Consensus on flushing auto trannies?

[HashiriyaS14]

I just recently bought a '93 S13 coupe. The engine seems to be in fantastic condition, but the transmission has been exhibiting some small problems.

Most notably, it shifts a little rough from 1--->2, sometimes not shifting before 3k, other times slightly lower. This DOES seem to get better with some driving, but then other times it doesn't, so it's hard to say what's going on. It doesn't really have any other problems.

I did the "cool" transmission fluid level check and it looked okay, but I'm tempted to either drain and fill or go somewhere and get the fluid flushed.

What do people recommend? I've heard rumblings on NICO (did some searching) that flushing can actually accelerate the death of an auto transmission. I do NOT want to make my situation worse, as I don't have the time to swap a transmission right now.

Should I leave well enough alone, drain & fill, flush & fill, what?

My goal here is to get as much mileage as is humanly possible out of this transmission before needing to swap in another.

Any advice would be appreciated.

[180fan]

I'd just do a run of the mill drain and fill.

[HashiriyaS14]

That doesn't address the fluid inside the torque converter, right?

(I'm new to auto trannies)

[180fan]

i don't believe it drains out the torque converter. But then again I am pretty tired and could be mistaken.

[ricebike]

nope... common sense says it doesn't drains out the torque converter.... u r only replacing the fluid in the pan (~4 quarts???)

you can change the pan fluid 2x if you want, though, to dilute the old fluid in there.... do the standard fluid change---drive a bit--- then change again <shrugs>

[HashiriyaS14]

But so you guys would not recommend an actual flush?

[ricebike]

sorry, hash, i gotz da stickshift!

try venturing over nissan online mechanic or http://www.batauto.com for a quicker reply

[180fan]

Nope, I wouldn't do a flush. Had an auto transmission for years on my 40, and still servicing an auto on my sisters cars so yeah. Don't like the gimmick of flushing especially when there's still all that other junk that goes into a flushing chemical.

[ken240sx]

flushing is not a good idea on a car like an s13, considering the age of it, the transmission is most likely adapted to running a cartain viscosity and fluid, if you flush now after so many years it could cause major problems. Back in one of the garages I worked, we never flushed trannies after 100,000 miles of using the same fluid...mainly because we did once for a customer and ended up having to replace their transmission a week later because it was ruined...and the customer didn't have to pay because technically it was our fault. But if the transmission fluid was relpaced say in the past 60,000mile so or so then flushing it wouldn't hurt anything. If it's flushed when its supposed to be according to the manufacturer then there shouldn't be a problem.. but since most people don't flush it at all, and its probably got over 100,000 miles then don't bother.

[onosqv]

^ I think the problem here is that after they got it flushed, they did not replace the transmission filter.

The thing is, when you do a flush, the transmission filter can get really gunked up. So, you have to do a drop pan & change filter thing afterwards. However, almost no one does this.

[HashiriyaS14]

Do most people generally not flush trannies?

Isn't it part of factory recommended maintenance like every 30k or something?

EDIT: I just did the "hot" check for my transmission fluid, and it's both full and nice and new looking (or at least, not brown and coffee-like, I don't have a good eye for this, first AT car and all).

The fluid level was at least up to the end of the cross-checked pattern on the "hot" side of the stick, possibly above (didn't think to check for overfill). Could an overfill of fluid be causing the rough 1--->2 shift?

[onosqv]

I've noticed a lot of ppl don't follow the factory recommended stuff... like how a lot of ppl wait 5k before they realize they need to get their oil changed, etc.

And the "color check" is actually not that good, it's a gimmick that jiffy lube popularized back in the day to get ppl to flush their transmission - got in trouble for doing that - officially they aren't suppose to do that anymore - court mandated I think, read about it a while back.

In anyyyy case, just to let you know, I flushed teh transmission on the Jeep (only been 60k miles), and changed out the filter/gasket. Runs significantly better now (was having hesitation problems before).

On my 240, helped a little bit, I did this one my own getto way w/ an extra long transmission line & a catch bucket while filling fluid thru the transmission hole - works, but you waste more transmission fluid - costs bout half as much in the end.

