Crankshaft Position Sensor DIY - PeachParts Mercedes-Benz Forum

dickiegoodman · #1 09-04-2004, 02:54 PM

Since no one volunteered their expert advice on the crankshaft position sensor (CPS) DIY, here it is...hopefully this will help others with what appears to be a common stalling issue in the ML series.

I checked NetStar for PO work (done under warranty) and learned the fuel system mod had been done at 29k (now have 48k). So I figured the stalling issue wasn't that. I may be wrong, the CPS was cheaper place to start!

I give this job a 1 to 1.5 stars (of 5) difficulty, and maybe a 3 stars for patience.

Here it is:

1) Get CPS at dealer, its a VIN specific part. $125 from my local stealer.

2) Tools needed: Socket screwdriver, Good lighting (portable) shop lights, size 8 outside torx socket, maybe a ratchet and extentions depending on your flexibility, magnetic part retrieval tool (skip this at your peril), bath towel, and long sleeve shirt, step stool, blue thread locker (optional)

3) Open hood and remove engine cover, it just pulls off and on

4) Set work light(s) toward back of engine, lighting behind drivers cylinder head

5) Set bath towel on front of ML to kneel on of your knees will die, wearing long sleeve shirt or your wrists will be cut.

6) Climb up on towel and look behind engine from above and right (see .jpg), finding torx attachment holding your CPS.

7) Remove torx screw and pull out CPS, disconnect one way connector (wiring)

8) Replace with new (leaving wire detached for now)

9) This is the hardest step by far, and requires patience and flexibility. Apply some thread locker and insert screw and start the threads. Tighten with torx on socket screwdriver. This step took about 1/2 hour and numerous dropped screws and retrievals with mag tool.

10) Attach wiring to CPS

11) Reinstall engine cover

12) Clean up tools, towel and lights and everything

13) Drink beer and toast yourself for saving yourself at least $100 and a day of your time dropping off and picking up cars at shop

Hope this helps someone in the community.

Dickie
00 ML 320
97 328i
87 325is

azinn · #2 09-04-2004, 04:47 PM

Great job and thanks for the instructions.

sdanville · #3 09-10-2004, 01:34 PM

Did this Cure your no start at times / stalling ?

Thanks

ANOTHER couple notes:

A 3/8" Drive E8 socket will not have enough clearance.
I went to 3 auto stores and 2 Hardware stores no luck.
My New CPS arrived today - and I got lucky at NAPA and bought a 1/4" drive E8 socket for $3.
Then it snowballs.... I trusted the Parts guy online to send me the correct sensor using my VIN Number. At 1st glance it looked great until iI installed it.
The elect connector was wrong. My 1999 ML320 has a 0 261 210 141
aparently their book read 0 261 210 171.
I will update later weather or not they will take the sensor back.
My parts guy said he'd take the sensor back. Note electric connection guides in Picture. Mine is 180 degrees from bolt , replacement was 90 degrees.

--wont let me duplicate my picture can be found searching " more crankshaft position sensor questions "

Ron in SC · #4 09-10-2004, 01:58 PM

Great write up.

I do have two questions.
1-Where is the CPS located? On the front of the engine near the fan belt or the rear near the firewall.

2- When you replaced the crankshaft position sensor did you need to have any sort of re-initialization process performed with the STAR DIAGNOSIS in the menu item control module adaptations? I read about this having to be done, but I really don't know what it means as it's over my head.

dickiegoodman · #5 09-10-2004, 09:30 PM

To answer a number of Qs, here here go!

1) It did fix the problem. No stalls since changing out CPS.

2) I should have noted, though it is stating the obvious, is that I would only do this on a COLD engine.

3) No resetting of anything required (as far as I know), as the engine was off and its not a vehicle/VIN specific part in terms of absolutes, just a range of VINs (and maybe 320/430/500 specific). The dealer wanted the VIN to make sure he gave me the correct one. I am not sure how many variations there may be, I did not ask.

4) It is on the back, drivers side of engine, where the engine/transmission mate up. Its kinda a PITA to get at. I purchased the part before I started so I knew what I was looking for. The external torx socket is difficult to see, but you can do it. Good lighting is essential or I don't know how you would find it.

Best wishes on your ML travels and DIYs.

Dickie
00 ML 320
97 328i
87 325is

PS-This vehicle, so far, is not as difficult to work on as my BMWs. Try replacing a cabin filter on a e36 BMW. Now that is a frustrating job in comparison to the ML cabin filter.

YuCrew · #6 02-21-2005, 04:30 PM

My 1999 ML430 (about 98,000 miles) just recently started acting up. About two months ago, I experienced a "longer than normal" crank/start time (in the garage) ONE time. Everything normal since then until last week when engine died at a stop light. Immediately restarted. Today, drove it about 2 miles. Came back to car 1 minute later and it would not start...cranks strong but won't start. Look for roadside service card and try to start one more time before calling for a tow. Engine starts. Make a few more stops, turning off engine and restarting without incident. Stop at the bank drive up window, leaving car running but in park. Put car into drive and engine dies. Doesn't restart the first time (good thing the bank is closed today). Wait one minute, car starts and head home to get it into the garage.

