Knuckledragger
Well-known member
What follows is a tale of woe about what went wrong with the engine. The reasons are close to the bottom. Suffice to say, that frequent motor oil changes are mandatory when burning WVO / SVO!
Over the last week, I replaced the stock turbo on my ’03 Jetta with a VNT-17 from KermaTDI. This was because of increased oil consumption w/o any external leakage or loss of compression. The I/C was also filling up with motor oil much more frequently than before. This led me to believe that the turbo oil seals were going.
More importantly, I pulled the head and thoroughly *cleaned*it*out! I had used a borescope a few weeks ago to look into the intake passages of the head (not just the intake manifold!) and found them heavily caked with soot/oil/tar. When I pulled the head, I was amazed to see just how much junk had built up in there. The valve stems and intake passage walls were so thickly gooped up that the engine was probably only getting ~25% of maximum air flow, even at full boost and full throttle.
Pulling, disassembling, cleaning, and restoring the head was no small task… I don’t recommend it if you have something else to do with your life.
Initially, the deposits were like a thick tar. Very tenacious and difficult to remove. They also didn’t come off cleanly. But I used a lot of mineral spirits to pre-soak the deposits and this removed the oil component. The remaining carbon deposits became “crispy” and very easy to chip off.
The running surfaces of the engine that I could inspect (cylinder walls, cam shaft lobes, hydraulic lifter bores, skirts, & top surfaces, valves & valve seats) were all in very good condition. No excessive wear, no scoring, and all well within specs. Compression had always been very good, so I didn’t expect any problems there.
The tops of the pistons were relatively clean. No burning, FOD, etc. Just a thin layer of very tenacious carbon that I decided to just leave alone rather than risk damaging the pistons or cylinder bores while trying to remove it.
The performance of the car had suffered for a good ~30,000 miles, and I had been down many paths to restore the performance. Some successful, others not so much. Here's a list of *all* the work done in the last year and the results of each:
1. Heavy smoking under load. Replaced the injector nozzles with Sprint 520s. No real improvement.
2. Replaced the MAF sensor & air filter. No improvement.
3. Bad fuel pump (clicking and then finally CELs and a dead engine). Replaced it, no big problems but no improvement either.
4. Took it to Jason in Madison. He removed the snow screen (it was clogged and I didn't know it existed). Also tweaked the fuel injection timing and used a can of diesel purge to improve performance some. Turbo surge was cured (probably because of the clogged snow screen). Some short term reduction in smoking, but it returned within ~200 miles.
5. Got rebuilt injectors (again, KermaTDI) that greatly reduced the smoking problems, but still had very poor performance.
6. Sent a VAG-COM trace to Paul at Kerma. He diagnosed a bad MAF. Replaced it. No improvement.
At this point, the MAF trace was showing that the air flow would increase to a maximum of about 25-30% of demand, and then flat-line. The symptoms certainly looked like a bad MAF sensor, but in fact, the engine intake was choked off by the restricted passages.
7. Replaced turbo & cleaned out head. Now it runs like new again! Plenty of response, torque, and horsepower. I cannot wait until spring when I have good long stretches of ice free roads to try it on!
Why all the problems? I should have known better. I've been running the car filtered, de-watered waste vegetable oil for the last ~70,000 miles. The WVO itself wasn't the problem, but rather the way that I've been using it has.
I have recently learned that with WVO, it doesn't matter how much money you spend on fancy motor oils, you still cannot run them 10,000 miles like I was doing. From now on, only cheap oil changed every 3K miles.
Of course, with the price of diesel now more reasonable, I may forego WVO all together. It has been a lot of fun and a great learning experience, but with all the parts replacements, I haven't saved a dime.
Many thanks to Paul at KermaTDI and Jason of JasonTDI in Madison, WI. These two gentlemen have been extremely helpful and supportive. I recommend them highly!
