Excessive blow by is NOT normal. Yes, on a diesel you need fuel, air, and compression. If the engine is running rough (compression), and it is "missing" (dead cylinder), the excessive blow by could certainly be a result due to worn or broken piston rings, cracked piston, cracked liner (though unlikely, and you may have coolant issues if so). I have built many diesel engines, and I have one right now that will be rebuilt. It is an '83 Volvo 760 turbo diesel, with a VW/Audi engine. It certainly misses from #1 cylinder, likely due to worn or broken top compression rings (common failure mode from folks using the incorrect oil or from using starting fluid). It, too, has excessive blow by. I have built diesels that have nearly no detectable blow by cold or hot, but that is after careful machining and matching of pistons and rings, and a lot of money. My 2005 TDI, now sold, which we bought brand new in 2005 had some blow by, even new. Never got worse or better, however, it was not excessive. What is excessive? With the engine hot, pop the dipstick out (engine running). Is it smoking like a chimney? That is too much. Almost none or none? That is normal. What is almost none? You need a flashlight or direct sunlight to see it. Now, insert the dipstick (no comments, please), and start the engine if not already running. Open the oil cap. Is there a lot of white smoke? Some is OK, and by some, I mean almost none, or VERY little. If it is a cloud, that is bad, and you have piston and/or piston ring problems. My CRD has 81K, and you cannot detect any blowby (smoke) hot, and if I use sunlight or a flashlight, you can see almost none. My buddy who has a CRD with nearly 170K also has nearly none. The notion that it is normal is not right. If you could get pictures or a video and post it or email it, I can help. I can post mine, if I get time, and also post what is not normal from the engine in which I am about to rebuild (the Volvo diesel engine). The best thing you can do from here is to do a compression test. It is cheaper than an injector. I am not saying you don't have another issue, however, missing and "excessive blow by" is not normal and is likely related to the rough idle and miss, and should be addressed and investigated.
_________________ Mike Rausch Bear, Delaware 2006 Liberty Sport CRD 253K
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