I have the new fuel filter arrangement (done about 30K miles ago). The MAF is new about 20K ago (and eliminated check engine fault light). I'm guessing it's the CPS (or hoping so because this is a repair I can do myself). Can a defective CPS cause a running engine to quit? Or does the CPS only "do its job" during starting conditions? Is the CPS a device that fails/degrades slowly or instantaneously? Thanks for any and all inputs.

sdanville · #7 02-21-2005, 04:36 PM

I would bet a 6 pack you need to replace your CrankShaft position sensor.
Under $100 (online)
10 minute job.

Been there
Done it.

YuCrew · #8 02-21-2005, 04:47 PM

Steve: I have followed your post and fine commentary since late last year. I kept wondering when I was going to experience this failure since I've had balancer failure, fuel pump failure, etc. So when the symptoms started, I immediately thought of your inputs on the CPS. I've already ordered it for $53 (dealer wanted $100).

Here are some part numbers that may help others:

Current MB number (at least for my 1999 ML430) 003 153 2828 (supercedes 003 153 2728);
on-line stores show this as F6010-140094;
The Bosch website shows this as Bosch 0 261 210 170
All the numbers seem to cross-reference to each other

I already have the 1/4" drive E8 external torx socket so I'm ready to get dirty when the part arrives.

Thanks for your response.

JimF · #9 02-21-2005, 10:36 PM

Quote:

Originally Posted by dickiegoodman

Since no one volunteered their expert advice on the crankshaft position sensor (CPS) DIY, here it is...hopefully this will help others with what appears to be a common stalling issue in the ML series.

. . without a lift!! But what troubles me is this thread seems to indicate that it's a common failure . . . and that makes me scratch my head.

On my car and many like it, the CPS is a passive device; it consists of a magnetic 'core' apon which there's a coil of wire. In the car's flywheel, there's four magnets spaced 90 degs apart. As the flywheel spins, the magnetic field induces current into the coil of wire producing a small voltage 'spike' that various ECUs use (and NEED!).

They NEVER FAIL! I've never seen one go bad!!! The resistance is around 820 ohms and if you can measure it, it's good. About the only way it can 'fail' is if you somehow break the wires in the cable by whatever means. But barring that, they just don't fail.

So what have the MB semi-nuts changed this part to??? Maybe it's an active part now containing electronics??? Boy, I sure hope not. . . .

YuCrew · #10 02-21-2005, 10:43 PM

You'll find the post by M.B.Doc on Aug 26, 2004 in the thread below an indicator of what the dealer sees on this part.

HELP! '98 E320 - engine dies, won't restart for 20+ min.

Additionally, when my fuel pump failed and the dealer called to confirm they had the vehicle, they initially suspected the CPS. It turned out to be fuel pump failure. Never thought about it again until I caught this topic in the forum.

Is it possible the wound coil has an intermittent "break" or insulation breakdown due to thermal stress or poor wire varnish, etc?

JimF · #11 02-21-2005, 10:54 PM

Quote:

Originally Posted by YuCrew

You'll find the post by M.B.Doc on Aug 26, 2004 in the thread below an indicator of what the dealer sees on this part.

HELP! '98 E320 - engine dies, won't restart for 20+ min.

Additionally, when my fuel pump failed and the dealer called to confirm they had the vehicle, they initially suspected the CPS. It turned out to be fuel pump failure. Never thought about it again until I caught this topic in the forum.

Is it possible the wound coil has an intermittent "break" or insulation breakdown due to thermal stress or poor wire varnish, etc?

. . technical info on how it's constructed; just that it goes bad alot. I've already got that from this post.

So does anybody know how it's constructed?

JimF · #12 02-23-2005, 12:00 PM

Quote:

Originally Posted by JimF

So does anybody know how it's constructed?

So does anybody know how it's constructed????

ML320 · #13 08-01-2005, 10:56 PM

Quote:

Originally Posted by JimF

So does anybody know how it's constructed????

JimF, AFAIK they are no longer passive inductance sensors but are active using "AMR technology", which may explain the high failure rate.. :-(
There might be some info on the BOSCH USA website.

Also, here's some AMR stuff:
http://www.sensorsmag.com/articles/1298/mag1298/main.shtml
http://www.sensorsmag.com/articles/0399/0399_18/main.shtml

Wolfgang

Strife · #14 08-02-2005, 12:08 AM

My guesses as to why the switch would be:

1. Higher potential accuracy and insensitivity to temperature.

and, the more likely:

2. Cost Reduction (but not to YOU).

JimF · #15 08-02-2005, 12:10 AM

Quote:

Originally Posted by ML320

JimF, AFAIK they are no longer passive inductance sensors but are active using "AMR technology", which may explain the high failure rate.. :-(
There might be some info on the BOSCH USA website.

Also, here's some AMR stuff:
http://www.sensorsmag.com/articles/1298/mag1298/main.shtml
http://www.sensorsmag.com/articles/0399/0399_18/main.shtml

Wolfgang

. . I was at my tech's shop last week and he had just replaced one of the "new-fangled" CKP sensor. He said that he regularly replaces most of the new car's CKP sensor. That was news to me.

As an engineer, one says there must be a better mousetrap. . . and the newer versions of CKP sensor made with AMR technology must that product.

But in truth, what it is, is cheaper, not better. It's "better" because it cheaper for the manufacturer, Mercedes to produce. But for the customer, it's most costly because they fail.

The wire wrapped around the ferrite will last forever as evidenced by the low replacement rate: in 12 years, at his shop, I've never seen one replaced on a 90's car.

Amazing world, isn't it???