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VW MKIV-A4 TDIs (VE and PD) This is a general discussion about A4/MkIV Jetta (99.5-~2005), Golf(99.5-2006), and New Beetle(98-2006). Both VE and PD engines are covered here.

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Old March 2nd, 2018, 12:12   #1
Join Date: Jan 2018
Location: California USA
TDI(s): 2002 Jetta
Default Strong diesel smell after replacing 3 IP seals.

The short story:
I recently replaced the top cover seal, the quantity adjuster seal and the Viton seal. Visual inspection reveals no leaking what-so-ever. Yet, after 10 minutes of driving, the diesel smell is so bad my eyes will water up.

The long story:
I recently purchase a 2002 Jetta TDI that had been run exclusively on bio diesel for the past 4 years. The owner warned me that if I switched to regular diesel, the injector pump would most likely leak. Hence I prepared myself, read this post (http://forums.tdiclub.com/showthread.php?t=287336) and bought both a Bosch kit and a Viton seal.

Sure enough, at about 1000 miles, it started to leak from the top and/or bottom seal. I quickly replaced two of the seals (not the Viton), adjusted IQ and was on the road again. As far as I could tell, no more leaks. Alas, not all was well. I drove the Jetta to South Lake Tahoe on a VERY cold weekend (10 degrees overnight) and lo and behold, the next day I had a leak from the right side of the pump. A BIG leak. It was not dripping, it was flowing.

So I towed it home (AAA rules) and set to work on it. I replaced the seal with a Viton seal as many threads here recommend that. Note that even though I did not have to remove the top cover or the adjuster, I did anyhow to avoid spilling too much diesel. After IQ adjustment, the car seemed fine once again. (Could this have damaged the top and bottom seals? I doubt it.)

At first I thought the diesel smell was just a side effect of having had diesel spilling for a while. I was hoping it would go away soon enough. It has been over two weeks (about 400 miles) yet the smell remains and I am fairly sure that it gets worse the longer I drive it.

I've not spent too much time under the hood since the Viton replacement, but a quick peak after driving it does not reveal any wet spots. (I do however have to clean the engine, will do that this weekend.)

So my questions are:

1. Are there other seals I may have to replace (do to switching from bio to regular diesel)?
2. Or is it normal for the smell to remain for such prolonged periods of time.
3. Aside from a visual inspection, are there other test I can run.

Extra notes:
In lieu of purchasing the Metalnerd Socket, I just took a dremmel to the head and turned it into a regular screwdriver head. Took some skill to take it off, but now I can readily take off and put it back on.
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Old March 2nd, 2018, 12:16   #2
Join Date: Jan 2018
Location: California USA
TDI(s): 2002 Jetta

Oh, I forgot to mention, when I was cleaning around the pump with brake fluid, I may have seen bubbles coming from where one of the glow plugs screws into engine. (Additionally, I have a bad glow plug #2 as per code reader.) Possibility exists that it is not tight all the way as previous owner recently replaced it. Could gaseous diesel be escaping through here? Hence the reason engine is dry but smell gets worse when driving... hmmm.... these are the thoughts that keep me up at night.
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Old March 2nd, 2018, 12:46   #3
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Join Date: Dec 2004
Location: Houston, Texas
Fuel Economy: 52/45/40

How's your fuel economy seem? Noticeably worse? Maybe you have a leak.
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Old March 2nd, 2018, 12:54   #4
Join Date: Jan 2018
Location: California USA
TDI(s): 2002 Jetta

Fuel economy went from 43 MPG to 38 MPG. But I attributed that to all the diesel that was spilled. If I do that math, that's about 1.7 gallons worth of spilled diesel. Which is a lot. But definitely possible if I had the leak on my drive to Tahoe.

To really know, I would have to refill again, and that's 600 miles in the future. Too long to go with the smell.
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Old March 2nd, 2018, 13:17   #5
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Join Date: Aug 2009
Location: Lompoc, CA

Did you feel under the pump head for any wetness?

Could be the shaft seal or the "cold start" solenoid but why the smell now and not before? Seems to me it's most likely that your head seal change was unsuccessful. O-ring might have been damaged.

