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Old 06-09-2018, 09:30 AM   #1
mike114
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Default Stuck CPS / RPM sensor

Manual 240 w Lh 2.4

I got the 10 mm bolt out without issue. Turns out that was the easy part..

Now i am trying to pull out the sensor but it seems to be fused / stuck in there. Tried spraying it w P B / liquid wrench, etc... nothing. I managed to get a small wrench in there to see if I could rotate it a bit. No movement.

Any suggestions?
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Old 06-09-2018, 02:02 PM   #2
dl242gt
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The rotation thing worked for me when I had a difficult one. Just keep spraying the penetrating oil on there and let it work for a good while. Use the tab with the bolt hole to try to rotate the sensor. If you get it rotating about a quarter turn or so. You can then grab it with some needle nose pliers and gently pull up with the pliers to get it out.
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Old 06-09-2018, 02:42 PM   #3
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Is your trans in or out? Are you intending to take the trans out or just fussing with the sensor?
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Old 06-09-2018, 09:42 PM   #4
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The rotation thing worked for me when I had a difficult one. Just keep spraying the penetrating oil on there and let it work for a good while. Use the tab with the bolt hole to try to rotate the sensor. If you get it rotating about a quarter turn or so. You can then grab it with some needle nose pliers and gently pull up with the pliers to get it out.
Thanks. I have a feeling this thing will test my patience. I sprayed the hell out of it with Liquid Wrench Silicone spray and will try again tomorrow. Engine/Trans still in car. Not planning to pull it unless...

How ridiculous would it be if I had to pull the trans for a small plastic sensor? Gawd I hope Iím not headed in that direction. That would suck.
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Old 06-09-2018, 10:29 PM   #5
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If you're not intending to pull it then def don't pull it lol. Dropping them isn't bad but it's not christmas either.

You COULD pop under the car though and loosen/disconnect your trans mount and jack the trans up a bit. This will rock the motor forward a touch and you may be able to get better purchase on the whole thing.
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Old 06-09-2018, 10:37 PM   #6
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It'll come out. overnight is good with penetrating oils. Even if it's plastic like this it has helped on these sensors for me. But yeah if it went bad there. That sure is a lot of work to fix the sensor.

I recently replaced the same kind of sensors on an 86 alfa spider. They put them on the side of the bell housing and down below where they are easy to replace. It was a bosch ignition system as well.
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Old 06-10-2018, 07:52 PM   #7
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How ridiculous would it be if I had to pull the trans for a small plastic sensor? Gawd I hope Iím not headed in that direction. That would suck.


Well, I think I jinxed myself, dammit.

Looks like I will be dropping the trans after all...
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Old 06-10-2018, 08:12 PM   #8
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There's no way man. At the VERY most you might need to crack the bell housing from the block.

Is the sensor bad? If it's bad I don't see any harm in just yanking it out once you remove the bolt(s)?
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Old 06-10-2018, 09:16 PM   #9
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Grab it with some mini channel lock pliers to remove it.
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Old 06-10-2018, 09:23 PM   #10
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Are you sure you need to replace it? The CPS is just a coil of wire around an iron core plus a magnet, so it's pretty reliable if kept dry. If the resistance measures close to spec, the sensor is probably fine. On the other hand, I think I've seen posts about water getting into the coil and both damaging it and causing it to swell up so that it's difficult or impossible to remove.
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Old 06-10-2018, 09:57 PM   #11
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I’m having trouble posting pics.

Here they are in my shared google photos:

If one of you is gentleman enough to display them I think it would benefit some shmo who will attempt this in the future.

https://photos.app.goo.gl/NWuJNkzFYDaWrBDx5

The pics speak for themselves.

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Old 06-11-2018, 08:30 AM   #12
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Old 06-11-2018, 08:36 AM   #13
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Well... That's unfortunate.
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Old 06-11-2018, 09:55 AM   #14
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silicone spray is not penetrating oil !
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Old 06-11-2018, 09:59 AM   #15
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I've certainly seen that happen before.

