My Jetta has 320,000 on the odometer, and after some engine work it's now losing an incredible amount of oil and I can't figure out where it's coming from. It's losing on the order of 2-3 quarts every 200 miles. None of it is coming out below the car, it's all going out the tailpipe, but I've inspected the turbo and see nowhere near the amount of shaft play that would be required for it to dump this amount of oil. A synopsis of how I got here might be helpful, so apologies in advance if this gets a bit long winded...
To start with, the car had been pressurizing the coolant reservoir for a while, and I just put up with having to top it off every month or so. Eventually it got bad enough that I sucked it up and pulled the head to replace the head gasket. I cleaned the **** out of the block and the head, using a very fine grit honing block on the block and a roloc disk on the head. I checked whether the block and head were warped with a machinist's straight edge, everything looked great. Slapped the head back on the car, bolted it all back together, drained the oil, refilled it, etc. After a bit of cranking it started right up, everything seemed fine.
Fast forward a couple days, and while I'm about 100 miles from home the turbo starts whining...badly. I thought I could make it the rest of the way home before things went too far south, but before I managed to do so oil was being dumped out the tailpipe so fast that I was leaving a smokescreen behind me. So I pulled over and got a tow the rest of the way home. I probably drove it a little longer than I should have, but nothing catastrophic seemed to have occurred. I pulled the turbo out and sure enough the shaft was just flopping all over the place, and I assumed I had missed something in the intake that impacted the compressor wheel and knocked it out of balance. So I bought a new CHRA for the turbo from turborebuild.co.uk and installed it, in the process cleaning out all the intake piping, draining a ton of oil from the intercooler, flushing the intercooler, etc. Started it up, calibrated the turbo VNT stopscrew using a boost gauge tapped into the exhaust manifold, and everything seemed fine. However, within 5 miles of driving I'm seeing oil under the vehicle. Hoping it was just residual I think I went a total of maybe 40-50 miles or so before deciding that something isn't right. The oil was coming from the not-quite-tight-enough exhaust clamp that joins the turbo to the downpipe. I pulled the turbo out and the brand new CHRA seemed to already have a large amount of axial play, to where it would juuuust contact the housing if I pushed it to the side.
At this point I started thinking maybe my oil pump is just not keeping up, or maybe I have some grit from honing the block still in the oil pan acting as an abrasive. So I dropped the oil pan, replaced the oil pump, the pump chain, the crank bearings and the connecting rod bearings for good measure. There were one or two that were a little scored, but nothing major, and I saw no signs of residue in the oil pan or damage to the crankshaft itself. I put everything back together, put the factory original turbo back on the car that had been sitting in the garage, re-tuned it back to factory settings, and started it back up. Smoke was still coming from the exhaust, but I crossed my fingers that it was just residual oil being blown out from the exhaust. That didn't pan out. It kept right on smoking, and I soon found out it was losing just an obscene amount of oil. Pretty soon it started missing periodically as well, within a small amount of local driving just to check out how things were running.
I've inspected everything I can think of, and while there is still a lot of oil in the exhaust it doesn't seem to be coming from the turbo. I don't have a vacuum leak that I can tell; I can hear air being sucked in the line when I remove the vacuum hose from the back of the valve cover 30 minutes after shutting off the engine. The camshaft and valves all look good, I don't see any fuel leaks around any of the fuel injectors, and the tandem pump, while original to the car, doesn't seem to be mixing fuel and oil at all that I can tell (and to my understanding that tends to pump fuel into the valve cover, not oil out into the fuel). I did a leak down test (while cold, oil pan off) and all the cylinders were testing around 95%. The compression test (while hot) looks a lot worse, reading 440, 300, 410, and 350, but even so the blowby does not seem to be that extreme, and the intake does not seem especially oily. I ran some logs of the injector compensation values and those numbers are just...all over the place. I can't make sense of them, and even it it were the injectors how would it be losing so much oil? Also, the timing measures 0.5 advanced.
