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Old 19th May 2007, 22:43   #28
Keith
This is my second home
 
ZT400

Join Date: Oct 2006
Location: Ellesmere, North Shropshire
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Default Vis motor failure observations

Three cars three stories

I repaired what was a brand new vis motor for Mike in the week, one of the Micro switches and become physically dislodged rendering the entire motor useless and Mike as a result had a subsequent loss of performance.
I had not really expected a new motor to suffer such a problem as this normally happen after time due to the soldered joints to the micro switches failing. Hence why Mike sent it to me in case there was something more sinister going on like his ECU was sick !

Yesterday (18 may 2007) I had two cars in for T4 sessions

Car one, in for a pre service check both Vis motors failed to budge, as the owner is selling the car he decided to tell the new owner he might need to get new ones so I got on with sorting out his jammed bonnet release and a couple of other jobs the car needed.

Car two a newly acquired MG ZT 190, 2003 plate with only 21,000 miles on the clock, in for a post purchase check and a good thing he did too!

Both Vis motor completely dead just the on board relay clicking during the diags test I must admit I have never seen a car with so few miles on it with both motors completely dead, I was at first wondering if my T4 was on the blink!

This owner wanted them fixed if poss so out they came both Vis Motors had the normal oily mess in them! The Power Valve Vis motor was the normal dry joints on the micro switches so I did the standard screw down mod re assembled and tested ok.

Then turned to the Balance Valve Vis motor again one of the micro switches had a dry joint so I repeated the screw mod and re soldered everything fitted it to the car and nothing, still just a few clicks.

I took it apart again and looked more closely one of the tracks on the PCB that goes to the motor was burnt out, did a repair, and also did a direct test on the motor itself using a spare battery, it turned but blew my 2.5A fuse. Sure enough putting it back in the car just burnt out the other track on the PCB.

It seems to me the Vis motor PCBS have a couple of thin tracks designed to act as fuse-able link possibly to protect the ECU if the motor fails goes dead short or something equally horrid. In the case of this one I think the oil contamination had done it in.

So the moral of the above
Vis Motor failure are not just to be expected after a higher mileage the new owner of the above 190 had no idea he was missing a huge chunk of performance and obviously test drove and accepted the car in that condition only a day or two earlier.

If you get the chance get yours tested asap on T4 (and no this is not a plug to come to me, just get them checked somewhere) it does not take long 30 minutes max and even then frankly I have seen so many of these that are intermittent due to the switch soldered joints failing you really ought to mod them anyway as per the howto in the howto forum and then get them tested.
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I used to own the only Celestial Blue MK1 ZT 400 in the world
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