2003 Jetta TDI, mostly stock. 130,000 miles. VNT-17 turbo, Sprint 520 nozzles. Running WVO since ~60,000 miles.
Over the last week, I replaced the stock turbo on my ’03 Jetta with a VNT-17 from KermaTDI. This was because of increased oil consumption w/o any external leakage or loss of compression. The I/C was also filling up with motor oil much more frequently than before. This led me to believe that the turbo oil seals were going.
More importantly, I pulled the head and thoroughly *cleaned*it*out! I had used a borescope a few weeks ago to look into the intake passages of the head (not just the intake manifold!) and found them heavily caked with soot/oil/tar. When I pulled the head, I was amazed to see just how much junk had built up in there. The valve stems and intake passage walls were so thickly gooped up that the engine was probably only getting ~25% of maximum air flow, even at full boost and full throttle.
Pulling, disassembling, cleaning, and restoring the head was no small task… I don’t recommend it if you have something else to do with your life.
Initially, the deposits were like a thick tar. Very tenacious and difficult to remove. They also didn’t come off cleanly. But I used a lot of mineral spirits to pre-soak the deposits and this removed the oil component. The remaining carbon deposits became “crispy” and very easy to chip off.
The running surfaces of the engine that I could inspect (cylinder walls, cam shaft lobes, hydraulic lifter bores, skirts, & top surfaces, valves & valve seats) were all in very good condition. No excessive wear, no scoring, and all well within specs. Compression had always been very good, so I didn’t expect any problems there.
The tops of the pistons were relatively clean. No burning, FOD, etc. Just a thin layer of very tenacious carbon that I decided to just leave alone rather than risk damaging the pistons or cylinder bores while trying to remove it.
The performance of the car had suffered for a good ~30,000 miles, and I had been down many paths to restore the performance. Some successful, others not so much. Here's a list of *all* the work done in the last year and the results of each:
1. Heavy smoking under load. Replaced the injector nozzles with Sprint 520s. No real improvement.
2. Replaced the MAF sensor & air filter. No improvement.
3. Bad fuel pump (clicking and then finally CELs and a dead engine). Replaced it, no big problems but no improvement either.
4. Took it to Jason in Madison. He removed the snow screen (it was clogged and I didn't know it existed). Also tweaked the fuel injection timing and used a can of diesel purge to improve performance some. Turbo surge was cured (probably because of the clogged snow screen). Some short term reduction in smoking, but it returned within ~200 miles.
5. Got rebuilt injectors (again, KermaTDI) that greatly reduced the smoking problems, but still had very poor performance.
6. Sent a VAG-COM trace to Paul at Kerma. He diagnosed a bad MAF. Replaced it. No improvement.
At this point, the MAF trace was showing that the air flow would increase to a maximum of about 25-30% of demand, and then flat-line. The symptoms certainly looked like a bad MAF sensor, but in fact, the engine intake was choked off by the restricted passages.
7. Replaced turbo & cleaned out head. Now it runs like new again! Plenty of response, torque, and horsepower. I cannot wait until spring when I have good long stretches of ice free roads to try it on!
Why all the problems? I should have known better. I've been running the car filtered, de-watered waste vegetable oil for the last ~70,000 miles. The WVO itself wasn't the problem, but rather the way that I've been using it has.
I have recently learned that with WVO, it doesn't matter how much money you spend on fancy motor oils, you still cannot run them 10,000 miles like I was doing. From now on, only cheap oil changed every 3K miles.
Of course, with the price of diesel now more reasonable, I may forego WVO all together. It has been a lot of fun and a great learning experience, but with all the parts replacements, I haven't saved a dime.
Many thanks to Paul at KermaTDI and Jason of JasonTDI in Madison, WI. These two gentlemen have been extremely helpful and supportive. I recommend them highly!
2003 Jetta TDI, mostly stock. 130,000 miles. VNT-17 turbo, Sprint 520 nozzles. Running WVO since ~60,000 miles.
So that could be a problem as well. 