DDK - Die Deutschen Klassiker

Yep thanks for the update

Thanks guys. I'll keep posting as I go through the photos. There was a lot of work that went into this that may help others.

As I mentioned a few years ago, the heat exchangers were old stainless steel SSI units. We had cleaned them up previously but oil had dripped from the engine onto these and they needed another clean. Gary used oven cleaner on them and they came out really well:



Cylinder Heads





To learn about these engines and the work involved I had watched a series of excellent videos on YouTube from Klassik Automotive Training School (I highly recommend watching these). From these I realised how much work goes into cylinder head restoration.

Gary and Giulio had assessed the cylinder heads back in 2022. A vacuum reading showed 10HG and a vibrating needle indicated worn valves/value guides and pistons. Cylinder leak tests results showed three cylinders had leakage well out of specification (on a rebuilt engine expected leakage is 10-18%)

Cylinder 1 38%
Cylinder 2 36%
Cylinder 3 20%
Cylinder 4 18%
Cylinder 5 20%
Cylinder 6 40%

To avoid wasting time and labour, we decided to replace all the valves, valve guides and valve springs. The cylinder heads were stripped down and all were ok except one which had been poorly worked on previously and had a stud screwed in at an awkward angle and another had an exhaust stud that had snapped off. They are original units date stamped 73 so we were inclined to repair rather than replace. Gary arranged for the first one to be welded and repaired and had a timesert added to the one with the broken stud. New valve guides and valve seats were cut in and cylinder head faces were machined.













Crankshaft

Gary removed the connecting rods from the crankshaft, cleaned and inspected it and said it was in good order. We had the crankshaft journals polished.



Gitesh

Great breakdown of what goes into a rebuild. Luckily looks like Engine was in pretty good nick compared to others

Inlet stacks and manifolds

Gary stripped the inlet stacks into individual components for cleaning and plating.





















The magnesium manifolds were in very good condition with little corrosion and the butterflies were operating well. They were stripped down and cleaned ready for blasting.



























Gitesh

Great thread, thanks for detailing the build. Amazing to see it all come apart and back together again (I love a happy ending)!

Engine Case



As mentioned earlier, one of the main reasons for the rebuild was the oil leaks. A fews years ago I asked Gary and Giulio to assess the engine condition. They had diagnosed an oil weep from a crack in the crankcase boss for the oil scavenge union and a weep from the bottom rear of the engine case where the clamping bolt boss had a crack. There was also an oil weep from the right hand chain case gasket, another weep from the left hand cam seal (could be coming from the injection pump), oil weeps from both cam carriers and an oil weep from the top of the engine around the oil pressure sender.









Gary had informed me that welding magnesium was difficult so asked me to look into laser welding. Through DDK, I was recommended EMP Tooling Services in Hampshire. Gary had another magnesium case that needed welding so he took both cases to them and I collected them a few weeks later. EMP were very impressive and spent a lot of time showing me around their premises and the jobs they were working on. They did an excellent job on my case and I would highly recommend them. Many thanks to DDK member "Stuttgart" for recommending EMP to me. Here are some photos of the areas once they were machined down:



















EMP also recommended a company in Slough called Ultraseal, who provide vacuum impregnation sealing to Magnesium. Magnesium is porous and I thought this would be good process for the magnesium engine parts to prevent oil leaks. After much consideration, I decided not to proceed with this since it may have impacted the chromating process we were going to carry out.

Once the case halves had been machined down, Gary removed the piston jets from the crankcases, bolted the crankcases together and sealed up all the holes and oil ways ready for bead blasting.





















Gitesh

Really interesting work Gitesh. Great to see those complex leaks being tackled.

Several areas of my gearbox are similar around the detents and a few other parts so I’ll see if I can get them repaired in the same way!

It’s great that you mentioned EMP Tooling Services as I know I will need my case welding.

Of interest didn’t those corroded areas have copper washers? Whilst googling the world of magnesium corrosion it seems that the copper sealing washers under the bolts are a really bad idea!

Add that to the fiddly areas likely to trap dirt and water and you’ve got a perfect galvanic corrosion soup!

Hi Gary - I am pretty sure that where the car was kept previously didn't help with the corrosion here either with wet grass in constant contact with the engine.

We also had the chip in the fan housing laser welded by EMP. Unfortunately I don't have a picture of this but they did a good job here too.

Moving on, Gary had all the parts shot blasted, dissembled the case and then took them to be chromated:

















The last photo shows that unfortunately the areas that had been welded did not take the chromating process well. Angus at Greatworth was very helpful in suggesting Cerakote paint since it is a good match and has lower build than normal paint. We had used it on my exhaust a few years ago and it has held up well. Many thanks, Angus, for the help here.

Gary ordered some Cerakote paint samples and then had these parts of the engine painted where the chromating hadn't worked well:



Gitesh

MFI Pump

My original plan was to send this to Fred Pentecost to rebuild but unfortunately he had retired. His business had been acquired by Mercedes specialists SLShop (Mercedes cars also used the Bosch MFI pump). I decided to have my unit refurbished by them and they turned it around quickly:













However, we had an issue with the pump when we put the engine on the dyno at Neil Bainbridge. There was a small leak from the unit, which Gary and Neil diagnosed to some debris. They were able to remedy this on the day. Unfortunately this was several months after the unit had been refurbished. After some back and forth, the SLShop reimbursed the labour and parts for remedying this (a couple of hours labour and some gaskets). It is difficult assessing time when working with different companies but I would advise trying to coordinate this better than I did. On a positive note, aside from this mishap, Neil and Gary said that the SLShop has done a very good job on the pump. Many thanks to the SLShop and also Neil Bainbridge for stepping in and helping to resolve the issue on the day.

Gitesh

After the chromating process, Gary had the line reaming and oil bypass modification carried out on the case, and fitted the case squirters:















Rebuild Parts

As I mentioned earlier, many of the components inside were ok but I chose to change them while we had the engine open e.g the oil pump. I also mentioned that the connecting rods had been ground down for some reason by a previous owner. Gary has said that a used set would be ok but would likely need some machine work on them so had suggested replacing them with a set of new forged Wosner ones. Unfortunately, these were out of stock with no timeframe on future availability so we bought a set of Carrillo con-rods instead.















Gitesh

I used the Carrillo rods in my 9K rpm 3.2 on the race car's engine.
Things of great beauty!
Lots of nice parts on the bench, will be a strong engine when done.

After line bore, did you need main bearings of larger dia to suit the 'new' case bore? Never sure how much metal is removed in the line bore, just remove a shave or take a 1/10mm out?

Hi Graham, I don't think we used oversized bearings here. As far as I know the case was pretty good so we only had to take a little material off here.

Rebuild

Gary Fitted the new intergear and checked it and then moved on to building the case.



























Gitesh

look at those rods