heinzboehmer's 2002 Topaz 6MT Coupe

[George Hill]

Have your seen a variety of results based on crush washer brand? That always seemed like a safer area to cheap out (just a circle of copper), not that I've actually been able to sell myself on doing it.

Not specifically, but I have replaced many non-OE crush washers that were leaking, I just don't know if it was a prior install error or part issue.

I have reused drain plug crush washers... a lot in the past with no know issues.

I'm not going to claim to be a metallurgist but its my understanding most BMW crush washers are aluminum is they are silver and copper if they are copper colored.

Now that I type this out it seems like BMWs are either copper M12 and smaller and silver/aluminum M14 and larger? As it relates to an S54, example:

• Copper - Drain plug, valve cover drain liner, vanos accumulator line, etc
• Silver/Aluminum - Tensioner, P/S Hoses, Rocker arm plugs on the back of the cylinder head, coolant drain plug, Upper T/C rail pin,

I have used aftermarket crush washers with success in the past, but they are generally so cheap I almost exclusively use Genuine now.

In this situation, 07119963418 is the T/C tensioner crush washer. On ECS:

• Genuine - $1.99, aluminum
• Elring - $2.03, copper

[Obioban]

What brand?

Have your seen a variety of results based on crush washer brand? That always seemed like a safer area to cheap out (just a circle of copper), not that I've actually been able to sell myself on doing it.

[George Hill]

The best part is that I replaced that crush washer a year or so ago because it was leaking

What brand?

Edit: I wonder if the uptick you're seeing is because most cars are no longer on the original crush washer and torquing the tensioner to spec in the engine bay is not easy?

You may be right. I've installed thousands (?) of crush washers and I can generally "feel" them crush. I've also reused them, without issue, but if they aren't getting crushed fully or are reused then maybe?

Its actually super easy to torque with the right setup: 3/8" flex head, 3/8 - 1/2 adapter, 32mm socket. Tons of room.

[heinzboehmer]

I don't want to start randomly throwing parts at the problem though, so I'm gonna rig up a pressure tester and grab some data first. Pretty sure I have a spare oil fill cap somewhere, so should just be a matter of drilling and tapping a hole for a pressure gauge. Stay tuned.

Coming back to this.

I did not, in fact, have a spare cap in the stash, so I ordered a cheapo one.

Turns out the cheapo cap is hollow inside:



Slathered a bunch of RTV on the threads to try and salvage this attempt:



But I'm not at all confident that it will seal. Think it's highly likely that the next update on this effort involves a CAD screenshot of a custom cap with NPT ports on it.

I'm seeing this more and more, somehow the timing chain tensioner starts to leak through the crush washer. I don't understand the physics of it, but I've replaced a bunch of tensioner crush washers recently.

The best part is that I replaced that crush washer a year or so ago because it was leaking

If that crush washer ends up being part of the problem, I'm not sure how I'm gonna fix it.

Maybe machine a groove in the tensioner to seal with an o ring instead?

Edit: I wonder if the uptick you're seeing is because most cars are no longer on the original crush washer and torquing the tensioner to spec in the engine bay is not easy?

[Bry5on]

Yep! Think Ted cracked the code. BCD makes total sense.

Funky implementation though. I know these are tiny (in terms of compute) embedded devices operating in a very constrained and well defined environment, but the complete lack of validation for most of the stuff on this bus is wild to me.

It was written in the mid-90s after all…

[heinzboehmer]

Yep! Think Ted cracked the code. BCD makes total sense.

Funky implementation though. I know these are tiny (in terms of compute) embedded devices operating in a very constrained and well defined environment, but the complete lack of validation for most of the stuff on this bus is wild to me.

[karter16]

Yes, input validation is not something these engineers really cared about.

I think 0xFF is translating to decimal 165 because of an overflow —

0xF = 15

So, 1515, but somewhere in the logic the 15 and 1 are being added to the same register.

Love it - that makes complete sense!

[t3ddftw]

Just curious - if that was the case wouldn't it mean that the max value you can get from a byte is 99? whereas Heinz is managing to get to 165?


Edit: actually I think what you're saying is that the cluster assumes BCD but its assuming it's going to get the right value and its actual implementation is looser and allows you to overdrive it in slightly weird ways.

Yes, input validation is not something these engineers really cared about.

I think 0xFF is translating to decimal 165 because of an overflow —

0xF = 15

So, 1515, but somewhere in the logic the 15 and 1 are being added to the same register.

[karter16]

I emailed you about this, but for the sake of the forum at large, I believe BMW is using binary coded decimals rather than converting the byte to decimal.

Just curious - if that was the case wouldn't it mean that the max value you can get from a byte is 99? whereas Heinz is managing to get to 165?


Edit: actually I think what you're saying is that the cluster assumes BCD but its assuming it's going to get the right value and its actual implementation is looser and allows you to overdrive it in slightly weird ways.

[t3ddftw]

Also, finished running through all Data[1] values and only came close to dying of boredom 15 or 20 times.

Anyway, this is how the values are encoded, to the best of my understanding:



Full investigation here if anyone is curious: https://docs.google.com/spreadsheets...it?usp=sharing

Worth noting that there is no x1000 multiplier. I must have sent 10x100 and seen 1000 earlier or something along those lines.

Even with the multipliers applied, the weird base10/16 counting still happens. I'm starting to wonder if this is an undefined-behavior-type bug/oversight. Maybe the mi/km theory has some credence and BMW only ever planned to display max 10mi/16km for each of the multiplier stages.

Regardless, the x100 multiplier still works with the 165 max. Not that I see it being particularly useful, but it's good to know that you can go that high:

I emailed you about this, but for the sake of the forum at large, I believe BMW is using binary coded decimals rather than converting the byte to decimal.

Would you use Siri to input navigation instructions?

You can do that with the BlueBus today, so yes .

[Slideways]

It would basically be a BlueBus with the ability to switch to "mirror" mode when you want to use it for maps. Even in our family Minivan, I prefer the factory UI over CarPlay -- CarPlay looks too cartoonish IMO.

It would also not require a video module, like Baris' solution.

Would you use Siri to input navigation instructions?

[Flow]

Good luck having carphonics answer to any type of communication.
I've written multiple emails and tried the website's contact form to no avail.

[George Hill]

It would also not require a video module, like Baris' solution.

You've already got me, you don't need to oversell it 🤣

But seriously, very cool.

[t3ddftw]

I'm a buyer when you do. I've been holding out for Carphonics, but just can't commit as I'm not 100% sold its as polished as I want. Your solution sounds right up what my alley.

It would basically be a BlueBus with the ability to switch to "mirror" mode when you want to use it for maps. Even in our family Minivan, I prefer the factory UI over CarPlay -- CarPlay looks too cartoonish IMO.

It would also not require a video module, like Baris' solution.

[George Hill]

Any pics of the G series mic? More than happy to help out with the design/testing for this if you need extra hands. Also recently bought a 3D scanner if you need any scans of the part or chassis

paging thegenius46m

My CarPlay / AA solution is less "headunit" and more of an add-on module for cars that came with Nav. The screen(s) I have been looking at would still drop into the factory BMBT as I lack the tooling to make automotive quality headunits. This might change in the future, especially as I know someone with an injection molding machine, but I want to focus on Nav cars for now, and maybe even develop some retrofit kits for factory Nav that don't suck to install.

I'm a buyer when you do. I've been holding out for Carphonics, but just can't commit as I'm not 100% sold its as polished as I want. Your solution sounds right up what my alley.