DISA Valve repair kit

Registered to subscribe to this thread, we did a temporary repair on a broken DISA valve on his 330Ci yesterday (involving a self tapping screw and some glue) which fixed the P0171 and P0174 system too lean codes immediately.

As @BikesStillRule noted, our unit was in perfect condition apart from the nylon part which fits in the bottom of the flap which had sheared completely of which a worrying amount was missing..

This looks like a much better option than stumping up for a whole replacement unit that could just fail again. I'm in the UK too so would definitely be interested in a kit if/when you can produce them.

I'm keen to get on this too!!
Is there a downside to the steel pin/bolt versus the titanium, if the titanium is going to be a hold up?
My DISA is clean and working but there is a small amount of play evident in the mechanism/flap, from what I remember.

Originally Posted by BikesStillRule

For those of you that have viewed my M52-M54 engine build and swap forum you know I posted there that I was working on internal replacement parts for a cost effective and long term fix for the DISA self destruct syndrome. Here is what I posted there plus the CAD models of the new internal replacement parts.







The 1st pic is of the flapper valve and lever arm that rotates the flapper valve. As you can see the end of the flapper valve has a hex shaped hole in it. The section of the lever arm just past the pointed and slotted end has what's left of a hex shape O.D..

In my opinion, the reason these fail is due to the following:

> Because the 2 parts are injection molded they need draft (taper) in order to release from the mold.

> Because of the draft on the ID of the hex hole and the OD of the hex section of the lever; and the allowance for manufacturing dimensional tolerances, the 2 pieces have to be made with a clearance in their fit together.

> The code PA66 GF30 on the flapper valve means it's made of 30% glass filled nylon.

> The code PA66 on the lever arm means it's made of just nylon, without glass fill.

> Because there is clearance between the 2 parts in their assembled state, and because there are strong pressure pulses inside the intake manifold, these 2 pieces vibrate against each other during normal operation.

> Once the nylon starts to wear a little, the tiny glass fibers in the flapper valve start to become exposed. Since the lever arm is plain nylon, the exposed fibers in the flapper valve start to wear it away, then it's all down hill from there. The lever arm was most likely not made with glass fill because it would eat up the sleeve bearing and seal that it rides in. I have seen this same erosion in other parts where a glass filled plastic moves or vibrates against a non-glass filled plastic.

My solution will be to machine both pieces out of aluminum, then anodize them for wear resistance. They will be made in such a way that they lock solidly together once assembled, and indexed so that the flapper valve is slightly preloaded against the rubber sealing lip inside the housing when in its closed position to prevent vibration.


New aluminum parts view 1.


New aluminum parts view 2.


New aluminum parts cutaway view showing fitment of the pieces.

A few things to note about the new design:

1) The new aluminum parts will be stronger than the OEM plastic parts.

2) Since all the internal parts lock solidly together they cannot vibrate against each other and erode like the stock pieces.

3) Since a worn and freely flapping about flapper valve is the most likely cause of the internal supporting framework breaking; if a current DISA valve still has a solid internal support structure, there should be no reason for it to break in the future.

4) Since the flapper valve is screwed to the lever arm, and since the lever arm can't get pulled through it's support bushing, even if the internal support framework were to break the flapper valve would remain captive. No possibility of parts running amuck inside the engine.

5) Same concept applies to the pivot pin on top of the flapper valve; it will be screwed and thread locked to the valve. With the OEM design the stock steel pivot pin is just pushed into the plastic flapper valve and falls free in the event of failure.

I hope to machine the first set within the next week. If everything goes to schedule I hope to be able to offer a repair kit in about 2 weeks. The kit will include all parts shown plus detailed instructions, a new O-ring seal and a mini tube of red thread lock. This should be a very easy DIY repair.

All feedback welcome.

Feedback.... Not so sure your solution is a good one. (note I stated not sure) first off, clearly the system works of resonance which will result in vibration on the flapper valve. The materials (and weight) your using are different than the materials used by BMW. Could be a good thing, or could be a very bad thing resulting in destructive vibration that tears the unit apart. Second, I believe the bearing point of the pin holding the valve is the valve itself. Yours is using the DISA body assembly as the bearing point. This may result in excessive wear of this area as it may have never been designed to function as a bearing point. Note I have stated "could", "may". I do not have any evidence that any of these issues could be a problem.

