Hello all,

My automatic transmission is starting to act up a little, so I need some advice. Here's the scenario:

I finally bought my first Maxima (1996 GXE) a couple of weeks ago, and I'm in the process of doing a lot of basic maintenance to get the car ship-shape. It has 78K miles on it, and I'm basically doing the 60K service.

Anyway, I took it to a shop last week to have the transmission fluid replaced with some synthetic (Valvoline synthetic blend) that I had bought. When I picked up the car, it turns out that the shop had done the standard drain & fill rather than the complete fluid replacement via the "Magic Sucker". I didn't know that there was more than one method until I started perusing this forum the past couple of days, so it never occurred to me to ask the shop before I had the job done. They used about 5 quarts of the new fluid, and according to AutoZone the total transmission capacity is more than 10 quarts.

Since I had the tranny serviced, it's started acting a little funny; nothing horribly wrong, but I don't think it was doing this before. When I'm cruising at about 30-35 miles per hour and let off the gas, the revs drop all the way down to about 1000 rpm. When I press the accelerator again, the engine revs to over 2000 rpm briefly before the transmission goes back into gear with a slight jerk. This sounds sort of like a slipping transmission, but it doesn't slip under normal acceleration or constant cruising. It's only when I resume acceleration after completely letting off the gas.

One mechanic has told me that you should not use synthetic tranny fluid in a car with 78K miles on it if it's never had synthetic before. Apparently, the transmission gets used to the conventional fluid and doesn't work right with synthetic at this point. I have never heard this before or since, so is there any truth to this, or is it one of those ubiquitous mechanic's legends? Also, is there any harm in replacing part of the fluid with synthetic (using the drain and fill method my mechanic used) and having it mix with the old stuff? If I've done something wrong here, is it too late to fix it without getting a new tranny? I've only put about 40 miles on the car since the transmission was serviced.

Two caveats:
1) I had only had the car a week or so before I had the tranny job done, so it's possible that the problem was there all along and I simply hadn't noticed it.
2) I think the problem is worse in the hot afternoons than in the cool mornings, but I need to verify this.

Sorry about the long-winded message, I just want to make sure that I don't leave out any vital details! Thanks in advance for any advice you can give. My default reaction is to do a complete fluid replacement with conventional fluid, but I want to make sure I do the right thing. Other than this problem, I'm very happy with my new Max!

 

Sounds normal to me for the revs be around 1000 RPM cruising at 35MPH. Actually it should be around 11-1200 RPM, assuming you are in overdrive (4th gear). 60MPH in overdrive turns at around 2000 RPM, so half that speed at 30MPH is 1000 RPM. My overdrive engages at a little over 30MPH.

Slipping is if the revs rise but your car doesn't accelerate. Don't mistake this for being "stuck" in a high gear due to the stupid transmission computer in our Maximas. Often I come to a rolling stop, step on the gas and get flat acceleration (really weak) because the transmission has not downshifted yet. This is not a slipping transmission, but rather just poor shift logic (which we can't really do anything about).

It's true that you should not go FULL synthetic at once on an old engine or transmission. But you did a 50% fill, so there should have been no problem. Actually a drain and refill on Maxima only uses 3 to 4 quarts, not 5.

 

The jerking and revving aren't normal however. The 'jerk' should be present in the morning before the tranny has warmed up, but shouldn't be very noticable after warmup.

 

I checked again on my way home from work tonight, and when I let off on the gas at 30-35 mph, the revs drop all the way down to about 700 (barely above idle). When I accelerate again, there's the slight revving before it goes into gear. Once it's in gear, there's no obvious slipping as I continue to accelerate, so that's why I don't think the transmission is slipping in the classic sense. The question remains: is this a problem I can easily rectify, or should I plan to get one of those extended warranties real soon? :-)

I'm hoping that doing the full fluid replacement will solve the problem, but I'd love to here any more ideas out there.

 

A few things. 1.)Is your dipstick/ fluid level fine? 2.)Did this ONLY start after the flush or just become worse and third, is it in every gear, or just in that one. It may be a torque converter problem.

 

I don't think synthetic fluid would cause this problem, since it should be fully compatible with normal fluid. Also, while the jerking transmission is felt when cold, it isn't unusual to feel the shifts even when the transmission is warmed up. Maxima automatics isn't that smooth.

Check your ATF level (read the owners manual for specific procedures).

 

I have another auto tranny question. I have a 97 with 50k on it and when I am going down the interstate at 70 or so in overdrive and let off the gas quickly I feel a little clunk. Is this normal? I bought the extended warranty but im not really sure if its still covered or not. I really just want to know if thats something I should be worried about. Everything else is smooth as can be except that 1-2 shift we all know about. Thanks.

 

How the h.e.l.l do you get rid of that annoying "jerk" in the morning. Would a complete switch to synthetic solve this problem?

One more thing, is it true that switching a relatively used tranny (around 70K) will ruin the tranny or have ANY sort of adverse effects?

 

The jerk went away for the first 500 miles after the flush, then it came right back for me personally, though less noticable. The second part? I don't get what you are asking. Are you talking about the fluid?

 

Yeah, sorry. Kinda tired Will changing the ATF from regular to synthetic have any adverse affects on a relatively worn tranny (70K)?

 

There is a theory that changing it all at once to synthetic can cause problems, so if I were to, I would do a regular change and have like a 50/50 mixture.

 

I had my trans fluid changed by a Tire shop....never again. The car was acting up not shifting right. They put almost 3 qts to much in. I took it to my mechanic and he drained and filled to the correct level. He also added a friction modifer....wow my 95 feels like new again. Moral check that fluid level.

 

WaarrEagle, this sounds to me like a motor mount. I'd have a dealer check it out. When running at speed, the engine will want to twist a little due to the torque its creating. When you pull your foot off the gas, that tendency to twist goes away. If a motor mount is broken, the engine will move more when torqued and then drop back into place, causing a slight clunk.

This may or may not be it but it's worth having checked out.

Jim

 

I had a 90 SHO with a broken motor mount... exactly same scenario... let off the gas, clunk... another thing to check...

 

It may be the motor mounts but if it's just a little clunk it's probably just the gear disengaging. Mine does that too.

The way to check your mounts is to step on the brake and put your car in drive, then reverse, then back to drive. If you hear a metal to metal sound, maybe your mount is too worn. The engine will torque back and front when you change between drive and reverse.

 

I took my car to a mechanic who did the full tranny fluid replacement, and it seems to have completely fixed the problem! I guess that switching to a partial synthetic blend on a well-used transmission is not a good idea. I'm very relieved to not be preparing to pay for a full transmission rebuild on a car I've owned for less than a month.

 

I don't hear any kind of sound like that when I shift with my foot on the brake. Can I inspect them myself or is this something a dealer really should look it?

 

Did you get a full synthetic replacement or go with a natural oil

 

If yours is not making any sounds, then you're ok. You can also visually check your mounts.

 

I went with the regular stuff.