Broken Crankshaft Position Sensor Bracket Solution


19BillyBob54
10-17-2006, 12:57 PM
Troubleshot non-start / stalling problem to the Crankshaft Position Sensor located on the top of the transmission bell housing. I carefully followed all but one removal instruction on http://www.brickboard.com/FAQ/700-900/EngineSensors.htm##Crank_Postition_Sensor . The one instruction I did not follow was the one that said be careful and don’t break the bracket!!:banghead: Not entirely my fault, though (things like this never are). Further inspection revealed what appeared to be some sort of sealant on the sensor. The front half of the bracket came off with the sensor and the rest stayed on the car. Even with the sensor/bracket in hand, it was still difficult to separate the two. Not wishing to pull the tranny to replace the bracket, I “invented” the following solution (MILAGE MAY VARY):

1. The bracket broke pretty evenly right across the center section of the ring that wraps around the sensor. As mentioned above, it was fortunate that the bracket remained attached to the sensor. I noted that the opening in the top of the transmission bell housing was only slightly larger than the bracket, although there was NO WAY I was going to be able to remove that bracket without pulling the tranny. I also noted that the top of the bracket that was still attached to the engine block was essentially flush with the top of the flat area on top of the bell housing
2. I cut a thin piece of aluminum sheet slightly larger than the bracket (about ˝ inch all the way around, except for along the back edge of the sensor, which was cut flush. I then drilled a hole just large enough for the body of sensor to fit through and a smaller hole for the retaining blot to go through.
3. I then used JB Weld (strong stuff) to glue the broken bracket to the aluminum plate. To hold everything in place and aligned, I mounted the sensor in the plate and secured it to the mounting bracket with the retaining bolt (I coated the sensor with petroleum jelly to keep things from getting glued together. I also used the old sensor for this).
4. Back out at the car, I test fit the bracket/plate/sensor assembly. Because of the way the thing broke in the first place, I could actually feel the two parts of the bracket line up when it was positioned correctly. I really wanted to install the whole thing as a unit, but the sensor wire would not permit the whole thing to sit flat on top of the bell housing, so I had to remove the sensor and just install the plate/bracket. Once happy with the fit (and how to get it in place), I cleaned the bell housing with solvent, spread JB Weld on the bottom of the plate and set the assembly in place on top of the bell housing.
5. Once everything was dry, I installed the new sensor (real pain). Installation was just like normal, except that now there is this aluminum plate covering the opening in the bell housing.
6. Car started instantly on first try – so I guess everything worked OK.

I suspect that I was able to do what I did for a couple of reasons. First, the way the bracket broke was conducive to this type of repair. Looking at the bracket, however, I suspect that most broken brackets would fail about the same way. Second, I suspect that the bracket, as it is attached to the engine block, is adjustable. Mine just happened to be adjusted so that everything was flush with the top of the bell housing which allowed the alternative mounting method I used without adversely affecting the spacing between the bottom of the sensor and the ring it senses. Wished I had taken pictures, but didn’t REALLY think this was every going to work; guess the car gods were smiling down on me!!!! Hope this helps someone else.

jsinton
02-13-2007, 10:25 AM
A very informative story, it really helped me a lot. Now I will try to replace my VSS. Thank you.

jsinton
03-13-2007, 02:54 PM
I was able to do my VSS no problem using the instructions from brickboard.com. I was careful about removing the bolt, and once the bolt came out, my VSS was already loose. My fat fingers and arms were my biggest problem. The new one was easy to put in. Now my car seems to run better. Thanks for the info.

jsinton
03-13-2007, 09:42 PM
FYI: This part failure is supposed to be one of the few common things that will go bad on a Volvo 240 and render you car useless. I was reading where a mechanic recommended taking an extra with you on long trips just in case yours goes bad.

Also, to help people in the future, this part is called a vehicle speed sensor, an RPM signal sensor, an Engine Speed Reference RPM Sensor, or an inductive speed pickup. It's part #3547847. I knew I had a problem because my "check engine" light was on, and when I read the code it gave me a 1-3-1 which is "Engine RPM signal missing". The first time the "check engine" light came on my car still ran ok, so I reset the code so the light went out. About 2000 miles later the light came back on with the same 1-3-1 code, so I knew I had intermittent failure.

