78 3.0 engine rebuild 2/11
 

I haven't posted a build for a while, I have 2 to do, been sitting in the garage all winter on stands so I could move them out of the way for other things.
The engine had a few defects that were purchased knowingly with the engine, just not knowing exactly the problems.
Bruce

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That's right man.. time to get busy! :D

Crankcase sealant cleaning.........
 

Bruce,

I'm also starting my 3.0 liter SC engine rebuild which is long overdue. I have a problem about getting the old crankcase sealant residue off the mating surfaces the PO used. What method would you recommend or suggest to get this hard and brittle residue off the crankcase. I've been scraping and cleaning the crankcase for 2 days in a row and still not near to completion. Thanks.

Tony

One trick I learned to clean up a sealing/mating surface is to use a small rectangular knife-sharping stone lubricated with WD-40. You can remove the old residue and clean up the surface with this method. You'll need to remove the oil residue, of course, before the new sealants are applied.

Dave

Getting everything clean is what about 80% of the time in a rebuild?

Well, the topend has been apart.
There is 24 993 dilivars in place, too expensive not to use.
The top was not torqued properly, very loose
The PO had dropped a tensioner on the left and wore a rail trail to the rear of the chain box.
One of the heads was date stamped different but is a proper big port euro so its a match.
The #5 has blowby between the cyl top and the head Head gasket in picture 3 shows what is and what should have been.
This engine hasnt run much since the top end redo but you can tell the heads were loose from the deposits on the new oil return tubes.

Bruce

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I was quite suprised as to how clean the inside the engine was, good oil and not letting it coke. Bearings are beautiful and original. The case through bolts have white O rings on them, original factory from the time, this thing has never been opened.
Bruce

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I pumped up the oil cooler since Friday, 75# for 4 days, will be good to go.
The case is de greased, doesnt look as good as it did wet but some stains are there to stay seeing they been there for 32 years.[img]
Bruce

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The first picture of the cooler didnt take
Trying again
Bruce

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Ill be getting everything together, the mains had lots of original standard spec, Im resealing the center case now that I can tell someone what I have for sale all the way to the bottom.
New chain rails and properly lining the chains, intermediae shaft bearings, return tubes, etc, check the heads at the shop, let the machinist decide what is perfect.
Bruce

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After noon it warmed up enough to get in the garage, 75 yesterday, 55 today..
I put the 2 halves together, got everything torqued and turning. New chain rails installed. The Yamabond looks rough until it seasons then can be cleaned up. The sealant works very well but it has to be applied to both sides of the centerline.
I took the fan system apart so I can get fan, housing and shroud cleaned up and on the shelf.
The time things take
Bruce

PP doesnt want to take my uploads right now so I ll post the pictures later.

Torco assembly lube?

Just some super slick to keep things rolling..
Bruce

Connecting rod orientation........
 

Bruce,

Is there a specific orientation of the connecting rods when installed. I tried to document my engine teardown but I missed this one. Looking at the pictures of my motor, the connecting rods for #1, #2 & #3 cylinders show the stamped number (face down when installed). The question is how are the other bank's con rods are oriented? Would con rod's stamped numbers for #4, #5 & #6 be facing upward when installed? I don't have a good history of this motor but obviously it had been overhauled prior to my purchase.
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How do you orient the connecting rods with respect to the crankshaft during installation. Thanks.

Tony

Tony, I ve already sealed this engine up. I have another crank open for the next build, anoother 78, I ll look to see how the factory did it.
I ve read a snipit on the numbers but I dont remember the high lights. I know I build it with the numbers up, the 6 rods pointing at me so I know the numbers match. That would be 3 up and 3 down. I ve done well over 200 motors and there hasnt been a problem.
Bruce

That's what I want to hear........
 

Bruce,

Thanks for the reply. I believe it was 3 down (for 1-2-3) and 3 up (for 4-5-6) but not certain. I've done a couple of top end rebuilds but this is my very first top/bottom project. Sharing your vast experience with us is priceless!!!!

Tony

I would think that it would not make a difference since the rods are symmetrical.

Agree!

rods are symmetrical and the only stipulation is that the numbers match-up when putting them together; both Wayne's book and factory manual information.

Of course, I am no expert, but I will share my findings with respect to number placement on my '78 3.0L crank as soon as I can get into my garage from all the snow we got. I haven't taken them off of the crank yet, since everything looked very good inside on a 120K mile engine. That way we will have another "factory" look at how things were done back then.SmileWavy

In this video, Nick Fulljames explains the preferred orientation of the rods on the crank

YouTube - 911 68 crankshaft assembly.wmv

Bruce - been fun watching you do the rebuild. Glad to know there was a lot of good left in that engine.

Tom, thanks for posting the link to this video!!

