Engine building notes and gratuitous pics

[dtw]

I've been prepping for this engine build for what seems like the entire year. Since I bought this car last December, I have been collecting parts for the "complete" engine that came with it and having machine work done. Now I've finally plunged into a rebuild, armed with the tools and advice of my experienced local wrench, Wayne's rebuild book, and the thousands of posts I've studied here.

First off -- let's talk about case cleaning. Wayne's estimate of case cleaning time is something like 2 or 3 hours in the book - let me just say this is way off base and completely wishful thinking. I'm calling you out Wayne! I actually spent the better part of 12 hours cleaning my case, and I was armed with all the right tools. Wire brushes of all types, scotch bright pads, compressed air, brake cleaner, acetone, kimwipes, you name it. Of particular note are the perimeter stud and through-bolt bores - the first time around on my case sealing attempt, these bit me on the ass. I had applied the orange goo and was mating the cases, when I noted fine dust and particulate settling in the goo. I had to tear everything apart and investigate. Fine scale in these bores had been dislodged by the studs, and required additional cleaning. I used some round brass bristle brushes that I found at a local gun shop. I would recommend trying the stainless steel variety - the brass bristles do indeed like to fall out of the brush easily. Second time was the charm, and the now-immaculate case halves went together fine. Here's a pic of a surgically clean case half:



Our next gratuitous pic is a trial fit of my intermediate shaft assembly with oil pump. As all three components (intermediate shaft, oil pump, and splined connecting pipe) came from three different engines, it seemed wise to check the fit. No problems.



Here's a shot of the case sealing process after the orange goop had been applied and the halves compressed. Though there were four hands working at this point, I made sure to lay out all parts, count all fasteners, and preset my torque wrenches before sealing. Note that I used Wayne's technique of installing through-bolt o-rings, which is with a shot of silicone sealant as a leak-guard. This didn't work for me. The silicone interfered with the seating of the o-rings, and many were crushed and squeezed out from under the bevel washers during the torque sequence. Maybe I applied too much silicone?? Anyway, I consulted with some other builders and picked up a new bag of o-rings, and installed them with a very light coat of motor oil. These all seated nicely.



This shot is kinda cool. It is a look inside the sump after the case sealing - you can even see squeezeout of the orange goop on the case innards. Everyone I talked to stressed the importance of checking the perimeter of the case for liberal, consistent, and unbroken squeezeout of the orange goo. No problems!



This engine is being built around 2.2T pistons with extra relief cut in by the machine shop to deal with Crane 288 cams and shaved heads. Here is the set of cylinders the machine shop was able to put together for me - most of the ones I supplied were no longer round! Also shown are the fresh pistons. I purchased new wrist pin clips from Porsche. Note that if you do the same, these clips require trimming in order to fit in the pistons. I removed ~3/8-7/16" inch from mine and they installed reasonably easily.



Next up is a shot of the pistons and jugs installed on the engine. This was a fiddly and difficult process for me as a first-timer. One thing I found myself doing during the build was relying somewhat blindly on what I had read or been told about a certain step or procedure- at these times I had to take the brain off auto-pilot and just think about what I was doing and everything seemed to fall right into place. As this engine is pretty heavily modified, I started with .5mm base gaskets instead of .25mm gaskets. This extension of the deck height should give me a better chance of properly clearancing my valves the first time around. The base gaskets really get in the way during the wrist pin installation - I'd recommend sticking them to the cylinder with a light coat of Curil T to keep them from getting underfoot.



Dry assembly of the top end for valve clearancing work is tedious in light of the fact that it all has to come apart again at least one more time- more if the clearancing fails. Two things have happened during the dry run that made me glad it was a dry run - I noticed one of the heads studs came loose and turned with the nut; it will have to be removed, inspected, and reinstalled with a fresh coat of thread locker. Also, my cam thrust washers are offset due to the head work; I was hoping I could get away with it due to the slop in the o-ring and the extra .25mm of shim I'm running. Dunno though, the offset is pretty noticeable here. I'm considering having them trimmed down 0.5-1.0mm. Here's a photo of the offset- any thoughts?



Lastly, enjoy a shot of the near-completed dry-run longblock. Sure fun to stare at...though I must say I'm looking forward to looking at the engine from underneath the car, and not on the stand.

[Pat S]

Very nice. When you pulled your through bolts and redid the o-rings, did you just do one at a time or did you end up splitting the case?