I think Autozone sells this part non OEM for $44, but I was able to find it on EBay for $20 and it was OEM Volvo. Also this part can be found here:

http://www.thevolvosite.com/shop/index.php?Cat=985&car_model=240

I think I probably put another 5000 miles on the car before I finally replaced the VSS and reset the code/engine light turned off. I let you know if the light comes back on anytime soon.

jsinton
03-14-2007, 12:39 PM
One more thing... Make sure you read the COMPLETE instructions at brickboard.com mentioned at the beginning of this post before you try to do this replacement. That URL again is:

http://www.brickboard.com/FAQ/700-900/EngineSensors.htm##Crank_Postition_Sensor

upret66
12-10-2010, 12:46 PM
Troubleshot non-start / stalling problem to the Crankshaft Position Sensor located on the top of the transmission bell housing. I carefully followed all but one removal instruction on http://www.brickboard.com/FAQ/700-900/EngineSensors.htm##Crank_Postition_Sensor . The one instruction I did not follow was the one that said be careful and don’t break the bracket!!:banghead: Not entirely my fault, though (things like this never are). Further inspection revealed what appeared to be some sort of sealant on the sensor. The front half of the bracket came off with the sensor and the rest stayed on the car. Even with the sensor/bracket in hand, it was still difficult to separate the two. Not wishing to pull the tranny to replace the bracket, I “invented” the following solution (MILAGE MAY VARY):

1. The bracket broke pretty evenly right across the center section of the ring that wraps around the sensor. As mentioned above, it was fortunate that the bracket remained attached to the sensor. I noted that the opening in the top of the transmission bell housing was only slightly larger than the bracket, although there was NO WAY I was going to be able to remove that bracket without pulling the tranny. I also noted that the top of the bracket that was still attached to the engine block was essentially flush with the top of the flat area on top of the bell housing
2. I cut a thin piece of aluminum sheet slightly larger than the bracket (about ˝ inch all the way around, except for along the back edge of the sensor, which was cut flush. I then drilled a hole just large enough for the body of sensor to fit through and a smaller hole for the retaining blot to go through.
3. I then used JB Weld (strong stuff) to glue the broken bracket to the aluminum plate. To hold everything in place and aligned, I mounted the sensor in the plate and secured it to the mounting bracket with the retaining bolt (I coated the sensor with petroleum jelly to keep things from getting glued together. I also used the old sensor for this).
4. Back out at the car, I test fit the bracket/plate/sensor assembly. Because of the way the thing broke in the first place, I could actually feel the two parts of the bracket line up when it was positioned correctly. I really wanted to install the whole thing as a unit, but the sensor wire would not permit the whole thing to sit flat on top of the bell housing, so I had to remove the sensor and just install the plate/bracket. Once happy with the fit (and how to get it in place), I cleaned the bell housing with solvent, spread JB Weld on the bottom of the plate and set the assembly in place on top of the bell housing.
5. Once everything was dry, I installed the new sensor (real pain). Installation was just like normal, except that now there is this aluminum plate covering the opening in the bell housing.
6. Car started instantly on first try – so I guess everything worked OK.

I suspect that I was able to do what I did for a couple of reasons. First, the way the bracket broke was conducive to this type of repair. Looking at the bracket, however, I suspect that most broken brackets would fail about the same way. Second, I suspect that the bracket, as it is attached to the engine block, is adjustable. Mine just happened to be adjusted so that everything was flush with the top of the bell housing which allowed the alternative mounting method I used without adversely affecting the spacing between the bottom of the sensor and the ring it senses. Wished I had taken pictures, but didn’t REALLY think this was every going to work; guess the car gods were smiling down on me!!!! Hope this helps someone else.

Thanks a lot for this advice and wish me well. Yesterday I did the EXACT same thing - BUSTED off the bracket at halfpoint, just like you have described. It was like 23 degrees here in NY and I think that the reason for the breakage - in hindsight - was that the cold made the bracket ring contract around the sensor. Make sense? It was really stuck and had I found this blog beforehand, it would not have happened! oh well, chalk one up for experience. I am out to buy some JB weld and will wait until tomorrow to apply. The temp is going up to about 40 tomorrow so that should help.

Question: How thick was the aluminum that you used? I am guessing like about a millimeter or so? I am going to go with a piece of flat duct if that is not too thick. Anyway, THANKS for the practical advice. I will let you know if it works!!!

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