355 bypass rattle buzz fixed

I realise you're not in the UK Ken, but there's also this part https://www.design911.co.uk/p/sport-exhaust-vacuum-replacement-unit/ for less than $60... mind you probably the same again for shipping.

 

Alright. This is super confusing. Let’s get a few things cleared up while it’s fresh for the sake of future 355 readers .

1. The numbers engraved on actuator itself are 722151 01 (OE 355). The engraved numbers on the Pierburg Porsche actuator are 722151 02.

2. However, when referencing these numbers, the Porsche Pierburg unit is sold as “722151 20”


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Now here’s the second part of the confusion. The cross reference number “99711168001” on Design911 site shows a unit with a shorter rod and probably a closer match to the 355 unit. However, if you Google “Pierburg 99711168001” every other site shows the unit I purchased, which is an incorrect unit.

My guess is the Design911 site has either the image wrong or the part number wrong on their site. Also doesn’t help that there is no part number engraved in their unit.



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@redwedge Does your unit have engraved numbers?

 

For those reading, it doesn’t appear 72215101 (or 72215110) is sold/available on the market, hence the reason I figured 72215120 was the new replacement. Every Google search leads to 72215120, which is the unit I purchased.

 

Actuator #290323 on Design911 site … my guess is not a Pierburg unit although it looks like it could work. I found samples of it elsewhere.

https://tikkosracing.com/product/exhaust-vacuum-valve-with-vacuum-actuator-76mm-open-baffle-r176906/

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* Sold as “722151520”

Notice there’s now an extra “5” added to the part # adding more to the search confusion.

 

Shortening the rod and re-threading probably would work. However, the vacuum inlet still wouldn’t sit facing the 3 o’clock position as the 355 OE unit. It would either sit in the 12 o’clock position or 4-5 o’clock position.

 

That should not be an issue. The cover on my no name actuator was not indexed correctly but I was able to rotate the cover to the correct position without damaging it.
You may be overthinking all of this.

 

I've ordered the design 911 part and will report back.

 

I couldn’t rotate it without feeling the risk of breaking it. Pierburg unit btw.

 

Btw, I have a 95, so the actuator is front and center. If I had a 5.2, I wouldn’t care as much where the inlet faced.

I think I’m ok with the inlet facing the 4-5 o’clock position as well.

My OE actuator isn’t broken. I just didn’t want to put the elbow grease into restoring its looks, which I ended up doing once I figured the Pierburg unit didn’t work.

I was also hoping a new Pierburg unit would be snappier … because it’s new or simply hoping somewhere along the line Pierburg improved design from what they had introduced in 1994. The new modern silver finish doesn’t hurt either.


I’m not sure I’d be ok with an actuator lower in quality than a Pierburg. It would have to be equal or better.

 

@ShineKen Could you please measure the length of the rod on your original valve... my car has a Porsche valve which I suspect is slightly too short since the valve is always slightly open (mild vacuum at the inner exhaust tips when the valve is "closed")

 

I saw this in one of my Porsche magazines awhile ago. My bypass doesn’t rattle but you never know when it could start, so always looking for potential solutions.
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It appears Gothspeed used the same Pierburg I purchased. As you can see, the vacuum outlet is either mounted in the 12 oclock or 4:30 o clock position.



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My opinion is gothspeed could’ve made holes in a way where the Porsche unit could mount with the vacuum outlet is facing the 3 o’clock position.

 

I have it all mounted, but I can measure the Porsche unit. I recall the OE unit is about as long where the Porsche rod starts to show threads.



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Not sure how these are constructed -- could you swap the internals of the 997 unit into the old 355 body? Basically use the Porsche part as a rebuild kit?

 

My opinion is the actuator outerbody would be destroyed if you pry this open.

 

What is it, an M8 thread? $2.27 at Granger. dive it with an 11/16 deep well socket.


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