Bypass oil filter, Mk3 Jetta?

Mongler98

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Mar 23, 2011
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
Don't
I've tried quote a few. Too many issues.
The 13k you can get out of the oil change and 20k you get out a filter means you change it once or twice a year. Just trust me. Don't
 

garciapiano

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Feb 12, 2018
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Southern California
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1997 Jetta TDI (1Z)
Apparently the stock large-capacity filter is good for 30k km / 18,000 miles, but given how positively massive it is I usually run them for 20,000 miles at a time. Obviously don’t run the oil that long. I do 10,000-mile drain and fill intervals on mine, changing the filter every other change.
 
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Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
Yep
This is a kinda of pain in the but place to get the filter out and back in, but it's not too bad. I've had worse. But over all it's just a bunch of fittings and hoses that can fail to get it to a place that there is even less room for!
I tried 4 different configurations, hated all of them.
The main issue I had was that there isnt enough room for the fittings to come out of the adapter because of the coolant pump and its pipes for the heat exchanger. I even had one welded up with 90* but the hoses just looked like a mess.
This is one area VW did a good job engineering. Leave it be.
 

clyde

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confluence, Snake/Clearwater
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1998 Jetta, 1959 DeSoto with leopard-skin seat covers
garciaplano, what is the "stock large-capacity filter" you mention? Is it a Mann or some other model?

What engine are you putting in the 944? AHU, ALH, or something else?
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
garciaplano, what is the "stock large-capacity filter" you mention? Is it a Mann or some other model?

What engine are you putting in the 944? AHU, ALH, or something else?
the stock oil filter is the large size oil filters. they are all the same capacity size, meaning that they have larger pleet area. the Mobile one and Mann and Porilator are the top 3 (among a few others as well) that have the largest pleet count. 30K is the limit on most of these but i never trust that, i would never go past 20K on any filters.
I am putting my AHU from my mk3 jetta into a 1984 944. funny enough though that im going with a dry sump oil system to get the engine to clear the sub frame bar. and because racecar!
 

clyde

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confluence, Snake/Clearwater
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1998 Jetta, 1959 DeSoto with leopard-skin seat covers
That makes sense; all the Mk3 diesel filters I have seen are the same size, noticeably larger than the filter for a gas engine.

Just transferred a Dieselgeek bypass filter adapter on a 2003 TDI from one car to another. Very little room, and that bypass filter butts against a couple hoses…
 

Steve Addy

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Iowa
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97 Mk3
The OE filter fitted to the AHU / 1Z was the smaller diameter 840/2 (068115561E) filter. The older diesel engines CR, ME, MF, 1Y etc all called for the larger 940/25 (068115561B) filter, which does fit without any problem, so many just use the larger filter on the AHU/1Z engines too.

For anyone who has multiple VW diesel cars it saves to just stock the larger filter and use it on everything.

Steve
 
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KLXD

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Lompoc, CA
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'98, '2 Jettas
Oil filter on these is a mess. Almost as bad as the Toy trucks.

What I doos is punch a hole in the low point with an ice pick and shove it in and wiggle it around to tear the element. Let it drain along with the oil. No more oil running down the side of the block.

Love the ALH's.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
you know a small sheet of aluminum foil is much simpler. also just let the filter just start to unwind and it drips down the side of it. i never have had more than a few drops on the block. not nearly as annoying as my escape where half the exhaust gets soaked ! again some foil makes a nice work around.
Another tip. go ahead and put the filter on full tight then back it off a little bit, this actually turns the grain of the rubber in the direction it comes off, MUCH BETTER!
 

KLXD

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Idunno. Poking a hole is pretty simple and I don't have a piece of aluminum to hold in place.

Different strokes.
 

Mongler98

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the #1 problem with poking a hole in it is that you MUST remove it. twice that has happened to me that i was trying to do a change and i got called to go to work on an emergency call, for the life of me, i could not get the filter off even with a proper tool. If i had poked a hole in it, i would not have been able to use the car that day. i had to go get a better oil filter wrench with teeth.
I guess its fine if you get the filter spinning first, i would not poke a hole in it otherwise. Like not pulling off the fill cap before draining a diff!
also the foil can be fitted to whatever shape you need, no holding needed.
 

