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So I had a go dead failure to crank last week. I feel fairly certain it was related to a low amperage on my 6 year old battery. The battery would show good voltage but would quickly drop. It turned the car over fine but it always started right up so it was never cranked and cranked so I don't know how much umph was left in it. It tested bad at auto parts store and I had noticed that the bass and subwoofer had stopped working as well.
Anyhow I went through the whole system and decided to replace the other possible culprits as I have no desire to be stranded. I have the key fob batteries on order, I now have a spare RCM and Crankshaft Position sensor as I figured I might had better order a spare before the parts become scares..
I decided to go ahead and swap out the CPS and it was a PITA to get to that bolt holding it in. So I came up with a possible solution to ease my pain if I every have to do it again. I bought an 8mm thread bolt with a 10mm head and a brass spacer to make the bolt the same length of engagement as the OEM but by being longer and a 10mm vs the E-Torx and it will stick out futher I think it will be easier to access for removal.
attached are photos.
I would like your thoughts. Is this a good idea or is there a flaw to my logic that I am not seeing?
I don't see a problem as long as the thread is the same. Should make it easier next time. Nice.
I took the OEM bolt with me to ACE Hardware. It is an 8mm with a 1.0 thread pitch. Total cost was $4.50 as the brass spacer was $3.50 and the stainless steel bolt was $.95.
I took the OEM bolt with me to ACE Hardware. It is an 8mm with a 1.0 thread pitch. Total cost was $4.50 as the brass spacer was $3.50 and the stainless steel bolt was $.95.
The brass spacer will get shorter as the screw is tightened, tubes are poor when it comes to compressive loads.
Depending how thick the wall of the tube is it may slowly get loose as the screw comes undone due to vibration. The recommended torque setting will not be maintained, so use some low strength Loctite.
I am pointing out the worst case scenario, it might be OK, but I would not do this.
Even a steel tube is weak, just not so weak as brass.
The brass spacer will get shorter as the screw is tightened, tubes are poor when it comes to compressive loads.
Depending how thick the wall of the tube is it may slowly get loose as the screw comes undone due to vibration. The recommended torque setting will not be maintained, so use some low strength Loctite.
I am pointing out the worst case scenario, it might be OK, but I would not do this.
Even a steel tube is weak, just not so weak as brass.
I don't think that will be a problem but I see your point. I had already planned to use some medium Loctite on it. The brass if you look closely is solid from the thread of the bolt to the edge of the spacer. is about twice the thickness of the wall of the socket. When I removed the OEM on it didn't take much force at all to break it loose so Im guessing the torque pressure is pretty low on this thing.. Also the sensor itself has a brass ring that the bolt tightens against.
The brass spacer will get shorter as the screw is tightened, tubes are poor when it comes to compressive loads.
Depending how thick the wall of the tube is it may slowly get loose as the screw comes undone due to vibration. The recommended torque setting will not be maintained, so use some low strength Loctite.
I am pointing out the worst case scenario, it might be OK, but I would not do this.
Even a steel tube is weak, just not so weak as brass.
I don't think that will be a problem but I see your point. I had already planned to use some medium Loctite on it. The brass if you look closely is solid from the thread of the bolt to the edge of the spacer. is about twice the thickness of the wall of the socket. When I removed the OEM on it didn't take much force at all to break it loose so Im guessing the torque pressure is pretty low on this thing.. Also the sensor itself has a brass ring that the bolt tightens against.
I think that's BRILLIANT! One thing. Are sure about the 1.0 thread pitch? M8-1.25 is the normal pitch for 8mm. 1.0 would be considered fine thread. I'm not saying you're wrong, I'm simply asking. Just like Frankenstein's head, you're the one with the bolt. I'm only looking at your picture and being honest. It doesn't look like fine thread to me. But I've been wrong very many lots of times!
In case I find myself at an Ace (not too difficult as it's inside the Piggly Wiggly, even using the PW cashiers!) do you know what the bolt's length is?
