I sort of bought a car that sort of runs. A 1998 SLK230 looks like a good deal at night.

a_florida_man said:

In reply to Dirtydog :

ughhhh

 

I don't like where this thread is 'going'. :)

I know what you mean.  By the way, how'd you know my name is Jim?

In reply to Dirtydog :

I didn't. :)

In reply to John Welsh :

The Mercedes-Benz R170 platform and shares 80% of its components with the first generation SLK. 

nice adaptive sawery on the alternator case!

Agent98 said:

nice adaptive sawery on the alternator case!

Thanks. It's easy when you have nothing to loose... lol.

Tonight was all success and awesomeness.

First off, last week I found a vendor on Amazon selling hood struts for the SLK in sets of two for 19.99.

Which is odd as the car only uses 1. So... 1 hood strut, $10.00 to the budget.

The nicest thing here is that now I can put the hood up in the service position for maximum access.

Previous to this, using the service position on the strut slider, held the hood up to the standard position because the gas filled portion was shot. I wonder if that was an intentional design, sort of a hood strut fail safe?

Also this weekend, I diagnosed the ABS/ASR issue. I started with checking for a signal at the ABS/ASR unit harness on the Right front speed sensor circuit. It checked out ok.

Next I checked the Left front circuit at the controller. As expected. Flat line, no signal.

Having found this was no surprise, it was expected. There was a new sensor on the left front, and the ABS/ASR module was responding with  a sensor error on the front left. 

So I ASSUMED that there was a break in the wiring or a bad connector or splice. 

I caught myself mid assumption and said, well why don't we test the sensor output at the 1st connector where the sensor attaches to the car. That's an easy spot, and I can then check the wiring at intervals approaching the controller untill I see it is lost.

Ok.

Checked the sensor and there was NO OUTPUT. Same flat line. Went back and checked the front right again, and there was a signal, so the meter was ok. Well, that's interesting. A new sensor with no output.

So I pulled the sensor and that is where things get interesting. It was ground down. It had been in direct contact with the tone ring on the hub in the knuckle. It had been ground to the point of being convex. Ouch.

Next I pulled the right sensor, it looked similar but it had certainly not been rubbing on anything.

I really wanted to fix this issue on Sunday, to the point that it felt like defeat, which in retrospect is funny because I had found a very verifiable issue that would explain why there was a code. The sensor was toast! But the bigger question was why? A trip to the Amazon command console (this laptop), and a Beck-Arnley replacement for $26.74 was on the way. 

Fast forward to today...and I think I have the answer as to why the part was ground down:

Here you can see that the bad part on the right is actually longer than the new one. I think that the replacement part was just that poorly made.

Here you can see how much smaller the bad one is in diameter. You can also see how the face was ground down.

Now you might look at this and think that it is actually the WRONG part. Mmmm could be, but every other aspect matched between the two. Cable length, connector, two hole offset mounting bracket, the positions of the two harness clip grommets. If it is indeed a part for another application, it's a heck of a near miss.

In any case, I cleaned the tone ring, and installed the new sensor, carefully checking for interference. There was none, and we now had a signal for the left front circuit.

I hooked up the computer, cleared the code in the ABS/ASR unit, and in the ECM for the bad left wheel speed sensor.

Test drive, and all is well. Drove about 40 miles and no lights or malfunctions. Also there was the expected bonus of now having cruise control. 

The last thing to check was the ability to turn the ASR on and off, which it did with no problems. 

In retrospect, it appears that this car had two major issues by the time I got it.

Here is a possible timeline for the failures.

First the left front wheel sensor fails.

The ABS/ASR light is on.

Car still drives just fine.

The k40 relay fails at a later date, shutting down the TCU, putting the car in limp mode.

A mechanic looks at it, scans for generic codes, and find the wheel sensor issue.

He replaces the wheel sensor, and the first test drive wipes it out.

Now he's stuck on a "wiring problem" for the wheel sensor (believing that new=good), and believes that the wiring issue is causing limp mode, without really understanding or investigating the limp mode cause.

