Replacing Crank Sensor on N42B20 Engine

[championc]

Hi all,

Can the Crank Sensor be replaced from below or must the whole inlet manifold come off and access it from the top ?

I was looking from underneath and can see a tube coming out horizontally from the dipstick tube but directly behind this seems to be some form of bracket with a U shaped metal pipe on it. I just don't know if these are manouvreable.

If I attack it from above, it would seem as though I could lose two or three hours just trying to undo the torx bolt on the forward end of the underside of the inlet manifold.

Any thoughts from anyone who has done it ?

[joewatkiss]

i managed to get both the torx bolts from underneath using a series of wobbly extensions, a 1/4 sockets and a 1/4 drive torx bit.
Ill get a picture now, both bolts were out and in easily.. i have the air con, too. You definitely can get round the air con compressor
Its not a bad job at all, just be careful with the nipple that connects the vacuum hose to the air box. i talk from experience
I took my time with everything, taking the dividing wall out at the back right side of the engine bay helps too..

Took me about 4 - 5 hours in total. I think i removed a lot more than i needed to tbh, but it made life easier for me and i was in no rush

Edited August 14, 2013 by joewatkiss

[championc]

So to clarify, while the rear torx 30 bolt is vertical, I assume the front one is horizontal - with the head of the bolt facing towards the gearbox ?

And if I remove the whole inlet manifold, are no replacement gaskets required ?

Regards

C

[joewatkiss]

thats where the location is of the sensor, just below the starter motor.. i dont know if this might help you see it a bit more easily from underneath

Both the bolts are vertical. I bought a new set of inlet manifold gaskets, but that was all that i needed. You might get away with re-using them, but its better to be safe than sorry and theyre not a huge amount of money

Edited August 14, 2013 by joewatkiss

[joewatkiss]

Removing the metal sump guard/pan thing underneath helps a lot with getting to them. There is a special torque procedure for the bolts when refitting though iirc.. you have to do an extra torque turn on them after using the torque wrench

[championc]

Removing the metal sump guard/pan thing underneath helps a lot with getting to them. There is a special torque procedure for the bolts when refitting though iirc.. you have to do an extra torque turn on them after using the torque wrench

thats where the location is of the sensor, just below the starter motor.. i dont know if this might help you see it a bit more easily from underneath

Both the bolts are vertical. I bought a new set of inlet manifold gaskets, but that was all that i needed. You might get away with re-using them, but its better to be safe than sorry and theyre not a huge amount of money

Not sure if I'll get a chance to get to a main dealers

Removing the metal sump guard/pan thing underneath helps a lot with getting to them. There is a special torque procedure for the bolts when refitting though iirc.. you have to do an extra torque turn on them after using the torque wrench

Looks like i'm going in from the top so - I don't have a small torque wrench

Having both done them, can I just cross check my symptoms - I can manage to get the car started, it runs for a bit and I can put the foot down, but it I then stop and idle, it just stalls and won't restart for at least an hour. Fuel pump is now being primed after I replaced the cars' battery which was 9 years old and was weak.

[joewatkiss]

My symptoms were different but getting to the stage yours is at. My car would stall randomly whilst driving but kick itself back into life, obviously jump starting itself. It would also stall at idle, but i could restart the car straight away afterwards. Have you had the codes read? Thats the only way i managed to diagnose the crank sensor on mine as a definite culprit. No codes showed up on a normal OBD reader, but using proper software showed there was a problem.

Edited August 14, 2013 by joewatkiss

[joewatkiss]

I wouldnt worry too much about the pan bolts, im just finicky with torquing stuff if i can.. i think you can do them with a 1/2 torque wrench if youve got one of those

[championc]

I wouldnt worry too much about the pan bolts, im just finicky with torquing stuff if i can.. i think you can do them with a 1/2 torque wrench if youve got one of those

I have a huge one about 2 - 3 foot long

[joewatkiss]

is it half inch drive? or 3/4 inch drive? half inch should be okay, what is the scale on it?

[championc]

3/4 with a 1/2 adapter. Not sure of scale but decent enough I reckon

[joewatkiss]

If its 3/4 it might not go low enough

[championc]

Hi again Joe

I was away on business yesterday and finally managed to get some free time to re-install GT1/DIS v44 on my new Laptop. It initially had several fault codes. I ran the engine until it failed. I then cleared the lot of them and cranked the engine over - which of course would not start and violla, code 277F, Crank Speed Sensor.

When Googling code 277F, I came across the following interesting post in another forum which really confirms as to why I needed to wait for about 1 hour before being able to restart the car

"As mentioned earlier by Assimilator1 the likely candidate would be the crank sensor, they are known to play up when they get hot, We have had a few members on the forum who have had similar problems when the car gets warm and had a non start issue until the engine had cooled back down."

Just coming back to the picture of all of the 1/4 extensions all joined together, was that for the front or rear bolt ? I can't see the front one and others seem to suggest that it's almost impossible to get to whereas when I was under the car on my back looking up, I could see the rear one quite easily and I don't think I need a huge extension to reach it. In fact, I think a decent reach with a T30 screwdriver would work.

Cormac

[championc]

Oh my god ...... that front Torx was a bloody nightmare to remove took friggin ages. Tomorrow morning it's the manifold off and hopefully a quick swap of the Crank Sensor. I certainly think I'll replace the Torx screws with M8 of whatever bolts.

[joewatkiss]

Sorry for the late reply, i'm glad you managed to get to it.. the set up for removing that front bolt i had was 1/2" ratchet - 1/2 six inch extension -1/2 to 3/8 dropper, 3/8 wobbly 2" extension - 3/8 wobbly 6" extension - 3/8 to 1/4 dropper, 1/4" extension - 1/4 drive bit driver - t30 bit. I just also used it for the rear as it was to hand while i was under the car. By 'wobbly' i mean an extension with a sort of rounded end rather than square to allow torque to be applied at a slight offset. I had the front wheels up on car ramps and the re-enforcement plate removed. I reached up around the front of the compressor and felt for the bolt, i then fed my contraption up between the compressor and the mount (iirc there is a gap) and guided the t30 bit in. Then it was a matter of undoing it, which is simple enough.. I dont know why i found it so easy. I did start off trying to remove it from above as recommended by the Haynes book of lies, but upon further investigation managed to get it like that.. Once the manifold is off the crank sensor is a piece of p*ss to change, its a ridiculous procedure for a simple job really.

Glad you managed it one way or the other though mate

Joe

[championc]

Ha ha, I did the BACK one with the long bars underneath and just used a tiny 4 inch screwdriver bit ratchet for the front one. And it was the front one that was the pain in the ass.

After that, I had the whole thing out quite quickly (well after I copped the bolt holding the dipstick to the manifold !!)

I oiled the threads of the T-30's and so I was able to hand screw in the front one and just tighten off. So the whole lot went back in in about an hour. I'm sure I saved myself a small fortune against going to a main dealer. It really wasn't as difficult as I imagined (or feared) it would be.