Pat

[dtw]

I pulled one through bolt, carefully re-cleaned the oil passage, washers, bolts, and re-torqued. Then I moved to the next one. This seemed to be a reasonable way to keep torque on the case/bearings without disturbing things too much. It took about 30 minutes to do each one, to get everything perfectly clean again.

[jhelgesen]

Cool Dave, all looks very familliar.

[Tim Walsh]

BTW how is the 912-6 comin? John?

[jhelgesen]

912-6 is coming slow. I'm installing the cam gears tonight to check alignment. Never goes as fast as I would like.

[Tim Walsh]

ya it's been the same way with dave's motor.. planned for 1 or 2 weekends but it's now going on 4 :/

[Wayne 962]

Originally posted by dtw First off -- let's talk about case cleaning. Wayne's estimate of case cleaning time is something like 2 or 3 hours in the book - let me just say this is way off base and completely wishful thinking. [/B]

I say if you haven't spent *at least* 3-4 hours cleaning your case, then it's probably too dirty. In reality, some cases require more cleaning than others. The mag case used for the book should take about 12-20 hours of cleaning.

It's a good idea to have the case, and clean it a little bit each day, so that you're not overwhelmed. Spend a month on it, using about a 1/2 hour of your day. That is really the best way to guarantee that your case is sparkling clean.

-Wayne

[dtw]

You're absolutely right- and BTW- I know what you were trying to say in the book. I was yanking your chain, man.

[Wayne 962]

Duly noted!



-Wayne

[aigel]

Dave:

Great series of pictures!

To get to the chain housing question first: The chain housing in your picture, is it installed with the gasket on the crank case in place? You may be able to install the housing without a gasket using your orange case sealer to gain some clearance. There is also some play in the holes that hold the thrust washer piece / O-ring on the cam side. Did you install the housing while keeping those three bolts on the cam loose? If you do that and have the O-ring in there, it will help self-center the cam covering piece ...

Thinking about this a bit more: Your cylinders and heads will expand more than the chain housing which will help the problem seen in the picture a bit? Still, the O-ring may not be able to take up the slack. Have you checked factory specs for this offset?

Unless some of the above suggestions help, I think you are going to have to machine the chain housing(s). The proper way to determine how much you need is to measure the distances with all parts un-installed and do the math on how much to cut to get things concentric. I would not rely on an eyeball after dry installation before cutting metal.

One more thing: I am wondering about is why you would use silicone sealant (RTV???) on O-rings in the first place? IMHO that is a very bad idea and you experience showed no different. The O-rings work very well by themselves and you may only want to apply some dressing to the O-rings to keep them plyable and movable. The silicone sealer will do the opposite: It will lock things in place. It will take up clearances that were to be filled by a plyable O-ring. Leaks can develop more rapidly when you introduce at least one more interface. The silicone sealer never will have the properties of the O-ring, it's shape is out of your control and its lifespan may be much shorter than the O-ring as well.

These O-ringed regions, were they leak prone from the factory? I dont thik so!? So why do it different than the factory? While I am for playing things safe, sometimes the blelt with suspenders method doesn't work. O-rings are a wonderful thing if they work right and we know what happens if they don't, at least since January 1986.

Cheers, George

[aigel]

Dave:

One more thing. I am wondering. Did you clean the case all by yourself at your house or did you have it washed at a machineshop first?

Did you try a pressure washer or you local self car wash (late at night ) A good 'hot tank' / engine dishwash around here is $80, sounds like money well spent.

George

[Doug Zielke]

Originally posted by aigel
I am wondering about is why you would use silicone sealant (RTV???) on O-rings in the first place? .....
These O-ringed regions, were they leak prone from the factory?

First of all, thanks for the images, Dave.
Keep 'em coming. I may be doing another motor for a friend this winter. Your pictures are good reminders as to what things look like.

About Georges quoted comment above....
Wayne Dempsey's Engine Rebuild book advises the use of RTV silicone on those o-rings. I don't like the stuff, and I think George makes good arguments against it's use.
If John Walker, Steve Weiner, or ? would care to comment, please.....

[dtw]

George,
Subsequent to my original post, I had the chain cases machined down ~.5mm. Everything is lined up well now- still a bit of offset, but very easy to live with now. Nothing like before. I considered final assembly using just orange goop instead of the chain case/crank case gasket. However, I tried it first with the gasket and was happy with the results. So, left it in place.

