Newbie - 996 turbo engine break in help

Hi, this is my first post and I'm hoping for some help as I'm at complete despair with my Porsche. So here we go, it's a 996-turbo year of manufacture 2002. Over the last 18 months the engine has received a complete engine rebuild the reason for the re-build was the timing chains had stretched and we had found aluminium in the oil, which I believe had come from the timing chain covers (but who knows). The engine has been completely stripped down, crank was sent away re-ground and balanced, new bearings, oil pump and all new seals. The pistons and cylinder liners were numbered kept in pairs and set aside. The liners were checked for tolerance and were in very good condition with the original honing marks still visible. The piston rings including oil scraper were all replaced with new. The cylinder heads were sent away ported and polished and received new valves, seats, guides, collets and springs. The exhaust buckets were replaced with new and intake buckets were serviced cleaned and re-sat in their original positions. The cams were checked for tolerance and were given a good state of health. Both cylinder heads were pressure tested before re-assembly. Every seal, gasket, grommet, has been replaced with new and every part has been purchased from Porsche, therefore I can confirm its pretty much a brand-new engine. The turbos are brand new hybrid K24's taken from a GT2, they are brand new with the turbine shafts balanced before installation on to the engine. The exhaust manifolds are the stainless steel Miltek type 30% larger than the original Porsche part and I also have the larger intercoolers which is a little inconsequential. All scavenge oil pumps have been rebuilt with new parts and all stainless-steel external oil feeds were replaced with new ones. The timing has been set correctly and the engine turns over lovely by hand. The car was turned over using the starter motor with plugs out and fuel pump fuse out and the oil pressure was very good. The car was then started and left to tick over until the oil temperature came up to 75 degrees and the car could register the oil level, I then topped it up with 500 ml of oil and then the engine was switched off. The car was very smoky when the engine was running but I assumed this would be normal due to the engine assembly process. No leaks of any kind were recorded whilst the engine was running and all data logging via the OBD socket was in its normal operating range. I have now tried to start the running in process weekend gone but aborted due to the amount of blue smoke pouring out of the right bank exhaust. I have now completed a compression test completing the test twice to all 6 cylinders and this gave a compression result of 230 psi per cylinder (all 6 cylinders gave exactly the same result). I then completed a leak down test setting each cylinder to TDC and this test was also completed twice. Each cylinder had a leak down percentage of 53% which on my gauge was a 'moderate leak" each of the 6 cylinders I can confirm leakage of air via the oil filler gap which could be heard therefore confirming leakage around the piston rings. The piston crowns are very oily, and the spark plugs were wet, both the hot and cold side of the turbos are dry and free from any traces of oil so it's not the seals on these. The oil being used is Millers competition running in oil which is a mineral oil. So, question 1 – Is a compression of 230 PSI per cylinder good? and; Question 2 – Am I being over paranoid regarding the blue smoke, and should I just run the engine in the hope that the piston rings bed in when the cylinder pressures increase under load. In conclusion have I completely missed something here does anyone have any ideas please, thank-you in advance. :frustrated:

Hi, was the air/oil separator replaced when the engine was rebuilt? It might just need o be run for a while to clear the oil and water etc however it doesn't sound right, Did you rebuild the engine? If not phone the guys that did for advice.

Hi, was the air/oil separator replaced when the engine was rebuilt? It might just need o be run for a while to clear the oil and water etc however it doesn't sound right, Did you rebuild the engine? If not phone the guys that did for advice.

Morning, yes i rebuilt myself however this is my first 6 cylinder boxer engine. I don't believe the Mezger engine has a air/oil separator but i like your thinking. I might have to just go out one morning early and try and clear the smoke.

So many variables BUT don't start a fresh engine and let sit idling. It's not good for piston ring/bore bedding in. Aside from a small amount of bedding in for crank/bearing and head mechanicals the running in period is mostly about piston ring/bore relation. As it beds in compression will increase slightly but not massively. Not enough to cause loads of smoke. If Temos don't rise and oil pressure is good I would drive the car and get the engine hot and under light load and see if it clears. The exhausts could be full of oil and coolant making smoke at idle, as it won't be hot enough to burn it off. Just my initial thoughts. I would not fret too much at the moment. If vitals are fine, drive the car.

Blimy you've done a lot of work there! I've checked my compression every couple of years since 2010 and it's always been between 14.8 - 15.0 bar which is 215 - 217 psi. That's with an old Gunson tester. I've never checked how accurate it is as I'm looking for differences to previous tests but does suggest yours is all good! Were they genuine Porsche piston rings? Did you put the rings in the cylinder and measure/adjust the end gap on each one, did you make sure the ring gaps were evenly spaced apart when you fitted the pistons in the bore. I'm assuming the oil scraper rings are made up of more than one part, are you sure they are fitted the right way / right way up? Why is it one side more than the other umm! Mac

Well that sounds a little more reassuring that yours are around the 215-217 psi. Yes I have done a load of work to my car, and to be honest I did not even want a Porsche, I wanted an Audi R8 when I turned 40 but I got talked to buying my 996 turbo 7 years ago and its now got under my skin and I love it to bits. Yes all rings were genuine Porsche items and they were put in the cylinders and checked for end gap prior to fitment. They were all clocked when installed on pistons (cylinder 2 and 5 were a nightmare). They were all the right way up I remember double checking this. Yes it is strange that's its only the right bank especially when I've now realised that the Dansk exhaust I have on it connects the left and right bank exhaust gases together before final exit. Weird!!

Interested to hear what the outcome of this was? Did it clear after driving?