I get the car, get good Mercedes Benz diagnostic codes, and sort of unwrap a two layered problem that includes a poor quality part issue that can't really be found out without doing real diagnostics with the o-scope.

I'm not trying to brag here, just the opposite, I'm sort of shuddering at the thought of how bad this could have been without a little luck!!

Budget Update

$1270.35 Total (Estimate)

$10.00 Hood Strut

$26.74 ABS Sensor

$1307.09 (Estimate)

List of remaining project tasks:

K40 relay surrogate project, completion and installation.

Belt Tensioner damper rattle.

Central vacuum system and related fuel lid / trunk lid issues.

Refill convertible top hydraulic pump with oil.

Rebuild 4 top cylinders. / Reinstall rear luggage trim.

Tires / Shocks / Springs

Alignment

ECU mods

I'm a Mercedes tech myself and have to applaud the diagnostic process there. I got a bad wheel bearing once (damaged tone ring in shipping or maybe was never magnetized) and ended up with a similar, very hard to diagnose issue.

No wheel speed on the LR wheel, but the RR wheel is good. Swap sensor, still bad. Ok, must be the bearing. Change the bearing (it was bad, tone ring had chunks missing and fell apart as I took the axle out), then re-test. Still no signal. At the time our scope was down and no one had a nifty pocket one like yours (link please?!) so I assumed the new bearing was good and carried on with a wiring diagnostic.

Eventually got to the point of the ESP/ABS control unit because all the wiring was testing good and the issue was still present even with a home-made jumper harness. Replaced it, fault still present. Our diagnostic foreman takes over, and 3 days later decides maybe we should just start from scratch with a new sensor (didn't fix it) and a new bearing (fixed it). 

Thankfully we were able to claim all the parts through Mercedes warranty after we explained how and why everything happened the way it did. Assuming new parts are automatically good can really throw you for a loop, but at the same time you can't just automatically assume the new part was bad if the same symptom and failure return. Damned if you do, damned if you don't.

I like this project and am interested to see where it goes. Our projects are very different but (will eventually) share the 2.3L Kompressor engine.

I checked out your build. Pretty cool. I could not however work where things freeze. Just couldn't. Too much of a whimp!!

Here is the one I bought off of Amazon.

Its a little quirky, and not really documented.

Shop around, there are others, this might be a good one. A friend got one for Christmas, said it was pretty good.

Not to derail your thread - it’s a great read and I love the victories - but could you explain how to use that little oscilloscope to check the sensors?

ive never used one and always thought they were a. expensive and b. black magic

jfryjfry said:

Not to derail your thread - it’s a great read and I love the victories - but could you explain how to use that little oscilloscope to check the sensors?

ive never used one and always thought they were a. expensive and b. black magic

This makes two of us. Pretty sure I need to own one if I keep messing with EFI

In reply to jfryjfry :

I’ve not used one of these pocket o-scopes(though I think I need one!), but in essence rather than just measuring voltage like you would with a multimeter, a scope allows you to see the actual signal/voltage in real-time. 

So say you have a pulsing DC signal from a sensor. It’s likely pulsing at a given rate/frequency depending on RPM or road speed. You adjust the frequency of the scope until you match the frequency of the signal, and the waveform appears stationary on the scope. You can now see the individual peaks & valleys of the signal, the width of the peaks vs. the valleys, and how consistent they are.  So you can actually see if a sensor is providing the correct output at the correct time. 

Also, because you’re seeing the waveform in detail, you can visually see how much noise is in the signal, which can indicate problems like poor grounds, missing shielding, or dirty connections. 

In reply to Pete Gossett :

Pete nailed it. The only thing I would add is just buy the cheap meter and play around with it. 

Keep in mind that a lot of these meters are 50v or so, so unless you have the right meter or probe don’t try to read the ac voltage in the house.

A safe way to explore is to do like I alluded to a few posts back. Try to read the signal from a Hall effect pick up coil in a distributor.

You will get a feeling of how to set the scope up and you can also see how the signal changes depending on how fast you spin the distributor.

After that graduate to measuring the signal on a running fuel injector, etc...

i think a lot of us around here learn by doing. Or at least learn what not to do.... lol.

