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Crank sensor failure after timing belt change

General Tech Talk

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Posts: 517
Joined: Fri Mar 12, 2004 9:04 am
Location: Bathurst

Crank sensor failure after timing belt change

Post by lowndsie »

My mechanic had my Triton for two days whilst he did a timing belt change. When I picked it up late in the afternoon I drove it straight home which is a 10 minute drive at best. I didn't notice any problems with it's performance.

Early the next day I went to start her up with no luck. She was trying to kick over but couldn't quite get there. I rang the mechanic and he came over to have a look at it. Neither he or his assistant could work it out and they told me it needed to be towed to them so they could spend some time on it. I have a friend with a tow truck so I organized for it to get towed at mates rates.

Later in the day I popped into the workshop to see how it was going and I saw my old girl with her timing belt exposed and a mechanic hard at work. I was told the Crank sensor had failed and that it had been replaced along with the Cam sensor. At this point I was thinking i must be the unluckiest person alive to have a part fail in the same place as where they had been working only the day before.

I mentioned the drama to a friend who is pretty cluey with engines and he told me that the Crank sensor is commonly damaged during a timing belt change especially when the water pump is being replaced as well (which it was). I did some research on the net and found this to be a common problem. One of the staff there also mentioned that this is what happens when the area gets "tampered" with.

I figured there was a stuff up with the original job and that I would only get a bill for the cost of the parts. However I just received a bill for over 500 bux with 240 of that being labour! This brings the cost of the job up to over 1500 or 2100 if you count some other work that they did besides the timing belt.

My question is am I being unreasonable in assuming that the failure in the sensor was due to the work done the day before or is it more likely to be coincidence. And, should I be just paying for the labour and copping it on the chin or is that something that the mechanic should be wearing. Any advice would be appreciated.
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Re: Crank sensor failure after timing belt change

Post by stilivn »

Would have taken time to change parts anyway so.maybe suggest splitting the labour cost as you also had to pay for towie.
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Re: Crank sensor failure after timing belt change

Post by mkpatrol »

Yep, you are being unreasonable. Electronic things can fail at any time and it was obviously at the end of its life. How many KM does your car have on it? Obviously more than 100,000 due to the timing belt change.

If they happened to bump it or whatever and caused it to fail, it was because it was about to anyway regardless. It just looks bad for a mechanic when things fail after being touched.

When I was in the trade I had two batteries go on me while doing a service. Both were minor services and the car started fine when I drove it in but wouldnt so much as give full power to the dash lights when I went to start it afterwards. The plates had obviously separated but all I did was check the water level.

One customer was OK but the other accused me of doing something to the battery which was impossible.

Shit just happens with cars.
Don't ask me, ask them. I'm just runnin for my life myself.
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Posts: 511
Joined: Tue Jan 15, 2008 1:33 pm
Location: Cooma NSW

Re: Crank sensor failure after timing belt change

Post by date »

I'll come clean about my mistake...

I changed the timing belt on my Pajero NL. I also changed the crankshaft oil seal when I had it all in pieces. To do this you have to remove the crank angle cam, which is a flat disc with a series of slots in the disc. When I started it up, there was a screeching sound, but that disappeared after a minute or so. The car drove really well - the best it had done for ages. I was happy. 2 weeks after, it stopped. I could tell it was trying to go but it wouldn't. It backfired and all sorts of things. I cannot remember why, byut I assumed it was the crank angle sensor and stripped it all again, only to find that the 'fingers' on the crank angle disc had rubbed against the plastic of the sensor. Sensor failed.The problem was that I had used a screwdriver to prise the disc off. In doing so, I had bent the disc a bit.

I bought a new sensor and fitted it. I panel beated the disc fingers as straight as I could. The big problem is that you cannot rotate the engine to see if the disc is running true, but I set it up as central as I could in the sensor gap. I reckoned that it had maybe 0.5 mm runout, but it was enough. The beast ran beautifully after that.

So I reckon that your 'mechanic' had bent the crank angle sensor disc when he was in that area and it scrubbed the sensor out. Ask to see the old sensor, and if it has scrape marks on the inside of the gap, you have him, because they certainly don't have scrape marks from new.
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Re: Crank sensor failure after timing belt change

Post by SCANAS »

Shit happens. Time for a change, disturbing it probably caused it to fail but it would have failed anyway. Probably on a track. 100ks from nearest town. On a stinking hot day. When you need to get back to work. Missus in the car blaming you for not maintaining it / spending too much money on it / your fault for buying it in the first place.

I've seen and heard them all. Customers car comes in for power steering pump battery goes flat three weeks later blames the dealer.... Customer buys new car, goes on holidays for three weeks, flat battery, demands a new car this one must be a lemon. Etc Etc Etc Etc Etc Etc Etc sigh
I'm not quitting drinking, I'm retiring at the top of my game - sporting comeback likely.
Posts: 511
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Location: Cooma NSW

Re: Crank sensor failure after timing belt change

Post by date »

"Shit happens".

Yes - it does, but too many times I have paid for service or repairs, only to discover later that said service or repairs had not been done, or not done properly. It is a simple enough check to examine the sensor and see if there are scrape maks inside the slot. Fortunately electronic components in cars are very reliable, but they do fail at time, as said at the most inconvenient times, but this one sounds too coincidental to be just a random failure.
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Re: Crank sensor failure after timing belt change

Post by B.D.R »

I would think IF it is such a common thing to happen, and people say ahh well shit happens, then the bloke doing the work can tell you he will replace the part WHILE he is in there, not button it up and hope for the best :shock:

Mechanics wonder why most people think they are only one step up from Real Estate Agents\second hand car sales men :D

I know the mechanic that looks after the wifes car will tell us, if there is a chance of doing something like this and gives us the price :D
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