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QASHQAI TRANSMISSION PROBLEMS SOLVED !!

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Joined: 10áMayá2018
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    Posted: 10áMayá2018 at 6:48am
Purchased Japanese Domestic market (JDM) 2008 Nissan 2 Wheel drive Dualis / Qashqai (KJ10) with 40,000km (25k miles) on the clock one owner in original condition. From the time I first drove it there were always two problems. Firstly when pulling away gently or moderately from stationary, particularly on a hill, the car would begin to accelerate then at about 10-15mphr the power would drop off and the speed would stumble for about 2 -3 seconds before picking up speed again. Secondly the CVT was dead quiet when cold (good), but once car had travelled some distance causing the CVT fluid to heat up to normal operating temperature, a grinding noise would come from the transmission when driven at steady speed but entering a hill such that engine torque was used and load came on the box. The grinding also seemed to occur over 100kmphr (60mphr) when load would increase on the box. This continued constantly until about 57,000km when I finally looked at the problem. I was worried as I felt the car couldn't be resold while in that condition. On researching the SONNAX site in USA the technical team there have developed quite a bit of knowledge and experience with CVT's, know how to repair and rebuild them, and manufacture replacement components for the valve body. The Sonnax site mentioned that CVT's are more sensitive to overfilling that a conventional auto box. That caused me to check the CVT fluid level (put engine in park with motor running, pull the dipstick wipe clean and recheck - use very small screw driver to push in on lock tab in order to pull the dipstick out with breaking the pull knob). When the CVT was checked COLD, the fluid level was correct being between the low and high mark for a COLD check - possibly at the high level for cold.
However after a 20km or so run to get the CVT fluid to operating temperature, on checking the fluid level it was significantly OVERFILL on the same dipstick !!! Confused ?? So I thoroughly cleaned around the CVT pan, waited for the fluid to cool, then removed the CVT drain plug and carefully drained off about 750 mls of fluid before reinserting the plug and tightening. As I may have drained off to much fluid which would require adding back some, I then filtered the drained fluid through filter paper into a jug / bottle to ensure no contamination before reuse. I then added back fluid until the CVT was filled to about the midpoint reading for cold fluid. I then did another run to get the fluid up to operating temperature and immediately noticed that the stumble had about 80% disappeared when pulling away. When rechecking the hot fluid the reading was at about the  MAX for a HOT reading. The CVT was still grinding under load but had decreased by about 80%. So when cold I removed more fluid and added back until the cold reading was at the MINIMUM of the  permissable range on the dipstick. Ran the car again for 30km before checking the hot fluid.  The HOT reading is the important one because that's the normal operating condition and where the car will do most of its service life. I adjusted the CVT fluid level to about 25% above the minimum hot setting or 75% below the maximum hot setting.
On road testing again the stumble had all but disappeared and the CVT was not much changed from the last test run. However over the next two to 3 weeks and after travelling about 500 - 750 km I noticed that all 'grinding' noise when under load had disappeared. On rereading the SONNAX site and how a CVT works, I learn't that there are high fluid PRESSURES generated inside the CVT pulleys in order for them to work as designed which operation is controlled by the CVT's computer. My conclusion is that by correcting an OVERFILL situation, the CVT was then able to relearn and set new operating parameters and pressures via the CVT computer and it needed to travel the distance it did in order to complete the relearn and recalabration. Sold the car last week and a very professional and thorough mechanic did NOT fault the transmissions operation. However through his scan tool he found an old code lodged in the diagnostic computer that related to the CVT. I then explained what I had done regarding the overfill situation before he invested the diagnostic code but he issued a final report to his client the purchaser with no criticism of the CVT's operation.
Lastly I should mention that at no time did any fault lights illuminate on the dash.
So if you are having any performance issues that resemble my experience you may wish to check the CVT fluid level when the trans is HOT.
It is unlikely the car had had the CVT fluid changed at 40,000km (25,000km) because it doesn't have a service interval to my knowledge. What is required is that Nissan through their CONSULT diagnotic programme, electronically test the CVT fluid for CONDITION and if the reading is less than 200,000 units, the fluid is still in servicable condition and does not require changing. Remember a CVT runs a push style steel belt over two pulleys and does NOT utilize clutch pads, as in the case of a conventional automatic, so the fluid is NOT being contaminated by clutch material. That benefit in additional to the considerably higher quality of CVT NS-2 fluid over dexron II, explains why the service life of the fluid is much longer in this particular CVT box (REOFO10A).
So did JATCO, builder of Nissan's CVT fit an incorrectly calibrated dipstick or did they overfill the boix at factory or did someone else overfill between the car being new and my purchasing it.
I hope this post is helpful to someone. Best wishes.
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