I haven't had to change my CPS yet but keep a spare on hand for when/if the time comes. My question is what is the material of the OEM bolt? Is that an aluminum or aluminum alloy bolt and what is the metal that bolt screws into? A stainless steel bolt screwed into an aluminum or aluminum allow receiver will corrode. Steel/Stainless Steel and Aluminum in contact with each other causes galvanic corrosion and you could end up with a real mess on your hands. I'll also note that brass in contact with Stainless Steel will corrode for the same reason.
My Ford F150's fuel pump relay was made of aluminum and bolted directly to the steel frame. I read about fuel pump issues with the F150 and 80% of the time it isn't the fuel pump but the Fuel Pump relay completely corrodes since it was attached to steel (wonder who the genius at Ford was who came up with that OEM attachment method and placement). I went under my F150 and luckily caught it in time... The back side of the relay where it was touching the steel frame was corroded to the point I pushed my finger right through it into the electronic insides. The replacement I put in came with stand-off rubber bushings so the aluminum Relay does not come in contact with the steel frame.
I personally won't be changing from the OEM bolt on that CPS. I like the idea but I sense the OEM bolt and the metal it screws into are like metals that will not corrode in contact with each other.
Maybe others can comment on my thoughts?
Last edited by Deepsea21; Feb 15, 2022 at 06:30 PM.
I think that's BRILLIANT! One thing. Are sure about the 1.0 thread pitch? M8-1.25 is the normal pitch for 8mm. 1.0 would be considered fine thread. I'm not saying you're wrong, I'm simply asking. Just like Frankenstein's head, you're the one with the bolt. I'm only looking at your picture and being honest. It doesn't look like fine thread to me. But I've been wrong very many lots of times!
In case I find myself at an Ace (not too difficult as it's inside the Piggly Wiggly, even using the PW cashiers!) do you know what the bolt's length is?
Damn your lucky our Piggly Wiggly has a hard time keeping groceries on the shelves lately let alone having other stores inside.
I haven't had to change my CPS yet but keep a spare on hand for when/if the time comes.
Same here. I even keep it in the trunk! Furthermore I bought a 'bendy' 6" long 3/8" extension shortly after buying the Xfire as someone on the forum suggested. I am so dumb have so much faith in you fellows that I never even put my ability to reach the bolt to the test! I simply looked at it and thought, "Yeah, that's doable." When next I find myself in the garage with time on my hands I'll assemble my tools together and find out what all the noise is about!
I haven't had to change my CPS yet but keep a spare on hand for when/if the time comes. My question is what is the material of the OEM bolt? Is that an aluminum or aluminum alloy bolt and what is the metal that bolt screws into? A stainless steel bolt screwed into an aluminum or aluminum allow receiver will corrode. Steel/Stainless Steel and Aluminum in contact with each other causes galvanic corrosion and you could end up with a real mess on your hands. I'll also note that brass in contact with Stainless Steel will corrode for the same reason.
Maybe others can comment on my thoughts?
I thought about this myself and a quick google search to ease my concerns found that the engine block on the M112 is Light Aluminum The OEM bolt was not aluminum as I dropped it and had to use a magnet to pick it up. Although you are correct about the possibility of corrosion according to google it is one of the safer choices as the area of contact is a minimal only the threads, the bolt head itself does not touch the engine block. And the sensor itself has a brass sleeve inside of it so apparently Mercedes Benz didn't feel it presented a problem. At any rate I will swing back by ACE hardware and see if they have an aluminum bolt. Just a side thought. Arn't spark plugs stainless and they go into aluminum blocks all the time.
Originally Posted by WD40
Same here. I even keep it in the trunk! Furthermore I bought a 'bendy' 6" long 3/8" extension shortly after buying the Xfire as someone on the forum suggested. I am so dumb have so much faith in you fellows that I never even put my ability to reach the bolt to the test! I simply looked at it and thought, "Yeah, that's doable." When next I find myself in the garage with time on my hands I'll assemble my tools together and find out what all the noise is about!