The case was cleaned at the machine shop using one of those industrial dishwashers- hot solvent sprayed from many directions while the case is spun around and around. What took me so much time to clean was the filmy, scaly buildup that covered just about every area of the case. To my knowledge there are no submersion-type hot tanks in my area anymore that will work with magnesium. The places I called just to iron; when I started talkin' about mag they wanted off the phone really fast.

Your comments about the o-rings echo the ones I ended up with after trying Wayne's approach. I know I'm going to get scolded for this, but I halfway wonder if some of the experts he consulted with told him to use "silicon" (ie, silicon grease like Sil Glide) and he wrote down "silicone" (ie, silicone sealer). Again, I think that part of my problem was that I applied too much of the sealant. Nonetheless, I didn't feel comfortable using it at all after viewing the results and will likely not be using it on my next motor.

I'd love to hear comments from Wayne and some of our resident pro builders on this issue.

[aigel]

Dave:

Geez, I kind of forgot tha the case is magnesium. I was thinking aluminum. With the mag case only a reputable porsche engine builder would have the right tools, e.g. a large ultrasound cleaner that is soap based. Since the EPA rules got stricter there is some amazing ultrasound / mechanical cleaning out there.

Cheers, G.

[Wayne 962]

Originally posted by dtw
Your comments about the o-rings echo the ones I ended up with after trying Wayne's approach. I know I'm going to get scolded for this, but I halfway wonder if some of the experts he consulted with told him to use "silicon" (ie, silicon grease like Sil Glide) and he wrote down "silicone" (ie, silicone sealer). Again, I think that part of my problem was that I applied too much of the sealant. Nonetheless, I didn't feel comfortable using it at all after viewing the results and will likely not be using it on my next motor.

I'd love to hear comments from Wayne and some of our resident pro builders on this issue.

My technical editor (Tom Woodford) and I discussed this at length, and also discussed it with a bunch of other people. This is one of those things where it's 'your preference.' Tom's been building engines for years (owned a shop in NJ for 13 years), and anyone out here on the West Coast knows his stuff is good, and leak-free. His comment was that in about 350 or so engines where he's used the silicone, he's never had an engine leak from there (he did once, on a mag case, before he used the silicone). Also, he typically services the cars that he rebuilds - never had one come back with a leak there either.

The factory o-rings alone are suseptible to leaks there - I have seen it, as have a bunch of people I have spoken to. So, based upon that information, it would seem like a good recommendation to encourage people to use the silicone...

-Wayne

[aigel]

Wayne:

We'll have to agree to disagree on the use of RTV on O rings. I have yet to buy and read the engine rebuild book of yours. Just like the 101 projects, I imagine the engine building book is meant as a guide, not the law or the ten commandments. Anyone tackling an engine rebuild likely has enough brains to decide for themselves what works best for them.

What I find often in life and at work is the fact that people decide to go one route and then stick with it. Once they are commited, they talk themselves into it being the perfect thing and keep convincing themselves over and over again. While this may be very good, e.g. in a marriage, it can be somewhat misleading if it comes to engineering solutions.

Has anyone gone throught the hassle and count all spots on a 911 where oil can potentally leak? I think it must be HUNDREDS. I think that will be a nice exercise for a rainy winter day ...

Have a good sunday all!

George

[Wayne 962]

Right - there are many ways to skin a cat. Pick up a copy of the Engine Book - if you haven't seen it yet, I think you'll be surprised. It is indeed a how-to step-by-step account of the rebuild process. I wouldn't really refer to it as a guide...

-Wayne

[Doug E]

Thanks for the pics Dave. As someone who is staring at some engine work this winter I appreciate the documentation and attention to detail.

[Bobboloo]

It is indeed a how-to step-by-step account of the rebuild process.

That in a nutshell is "the" best reason to buy the book in my opinion. Rebuild info has been out there for years but never organized step by step in the manner of Waynes' book. It's kinda like..."scalpel..check" "forceps..check"

Outstanding work Wayne.

As for the silicone on the o-rings I opted to go without because I didn't want to take a chance on some goop oozing out inside the case breaking loose and risk being lodged somewhere. Loctite excess just washes away with the oil but not the case with silicone.

It also seemed to me that it would interfere with the sitting of the O-ring as it did in Daves' situation. I think the important thing is to make sure the o-ring is lubed so it sits correctly.