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Need advice on re-build of a rebuild

Books are dangerous! Especially Wayne's book...


Hi everyone, I've decided to change forum for a while while I get my hands dirty instead of dusty lungs.

Here's the story, or what I know of it: Car was purchased two years ago in a very sorry body shape, but with an engine that had been rebuilt, according to what the garage that sold the car had been told by the PO. True enough, the engine had a nice-looking red fan, new bolts, and dabs of yellow paint on the studs to mark where they had been tightened. The engine had obviously run after the rebuilt, judging from the oil and presence of carbon deposits on the intake manifolds and spark plugs.

So what to do? I originally intended to start up the engine on a stand to see if/how it ran, and then decide what to do. Then, I decided not to take the chance of a loose/worn something and though about opening up the engine to see if everything was ok. What if only the top end had been rebuilt? Maybe someone just changed a few bolts to up the value? Too much reading of Wayne's book tipped the scale, so there I went. Also, the engine was a bit grimy with dust and debris, and who knows if some didn't get inside to further solidify the old oil and fuel...

Before I show the details, here is what I found and a few questions as to what I should do/replace. Basically, I would welcome advice like: "yes, that looks brand new" or "no, it's best to replace it", or even, "look: they forgot to..."

-Clutch plate is brand new, doesn't seem to have seen a single Km.
-the engine has been completely taken appart, and the pump upgraded to the 84-89 model pump (911.107.105.1R), oil bypass is done
-All joints looked new as I took them off, and no signs of missing bolts or washers. Blue o-rings on through-case studs along with some RTV.
-The cylinders are stamped, 9/71, which fits for a 72 Targa delivered in january of '72.
-No scoring on inside of cylinders, a small lip on top indicating some wear. Cylinders still have cross-hatch pattern, but not everywhere.
- Absolutely no wear signs on rockers (reground?), cams look perfect except one spot (see below) and wear marks on end.
-The main journals are still dull, I guess they are new? If so, should I also take appart the rods and inspect the rod bearings?
-No sign of any damage or scoring on the crankshaft

My current idea is to completely clean it through and through, and then reassemble it with new gaskets and fasteners. Then, do I also:
Change the piston rings?
Change the main bearings on the crankcase?
Remove the rods and change the rod bolts and rod bearings?

I can see how one can go overboard on this, and it does really look like the engine has had a total rebuild just before being delivered.

I'm thinking about the heads: The exhaust valves look totally new, the intake ones do not. I can test for leaks by seeing if they hold cleaner fluid, but I wonder if it wouldn't be best to have them taken appart and checked anyway. Opinion?

Ok, here goes the build, in time-laps mode!

The beast!

Scary, but it worked...

The clutch plate is brand new


but the right stacks saw some serious heat, like this thing's on FIRE!

MIF, at least it's the right model for the engine type...



Quickly checked that it wasn't frozen, and the little elves that turn the knobs are still at work, if a little slow

eventually, got all the top end stuff off:

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Old 01-08-2017, 05:38 AM
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Seriously?

So, on to the bottom. I should confess that this must be the most painless teardown ever: even the exhaust studs put up no fight and everything just came right off...




Got myself a long block...







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Old 01-08-2017, 05:45 AM
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The insides

Right, here are the ends;


Cracked it

it really is incredible... Plus the pump is recent.






So, any thoughts on what to do (or not do)? I marked everything accordingly, so I can put it back where it was with the same orientation if necessary. I'll take some measurements of the crankcase journals and piston ring clearances and report back.

Thanks for any comments or advice, and Happy New year!

Dario
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Old 01-08-2017, 05:54 AM
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2.4s

Nice 2.4S ENGINE.I would take the heads apart and make sure the valves were lapped in.Then put a head on a cylinder & do a leakdown test.Check the rings for end gap.Nice find.Fred
Old 01-08-2017, 05:56 AM
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Thanks!

I forgot to upload the camshaft with the small bruise:

And the end journal has a light score where the seal fits. I saw there are end-caps that can fix this, any feedback whether they work?



I also checked the pistons. They are marked

Mahle
E
84P11+

on the inside and are fitted with 1.5, 1.5, and 4.0 mm rings. Does this say anything to someone?
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Old 01-08-2017, 06:44 AM
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Safety concern.......

Quote:
Originally Posted by florio View Post
Books are dangerous! Especially Wayne's book...
..............

I'm thinking about the heads: The exhaust valves look totally new, the intake ones do not. I can test for leaks by seeing if they hold cleaner fluid, but I wonder if it wouldn't be best to have them taken appart and checked anyway. Opinion?


Scary, but it worked...




Florio,

Something caught my attention looking at some pictures of your set up. That piece of rope you used to hold the complete engine up in the air scares me a lot!!!! It is better to err on the side of caution than be sorry later. If I were you, I would use a chain or braided cable instead of a rope. The rope could break or snap while you are lifting the engine. I could visualize you standing close to the motor cranking the come-along hoist to lift the engine. Stay safe.

