain housing. The new style idler arms will be on the new parts list for sure.



Pulled the cylinders off, to reveal the shortblock:



Exhibit A - #6 piston. This was the one cylinder with 44% leakdown. I expected to see the "48 piece ring kit" here, but only found two cracks as shown in the next photo. I also noticed that the ring gaps were aligned. Look how much crud has accumulated between the top ring and the top of the piston. I suppose this is due to oil passing by the rings and burning in the combustion chamber.



Exhibit B - A closer inspection of #6 piston reveals the real reason behind the poor leakdown. Look at the top ring gap in the next photo. Its HUGE. I'm thinking that this piston got so hot at some point that it deformed. I also found that the 2nd ring was stuck in the land and would not rotate. Ugh!



Exhibit C - #5 piston also had a broken ring...only a few pieces though. Compare this to the previous photo and you can better appreciate the crud build up on #6. This cylinder showed about 10% leakdown. The 2nd worst of the bunch.



Exhibit D - #2 piston. Here at long last is the "48 piece ring pack." As I look back at my notes, I do see that #2 showed 6% leakdown, and was the 3rd worst. The other three cylinders were 2%-4%. So that cylinder #2 had the most badly shattered ring is surprising to me.



And another shot of the #2 piston and ring pieces:



Next up: splitting the case. Hopefully the crank is in good shape.

[onboost]

J.Was...

Nice group of photos man.. looks like it was time. You will enjoy the 100mm P/C's w/the bump in compression. I know. Again, good luck with the journey!

P-

[MikeD930]

Wow, how long were you driving with broken rings? You even participated in '09 TurboPalooza!?! You're an abuser! Joking. Imagine how much better and stronger your 930 will run with your build up. It's going to be worth it.

[jwasbury]

Originally Posted by MikeD94

Wow, how long were you driving with broken rings? You even participated in '09 TurboPalooza!?! You're an abuser! Joking. Imagine how much better and stronger your 930 will run with your build up. It's going to be worth it.

I don't know how long its been driven like this. Its entirely possible that I bought the car with these issues. So I am indeed an abuser, but one who will repent by not cutting any corners in this rebuild.

What is amazing is how well the car ran. It was not a weakling, and idled very smooth and produced no visible smoke from the tailpipe under any conditions. I'd guess that there are a lot of us 930 guys running around with busted rings and no idea whatsoever that there is a problem. The worst cracked ring on #2 showed 6% leakdown. That's not a really bad number. It was also dead on even with the other good cylinders on the compression test.

I'm pretty excited to see what it will do once its set right again (with some nice mods to boot).

[JFairman]

Porsche rings would probably last longer if they made them from recycled glass.

I've been around cars a long time and have never seen this kind of broken shattered piston ring crap from any other car other than an extremely expensive porsche.
It's absolutely ridiculous.

[A930Rocket]

Looks like a lot of carbon build up on the pistons. I suppose that might be from blow by and then oil gets in there to create detonation, breaking the rings? Either way, as JF says, it amazing how many of our cars run with broken rings. I had the 96 piece ring kit myself when I rebuilt my engine.

[jwasbury]

Case splitting was the biggest PITA yet on my project. See this thread for details:

My case does not want to separate

Anyway, its apart now. Almost ready to make a trip to the machine shop now.

The first look at my innards:



Other case half. Really cool to see firsthand how the oil flows through this thing.



Staring down the bearing saddles...



The crank has a couple of journals that have me concerned...with a noticeable groove right where the oil holes are...I suppose this is a sign that some abrasive junk has been pumped through the oil system. It doesn't look really bad, but I'll let the machine shop make the call on this.

[9dreizig]

Jacob, congrates.. I know how lonely those late nights when nothing seems to be going well are.. What machining are you having done ?

[TibetanT]

Very good timing on the rebuild and a lucky thing too! My God, do you get the feeling that it may have been close to a REAL problem? Ha.

Just loving this thread and all the detailed pictures and great documentation of the process. Especially the superior investigative finding.
I really hope my "78 case splits easier than yours did...holy cow.

I think you can start your own "Porsche Special Tools" store with that yankee ingenuity you used to get this puppy apart.

Good luck and I won't say "have fun" because I know you are.

[jwasbury]

Originally Posted by 9dreizig

What machining are you having done ?

Other than the usual stuff?

Case spigots will be opened 2mm to allow for the 100mm cylinders (for a true 3.5 liters displacement). Since each case half will be precisely mounted in a fixture for that work, I will have them deck the case spigots as well. Heads will be machined for twinplug and the intake ports opened to 37mm. I'll have the manifold opened up to match the intake ports. I'm considering having the manifold extrude honed as well.

[konish]

Originally Posted by JFairman

Porsche rings would probably last longer if they made them from recycled glass.

I've been around cars a long time and have never seen this kind of broken shattered piston ring crap from any other car other than an extremely expensive porsche.
It's absolutely ridiculous.

Even on turbo cars? I see a lot of guys in the auto hobby shop here on base (Yokosuka Japan) with really high-strung Skylines, STi's, and Supras. From what I've witnessed if the car has anything wrong with fuel delivery or timing, you see the destroyed rings from time to time.

[sand_man]

Glad the the right half finally decided to divorce the left half! SHEEESH! Biatch!