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Author Topic: 98 Jetta has whitish exhaust especially when accelerating  (Read 2879 times)

November 09, 2014, 10:44:36 am

SR Heer

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98 Jetta has whitish exhaust especially when accelerating
« on: November 09, 2014, 10:44:36 am »
I am thinking of acquiring a 98 Jetta - it blows whitish smoke especially when accelerating ( but at idle it is may just barely be noticeable ) - smoke has a slight grayish or blueish tinge to it but most definitely white and I have been told that white smoke means unburned fuel -correct? However this AHU motor runs smoothly and when I separately crack each B-nut at the injector RPM drops and runs comparatively same as others did -

Is there any way to distinguish between whether it might be the rings or turbo that is allowing oil to bypass?

Everyone says do a compression check - well I have and in cylinders 1-3   I got a compression reading of 450 - in cylinder 4   I got a reading of 550 - so that seems odd - 450 should be good enough to run well and 550 even better but the 100 difference is not understood to be a good thing - now PO did do an in house hone and re-ring or engine bay ring job - I don't think hitting one of the oil squirters with hone would be cause for white smoke but would it be possible that they did not split or clock the rings ends correctly like at 120 degrees from each other? Has anyone ever had a diesel motor bypass oil through rings ends after a ring job without clocking them 120 degrees apart ( resulting in white smoke )?

This AHU motor is timed correctly (blue line) and IQ setting at 4.0 with VAG-COM

I did notice a bit of blow-by at the oil filler cap but nothing extra great and blow-by seen did seem to be a bit bluish there or maybe gray white - I could not tell - I should have had the owner step on accelerator while I watched blow at oil filler cap to see if it blew whitish smoke more or not - if so then I would assume that the problem would be with rings and not necessarily turbo - is the a correct assumption?

Of course it could be both rings and turbo but I am just looking for a way to distinguish between the two.

I also thought of disconnecting and capping the turbo oil line just for a few seconds while motor started and then rev motor to check for white smoke - thinking this might not cause harm just for a few seconds while it ran and accelerated. Everyone is probably going to say "NO" don't do it but if done right while engine is cold it may not be harmful - is this correct - has anyone successfully tried this or anything else before?


97 Passat 1Z, 98 Jetta AHU, 91 Jetta AAZ TD, and 81 Rabbit Pickup

Reply #1November 09, 2014, 11:31:03 am

vanbcguy

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Re: 98 Jetta has whitish exhaust especially when accelerating
« Reply #1 on: November 09, 2014, 11:31:03 am »
The turbo will get destroyed quite quickly without oil, it's bearing basically IS the cushion of pressurized oil running through it. As soon as there is any sort of damage to its shaft or journal it is DONE.

Bryn

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

Reply #2November 09, 2014, 05:25:01 pm

air-cooled or diesel

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Re: 98 Jetta has whitish exhaust especially when accelerating
« Reply #2 on: November 09, 2014, 05:25:01 pm »
white exhaust can also be water; although it sounds like its a problem possibly with him honing. why would you hone a 98, how many miles on it? you dont hone unless you have a big enough ring ridge you need to, like i have 800k miles on one of mine and i didnt have to hone, id be careful of buying, or reduce price and expect to have to work on it to get it right. the hone job may have ruined the block, unless you overbore it and put over-sized pistons in.

Reply #3November 10, 2014, 12:00:07 pm

libbydiesel

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Re: 98 Jetta has whitish exhaust especially when accelerating
« Reply #3 on: November 10, 2014, 12:00:07 pm »
Is there air in the clear line to the injection pump?

 

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