1997 passat smoke

Mrmolasses

Well-known member
Joined
Jul 18, 2023
Location
Pa
TDI
None
i just bought this 1997 passat and i swear this just started once i brought it back home on a car dolly where it will have a big puff on start up and free rev especially when cold so im concerned now its the oil control rings i know its not the turbo leaking. this car starts perfectly and runs great and it does not smoke at idle. any ideas? i hope i didnt get scammed lol
 

jdulle

Veteran Member
Joined
Feb 4, 2017
Location
Ithaca, NY
TDI
96 B4, 97 B4
A lot of these smoke a bit for the first minute or two after startup. It helps to have new glow plugs, verify that they are getting power, etc.
 

TDeanI

Veteran Member
Joined
Oct 14, 2007
Location
Bremerton WA
TDI
'97 Passat TDI Wagon w/ 286K mi.
Blue smoke at start up is a sign of bad valve guide seals. Oil trickles down past the seal and down the valve shaft when motor is off and is instantly burned up at startup It’s such a slow oil leak the motor has to be off awhile before enough accumulates to show blue smoke at startup. Pretty common on high mileage motors. If blue smoke goes away quickly it’s not a concern.

black smoke is over fueling and a different problem.
 

Mrmolasses

Well-known member
Joined
Jul 18, 2023
Location
Pa
TDI
None
A bit more detail here might narrow things down a little: "free rev" as in a high idle, or accelerating all on its own, or ??
especially under high throttle but less on slow rev up and seemly goes away when completely up to temp
 

jdulle

Veteran Member
Joined
Feb 4, 2017
Location
Ithaca, NY
TDI
96 B4, 97 B4
Have you checked the glow plug system? It's easy to check the resistance of each glow plug and then check that you are getting power to the tips of the harness. This reduces smoke in the first couple of minutes. I would just start driving after idling for 20 sec or so. All of the ones I have had make smoke for the first couple minutes when cold. If its above 60 or so there is usually no smoke. Also it helps slightly to wait a couple of seconds after GP light goes out, because apparently the gp's stay on for a few seconds afterward. If it goes away after 2 minutes of driving I wouldn't worry about it.
 

Chungus

Veteran Member
Joined
Jul 23, 2022
Location
Vancouver
TDI
B4 Wagon
Thick white smoke is unburnt diesel. I would check either timing or compression. Glow plugs shouldn't cause an issue after the car has already started. I filled an entire 2 car garage with thick white smoke trying to start my car with the timing out to lunch
 

alanack

Veteran Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
My car ran fine with timing super advanced and/or retarded. If the timing is that far retarded the car will be very difficult to start.

A bad turbo will smoke like hell and smell like oil..

If compression was low the car would be difficult to start.

Older diesels will smoke a little bit no matter what, and this becomes more pronounced as injectors get old
 

jdulle

Veteran Member
Joined
Feb 4, 2017
Location
Ithaca, NY
TDI
96 B4, 97 B4
I am pretty sure the glow plugs continue to heat once the engine is running until it is up to a certain temperature to reduce smoke.
That is a good point on the timing, I should probably check timing on my silver car though just to make sure it is ok.
 

alanack

Veteran Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
It may be the timing. The crank sprocket on these are known to walk (move), which will retard the timing causing the issue you describe, and it goes away when up to temperature.
Crank sprocket issue was fixed for the 1Z engine.

You will notice other issues before the timing gets thrown out of wack from a loose crank gear
 

alanack

Veteran Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
Fixed, but only partially. The "D" snout was an improvement over the AAZ key notch, but the "D" still does get worn out.
Personally I think the gear gets beat up first.

AHUs band-aid was the clutch on the alternator to prevent them from getting thrashed.

ALH actually had the fix iirc
 

volksguy

Veteran Member
Joined
May 29, 2003
What was the recommendation on replacement of the crank gear?
Some thing like after one hundredth and fifity thousand miles?
Or when the 3 timing belt change is due if i recall.
Any chance this so called 1997 passat still has the BK ECU With the fifth injector operating?
That would account for the start up smoke.
And what the
ALH fix??
 

alanack

Veteran Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
There is no replacement interval. If you notice the Damper wobbling replace it.

In my own experience they only have problems when someone doesn't follow the torque procedures, uses an impact on it, fails to replace strech bolt ext.
Example.
Non car person takes the car to a general mechanic and they screw it up. Owner doesn't pop their hood because they aren't a mechanic. No body knows its loose wobbling away...

4cyl diesels arent very balanced and pulsation combined with Belt drive issues can cause the bolt to work loose which then wrecks havoc.

Someone replaced my front main seal at some point and reused the bolt, didn't torque it correctly and it started wobbling.

If you keep an eye on it you won't have an issue.
 

Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
Crank sprocket issue was fixed for the 1Z engine.

You will notice other issues before the timing gets thrown out of wack from a loose crank gear

There is no replacement interval. If you notice the Damper wobbling replace it.

If you keep an eye on it you won't have an issue.
Yeah, not so much. I have seen and repaired a number of the crank gears moving on the 1Z/AHU. They may have changed the engineering, but it is anything but a ”fix”.

And no, you won’t notice other items out of whack before the timing starts moving. It doesn’t take a lot of movement to throw the timing off enough for hard and smoky starts. Often times people will attribute it to injectors or some other issue. There is tons of documentation on here about it.

If the dampener is wobbling, then it’s due to a bad dampener and not the crank sprocket. The crank sprocket does not move around enough to notice or even determine without the timing tools. Every one I have diagnosed and corrected never showed other issues but the crank sprocket was hammered when inspected upon removal.

There is no “keeping an eye on it” since you can’t see it happening. There is only the symptoms to go by that may point to the issue. When diagnosing problems on a TDI I always start with the basics: timing, fuel, air. The first has always revealed any crank sprocket issues.
 

alanack

Veteran Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
Im not making stuff up up. Im explaining exactly how it went down for me.

i dont think the crank sprocket is really a problem, unless something else screws it up.
 
Top