[Deejay100six]

Make of car - Vauxhall

Model - Zafira Comfort 16v Auto

Year - 2000

Engine size - 1.8L

Mileage - 53k



So, my cambelt snapped and all 16 valves had to be replaced.

Mechanic said the job was done but he was getting a fault from the camshaft positioning sensor. When he removed it, he found that all three wires going to the sensor were bare and touching each other. He had no way of knowing how long it had been like that and wondered why it hadn't caused problems before. I'm not sure if it was because the part was too expensive or difficult to get hold of but he got a used sensor from the breakers. It apparently came from a vehicle that had only done 40k but after fitting, the fault remained.

I hadn't gone but a few yards down the road when I turned around and took it back. The only way I can get 1st, 2nd, 3rd gear? is to select them manually. If I select drive, it starts off in top gear, (not sure if there are three or four gears).

I trust the mechanic but he said that when I took the vehicle to him, it was not running so he can't know whether this was a pre existing condition or not.

There wasn't any problems with the transmission before but I have to ask some questions.

• Could it be that, when the cylinder head was replaced, something was not reconnected properly?
• Is it possible that damage could be caused to the transmission as a result of the cambelt snapping?
  
• The vehicle has a 'Sport Mode' button and a 'Winter Programme' button. Neither of these are functioning now although they worked fine before. Could this be a clue since both of those functions are quite obviously related to the transmission?

Any more information required, fire away.

 

[Ooudestomp]

It could be that the box is damaged due to the cambelt snapping. under what conditions did it snap? Problem is, the oil pump for the gearbox is connected to the part of the torque converter that is bolted to the flywheel. Therefore if the engine stops dead but the vehicle keeps moving, then the gearbox is still turning with no oil thus possibly cooking the oil and burning the brake bands inside the box. Unlikely though as you can select the gears manually.

If you are still getting a cam position fault, that may be interfering with the auto box ecu as it relies on data given by the engine to select gears correctly. It could be that the timing is out, or it could be that the crank sensor is faulty. Because the ecu relies on both cam and crank sensor to give data, if one is faulty then the ecu has a hard time figuring out which is at fault because they both contradict each other. A lot of the time the ecu will throw up the cam sensor as at fault just by default.

Try changing the crankshaft sensor, I know from experience that they tend to be common to fail.

 

[kendallt]

In addition to what Ooud says, check wiring and grounds to the transmission. Newer cars from the late 90s up, have electronic transmission controls that depend on a signal from the ECM to shift. The wire harness to the transmission sometimes run right up along the heads and pushing them out of the way will often create a bad connection.

 

[Deejay100six]

Hi, long time no see. :smile:

Thanks very much for the response, you seem very knowledgeable about such things.

It could be that the box is damaged due to the cambelt snapping. under what conditions did it snap?

I'd only just left the petrol station, there was a service road only about 100yds going up to some traffic lights. The lights were red so I can't have been going more than about 10 mph when it snapped.

A lot of the time the ecu will throw up the cam sensor as at fault just by default.
Try changing the crankshaft sensor, I know from experience that they tend to be common to fail.

I'm not really equipped to do anything myself but, wouldn't a crankshaft sensor fault return a different code or are you saying that the ecu may have problems differentiating between the two (crankshaft/camshaft sensor)?

I've been on quite a few Vauxhall forum sites last couple of days and, as I remember different clues, research seems to shoot off in different directions.

I've been very irresponsible, the car hasn't had a service or even an oil change in probably seven or eight years. :blush:

One of the first posts I saw from someone with a similar problem was told that if the automatic transmission fluid hadn't been changed for more than a year......do it now! Mine almost certainly has not been changed in the 12 years that I've had the vehicle.

I thought about having a go at changing it myself but as I continued reading, there was talk of flushing out the old fluid and sounded like something that could only be done properly by a garage.

Interestingly, I read somewhere that the coolant system is connected to the automatic transmission and if the seals go, the coolant can mix with the atf which would cause problems with the transmission. The coolant was changed as part of the job.

I've got to be honest, rather than posting here as a diy mechanic as most probably do, I'm just trying a bit of detective work because I know all about the power of coincidence, especially with cars, but I'm not having it.

If there is any possibility that the problem has been caused by eg., something not being reconnected properly, I need to prove it, I've spent far too much money on this already. :sad:

I spoke to the mechanic the other night in my local and he seems prepared to give it another check over but that his partner did the job and he's off sick. I'm to ring him later in the week to arrange something.

Another interesting point I found,

Changed cam sensor. Insulation totally missing in the business end. I.E. totally short cut.

P0340 Changed cam sensor.Engine don´t star - Vauxhall Zafira Owners Club Forum's

A different issue maybe but, he appears to be describing the same thing with the camshaft sensor wires being uninsulated. Its as if the top 2 inches of the insulation has disintegrated. The outer insulation which keeps all the wires together seems to be progressively more brittle closer to where the inner insultion is stripped. Probably unrelated but maybe worth mentioning.

 

[Deejay100six]

In addition to what Ooud says, check wiring and grounds to the transmission. Newer cars from the late 90s up, have electronic transmission controls that depend on a signal from the ECM to shift. The wire harness to the transmission sometimes run right up along the heads and pushing them out of the way will often create a bad connection.

Thanks for that, I will.

Looking at the fuse box list earlier and it seems there are quite a few fuses related to transmission.

I daren't even hope for a blown fuse but I'd be very happy with that! :grin:

 

[Ooudestomp]

wouldn't a crankshaft sensor fault return a different code or are you saying that the ecu may have problems differentiating between the two (crankshaft/camshaft sensor)?

The engine timing is sensed by the cam sensor and the crank sensor. If the cam sensor is saying, for instance, +5 and the crank sensor is saying -5, the ecu cant tell which is at fault, so it defaults to the cam sensor as a fault code.

As for the oil changes, it probably need them due to age and mileage. though this wouldn't necessarily cause the problems you're having, especially because of the cam sensor fault. Changing the gearbox oil, depending on the type of gearbox, is quite a complex job as most gearboxes need the engine running to change the oil otherwise you can't get the oil out of the torque converter or brake band valves. I'm not too sure about the coolant, I'm pretty sure the older boxes didn't have cooling systems aside the oil cooler.
http://www.zafiraowners.co.uk/forum...d-cam-sensor-engine-don-t-star.html#post26545

A different issue maybe but, he appears to be describing the same thing with the camshaft sensor wires being uninsulated. Its as if the top 2 inches of the insulation has disintegrated. The outer insulation which keeps all the wires together seems to be progressively more brittle closer to where the inner insulation is stripped. Probably unrelated but maybe worth mentioning.

It could be a problem, but all I'd suggest is that you ask your mechanic to replace the wires that are damaged, or at least insulate them with tape temporarily. Check the earth straps as mentioned above, plus all the fuses just to rule it out. Other than that, I'd definitely recommend changing the crank sensor as it can cause this problem as it governs the ignition timing thus causing the bad running. A lot of the time a bad cam sensor will throw up a light and a code, but no really effect engine performance. I don't think crank sensors are too dear either.