DDK - Die Deutschen Klassiker

Part 1 – why I needed to rebuild:

Some of you may have seen a post of mine showing the carnage that occurred when my #1 inlet valve came a little too close for comfort to the corresponding piston due to one of the intermediate shaft gears letting go http://www.ddk-online.com/phpBB2/viewtopic.php?t=18395

Top teeth missing and rest ground down



Remains of valve and piston



So nothing more to do than accept it and get stuck in with my first 911 engine rebuild - thought I would share my experience along the way. I share these for other people’s curiosity / interest – if you spot an obvious mistake please let me know!

So here goes…

Part 2 – Strip down, inspection and deciding spec

Using the Dempsey book as a guide, I had the engine looking like this in about 8hours



It went really well, no snapped/pulled head studs, no broken exhaust studs/nuts - I think the main reason it went well was because I’ve invested a small fortune in obtaining the correct tools to do the job. I wont repeat all the steps, the book is pretty good, or saving that see a nut and undo it! What I did find was a pretty tired old engine, but knowing what was reusable and within spec meant loading the car up and having a trip up to see Mike Bainbridge.

That trip left me with quite a shopping list, firstly:

Rod bearings were shot – one had spun and 3 others were heavily scored/damaged





The crank had suffered on the rod bearing surfaces too, it was out of tolerance.

Main bearings were pretty good really







Intermediate shaft bearings were worn, but this appears to be quite common from what I’ve read.

So it was either regrind the crank and fit oversize bearings OR source new std:std crank with normal bearings. Financially it was cheaper to source a new crank, which I did via Pelican, and got a freshly magnafluxed, polished and inspected std:std crank.

I decided to have the oil by-pass modification done to the case whilst it was all apart





Which also means fitting later style oil relief pistons

My oil pump was quite badly scored on the inside case and there were a couple of dings on the gear surfaces, although it was turning freely enough I decided to upgrade to a later style 4 rib pump





you can see the overall dimensions are the same but the inlet part of the pump is larger

Obviously I needed new intermediate gears which I was able to source from Mike, luckily he had a ‘0’ size on the shelf with virtually no signs of wear. Only trouble is to install the new ones means heating them up without the wife noticing what’s cooking in the oven, managed to get away with this one though.

The rods had been subjected to a fairly hefty force when the piston went south and I wanted to get them checked to see if they were reusable, all be it with new bushes shot peened and possibly machined, but I was able to source some NOS ones at the same time as shopping for other parts – still in the old style made in W Germany box and still in their old plastic bags





(the numbers are their weights which I checked) although they are for a 2.0 litre engine (and hence 50mm rod bolts not 58mm they should be ok as their length is the same)

Flywheel was well worn, so needed a new one of them too!
Next was Pistons and cylinders, I found 2 broken rings on other pistons (as well as the destroyed number 1 piston) and 2 cylinders were damaged in the carnage. So I needed a new set of them too. £££

Then the heads; all the valves were completely shagged and the exhaust valve guides too. That meant 6 new valve guides, 6 new exhaust valves and new intake valves.

Next the cams – two lobes on the left cam were pitted and corresponding rockers were damaged. Again it was cheaper to source a second hand good set than have mine refurbed, which I did from the same guy on Pelican who sold me the crank.

Luckily I had very recently replaced the chain tensioners, ramps, idler pulleys and cam pulleys so they were still like new, but Mike suggested junking the new split chains for continuous ones given that the chain had jumped. Then there was all the other little bits like making sure that the oil cooler and oil tank were ok to use again after having so much junk floating around inside. I had them ultrasonically cleaned and was very pleased with the result





I now needed to decide on which bits to buy to give me some extra horses. I knew I didn’t want to rebuild on my magnesium case a screaming banshee living its life 7krpm+, I think the case would have needed too much work and I wanted to keep it a numbers matching car. OK, I could have put in a donor engine, kept the cases and rebuilt later, but funding one engine is enough! My car’s main use is as a daily driver, with fast road use so I thought a little extra wouldn’t go a miss. My main focus though was on adding some reliability upgrades whilst retaining a period spec.

JohnM recently posted a fantastic thread, that I have consulted many times, detailing some of his recent 2.2E rebuild http://www.ddk-online.com/phpBB2/viewtopic.php?t=17139 – and in the end I’ve gone down a very similar direction, more of that later.

Part 3 – Short block

When the new crank arrived it had been completely stripped down, including the intermediate drive gear and distributor drive gear, I had to reassemble those onto the crank after I had thoroughly cleaned it. Again this meant heating the parts up in the oven, but this time I was caught, and using her oven glove!



My old crank is shown at the side of it which I used as a guide when installing the gears

I then set about thoroughly cleaning the crank again, this time mounted to the old flywheel that I would replace



and then fitted the rods

The 2 case halves were then cleaned





This took 16 hours of scrubbing with brake cleaner and 80 household pan scrubbers – I kid you not, I thought I would never finish it, but it will be worth it not to have a leaking 911 engine!

I then went round and JB welded all the areas on the case that originally had epoxy on them as per the Dempsey book

I decided to leave the oil pump screens (only seen in early cars) out of the rebuild as I had read that they serve little purpose but to sap a few horses



I installed the new Glyco bearings which I thoroughly inspected and cleaned before assembly – there is quite a bit of concern over the quality of these recently, luckily mine seemed ok but the proof of the pudding is yet to come…

Next was the #8 bearing, apols for the crap pic, but before installing the oil seal it is worth taking off the rough edge next to the indent as it can nick the seal



Then install on the crank with the flywheel seal and in she goes..



Then the new oil pump and intermediate shaft assembly, with new continuous chains



were installed

Then it was time to put the case sealant on and mate the two halves



I personally found that even after tapping the 2 halves together with a rubber mallet there was still about a 1 / 2 mm gap between the halves until I had tightened the through bolts and perimeter bolts. Thankfully there was a nice even layer all around the joining surfaces after. I also used some silicon on the o rings in the through bolts as per the Dempsey book to insure against any leaks.

Finally, after installing the flywheel and crank pulley I was able to test to see if the crank would turn properly without any hang ups – which it did !!

Here it is complete with oil breather, sensor, thermostat and cam pulleys holding the chains



Right, next the cylinders and pistons….

well blow me over what a great thread I am watching this one.. I will do the same when I put the next 912 motor togeather..in a few weeks..

Looking Good James

Regards

Great thread James.

Matt

Fantastic thread, when you are finished you can come and do my engine

Looks great, I've got to say that the clean mating of the two case halves does worry me a bit. Which case sealant did you use ?
Cheers
Tim