Poor starting cure? Crankshaft sensor replacement

pc759

pc759

A2OC Donor
I bought a replacement crankshaft sensor last weekend (c£70) on the advice of a bosch agent (some of you will know that i have had several months of niggly starting problems).
On Thursday the car refused to start at all so I resolved to fit the new sensor myself this weekend.
It was a real pain in the backside, probably made worse by my taking things off to get it at it that didnt really need to come away in themselves.

I attach some pictures:

Pic 332. With everything in sight as normal, the crankshaft sensor is invisible under the oil filter housing and associated cooling pipes and elements.
Pic 343. This picture is more revealing with water pipes moved from oil filter housing but, by now I was beginning to brick it
Pic 346. This picture shows the oil housing off the engine (already, I had completely sh*t myself and was on 2nd pair of tracky bottoms) with crankshaft sensor completely in view ( pic 347)
Picture 344 and 345 show relative strength of the magnetised sensor - it's not really effective to see here but the newsensor (pic 344) could pick the wiper arm up from the windscreen and the old one (pic 345) could just not do it. Hopefully this will resolve my problem as a stronger impulse will be signalled.

I put everything back together and it seems to have worked ...

Some other points worth discussing?

The old sensor was covered in oily residue and there seemed to be oil down it's chute - is this normal?
TDI club (usa) articles suggest that poor hot starting is a VAG issue due to the ECU some people are wiring in temporary fixes to solve this, though this is not for me. At one point I thought this was my problem too...
A friend at work who subscribes to 'Which' magazine said that they (Which) strongly suggest there have been ECU problems with A2 ...
Needless to say this all began to give me the willies and I was contemplating a new car, now hopefully, I don't need to change it.
It's fired up 7 out of 7 today after being left in various states of cooling, typically the medium hot state where invariably it refused to go.

Paul
 
Hi Paul (and Sarge!)

I can see this was ages ago when you did this - but I have just found I have the same problem!

Been on holiday for two weeks and came back and car cranks but doesnt start (and flashing glow plug signal). AA guy hooked it up to diagnostic and showed definitely the crank sensor has gone (fault code PO727 engine speed circuit no signal) and no resistance at the plug when he checked it. So looks like I have to do the same job as you!

I just wondered - its clear that I have to remove the oil housing. Should I get new gaskets for it as its coming off? If so, do you know where I can get these from?

Are there any tips you learned along the way of doing this job, which you can tell me? It looks like a bit of a pig of a job, so looking to see how easily I can do it!
cheers
David
 
It looks like I've got this job to do and have two questions:

1. Is it possible to replace the sensor by dropping the oil cooler off and is this easier than removing the oil filter housing?

2 What are those strange multi Spline head bolts. They are not Torx. Where could I get a set of suitable sockets, probably need to be 1/4 drive for access?

Thanks

Phil
 
A few tips, this can be a very straightforward job (55kw Tdi):

Lift the car and remove the engine bay under tray

Remove the oil cooler, catch small amount of oil spill, leave connected to water pipes and move to one side (I also removed the oil filter to minimise oil spillage)

Cover oil cooler to avoid dirt contamination.

Remove old sensor and replace with new

Fit oil cooler with new O rings

Top up oil, start engine check for leaks.

Refit under tray - job done
 
Well I may have replaced the crank sensor quickly and easily but it didn’t solve my problems.

The car starts well when cold and fully warmed up. However when part warmed up, or cooled down, it can hesitate to start. It spins the engine without firing, a little like when the fuel filter has been replaced and fuel has yet to reach the injectors.

Any suggestions, threads I’ve not found, or it a case of finding a fault reader?

Thanks.
 
Hey are you getting any other errors in vcds?
Camshaft angle senso sounds like your issue
 
Thanks for letting us know how u got to it,
I'm Gona attack mine at some point on your instructions
 
philward said:
A few tips, this can be a very straightforward job (55kw Tdi):

Lift the car and remove the engine bay under tray

Remove the oil cooler, catch small amount of oil spill, leave connected to water pipes and move to one side (I also removed the oil filter to minimise oil spillage)

Cover oil cooler to avoid dirt contamination.

Remove old sensor and replace with new

Fit oil cooler with new O rings

Top up oil, start engine check for leaks.

Refit under tray - job done
Click to expand...
Thanks for the advice. Followed this procedure today without too much trouble. My tdi90 suddenly failed to start last week, normally first turn starter. A scan showed crank sensor fault along with flashing glow plug warning light on dash. New sensor fitted, back to first turn starting. £15 fix and about an hour fiddly work. I recommend a 1/4 socket set and extension as it makes it easier to get to the trickier 10mm bolt behind the water pipes for the oil cooler removal. Cheers
 
Just fitted one this morning (2:30am I got to bed) after my friends car wouldn't start on my drive, he knew it was a problem but kept using the car regardless!
With a bit of modifying the sensor with a file and sandpaper I managed to get the sensor replaced without removing any thing else other than wiring plug to oil pressure sensor however it goes against the grain but I had to pull the sensor in with the bolt having decided trying to bar in the sensor would almost certainly break it.

Does anyone know the part number for the seal for the oil cooler to oil filter housing as I feel that's the best way to do the job and have a fight with the undertray lol
 
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