If I understand the thought process correctly, this would suggest that all the connecting rods have their respective (stamped) numbers facing one way, correct?


I also took notice that they did not use Red Loctite on the rod bolts to secure the nuts.

Do a You Tube search on "Nick Fulljames". There are about a dozen short clips describing the disassembly and rebuild of a '68 Mg case engine.

So, is it just so that you see which rod is which? Is there a reason the numbers have to be up?

Okay, I was able to get out into the garage today and check my 3.0L crankshaft. Here is what I have found:


All numbers stamped on the connecting rods are facing one way. I double checked the Bentley and it states that "all marked numbers should face exhaust side of engine."

Makes perfect sense when you think about the physics involved with the crankshaft moving in a clockwise rotation.

Hope this helps.

But if the rod is symmetrical, why does it matter?

The rod is actually not completely symmetrical. The non-symmetry comes in because of the bearing notches in the big end. The trick is to orient the rods so the the notches are on the end opposite the side load.

Thanks, I will accept that. I did not know they were asymmetrical.

Incidentally, I saw an Aluminum connecting rod cap from an engine AJ Foyt used at Indy. It was cracked in half and the crack clearly began at the stamped number "3" where there was a sharp edge on the top (straight line) of the 3. It was pretty shallow but stamped on the thinnest part of the cap, right on the bottom middle. You could see the fracture pattern pointing to the initial crack. Premature fatigue due to a stress concentration.

I think with the Porsche rods it is the bearing notches that are the stress risers. Orienting them on the non loaded side of the rod journal reduces the risk of rod failure.

Clarification.......
 

Tom,

Would you be kind enough to illustrate or demonstrate this with some show & tell (pictures)? I'm still a little bit lost in your explanation because of my unfamiliarity with 'bearing notches' and 'end opposite the side load'. Really appreciate your posts. Thanks.

Tony

Tony, I ll be at the shop tomorrow and get a couple pictures of the rods to answer your problem.
A few days ago PP wouldnt upload the pictures and now I found the patch cord to get the pictures loaded. The sealant seems excess but it requires application to both sides..but then I ve not had problems with center sealing.
Bruce

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Is this the Y- bond on the crankcase?
 

Bruce,

Is this the Y- bond (???) you mentioned to me one time? How many type of sealants do you use for your assembly? What happens to the excess sealant inside the crankcase? Could it peel off and get mixed with the internal oil? Just curious to know and learn from your engine rebuild successes (hundreds and counting). Thanks.

Tony

The Y-bond doesnt break off, its actually hard to peal off the outside..
I use three different sealants for the engine, aircraft permatex for the heads to cam carriers. 574 for the lower parts of the chain case and cam gaskets.

Now the rods
The chat was the numbers are embossed on the side with the bearing notches.
The pictures are 2.4/2.7 rods just randomly pulled out of a box, it appears the number stamp can be on either side of the rod, no correlation with the notches for the bearing.

Bruce
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The shroud came back from a weekend at the spa on Monday, looking good, thanks Gary. Thats not paint, thats clean,
Bruce

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awesome!...... i just took my 78' sc for its last drive before i start its motor over haul. thanks for the info

The engine is a 78 euro. I installed the .25 base gaskets so it will have the 8.7 CR that the engine calls for.
Put a couple hours on it, P/Cs installed and the cylinder tin, all the circlips accounted for...
Bruce

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Crankcase cleaning........
 

Bruce,

How do you clean the your crank case? I've been cleaning and brushing my crank case for many hours and it is not cleaned and bright as yours. Any particular method or cleaning solution you used? The parts are all here now and ready for assembly but my crank case needs some TLC. Thanks.

Tony

I have a Safty Kleen large sink and clean fluid, bunch of different brushes, AND the cases always look better in the pictures.
Bruce

I ve been walking and working around the engine for a while and the 4 cam carriers full of heads as I m doing another 4.0 at the same time. Its time to give the heads to the machinist
Mike, you were righ about the broken spring on #1 intake, here is a picture of the spring as I just pulled the head from the cam carrier. There was nt a substantial sealant between the heads and the carrier as noted in the picture.
The heads in the shop first thing in the morning.
Bruce

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Two questions for you Bruce:

1. How many miles were on these motors, specifically, the one that had never had the case opened that looked so good?
2. How did you get the engine shroud so clean?

Both of the engines I m doing right now have about 100K miles. I open the cases basically to reseal because I have rebuilt 100K engines, 3.0 and 3.2 and if the owner was standing next to me questioning why the old bearings look like the ones going in, there is no wear on the old bearings. I have seen 300K on the bottom and the bearings look great.
A friend said he would clean the shrouds and they came out near mint. I dont have the desire to stand and polish.

Bruce