white smoke, no power, backfires - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

• white smoke, no power, backfires by jimfoo on 13 Jun, 2008 10:55
• Ok, I got my flywheel on and started it. It starts ok, seems to idle ok but smokes a ton and won't rev past 3k, plus it backfires some out the exhaust at 3k. With the timing light, timing seems to be where it was before the "incident". So I am assuming this provides more evidence towards bent valves unless the cam slipped? BTW, there is no blowby, so rings are still good.
• #1 by jimfoo on 13 Jun, 2008 11:00
• Oh, and I will be doing a compression check before I pull anything apart.
• #2 by jtanguay on 13 Jun, 2008 11:06
• did you verify cam timing?  bent valves suck
• #3 by jimfoo on 13 Jun, 2008 11:22
• No cam timing yet as I have to pull a bunch of stuff to get the valve cover off like the oil filled IC hoses. I can't get too dirty as I have to go shopping for a wedding gift when the wife gets home. Probably tomorrow afternoon after the wedding.
• #4 by jimfoo on 15 Jun, 2008 15:18
• Ok, the cam timing is still on. I checked compression in the 3 cylinders I can easily get to, and all are at 400 psi which doesn't seem like it indicates bent valves to me. What is the compression on a TDI supposed to be? Maybe I still have oil feeding in, and in the exhaust, accounting for the smoke. I have started wondering if the pump could be having some problem with the governor or advance. Any other thoughts?
• #5 by jasonsansfleece on 15 Jun, 2008 18:28
• Dodgy injector?
  Guy
• #6 by jimfoo on 15 Jun, 2008 19:14
• I found the timing advance cover was dripping a little. I took it off, sanded it smooth, cleaned everything and put it back on. I decided to advance the timing a little to see what happens. The smoke decreased dramatically, no more backfiring and it would rev much better. Maybe I was looking at the wrong mark when I checked the timing before. The question now is why did it change? I did find that two of the 3 front bolts were stripping out. I managed to get one out and weld a new bolt in place, but the nut just spun on the other one, not coming off. Maybe it rotated a little because of them. I will take the gear off tomorrow to cut off the nut and replace the other bolt.
  As far as the turbo, I cleaned all the oil out of it that I could with it installed. With the turbo intake blocked off and the engine running, it quickly filled up to a certain point with oil and seemed to hold that level. I'll take it off tomorrow and drop by a local place to see what they say about it.
• #7 by burnt_servo on 15 Jun, 2008 22:21
• when you dumped the clutch , i wonder if the timing belt jumped a cog ?
  
  without actually hearing the engine , what you decribe sounds like the timing belt is out one tooth , or the cam has turned in it's sprocket .
• #8 by jimfoo on 16 Jun, 2008 07:02
• The TB didn't seem any looser and I didn't have to move the pump anywhere near 1 tooths worth. The long ribbed belt for the alternator jumped 2 ribs however and is now too stretched out to stay in place.
• #9 by burnt_servo on 16 Jun, 2008 14:21
• so that leaves the posibility of the cam slipping in  the sprocket a bit .  or maybe a partially sheared key on one of the other sprockets .
  
  or maybe the timing  belt stretched  a bit ?
• #10 by jimfoo on 18 Jun, 2008 19:42
• No clue. I can't get the dial indicator on due to the location of a bunch of other crap like steering, hoses, footwell.
• #11 by jimfoo on 19 Jun, 2008 17:16
• Well, I got my turbo sort of half assed put together with other parts and put back on the engine. I also have the new pressure plate and clutch disc on. I had advanced the pump a little more after replacing one of the mounting bolts. I started it, and it was still smoking, so I got the timing light out again and checked. It was at 13 BTDC, so should have been plenty. I decided to check it while revving it a bit, and found the timing didn't change, so it looks like something is screwed in the pump, so I will have to pull it tomorrow.  :evil: At least the turbo isn't blowing any oil.
• #12 by jimfoo on 19 Jun, 2008 17:18
• BTW, pulling the wire off the solenoid on the timing spring cover (ALFV) retards the timing by about 10 degrees.
• #13 by jtanguay on 19 Jun, 2008 17:27
• Quote from: "jimfoo"

  BTW, pulling the wire off the solenoid on the timing spring cover (ALFV) retards the timing by about 10 degrees.

  
  
  hmmm makes me wonder if you could wire that solenoid up to the accelerator cable somewhere with a switch.  so at idle it retards the timing for a nice quiet, less fuel hungry idle.  or would the timing advance react quick enough?
• #14 by jimfoo on 19 Jun, 2008 17:49
• Yeah, it seems to react instantly, so it would be possible.I found a graph of someones VagCom timing, and it looks like it should be at 4* at 1K rpm, and gets up to about 19* at 5k rpm.