This aside, kudos to your engineering and prototyping of this. Quite cool!!

we can always have some pioneers which can buy and use this staff
then we will have a real Feedback
subscribed

I will be a test pilot.

As far as I am concerned, BMW are totally inept with material choices (rubbers, composites and plastics that fail), so I would gladly follow this man's ideas with more faith.

Originally Posted by gtxragtop

Feedback.... Not so sure your solution is a good one. (note I stated not sure) first off, clearly the system works of resonance which will result in vibration on the flapper valve. The materials (and weight) your using are different than the materials used by BMW. Could be a good thing, or could be a very bad thing resulting in destructive vibration that tears the unit apart. Second, I believe the bearing point of the pin holding the valve is the valve itself. Yours is using the DISA body assembly as the bearing point. This may result in excessive wear of this area as it may have never been designed to function as a bearing point. Note I have stated "could", "may". I do not have any evidence that any of these issues could be a problem.

This aside, kudos to your engineering and prototyping of this. Quite cool!!

Excessive wear on a part that was 1/2 - 3/4 through its expected lifespan, versus a destructive failure that wrecks your engine?

Hmmm.

Feedback.... Not so sure your solution is a good one. (note I stated not sure) first off, clearly the system works of resonance which will result in vibration on the flapper valve. The materials (and weight) your using are different than the materials used by BMW. Could be a good thing, or could be a very bad thing resulting in destructive vibration that tears the unit apart. Second, I believe the bearing point of the pin holding the valve is the valve itself. Yours is using the DISA body assembly as the bearing point. This may result in excessive wear of this area as it may have never been designed to function as a bearing point. Note I have stated "could", "may". I do not have any evidence that any of these issues could be a problem.

Thanks, I appreciate all feedback, positive or negative.

1) With regard to bearing pivot point, the stock unit has a steel pin pressed into the flapper valve and the body has a pressed in PTFE or moly coated bearing supporting the pin. The pin rotates within the body, not the flapper valve, and my design does not change that.

2) I agree that the new ass'y will be heavier. That is the reason for going with a much more expensive custom 'titanium' pivot screw (The CAD pictures you referenced here are the Rev 1 not Rev 2 pictures that were posted later). Another point to note is that the stock steel pin is 4mm (.157") in diameter, and the bearing I.D. is 4.37mm (.172"), leaving a pin to bearing clearance of .015". My design reduces that clearance to .002"-.003", which drastically reduces room for vibration between the pivot and bearing. I have checked 2 used (8 years old) and 1 brand new unit and the bearing I.D. is consistent, so I feel comfortable closing up this clearance.

3) The valve spends 90% of it's life in the closed state (low to mid RPM part throttle driving) where the flapper is fully seated against the silicone seal molded into the DISA frame work. In it's closed position all vibrations of the flapper will be damped.

4) The DISA ass'y has a molded in silicone seal around the perimeter of the frame work which dampens vibrations transmitted into it by the valve to the larger mass of the intake manifold.

5) I have a bunch of electronic test equipment here and we plan on testing the ass'y to see if it has any strong resonances that fall within frequencies generated by the motor (2000-6000rpm = 100-300 Hz).

I've spent a considerable amount of time trying to anticipate all failure modes and have had the design reviewed by another engineer. That being said, if anyone sees any other potential problems, please post them for consideration before this goes into production.

Thanks again to everyone who is supporting this project.

subscribed

And they say Americans have become fat, stupid, and lazy.

Originally Posted by BikesStillRule

Thanks, I appreciate all feedback, positive or negative.
I've spent a considerable amount of time trying to anticipate all failure modes and have had the design reviewed by another engineer. That being said, if anyone sees any other potential problems, please post them for consideration before this goes into production.

Thanks again to everyone who is supporting this project.

I have a old DISA, pulled this past summer, and the new replacement unit. I have total faith in you and I am willing to try your design out on my older unit.
Anyway, I am totally supporting your project. I don't think the DISA with the improved flapper will destroy itself.
The vibration might be an issue, but your design (i think) is fixing it, because of the material and the gap mitigation.
I know only a bit about vibration, but enough to state that it's a major pain in my work environment (oil & gas wells drilling). Downhole vibrations kill very robust tools made out of some very exotic steels.
The original flapper does not fail due to vibration (in my opinion) but merely due to the material incompatibility which in turn will fail after so many cycles. The DISA fails due to cheap parts made to last as long as the car is under manufacturer warranty. Just like too many parts - CCV comes to mind, or cooling to mention the heavy hitters. Cup holders are just an annoyance.

