Author Topic: How to disable your 1.6TD's blow off valve  (Read 45150 times)

December 02, 2005, 11:59:07 pm

fspGTD

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How to disable your 1.6TD's blow off valve
« on: December 02, 2005, 11:59:07 pm »
Note: this procedure can be done with the blow off valve removed (as shown) or with it mounted on the engine.

Step 1: using a flat-head screwdriver, unscrew the brass pressure adjuster completely from the center of the blow off valve and temporarily set it aside.  Permanently remove the spring that's behind it:


Step 2: Get a 6mm allen-head bolt of about 20mm total length (from tip to tip.)  You can hacksaw or grind down the threaded end if the bolt is too long.  Also sand the OD of the bolt head if necessary so that it fits down and into the hole of the blow off valve:


Step 3: Install the bolt and make sure it seats down all the way squarely.  The protrusion that was underneath the spring should now engage into the allen recess of the bolt head.


Step 4: Screw the slotted-head adjusting plug back in over the bolt.  Only light torque is needed.  From the point where it touches the bolt, only add about 1/4 of a turn.  Cranking it down with excessive torque unnecessarily strains flimsy plastic and rubber parts of the blow off valve.


If you stick you finger down into the hole from the intake manifold side and aren't able to move the rubber diaphgram with a good push, it should be good to hold about as much boost pressure as you can spool at it.  :twisted:


Jake Russell
'81 VW Rabbit GTD Autocrosser 1.6lTD, SCCA FSP Class
Dieselicious Turbocharger Upgrade/Rebuild Kits

Reply #1December 03, 2005, 01:05:13 am

dubCanuck1

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How to disable your 1.6TD's blow off valve
« Reply #1 on: December 03, 2005, 01:05:13 am »
So, why would you want to disable your BOV? Isn't this designed to relieve potentially damaging pressure build up under undesirable engine load times?

Reply #2December 03, 2005, 01:17:34 am

jtanguay

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How to disable your 1.6TD's blow off valve
« Reply #2 on: December 03, 2005, 01:17:34 am »
Quote from: "dubCanuck1"
So, why would you want to disable your BOV? Isn't this designed to relieve potentially damaging pressure build up under undesirable engine load times?


Only if the wastegate stopped working.  Plus the BOV opens at around 12 PSI, which makes boosting above that impossible.  Only in a gasoline powered car would this be a big mistake  :)


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Reply #3December 03, 2005, 01:20:36 am

dubCanuck1

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How to disable your 1.6TD's blow off valve
« Reply #3 on: December 03, 2005, 01:20:36 am »
And now I know.....

Reply #4December 03, 2005, 01:28:34 am

DVST8R

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How to disable your 1.6TD's blow off valve
« Reply #4 on: December 03, 2005, 01:28:34 am »
As always Jake, you bring diy to a whole other level. Keep it up  :D

dubCanuck1, not to worry, I asked the same question like 3 or 4 years ago on the old hostboard when I was starting out, its a bit of a learning curve but its worth it.
The Brett of the board...



The Dark Side of Beauty.[/i]

Reply #5December 03, 2005, 01:28:05 pm

jtanguay

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How to disable your 1.6TD's blow off valve
« Reply #5 on: December 03, 2005, 01:28:05 pm »
Quote from: "libbybapa"
A couple of weeks ago I used the exact same method except instead of a bolt I used an aluminum spacer of the correct diameter and length from the hardware store.  Worked like a charm.  I also screwed the wastegate closed on my K14 and the boost jumps right up to 17 psi.  What a joy, except now I'm having tranny trouble. :cry:

Andrew


I was having huge tranny trouble on my car...  So I had the transmission oil changed and after a few trips it was easier to put into gear, and the shifter was a lot looser in cold weather :D  I guess 380'000km on the tranny with no oil change will do it  :lol:


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Reply #6December 03, 2005, 02:44:44 pm

fspGTD

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How to disable your 1.6TD's blow off valve
« Reply #6 on: December 03, 2005, 02:44:44 pm »
There are definitely a few ways to disable the 1.6TD blow-off valve...

* You can use a plug that replaces the blow-off valve.  It also nicely cleans up the engine compartment a bit:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=107
http://www.vwdiesel.net/phpBB/viewtopic.php?t=2511&start=2

* You can block off the blow off valve outlet...
...by capping it with an appropriately-sized rubber cap:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=781

...or by plugging it with the cut-off end of a broomstick handle:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=346

* You can swap to an eco-diesel intake manifold, which doesn't have the blow off valve.
Jake Russell
'81 VW Rabbit GTD Autocrosser 1.6lTD, SCCA FSP Class
Dieselicious Turbocharger Upgrade/Rebuild Kits

