W639 Viano Cranshaft Sensor

[schneckster]

Hi all,

Had some fun with my Viano lately (as always!). The latest one is that it starts when cold, but refuses to restart when warm, which is a problem when it's mostly used for the school run!

And on longer runs, it just cuts out completely, though this is a newer symptom. I went to rescue the missus yesterday who couldn't restart it after dropping the kids off. I get there 45 mins later, sparks up first time. Drive 3 or 4 miles, wait at some traffic lights and it just cuts out and won't restart. As you can imagine, stopped at the front of the queue at traffic lights made me very popular! 90 minute wait for the AA and it sparks up again on the first turn of the key! Get it home, and he has a look at it including using his diagnostic reader (not a Star, I know, but better than nothing). No codes found.

AA bloke suspected the crankshaft sensor telling me that when they're failing, they're ok at cold, but knackered at hot. The ECU loses the signal from it and shuts the engine down to prevent damage. Sounds reasonable to me.

Anyway, as this has done 100k, I'm thinking I'll just replace it. What I was wondering, though, is:

a) Is the AA man right? From other threads on here I suspect he may be
b) Are they expensive?
c) Are they easy to replace on a Viano, given that I'm no mechanic?
d) And if so, where the hell is it on a W639???

The car is 04 plate W639 Viano Ambiente 2.2CDi 5 speed auto.

Thanks in advance for any help (One of these days I'll learn enough about Merc's to help others! )

Schneckster

 

[schneckster]

Looking on the EPC gives me part numbers of A 003 153 27 28 and A 003 153 27 28. A search on Google for these also brings up a CLK 230, so it does have some commonality with other cars. They seem easy enough to change (one plug, one bolt, and some extensions of arms or socket drivers)

OK, so I know the Viano isn't exactly a popular car on here, but am I at least barking up the right tree with the crankshaft sensor?

Do the symptoms sound right for this regardless of the car?

Cheers,

Schneckster

 

[zenman63]

Get it on Star to read the codes, they will be there.

 

[schneckster]

If I know it is likely to be the sensor, I'll just change it and then get it somewhere to read the codes. It's old enough that it's probably worth changing anyway.

But is it the likely problem?

 

[Wilfie]

It sounds pretty similar to my cps failure, the only reason I didn't get it on star was due to it finally giving up 120 miles from home and the AA did me a deal. At the end of the day its up to you but it wouldn't hurt to get it on star first or you could just take a gamble.

 

[DRBC43AMG]

I would aim for the cps (typical symptoms) but as said by others get it on Star b4. It may point out other problems...

 

[schneckster]

Thanks for all your responses, guys.

Getting it to a Star might be a problem. The nearest one is 8 miles away with some pretty major roads in between. Not sure I want to risk it cutting out on those roads and sitting there waiting for it to cool down before moving again. As the AA came out for it already, they're unlikely to want to move it for me.

I would prefer to do what you all suggest and get it read first. But, I'm not sure how I'm going to do that under the circumstances.

Rang my local Car Spares place and they reckon they can do a new CPS for £30 + VAT. Cheap enough to be worth a go and then get it read, I think... assuming I can find it on the engine, of course!

Thanks again. I'll post back with an update.

Schneckster

 

[DRBC43AMG]

Not sure about a Viano, but knowing where CPS's are situated on other MB engines, it should be found somewhere on the rear of the engine block on the bellhousing.

 

[BTB 500]

The engines in the 639 Vito/Viano are all standard M-B ones shared with other models so it's very likely the CPS location will be the same. Access may be trickier though if it is at the back of the engine.

 

[schneckster]

Well, I now know where it is after using a pic from the EPC to help work it out. And yes, at the back and at the bottom.

Of course, being based on a van rather than a car, half the engine is under the dashboard so I've got no chance from above. The only way I can see it going in is to jack it up and drop the sump guard. And I don't have the gear to do that.

I've got a decent mobile mechanic coming out to do it for me, then I'll get it to my favourite indie to check it over with a Star.

Update when I have it.

Cheers,

Schneckster

 

[schneckster]

[solved]

I managed to get the car to my favourite Indie by driving a mile and a half, pulling over to let it cool down, then going again. Took about 2 hours to do 6 miles!

Anyway, they put it on Star and sure enough, loss of comms with the Crankshaft Sensor. They're replacing it as we speak.

Of course, I had intended to do it myself and so bought a new sensor from Car Spares for £22, compared with £122 from Mercedes. But my Indie just phoned to tell me it doesn't fit and despite having the right part number, it is visibly bigger than the part they took out... and isn't even circular! Might explain the price difference. So I told them to get one from Merc so it's at least the right part and I get my car back working... there goes my overdraft again!

Oh well, win the Euro Millions tonight, get a new car tomorrow!!

Cheers,

Schneckster

 

[donr]

I had exactly the same problem when driving my sister-in-laws car in America. It did turn out to be the sensor, and when replaced the problem was solved. Her car is a Nissan Altima. I bought the replacement part from a general car parts dealer, and I had exactly the same experience-the first part he sold me was the wrong thing ! it would not fit. However he changed it with no problem, and all is now ok