WD40 what the noise is about is for me I have large hands and it is a somewhat tight fit. There are two heat shields that cause problems. The one right next to the sensor is a heavier gauge aluminum that with a long extension or a heavy set of plyers can easily be bent back a little in order to get your hand or tools in. The second heat shield is the tall one that comes up by the brake master cylinder. There is an 8mm bolt that holds it on just in front of the master cylinder that is easily removed, and this is very pliable material and can be folded down to give a bit more work room and a better angle to get to the bolt. It is also very sharpe and will cut up your arms and hands. If your extension is too long it will hit this shield and you won't be able to get the angle needed to get a purchase on the bolt. a shorter extension of about 10 inches I think is best.
You are right most metrics are 1.25 or .7 but this is a 1.0 It screwed in smooth as butter. Im not sure what the length was I think 30mm but not for sure. I had planned to buy longer and cut it down with a dremel to the right length but the spacer made it just right.
I replaced the sensor this evening when I got home, and it went in easy peasy. The longer bolt made it very easy to line up and I could see it well enough to put the socket on it. below are the pics installed and screwed in. The bolt was easier to see before tightening it down but still half visible from the top even after it was tightened.
Last edited by TearlessTom; Feb 15, 2022 at 10:00 PM.
When next I find myself in the garage with time on my hands I'll assemble my tools together and find out what all the noise is about!
It's about making things harder than they are (reason for so much divorce as well).
There is nothing hard about changing the CPS. My mechanical skills are about as low as you can get, and I can change a CPS faster than I can replace an oil filter.
The mistake everyone makes is they try to remove the bolt first, then yank the CPS, or they put the CPS in and THEN try to put the bolt in. WRONG. Loosen the bolt and remove the bolt and CPS, holding the bolt in the CPS' hole with the rachet and lift it all out together - easy. DO NOT unplug the connector from the CPS till you get it all out of there.
Use the reverse technique to install the new one. With the right extension, you are done in a few minutes.
It's about making things harder than they are (reason for so much divorce as well).
There is nothing hard about changing the CPS. My mechanical skills are about as low as you can get, and I can change a CPS faster than I can replace an oil filter.
The mistake everyone makes is they try to remove the bolt first, then yank the CPS, or they put the CPS in and THEN try to put the bolt in. WRONG. Loosen the bolt and remove the bolt and CPS, holding the bolt in the CPS' hole with the rachet and lift it all out together - easy. DO NOT unplug the connector from the CPS till you get it all out of there.
Use the reverse technique to install the new one. With the right extension, you are done in a few minutes.
I agree completely , the operative term here is using the right extension. Once that is figured out I can swap it in 5 minutes.
Arn't spark plugs stainless and they go into aluminum blocks all the time.
I googled it and read, "Many spark plugs have nickel-plated threads on the plug shell to prevent corrosion between the steel threads on the plug and the aluminum threads in the cylinder head". That must be why the threads are so shiny... they are nickel-plated.
I googled it and read, "Many spark plugs have nickel-plated threads on the plug shell to prevent corrosion between the steel threads on the plug and the aluminum threads in the cylinder head". That must be why the threads are so shiny... they are nickel-plated.
Ford has a problem on their aluminum 5.4 modular engine with the spark plug breaking upon removal, leaving behind part of it in the hole. (They even came up with a special tool to remove it!) To prevent this from happening they recommend coating part of the spark plug with nickel anti-seize as shown in the illustration here: https://www.enginebuildermag.com/201...lar-engines/2/
The reason the ford plugs break is because of the long, smooth "tube" that extends beyond the threads. This section gets carboned up, and then will not initially move, and then gets stuck in the threads. Horrible design that never should have made it to production.
Being a Florida boy I wondered what the go-to product is that people in a marine environment use for this problem. There seems to be general agreement that nothing is better than ULTRA Tef-Gel, and the company is based right here in South Florida (Riviera Beach).
Crankshaft Position Sensor Modification