Reply #7December 06, 2005, 07:34:01 pm

mk1vdub

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How to disable your 1.6TD's blow off valve
« Reply #7 on: December 06, 2005, 07:34:01 pm »
I wanted to keep mine active as I thought vw probably put it there for a reason, so I just put a slightly stiffer spring in and screwd it down untill I got the desired blow off pressure, it now blows at around 1.3 bar with my manual boost controller set at 1.2 bar so it will still work if theres a problem - just as easy as disabling it and I get peace of mind :)

1983 mk1 golf GTD
1980 mk1 scirocco Gli, in bits, in the garage, awaiting full restoration

Reply #8December 07, 2005, 02:34:39 pm

89VWdieselGolf

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How to disable your 1.6TD's blow off valve
« Reply #8 on: December 07, 2005, 02:34:39 pm »
Quote from: "mk1vdub"
I thought vw probably put it there for a reason


HA :roll:

Reply #9December 10, 2005, 04:33:24 am

zagarus

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How to disable your 1.6TD's blow off valve
« Reply #9 on: December 10, 2005, 04:33:24 am »
so by disabling the BOV, you get more boost?  So if i did this to a very very stock 1.6TD, what exactly would be the outcome?
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Reply #10December 10, 2005, 12:16:49 pm

VWRacer

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How to disable your 1.6TD's blow off valve
« Reply #10 on: December 10, 2005, 12:16:49 pm »
Quote from: "zagarus"
so by disabling the BOV, you get more boost?

No. The BOV is a safety device in case the wastegate fails. As noted elsewhere, only adding more fuel will increase boost.
Quote
So if i did this to a very very stock 1.6TD, what exactly would be the outcome?

You would not see any change with this mod alone. According to my Bentley, the stock boost for a 1.6TD is 0.64-0.72 bar (9-10 psi), while the BOV opens at 0.81-0.86 bar (11.5-12.2 psi), so you can see that there is no point in disabling the BOV on a stock 1.6TD.

The only reason to disable the BOV is to allow boost pressures greater than stock, and the only way to get more boost is to add fuel.

See the many threads on how to add fuel...  :D
Stan
C-Sports Racer

Reply #11December 10, 2005, 12:51:33 pm

VWRacer

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How to disable your 1.6TD's blow off valve
« Reply #11 on: December 10, 2005, 12:51:33 pm »
Andrew, what you describe is TWO changes, not one. I did exactly what you describe to my Quantum and saw a rise in max boost of 2 psi (from 10 to 12 psi), but no difference to performance on my G-Tec. In other words the engine was burning a bit cleaner (more air for compustion from a little more boost), but because no additional fuel was introduced there was no increase in performance.

But my answer to Zagarus remains that just blocking the BOV (with NO other mods) will change nothing.
Stan
C-Sports Racer

Reply #12December 10, 2005, 01:05:03 pm

zagarus

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How to disable your 1.6TD's blow off valve
« Reply #12 on: December 10, 2005, 01:05:03 pm »
so since stock boost is below the release valve of the bov, there is no familiar air discharge that is common with turbo cars right?  So by adding more fuel and therefore increasing boost above the specified 12-13 psi, the bov would then acutally be used, and that sweet sweet sound of a bov would be heard?
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Reply #13December 10, 2005, 01:24:48 pm

vwmike

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How to disable your 1.6TD's blow off valve
« Reply #13 on: December 10, 2005, 01:24:48 pm »
Quote from: "zagarus"
so since stock boost is below the release valve of the bov, there is no familiar air discharge that is common with turbo cars right?  So by adding more fuel and therefore increasing boost above the specified 12-13 psi, the bov would then acutally be used, and that sweet sweet sound of a bov would be heard?


I think you have this pop valve confused with a blow off valve on a gas car. It will never make a "sshhhhhhhhh" noise like a gas car because there is no throttle body. Since engine speed is regulated by fuel there is no throttle body and therefore no throttle to slam shut between shifts and cause a back-up of boost pressure which would then be the spike vented when the blow off valve opens. If boost were increased past the breaking point it would simply open and vent the excess boost back into the intake making whatever you did a waste of time.

Reply #14December 10, 2005, 01:28:25 pm

VWRacer

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How to disable your 1.6TD's blow off valve
« Reply #14 on: December 10, 2005, 01:28:25 pm »
Quote
So by adding more fuel and therefore increasing boost above the specified 12-13 psi, the bov would then acutally be used, and that sweet sweet sound of a bov would be heard?

Strictly speaking, no.

That's because if you merely add fuel you will cause the wastegate to open first, bleeding off excess boost before it gets a chance to open the BOV. The "sweet sound" you seek occurs in turbo'd gassers when the throttle closes suddenly as the driver lifts off the go-pedal during gear shifts. We don't have throttles, so the sound of the BOV opening will be masked by the engine noise at full power, and you will never hear it.
Stan
C-Sports Racer

 

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