Does any of that give any clue to where this oil may be leaking out from? None of this makes any sense to me at this point, and every time I have another bright idea about what might be the cause it just winds up being another dead end. I really wish I had replaced the rings while the head was off, but I'm having trouble convincing myself it's possible to lose that much oil past the rings.
To start with, the car had been pressurizing the coolant reservoir for a while, and I just put up with having to top it off every month or so. Eventually it got bad enough that I sucked it up and pulled the head to replace the head gasket. I cleaned the **** out of the block and the head, using a very fine grit honing block on the block and a roloc disk on the head. I checked whether the block and head were warped with a machinist's straight edge, everything looked great. Slapped the head back on the car, bolted it all back together, drained the oil, refilled it, etc. After a bit of cranking it started right up, everything seemed fine.
Fast forward a couple days, and while I'm about 100 miles from home the turbo starts whining...badly. I thought I could make it the rest of the way home before things went too far south, but before I managed to do so oil was being dumped out the tailpipe so fast that I was leaving a smokescreen behind me. So I pulled over and got a tow the rest of the way home. I probably drove it a little longer than I should have, but nothing catastrophic seemed to have occurred. I pulled the turbo out and sure enough the shaft was just flopping all over the place, and I assumed I had missed something in the intake that impacted the compressor wheel and knocked it out of balance. So I bought a new CHRA for the turbo from turborebuild.co.uk and installed it, in the process cleaning out all the intake piping, draining a ton of oil from the intercooler, flushing the intercooler, etc. Started it up, calibrated the turbo VNT stopscrew using a boost gauge tapped into the exhaust manifold, and everything seemed fine. However, within 5 miles of driving I'm seeing oil under the vehicle. Hoping it was just residual I think I went a total of maybe 40-50 miles or so before deciding that something isn't right. The oil was coming from the not-quite-tight-enough exhaust clamp that joins the turbo to the downpipe. I pulled the turbo out and the brand new CHRA seemed to already have a large amount of axial play, to where it would juuuust contact the housing if I pushed it to the side.
At this point I started thinking maybe my oil pump is just not keeping up, or maybe I have some grit from honing the block still in the oil pan acting as an abrasive. So I dropped the oil pan, replaced the oil pump, the pump chain, the crank bearings and the connecting rod bearings for good measure. There were one or two that were a little scored, but nothing major, and I saw no signs of residue in the oil pan or damage to the crankshaft itself. I put everything back together, put the factory original turbo back on the car that had been sitting in the garage, re-tuned it back to factory settings, and started it back up. Smoke was still coming from the exhaust, but I crossed my fingers that it was just residual oil being blown out from the exhaust. That didn't pan out. It kept right on smoking, and I soon found out it was losing just an obscene amount of oil. Pretty soon it started missing periodically as well, within a small amount of local driving just to check out how things were running.
I've inspected everything I can think of, and while there is still a lot of oil in the exhaust it doesn't seem to be coming from the turbo. I don't have a vacuum leak that I can tell; I can hear air being sucked in the line when I remove the vacuum hose from the back of the valve cover 30 minutes after shutting off the engine. The camshaft and valves all look good, I don't see any fuel leaks around any of the fuel injectors, and the tandem pump, while original to the car, doesn't seem to be mixing fuel and oil at all that I can tell (and to my understanding that tends to pump fuel into the valve cover, not oil out into the fuel). I did a leak down test (while cold, oil pan off) and all the cylinders were testing around 95%. The compression test (while hot) looks a lot worse, reading 440, 300, 410, and 350, but even so the blowby does not seem to be that extreme, and the intake does not seem especially oily. I ran some logs of the injector compensation values and those numbers are just...all over the place. I can't make sense of them, and even it it were the injectors how would it be losing so much oil? Also, the timing measures 0.5 advanced.
Does any of that give any clue to where this oil may be leaking out from? None of this makes any sense to me at this point, and every time I have another bright idea about what might be the cause it just winds up being another dead end. I really wish I had replaced the rings while the head was off, but I'm having trouble convincing myself it's possible to lose that much oil past the rings.