3rd gear is weird

[chhcope]

Hello, I recently purchased a 1996 Automatic that needs some attention. Sometimes it will skip 3rd entirely and other times it will rev high and the rpm will surge before it will shift into third very briefly and then into 4th - too early for 4th so the rpm is low and the mini is slow. It will almost never shift to third normally while in D. BUT- If I manually shift through the gears (letting off the gas as I shift) it will shift through all the gears. If I don’t let off the gas as I shift manually it will shift through all the gears except 3rd where it revs and surges before shifting eventually.

I’ve changed the oil twice and filter once and am using Valvoline VR1 20w50. I see, from reading/researching on this site, that switching to 10w40 may be in order and am okay with that idea but am not convinced it would solve the issue. Should I switch immediately or try something else to troubleshoot? I wonder if anyone has input based on what I’ve detailed above as to what the issue could be; any and all questions welcome. Thanks for reading!

[jockduck]

I was waiting to see if anyone else would jump in but since no one has Ill try, I have no experience of "modern" auto Minis mine is a 68 998, you box woes sound all too familiar. using a 20/50 will not help engagement especially in cold weather. The boxes do tend to go into 4th a bit early even with a bit of throttle on, adjustment of the kickdown rod helps a bit but I hold in 3rd to prevent early shifts. The operation of the valve block seems a bit erratic, was the car in storage for a long time? The high revs between changes is called flaring. mine flares into 4th when cold because the oil is slow to pressurizer the top/reverse clutch. I assume that 3rd holds when it engages and does not slip sounds a bit like the 3rd gear band is slow to tighten. It is possible the valve block may come good with use and clean oil. If you have a good manual and some equipment it would be worth while doing a pressure test on the oil filter head and a stall test, both are outlined in the manual. Just had a sudden thought are you sure the oil level is correct, being a pint short will starve the pump on corners and hills especially when cold, the oil "hangs up" in the engine until warm and flows correctly.
Jock

[chhcope]

Hi Jock - Thanks for the reply! I'll get some 10w40 MA2 and put that in with a new filter when I get the mini back from the shop. It's getting a new A/C compressor installed. The guy I bought it from recommended the kickdown adjustment too so I'll look at that for sure. I don't know that it was in storage for a long time but my intuition tells me it has been; when I replaced the oil/filter I took the filter apart and noticed some sludge in the filter which made me think it was sitting for a while. I'll plan to change to 10w40 with a new filter, do a kickdown adjustment, and give it some time to see if it gets better.

I only have a Haynes Repair Manual, not sure if it has an overview of the pressure test and stall test but I'll look this evening. What manual should I get? I am new to the classic mini world so I planned on investing in some good resources for maintenance and repairs. If you have a recommendation, I'd appreciate it.

I did check the oil a few times and made sure it was right up to the line so I'm confident that it's not low. I'll check it again when I get it back from the shop, though.

Thanks for the input, I really appreciate your help. I'll update you after I get it back in the garage and make those adjustments. I assume it's better to drive it with the manual gear selection to keep it from flaring and skipping 3rd until I can get to the bottom of the issue, would you agree? I don't want to do more damage...

[6886auto]

If you search for "dropbox" on this forum there is a link to some documents which should explain the pressure and stall tests.

[richard1]

I would buy a bottle of AutoRx from Amazon and add it to the oil for a couple thousand miles. That will re-solubilize the sludge and get it out of the valves if there is any. It also swells the o-rings to their correct size to seal better. A couple of months ago I put a bottle in my Grandson's KIA when the check engine light came on with a failure of the hydraulic VVT system. The scanner said it needed replacement, but the AutoRX cleared the fault in 3 or 4 days.

And yes, stay with 10W-40 MA2. If you need to understand the why's of Mini oil, check this paper out: www.widman.biz/mini_pics/classic-mini-oil.pdf

Finally, the Kickdown may be causing the immediate/early shift into fourth. The manual shows how to adjust it so that it waits until the right speed to kick in.