In reply to TurnerX19 :

They are overly well made aren't they!

dansxr2 said:

In reply to TurnerX19 :

They are overly well made aren't they!

dan, which post are you referencing?

:)

I did a little more work on the K40 relay board overhaul.

I think that when I look back, I'm going to say that the hardest part to this was removing the relays from the board without damaging the board.

Here is a shot of the board, it still needs to be cleaned and desoldered further, but I wanted to pause and demonstrate the concept...

The new relays will be attached to pigtails, which will be soldered to the old board. This will allow individual diagnosis and replacement.

The final job will be a LOT neater of course, but you get the idea.

I will also be mounting new ballast resistors.

Nice move on the board separation. When soldering to a board like that with wires of heavier gauge, do you just stuff them in there and solder away? Any specific tips for that sort of work?

Nice progress! 

Just wanted to add i bought one of those DIY $30 scopes last year and put it together, realized i didn't have the power supply (/'wall wart') it needed, and set it down somewhere and forgot about it. It wasn't super hard to put together but i'd sure pay $10 extra to have a nice pre-assembled case and a power supply. I have enough menial tasks to do! 

Mezzanine said:

Nice move on the board separation. When soldering to a board like that with wires of heavier gauge, do you just stuff them in there and solder away? Any specific tips for that sort of work?

Yes, that is why I mentioned that the final version would be a lot neater. LOL

In this pic I had been experimenting with which gauge hole to use on the wire stripper to over cut the wire diameter down to the right size for the PCB and strip the wire at the same time.

The wires in the new relay harnesses are a bit bigger than what is needed for this application.

Vigo said:

Nice progress! 

 

Just wanted to add i bought one of those DIY $30 scopes last year and put it together, realized i didn't have the power supply (/'wall wart') it needed, and set it down somewhere and forgot about it. It wasn't super hard to put together but i'd sure pay $10 extra to have a nice pre-assembled case and a power supply. I have enough menial tasks to do! 

Funny that's the exact reason I bought the one I did...

Didn't do anything with the SLK this weekend.

The garage had attained critical mass, and I was about to go nuclear with lost stuff frustration.

You can only blame the kids for so much.... lol.

It all started innocently enough.

The idea was to rearrange the equipment wall and get a better path trough the garage.

That was plan A.

Then came plan B, remove 2 9ft cabinets and replace with an 'extra' refrigerator. 

I feel scope creep....

(I wasn't planning on this being a weekend long project, so no true before pics, just during and after.)

The important thing here is that the fridge is in and there is a better 'line' now in front of the equipment to accommodate the C4 Challenge Car project's new room mate, the '58 Healey.

The satin color of the Healey is from the dew, I took this pic at midnight on Saturday night. 

So mission accomplished right?

Nope, there was the REST of the garage that by comparison now looked like the poop pile it really was.

Here is where I went all in.

I decided, EVERYTHING else including the stuff in the cabinets was now getting sorted....

So that sorting and culling became a day and night long effort over Sunday and into Monday AM.

It was really long overdue. For the last 4 years I had been in Tallahassee (2 hours one way) for many, and at the end most weekends helping my folks with health issues. 

Dad passed in November, and I inherited our Healey.

That really was the final straw in the garage madness.

The Healey deserved a better spot.

There was WAY too much STUFF, and I ended up with a truckload to storage, and a truck load to the dump.

Along the way I found a few things...

Remember when Auto Zone had another name and ran into a little trouble with Radio Shack? I do. :)

Mid to late eighties IIRC.

Does any one remember Scrooge McDuck?

He was famous for having kept the first dime he ever made.

About 20 years ago, when I was at dad's house (where I grew up), I came across the first auto part I ever replaced on a car I owned. It was a sway bar bushing and bracket on my first car, a '70 RS Camaro. It had been bent by hitting a parking berm. For some reason, as soon as I found it, I thought of Scrooge McDuck, and the old part has had a prominent place ever sense.

May I present: "Part Number One"

I'm still looking for an appropriately sized velvet pillow...

I'm weird.