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Big Gaz (1)

2nd Crank Sensor failure in 6 Months...

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Hi Guys,

 

I had what I assume to be the original 1997! BMW crank sensor fail back in May I think, duly replaced with a new genuine BMW part at £123 and now this one has failed checked on me laptop, also same symptoms as before.....:angry:

 

So thinks me, I'll call up the BMW parts dept that I bought the sensor from to see how to go about warranty replacement etc.

 

- So says they: 'You have to bring in the vehicle for diagnostics check, if it shows faulty sensor then we will sort it and diagnostics is free, if not you have to pay for the diagnostics.'

 

I asked if they can perform a bench test of the sensor and I was told 'no, it must be on the vehicle in case it is a wiring issue etc...' (Surely a bench test of the sensor would make more sense as it rules out wiring issues?)

 

So I asked them if they keep the sensor in stock as last time it had to come from Germany, 'none in stock and we won't order it unless you pay for it...'

 

And then I asked how much the diagnostic check is.... '£168+VAT'!!!!!!!!!!!! WTF - how much!! - I confirmed that would be the cost even if I just want them to look at the crank sensor signal only!

 

So effectively to keep continuity of driving my vehicle i need to stump up nigh on £300 

 

You can drive it but it has stalled a couple of times and mostly the Mrs and kids are in it.

 

Sod that, so I bough a HAAS unit for £58 and swapped it in, car fired up straight away and all fine. fearing a wiring fault and me fitting the new sensor just nudging wires back in to contact etc. I swapped between the BMW and HAAS unit 6 times and the fault 100% followed the sensor so I am as sure as can be the sensor is faulty.

 

So, am I being overly sensitive! - It's an old car and not many seem to appreciate them anymore, everyone just wants a range rover on hire purchase etc. but customer service seems to have been lost a bit here really, so I'm thinking of writing a slightly pi$$y e-mail to BMW UK demanding they bench test the sensor or send it to the OE supplier to test and then refund me the cost...

 

Anyone done this before? - Any luck? - I want my £123 back! - or another BMW part at least for when the HAAS one fails!

 

Can the ECU kill its own sensors? - The one I removed seemed ok, no damage to sensor, wiring or plug... was it an inside job! :)

 

 

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These M52 crank sensors working with 5 V are notorious for problems when the wiring etc. ages. One alternative is to convert it to 12 V crank sensor like on M52TU (9/98->) engines. It also needs an adapter cable for the changed supply voltage. I think in USA there was official recall which also made this same update.

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Hmm, thanks Clavurion, I'll look on Realoem for the part numbers and ask if BMW want to supply the updated set maybe FOC! :) - Yeah right

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One thing I did notice was how stiff the sensor wire had gone even though only 6months old, I guess a bit of thermal degradation to the insulation is to be expected but surely a more suitable insulator material should have been specified considering where it sits!

 

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I replaced this sensor about 3 or 4 times (if I remember correctly) within 6 months on my old E39. I always went with cheap parts, approx. €30-€40 a pop. The original, and the cheapo versions failed due to a very small leak in the thermostat housing above it. So just make sure this is not the root of your problem here. Most of the time I would not notice any leak there due to it evaporating with engine heat but there was definitely evidence of coolant having gotten into the resin sealed sensor body. Once I finally took care of the leak the short life span of crank sensors suddenly stopped being a problem.

Keliuss

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Hi Keliuss,

 

Good call, I will have a look mate, I had to loosen 1x thermostat securing bolt to remove the front lifting eye to route the wire so this could be the case.... I will check to see if there is a leak when the missus gets home. 

 

By the way BMW UK don't want to know, told me to take it up with the stealership as they are all privately owned and set their own costs and rules.....Well done them for not giving a crap! :)

 

 

 

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2 hours ago, Big Gaz (1) said:

Good call, I will have a look mate, I had to loosen 1x thermostat securing bolt to remove the front lifting eye to route the wire so this could be the case....

 

Ah yes, the memories come flooding back. The location of the connector is a pig to get to under the inlet manifold. I was in and out of there so many times I considered making up an extension cable for the sensor.

Just remember that the leak could be tiny/unnoticeable 90% of the time. I think the root of my issue was not using a torque wrench on the thermostat housing bolts and probably over-tightened/warped it.

I reckon in my case, the odd drop would fall on the cable, roll down and soak into the sensor.

 

keliuss

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Thermostat housing made of plastic will, with time and exposure to heat and pressure cycles, invariably deteriorate, crack and consequently leak. The hairline crack is only visible form the inside. On the outside it looks as good as new. So if you happen to have a gradual coolant loss which you cannot trace down this may be the culprit. I had it fail in both my E38 and E39 with M52TU/M54 engines - exact same spot exact same timing - 16 years from new.

Edited by dmarkovina1
Added more info.

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Hi Gents,

 

I may look in to replacing this (Thermostat housing) then as Mine is 21yrs old and original I think!! 

 

Mines not a TU, just a single Vanos job which I think has a slightly different design but might be wrong, but the housing is still plastic, and coolant does disapear even after hoses and radiator etc. have been replaced.  

 

I'll have a look at costs...

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Sorry I must have been under influence when I wrote whst I did... what cracks is the top radiator hose - the plastic ending that attaches to the engine - and not the thermostat housing. I have no idea how I managed to mixe those up... sorry again about that. I have actually never replaced a thermostat on those two cars - combined mileage more than 500k miles...

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No stress, part was only 12 quid and I've disturbed it twice already doing the crank sensors, I'll check out the hose situation, I can't recall if my M52 has the plastic hose connections or is standard old school rubber hoses and jubilee clips...

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Got to be honest, when I did the thermostat housing on my 530d, I didn't torque them.. just tightened them up about as they seemed when undoing them. Ran it up to temperature checking closely for leaks, and it seems to be tight as a drum so.

 

However from reading around it seems to be 10nm / 7 ft-lb.

Edited by chicaneuk

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Cheers chicaneuk,

 

to be honest I normally take that approach with most bolts etc.! - I expect there are compression limiters in the part to stop it being crushed at least so should be ok, I'll potentially be doing it tonight....I'll try to remember to feedback on anything I find! 

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