Tony
Old 01-08-2017, 06:49 AM
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Thanks Tony, you're very right to be concerned. I bought new rope rated for 900 lbs that is much stronger than the welded chain they had for sale nearby. I was a bit concerned by the wooden beam that could let go, but it held ok. Either way, I was keeping very clear of that lump of metal.

Along the list of things that surprised me is the amount of oil hidden in these engines! Practically every time you turn the engine, more comes out! I'm wondering if 911's weren't actually part of a german plan to have strategic oil reserves spread out all over the country...

Dario
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Old 01-08-2017, 12:18 PM
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update on pistons and cylinders

Ok, here's the latest: I guess the previous rebuild isn't to be fully trusted. When inspecting the cylinders, I noticed they have a definite ridge from the piston ring near the top. To me, this indicates that the the cylinders were not really machined correctly, Am I wrong?

I would hesitate to rebuild an engine and leave a ridge for the new oil rings to catch on, or not? Anyway, this engine has seen some miles or insufficient oil changes. Anybody with experience with a guess as to how many miles?

So I checked the ring gap top and bottom of the cylinder, and there is indeed a small taper on all cylinders. I had the worst one checked at the machine shop when I dropped all the metal off, and the cylinder was ok in one dimension (84.06), and tapered in the other (84.08 on bottom vs. 84.10 on top). Tolerance is 84.08, and I would guess that that this cylinder could still come out ok when measured 30mm from the top as the factory manual states. Still, the cylinder is somewhat oval.

Any thoughts or advice? I guess it's at the limit between getting reused as is and getting rebored and using larger pistons...

BTW, the machine shop will begin by deglazing them to restore the cross-hatching and reducing the ridge. more to come...
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Old 01-11-2017, 01:55 PM
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You need to trim the cylinder dividers for better cooling of the cylinders.
Bruce
Old 01-11-2017, 03:48 PM
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Thank you for the advice, can you or someone expand a little? I tried a search with engine dividers both here and in the technical forum, but nothing came up.
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Old 01-11-2017, 11:57 PM
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Quote:
Originally Posted by florio View Post
Thank you for the advice, can you or someone expand a little? I tried a search with engine dividers both here and in the technical forum, but nothing came up.
Porsche 911 Engine Tin Cooling Modification | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article
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Old 01-12-2017, 10:22 AM
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Duh! How could have I missed that! To think I even have the 101 book... I should put down the engine rebuilding one for a while.

Ok, so I also removed the rods from the crankshaft having decided that corners may have been cut during the previous rebuild. The bearings are new, and the crankshaft rod journals are all within spec and round. I just received the plastigage so I guess I will be checking clearances this weekend.

Here is the pulley end, with some apparent scoring from the sealing ring on the end of the no. 8 bearing. Any advice on what to do or whether this will leak like crazy?

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Old 01-12-2017, 11:57 AM
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Right, speed-sleeve it is...
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Old 01-13-2017, 12:17 AM
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how it went

Time for an update!
After inspection, it seems that the engine was taken appart possibly due to a failed tensioner as there were marks from a loose chain on one side of the case. The pump is a later one, so that much was improved. Some things were left half done: the oil relief plungers were the later type, but the oil bypass modification was not done. Also, the valve stems are worn.
The crankshaft checked out nicely, as did all the rods.


Unfortunately, the cylinders are at the limit: 0.1mm over for some of them, and a bit oval. As it turns out, this is a common problem with the biral cylinders... I was hoping to get away with a reaming, but had to bite the bullet after measuring and remeasuring...



After reading lots of the forum posts, the choice seemed to boil down to either bore them oversize and source larger pistons, or replace them with new ones. I wanted to stay stock, but did not want to take my chances with the internet lotto of cylinders. So I wrote to Henry Schmidt who was truly as helpful as everyone says he is. He suggested using a refurbished set that was coated with Nickasil, and he would trade with my old ones.
here is the info from Henry, which I think is worth sharing,
"If the pistons are truly good and improved performance is not a goal, what I would do is coat your existing cylinders with Nikasil.
It basically returns the bore to new+. I say plus because the Nikasil can be hones to a better finish than cast iron and the bore will out-last the standard bore 3 to 1."
The extra bonus is that the appearance will be the same, but the coating harder and stronger. The price was very good compared to anything else, and this is what I wanted to do. Unfortunately, I had to add in the shipping and customs charges, which made this very expensive.
After some searching in the motorcycle forums (where Nickasil re-coatings are common), I finally found a shop that did this in France. They also did Porsche engines for dealerships to treat the lockasil failure and seemed to know their trade. The idea was to bore the cylinders round again, then deposit a relatively thick layer of nickasil, and then bore them to the correct size. For info, it came to just under 1000 euros, which is well above what Henry was asking. Oh, well...

Here is the result!


I rechecked the measurements, and they were all spot on!



So, treated to new Mahle rings, time to get on with it

I love the way the flash makes the metal sparkle like new. I wish it was really as shiny as it looks, but it really is very clean! The only thing I did extra was to go over all the mating surfaces (case, heads, etc) with a wet stone and WD40.

