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Author Topic: 1998 Jetta TDI white smoke no start..  (Read 2257 times)

April 08, 2015, 05:25:53 pm

Sohio

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1998 Jetta TDI white smoke no start..
« on: April 08, 2015, 05:25:53 pm »
Recently purchased a 98 jetta tdi with 300k on it. got it for a swap into an 82 rabbit. i sent the head out and decided to just get a new casting.
it started right up after having installed head, rebuilt injectors with new nozzles. took it down the road and it bogged down around 3k.
upon returning it shut down completely and now blows white smoke and wont start. the timing looks to have slipped slightly so now in the process on setting it again.
my question, are there any known issues that would case it to so easily come out of time? i read something about the


82 rabbit
98 jetta
Volvo 940
88 ford POS pickup

Reply #1April 12, 2015, 12:04:02 pm

air-cooled or diesel

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Re: 1998 Jetta TDI white smoke no start..
« Reply #1 on: April 12, 2015, 12:04:02 pm »
i dont know what to tell you; if timing slipped most likely scenario, some valves mashed into pistons. if perchance you do start it you ll endup with more damage/bigger bill. personally i think at first you ll be taking that head off, either think about replacing bad valves now; and figuring out which ones need to be replaced now; or end up replacing more later; like real soon; you can end up losing head, and a piston or more,,

Reply #2April 12, 2015, 04:13:03 pm

vanbcguy

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Re: 1998 Jetta TDI white smoke no start..
« Reply #2 on: April 12, 2015, 04:13:03 pm »
Improperly adjusted tensioner or improperly torqued cam gear are the only possibilities really. Either one may have caused valve to piston contact. At the very least pull the valve cover and look for spiderweb cracks on the cam followers. If you see ANYTHING like that the head needs to be pulled and at least a few valves are going to need to be replaced.
Bryn

1994 Jetta - AHU M-TDI - Jezebel Jetta
2004 Jetta Wagon - 1.8T - Blitzen

Reply #3April 12, 2015, 06:29:24 pm

air-cooled or diesel

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Re: 1998 Jetta TDI white smoke no start..
« Reply #3 on: April 12, 2015, 06:29:24 pm »
theres a couple of ways to check valves; im guessing you can get some kind of general reading with a compression test; leak down test, not cheap; disassembling head; having a shop check valves; i take a med/small sheet of glass, not thin, about 10"x10" should do, take valve and lay down on glass(as glass is perfectly flat), roll valve, stem and margin sit on glass as you roll; a bad valve will wobble. of course any valve that has made an impression in piston top is no good; try glass-rolling trick on these and see how it works.

Reply #4April 12, 2015, 10:34:17 pm

vanbcguy

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Re: 1998 Jetta TDI white smoke no start..
« Reply #4 on: April 12, 2015, 10:34:17 pm »
of course any valve that has made an impression in piston top is no good

^^^ This.

Since the valves on these engines are perfectly perpendicular to the piston they tend to 'squash' their stems rather than bend when a timing belt event happens.  Throw a new belt on and the engine runs, you think "Whew, I sure dodged a bullet!" and drive on.  Compression is good, everything is fine right??  The valve still seals since the face is still perpendicular to the seat...

Unfortunately the valve stem that was damaged is now ruined.  It will keep working for a while, often 1,000 miles or more before one day you have a giant BANG and the head drops off the valve.  It then gets crushed in to the top of the piston and in to the head.  Your piston is now ruined, you may have a bent rod and your head is destroyed.  If you're particularly unlucky it's wrecked the cylinder too.  Now what would have been about $15 per valve that was impacted plus a head gasket will cost you a whole hell of a lot more.
Bryn

1994 Jetta - AHU M-TDI - Jezebel Jetta
2004 Jetta Wagon - 1.8T - Blitzen

Reply #5April 22, 2015, 05:04:28 pm

Toby

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Re: 1998 Jetta TDI white smoke no start..
« Reply #5 on: April 22, 2015, 05:04:28 pm »
Resetting the timing was a BIG mistake. Now you have know way of KNOWING whether it slipped or not. Now you are stuck pulling the head and replacing all of the valves at the very least, for the reasons VancBC Guy said. They are only about $100 + gaskets, but it is just money pissed away if you did not have minor crash. If you had CHECKED the timing before you screwed with it you may have saved yourself a lot of grief. Any time you are not absolutely certain about a bunch of things with these motors you are risking catastrophic failure.

« Last Edit: April 22, 2015, 05:06:19 pm by Toby »

 

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