Unfortunately, the lower portion of the sensor can corrode internally, and then it expands slightly. And at that point, it's not going to come out of that flimsy alu bracket very easily, if at all. And if you manhandle it too much, the bracket breaks, then you're stuck pulling the bellhousing off (at least a few inches) and getting a new bracket.

Hopefully someone has a used one for you, worst case is: https://www.ebay.com/itm/Volvo-Speed...IAAOSwQO9a3knF
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Old 06-11-2018, 10:19 AM   #16
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Can JB Weld or some other product reattach the broken bit, or must the OP replace the whole bell housing / transmission?
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Old 06-11-2018, 10:23 AM   #17
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Just pull the trans, clean everything and do the rear main seal while in there and replace with a good bracket. Don't try to jbweld that, you'll just have to redo everything in a while, not worth it.
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Old 06-11-2018, 10:37 AM   #18
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Can JB Weld or some other product reattach the broken bit, or must the OP replace the whole bell housing / transmission?
Almost certainly not. It's a very small area where it's broken, and with the bellhousing you really can't get to it very well, you're working through a narrow notch in the bellhousing. And the positioning has to be precise, it's exposed to a lot of heat/vibration/oil, it's just practically guaranteed to leave you stranded on the roadside in the near future.

It would have been NICE if the bellhousing notch was bigger, or the bracket bolted on from the outside of the bellhousing and the sensor just poked through the notch from there, etc, etc.

But it isn't.
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Old 06-11-2018, 11:40 AM   #19
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I recently went through this with my 780. John is correct. The sensors will corrode internally and swell up like an expansion plug. I've seen them so swollen that the only way to get them out would be to drill them out once the bracket is off the engine. Or, hit the bracket with a heat gun so that the housing of the sensor melts and it slides out.

My 780 crank sensor quit over two years ago. I wasn't driving it, so, I just kept spraying PB Blaster on the bracket every few months and when I finally had some time, trailered the car to my shop. I planned on having to remove the trans, thus, I didn't want to attempt the replacement at home. I took the distributor cap off and was able to see the sensor with a mechanic's mirror while trying to get a small set of vice grips around the body of the sensor. I was able to get them to lock onto the body and carefully rotated it clockwise/counter-clockwise about 10 degrees for about 5 minutes to grind away at the corrosion build up on the inner bore of the bracket. It finally crunched up enough corrosion it pulled right out when I pulled up on the cable. I got lucky. 3 minutes to drop another sensor in and replace the bolt and it fired right up, on three cylinders. Two years of sitting caused one of the injectors to glue itself stuck. Replaced that injector and it runs great now.

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Old 06-11-2018, 11:47 AM   #20
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Plus side... it's quite easy to expand the hole on the bell. Just hit that hot action with a wire wheel on a drill (at least... this is how I cleaned it up on my swap...)
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Old 06-11-2018, 11:52 AM   #21
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Quote:
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I recently went through this with my 780. John is correct. The sensors will corrode internally and swell up like an expansion plug. I've seen them so swollen that the only way to get them out would be to drill them out once the bracket is off the engine. Or, hit the bracket with a heat gun so that the housing of the sensor melts and it slides out.
So is this a climate related thing, heat, age, etc?? I want to do my very best to never let this happen, though all 3 of them on our bricks have come out with ease
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Old 06-11-2018, 11:55 AM   #22
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If you're "lucky" enough the sensor will fail due to bad wiring before the bottom part has time to expand and lock in place. And then if you have a few engine oil leaks, it helps everything stay nice and fresh under a layer of corrosion preventing oily grime.

I have a couple of these brackets sitting around home somewhere, but the last time I looked for one I couldn't find it.
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Old 06-11-2018, 01:14 PM   #23
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OP, I have an extra bracket I will sell if you need one.
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Old 06-11-2018, 01:29 PM   #24
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Freeze the sensor so that it shrinks. CRC Freeze-Off? Canned Air duster?
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Old 06-11-2018, 03:52 PM   #25
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threadjack: Welcome back Art!

OP: sorry to see this. Best of luck with it.
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