Steve Addy

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Iowa
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97 Mk3
Idunno. Poking a hole is pretty simple and I don't have a piece of aluminum to hold in place.

Different strokes.
Exactly what I do, avoids all the nasty overflow while you're trying to get it unscrewed.

Best thing is to bag it while unscrewing it...and the best bag I've found for that is old bread bags. Big enough to go around the filter but not big enough to bunch up like a plastic grocery sack. And the bread bag plastic is heavier too.

I've always believed that if the filter won't come off then it was either 1) on too tight or 2) the seal was insufficiently lubed before install.

Steve
 

oilhammer

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outside St Louis (where it's safe)
TDI
There are just too many to list....
If you crack the drain plug loose, and let it drain for a while, the filter will siphon itself down enough that you won't make any mess at all. That is what I always did on my own AHU Jetta (running the larger Mann filter). Which is why I never changed the oil on that particular car at the shop, because I couldn't leave it sit on a lift long enough... but at home in the driveway... I let it sit overnight.

Oddly enough, my AWM Passat, which uses the same filter, and is in the same basic orientation, will absolutely NOT ever siphon down low enough to not drip at least some. And it is FAR worse for making a mess, as on the B5s, the filter area is right above the subframe, which is full of holes, so oil leaks down and runs a couple FEET away and dribbles there, too. So on that, I do the bag method, with a rag, and it minimizes any mess.
 

Steve Addy

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Iowa
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97 Mk3
If you crack the drain plug loose, and let it drain for a while, the filter will siphon itself down enough that you won't make any mess at all. That is what I always did on my own AHU Jetta (running the larger Mann filter). Which is why I never changed the oil on that particular car at the shop, because I couldn't leave it sit on a lift long enough... but at home in the driveway... I let it sit overnight.

Oddly enough, my AWM Passat, which uses the same filter, and is in the same basic orientation, will absolutely NOT ever siphon down low enough to not drip at least some. And it is FAR worse for making a mess, as on the B5s, the filter area is right above the subframe, which is full of holes, so oil leaks down and runs a couple FEET away and dribbles there, too. So on that, I do the bag method, with a rag, and it minimizes any mess.
I always drain the pan first, and I've never had it siphon off the filter, always makes a mess, and I let the pan drain completely before going after the filter.

Steve
 

steves96tdi

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If anyone has put a bypass oil filter on a Mk3 Jetta, what filter did you use and where did you mount it?
Here's what i used on my B4, I don't know if you have the same amount of room on the Jetta:
Here's the link to were this came up years ago:
 

Mongler98

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ah yes, yes i would, like i said i tried a few different high end stuff and even made my own and they all where so ugly (like yours, no offence) or just had issues like leaks or too complex.
just more $ you never will have again for no gains whatsoever.
 

Phi1osopher

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Jul 31, 2019
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Austin, TX
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'96 B4V TDI Passat Wagon
Here's what i used on my B4, I don't know if you have the same amount of room on the Jetta:
Here's the link to were this came up years ago:
I have this configuration with the AMSOIL dual bypass oil filter that I have had for decades... I tend to pop it off and put it on each car when I buy and sell them, transferring it from one to another. Had to replace the hoses once 10ish years ago. I love this system, oil analysis always surprised me with how effective it was.

It's currently sitting in the garage, and I have surprisingly have not put it on my B4V. I really should!
 

Mongler98

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Northern MD (HAGERBUSH)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
yet we still see cars getting into the 500+ area almost completely stock. do whatever 1970's hot rod mods you want its your car and your money! i know i've wasted so much on tying to improve a part on a car that had millions of man hours and $ invested into it over the decades by engineers far above my pay grade! what makes you think you know better? just like a cold air intake. that's all i see this as, hood bling! im also guilty of such crimes soo.....
 
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