Did you change the o-ring on the big plug between the delivery valves on the pump head?
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Old March 2nd, 2018, 13:34   #6
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Join Date: May 2010
Location: Beaverton, ON

If you have bubbles from a glow plug that could definitely be an issue, the old owner may have done a replacement and stripped the hole, put a new plug but not sealed it 100% and sold it for that reason.

I cant offer much on the IP itself as I have never changed those seals.
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Old March 2nd, 2018, 13:48   #7
Join Date: May 2004
Location: central Ohio
Fuel Economy: 50/45/35

You should be able to see the leak, remove lower cover, use mirrors if you have to.
I thought pumps only reacted badly when switched from D2 to bio.
Do you know the mileage on the pump? If it's real high you might consider sending it up to DFIS in Oregon for a rebuild. They are expensive.
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Old March 2nd, 2018, 14:50   #8
Join Date: Jan 2018
Location: California USA
TDI(s): 2002 Jetta

Originally Posted by KLXD View Post
Could be the shaft seal or the "cold start" solenoid but why the smell now and not before?
Now that you mention it, there has always been a smell to it. But when running bio, it smelled like a Chinese wok. (A rather pleasant smell.) But I am sure that smell accompanies all engines running bio. (I had a Mercedes a long time ago that I ran on bio and it smelled delicious.)

Last edited by ezjamm; March 2nd, 2018 at 15:18.
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Old March 5th, 2018, 00:09   #9
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Join Date: Oct 2016
Location: CA
Fuel Economy: 42mpg

I had a fuel line leak that made my eyes sting after a few seconds on the street, fuel was everywhere. I would imagine you could see the spilled fuel somewhere. Nothing looks shiny/oily? Did you hose it all down with brake cleaner?
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Old March 5th, 2018, 01:00   #10
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Join Date: Oct 2012
Location: Kitchener, ON

Originally Posted by BobnOH View Post
I thought pumps only reacted badly when switched from D2 to bio.
Seal's don't like change. If your pump only ever ran on ULSD, it would probably leak shortly after switching to LSD. Same with Veggie, Bio, etc.
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Old March 5th, 2018, 06:59   #11
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Join Date: Oct 1999
Location: Conkud, New Hampshiyuh, USA
Fuel Economy: pretty freakin' good.

Bubbles around a glow plug base indicate 2 things: 1) the glow plug is not sealed well in the threads, and 2) there is fuel (or some other liquid, but fuel is the most likely) around the glow plug base.

First things first: the glow plug threads in the head are aluminum. Some people really shouldn't do their own work, and if a ham-fisted owner or mechanic worked on them, it only takes the strength of a 4-year old to strip the threads. They are aluminum and fine, so 11 ft-lbs is it. Not much, really. Did the previous owner clean the threads and seat before replacement? You can figure that if it is leaking now, you'll need to check it. If it is leaking while the engine is warm, then you can be assured the threads are getting packed with carbon. You need to find someone with the proper tool if you don't already have one to clean the threads, then clean the glow plug seat, then properly seat the glow plug so that it won't leak anymore. And don't over-torque it or you have an expensive problem on your hands.

Second: the fuel. There are 2 sources for a fuel leak right there: the injector hard line sealing nut, or the fuel return hose. You should be able to see if the hard line nut and the hard line are working well with the injector as the fuel will be leaking from underneath it. The fuel return line is the fabric covered line, particularly if it is original it would be wet if it is leaking. Replacement line looks just like vacuum line, but vacuum line won't last on exposure to diesel. Make sure you get the correct kind of line here. Unfortunately, I'm not so sure you can always trust VW dealer parts people, so question them until they roll their eyes and then ask the other parts guy if the first one rolls their eyes immediately on the first question. Or go to one of this forum's vendors since they're more concerned with getting it right the first time.

My wife's NB was leaking fuel - it turned out it was the fuel cutoff solenoid o-ring. But that one showed a wet pump case, so it probably isn't your problem.

Good luck,

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Old March 7th, 2018, 02:10   #12
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Join Date: Dec 2014
Location: PNW

Just follow ^^^. I suspect fuel return lines. GP issue is possibly serious: but generally you'd have more exhaust smell rather than raw fuel smell.
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