While waiting for the cylinders, I cleaned up the fasteners and zinc plated them


Then, did a chromate conversion to recover the nice yellow color and protect the zinc! (side by side, two chrome and one zinc)
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Old 04-22-2017, 02:29 PM
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hey florio..... got any updates on this build???
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Old 10-23-2017, 01:16 PM
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reassembly

Right, yes!! I need to fill in what happened after... The heads came back from the machine shop cleaned and with new valves (intake and exhaust) and new seals (obviously). Somehow, the valve guides were ok, but the valve stems were worn. Of course, I would have preferred it the other way around once I saw the price of new valves, but that could have been what the PO had said and done.

Here is the rebuild process. First on went the rods. I lost a few days here since I over-tighten one of the bolts. It was new, but had had an extra half turn of the wrench by mistake. After nightmares of a broken bolt leading to a thrown rod, I ordered two new bolts and patiently waited.



Lower in the assembly


After lots of reading, I decided to go with the factory spec sealant and not worry too much. I figure if the seams are cleaned right (and they are), then it won't leak.


Close it, torque it up quickly in steps


And remember to breathe!


Everything was surgically clean and I used a trick from the lab, new aluminium foil, to keep grit away.


Unfortunately I lost the pictures of the refurbished heads. I was so excited to start the engine (fast forward), that I tossed the camera by mistake while cleaning up.

The only two mods I did were on the cooling baffles (see above) and to drill the oil bypass hole. I did this myself without drama.



Other side was the same, and here is the milestone picture everybody wants on their wall:
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Old 10-24-2017, 02:55 PM
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By this point, things were moving along as fast as I could find time to dive into the garage, great satisfaction to see something like this come together!

Chains and ramps went in, housing had been cleaned and detailed


Then check the valve timing. You really need the right tool here. The magnetic base works but it's a pain to set up and you have to be careful not to let the valve stem touch anything.





Then it's time for the ancillary components. The throttle bodies are dirty and will be disassembled and sent out for cleaning. The MFI pump was opened and cleaned of old oil, and the distributer taken appart and reassembled with new grease.




I just love this sight!


Time for a good clean up of the work space, and then the final stretch! Time also to give credit where it is due:


Now the chassis can find a new purpose other than holding up the spec sheet for the torque settings!
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Old 10-24-2017, 03:13 PM
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Then came a few overseas trips. I saw this in a fish restaurant in taipei. Cool ride or what!


Getting back to my night job, I installed the MFI pump


I got the throttle bodies reassembled. The linkages are not yellow anymore, but I'm assuming that this will not affect their performance...


All 6 injectors were sonicated at length and tested out fine on my home made pressure squirter. I used methanol as a gasoline substitue since it has about the same viscosity.






Almost there! I realise the coil and fan stick out. I'll do something about the coil (old one is toast), but I like the red fan
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Old 10-24-2017, 03:22 PM
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The end...

May 28, 7:39 pm. All good to go: engine on stand, oil lines connected, wire loom connected, battery is live, 1 gallon of gas ready to catch fire.

Of course, I took plenty of pictures as you will not see below. I do have a video of the engine running, though. I just had to figure out how to embed it here.

Everything was so exciting that I got carried away and didn't notice that the camera was (probably) in the large bag of plastic sheet tossed out :roll eyes:




Here is the video link, hope it works as well as the engine! The first time was incredible! After turning the engine to build up pressure, I flipped the switch and the CDI box started it's whine. Then the fuel pump, and cranked the engine. First nothing. Then a pop. Then another. Then it roared!

A few things you can see (and hear). There is a bit of popping from the intake. I figured out too late, started running out of gas-already- that adjusting the throttle linkages has a big effect. So, I guess all this needs adjusting properly. Also, the rpm control box rattles like all the transistors are loose inside. Still, the engine will not start without it at least being connected.


https://youtu.be/xQ4XsnzMCiE



This is actually the second run, but it won't be the last!. I'm thinking that maybe I'll do a little tuning of the throttle bodies before installing it in the car. Much easier like this.

Oil leaks? A couple: oil seal on the flywheel side moved, I will replace it. A small one from one of the through case bolt (I have to check) remote from the cylinders. I guess the oil ring moved on assembly. When I took out the oil, no metal bits but a lot of goo from the sealing compound. Hope it all came out.


Thanks to everyone for their help and support, and also for just following along. It's nice to know you're not alone, especially those times when you get that sinking feeling in your stomach
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Last edited by florio; 10-24-2017 at 04:00 PM..
Old 10-24-2017, 03:53 PM
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Nice work and well documanted. Congratulations!

I am literally a few steps away from completing my 2.7 rebuild and I have both excitement and a bunch of nerves at the thought of the first start up.

A few things holding me back is money and time at the moment. I'm not in a hurry as the weather is slowly changing here in the German Eifel region, but it is approaching 12 months since I pulled the engine out of the car and I would love to have it back in before Xmas.

If it starts and runs as effortlessly as yours then I will be very happy.

Cheers,
Jason.
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