Originally Posted by doru

I have a old DISA, pulled this past summer, and the new replacement unit. I have total faith in you and I am willing to try your design out on my older unit.
Anyway, I am totally supporting your project. I don't think the DISA with the improved flapper will destroy itself.
The vibration might be an issue, but your design (i think) is fixing it, because of the material and the gap mitigation.
I know only a bit about vibration, but enough to state that it's a major pain in my work environment (oil & gas wells drilling). Downhole vibrations kill very robust tools made out of some very exotic steels.
The original flapper does not fail due to vibration (in my opinion) but merely due to the material incompatibility which in turn will fail after so many cycles. The DISA fails due to cheap parts made to last as long as the car is under manufacturer warranty. Just like too many parts - CCV comes to mind, or cooling to mention the heavy hitters. Cup holders are just an annoyance.

What are you talking about, the CCV is designed to fail annually...!

Unfortunately ...
The CCV soooo needs to be re-designed, or deleted...!

Originally Posted by Jason5driver

What are you talking about, the CCV is designed to fail annually...!

Unfortunately ...
The CCV soooo need to be re-designed, or deleted...!

There should be a way of using a "regular" 5 bux PCV valve that dumps the oil in a catch-can, which in turn release the oil via the dip-stick guide, and the gases back in the intake manifold. There are a few posts that have something similar (Poolman I think or was it Fudman? has a catch can in his), the thing I am not sure about a "home-made" design is the correct opening-closing pressure of the PCV valve.
Basically Have a hose from the Valve cover just how the OEM design is, that hose attaches to a PCV valve. From the PCV valve, another hose into a catch can (there are some nice and expensive models on the web). The catch can then releases the oil into the dipstick and the gases back into the intake manifold - the OEM has 2 lines. Not sure if you would need 2 lines with the "home-made" design?

With this method, all your CCV maintenance would be the normal PCV change every 30 k miles or for 5 bux. I would also place the PCV valve at the top somewhere, where you could change it in 2-3 minutes. If this "home-method" could work.

Deleting the CCV/PCV is not a good idea.

Originally Posted by doru

There should be a way of using a "regular" 5 bux PCV valve that dumps the oil in a catch-can, which in turn release the oil via the dip-stick guide, and the gases back in the intake manifold. There are a few posts that have something similar (Poolman I think or was it Fudman? has a catch can in his), the thing I am not sure about a "home-made" design is the correct opening-closing pressure of the PCV valve.
Basically Have a hose from the Valve cover just how the OEM design is, that hose attaches to a PCV valve. From the PCV valve, another hose into a catch can (there are some nice and expensive models on the web). The catch can then releases the oil into the dipstick and the gases back into the intake manifold - the OEM has 2 lines. Not sure if you would need 2 lines with the "home-made" design?

With this method, all your CCV maintenance would be the normal PCV change every 30 k miles or for 5 bux. I would also place the PCV valve at the top somewhere, where you could change it in 2-3 minutes. If this "home-method" could work.

Deleting the CCV/PCV is not a good idea.

My thoughts were to run a hose from the intake manifold/ air distribution piece, to a check valve (PCV), then another hose from the PCV to the valve cover.
Then, cap the drain pipe that connects to the dipstick, or find another dipstick tube that does not have that drain pipe incorporated in the dipstick tube base (540i/M5 dipstick tube?)...
Hence, replacing the PCV would be old-school maintenance, as it should, not over-engineered, and designed to fail (what emissions...?)...

What are you talking about, the CCV is designed to fail annually...!

I don't want to speak too soon but..... we have had several design reviews about the CCV issue, so look for some re-design ideas coming in the next month. Current direction is an easily serviceable unit that requires minimal amount of labor. Problem is all of this stuff is keeping me from progressing on my M54 engine build.

Originally Posted by BikesStillRule

I don't want to speak too soon but..... we have had several design reviews about the CCV issue, so look for some re-design ideas coming in the next month. Current direction is an easily serviceable unit that requires minimal amount of labor. Problem is all of this stuff is keeping me from progressing on my M54 engine build.

Too bad we live so far apart. I would come daily to your garage to help (or vice-versa).
Maybe there are some forum members close to you that wouldn't mind spending a few Hrs/week for a good cause?

Originally Posted by BikesStillRule

I don't want to speak too soon but..... we have had several design reviews about the CCV issue, so look for some re-design ideas coming in the next month. Current direction is an easily serviceable unit that requires minimal amount of labor.

OH, no you di'int!!

I'll keep my eyes open for this one, too.

I'm very interested in this proposal. However, what will be done to incorporate a seal between the two components or did I miss that part?

I've had several people PM me on when this kit will be available, so here is an update for everyone.

Six sets of the machined parts (now rev-3) should be ready by the end of the week. I'm working on the last of the fixturing tonight.

The ETA on the custom titanium screws is mid February.

I still need to make detailed instructions with good step by step pictures.

Vibration testing (checking for any destructive resonances) will happen as soon as the Ti screws arrive.

A realistic date for a fully vibration tested kit with detailed instructions ready to ship is the end of February.

I would be willing to send out some kits with stainless steel versions of the screw and written instructions under the understanding that no vibration testing will have been performed on that combo. ETA for a stainless screw and written instruction kit is around the first of next week if everything goes to plan. I'm working on this mostly nights and weekends so it slows the process a bit.

Thanks everyone.

I'm very interested in this proposal. However, what will be done to incorporate a seal between the two components or did I miss that part?

I am assuming that you are refering to the possibility of air leaking past the mating surfaces of the flapper valve and bellcrank cam.

The tapered mating surfaces on both pieces are precision machined and should form an air tight seal on their own. As an added precaution the instructions will state to apply a very light film of the supplied threadlocking agent with a cotton swab to the I.D. of the flapper valve hex mating surface. The threadlock is not required to hold anything together but is used because it will wick into any possible voids between the mating of the two surfaces during assembly. The screw threads are also threadlocked during assembly which seals that area as well.

I hope I understood and answered your question correctly.

BikesStillRules, you're a good man.

Originally Posted by BikesStillRule

I am assuming that you are refering to the possibility of air leaking past the mating surfaces of the flapper valve and bellcrank cam.

The tapered mating surfaces on both pieces are precision machined and should form an air tight seal on their own. As an added precaution the instructions will state to apply a very light film of the supplied threadlocking agent with a cotton swab to the I.D. of the flapper valve hex mating surface. The threadlock is not required to hold anything together but is used because it will wick into any possible voids between the mating of the two surfaces during assembly. The screw threads are also threadlocked during assembly which seals that area as well.

I hope I understood and answered your question correctly.

Great answer, thanks. By the way, as I understand it the OEM can fail which would send a piece of plastic or nylon into the combustion chamber causing severe damage as the bit is chewed up by the piston, perhaps along the cylinder wall. So what would be more desirable... having a piece of nylon in there or perhaps a pice of steel or titanium? Just asking as I am interested in your design but is the assurance of a proper fix mainly the better engineered piece with tighter tolerances and threadlock?

Originally Posted by fortunateson

Great answer, thanks. By the way, as I understand it the OEM can fail which would send a piece of plastic or nylon into the combustion chamber causing severe damage as the bit is chewed up by the piston, perhaps along the cylinder wall. So what would be more desirable... having a piece of nylon in there or perhaps a pice of steel or titanium? Just asking as I am interested in your design but is the assurance of a proper fix mainly the better engineered piece with tighter tolerances and threadlock?

Good question, only for now the OEM design burps the steel pin into the engine, not the plastic parts. Hence BikeStillRules designed this new model which we hope will last. Also, FYI, the DISA *****y design is due to 2 factors (BMW):
-Cost
-the DISA will last 100k miles. Until the car is out of warranty

Originally Posted by BikesStillRule

I don't want to speak too soon but..... we have had several design reviews about the CCV issue, so look for some re-design ideas coming in the next month. Current direction is an easily serviceable unit that requires minimal amount of labor. Problem is all of this stuff is keeping me from progressing on my M54 engine build.

I figured you had something in the works!
I will be VERY interesting in this!
I am on my 3rd CCV....!
I almost bought a 4th...!
Tired of this sh!t!
Sorry for these common problems/ questions keeping you from your M54 re-build.

Thank you MUCH!
Jason

Originally Posted by Jason5driver

I figured you had something in the works!
I will be VERY interesting in this!
I am on my 3rd CCV....!
I almost bought a 4th...!
Tired of this sh!t!
Sorry for these common problems/ questions keeping you from your M54 re-build.

Thank you MUCH!
Jason

Jason, take a few days holidays and go help the man!!!!

Well ima need me one a soon as there available

That's pretty darn awesome and impressive...