[JNM240]

Automatic transmission fluid is very detergent. After 100,000 miles that starts to break down and creates a varnish on the gears and such. Replacing the fluid to solve a problem, like slippage, will only make matters worse. Putting new fluid in, either by flushing or dropping the pan, on high mileage cars replaces that detergent and now cleans the varnish off the gears ect. This will only make any slippage worse. Best thing to do is change it every 30,000 - 45,000 miles. Replacing the filter is recommended with a flush, either before or right after the flush. If you are really high miles most shops wont touch it for fear of having to replace your transmission.

Also you should always check the fluid level when warm. And yes, overfill might cause some slippage.

[HashiriyaS14]

Best thing to do is change it every 30,000 - 45,000 miles. Replacing the filter is recommended with a flush, either before or right after the flush. If you are really high miles most shops wont touch it for fear of having to replace your transmission.

Yeah, that's not really an option here. Car has 128k on it and I have absolutely no idea how it was treated in the past with a 0% chance of ever finding out. It is a black box, complete question mark.

I have to assume from the get-go, in regards to EVERYTHING on the car, that nothing was done right the first time.

So hang on, if some shop flushes it, and the trans dies, they're liable for replacing it? I would've guessed that I'd be SOL.

[180fan]

I'd still do a fluid change on the AT with a filter change. Those two things were always done much to my dismay together (btw keep those bolt locations on a piece of carboard or something when you pull the filter, those bolts are not all interchangeable don't ask how I know that lol). Couldn't hurt to change the fluid/filter/ and if you were as unlucky as I was the gasket that goes around the pan (mine didn't have the little drain hole on the pan) and see how that runs.

[ken240sx]

jnm240 tahts pretty much what happened at the shop I worked at 3 years ago, they changed the transmission fluid on a high mileage toyota and the car was towed to our garage a week later lol. The car had 160,xxx miles on it and the transmission just gave up a few days after the fluid was changed aparently. they refused to change transmission fluids on cars with over 100,000miles since then. your post is right on the money and its kind of what iw as trying to say, only change the tanny fluid if it's been changed every xx,xxx miles that the manufacturer specifies..otherwise leave those 100grand mileage trannies alone.

OH and about the rough 1->2 gear, many s13's behave like this, not sure why...maybe just corroded wiring mixed with the torquey ka but mines done it since i got it and i have no problems at all with the transmission...infact the transmission was rebuilt at 125k because the 2nd owner(the person i bought it from) thought the transmission was acting weird so they got it rebuilt and 1->2 gear was still a bit rougher than the rest of the gears. IMO I don't really think that it's a problem.

[JNM240]

So hang on, if some shop flushes it, and the trans dies, they're liable for replacing it? I would've guessed that I'd be SOL.

No, what im saying is that most shops who dont rebuild transmissions wont touch it due to liability issues. I have flushed and changed filter on a dodge pickup with over 150,000 and never been serviced, but the service manager made damn sure to note on the ticket and receipt that there is absolutely no liability or warranty and fully explained the consequences if something were to go wrong.

Your absolute best bet is to bring it to a transmission shop, like Cottman Transmissions (down here that is). They can tell you a whole lot more. And they can give u a price to rebuild/replace the transmission in case the fluid is bad looking enough. But, if you can take it to a qualified mechanic to at least give the fluid and running condition of the the transmission a once-over, you may be fine. If the fluid looks clean, no burnt smells, no leaks, then there is a possibility the previous owner(s) took care of it. But you are right, you have no idea.

Soooo.....If you cant afford to swap to a stick, cant afford to rebuild your current one, and can live with a little hesitation going from 1st to 2nd, i would leave well enough the hell alone and drive it till it breaks, cause flushing or replacing fluid right now is an unknown unknown . Either it will work or it wont. So my advice is leave it alone and drive it. Should last for a while.

[HashiriyaS14]

Soooo.....If you cant afford to swap to a stick, cant afford to rebuild your current one, and can live with a little hesitation going from 1st to 2nd, i would leave well enough the hell alone and drive it till it breaks, cause flushing or replacing fluid right now is an unknown unknown . Either it will work or it wont. So my advice is leave it alone and drive it. Should last for a while.

Ok, looks like this is what I'm going to do.

In the meantime, I'll try to get my hands on an S13 auto trans in better condition and then swap it in when I've got the time.

Thanks.

[ACESXX]

--> when i took my altima to get serviced the mechanic told me that there is so much junk in my transmission that "the junk" is what is holding it together..., since then I just add more fluid when it needs it!

[sxcoupe]

( i know this might get flamed but here go"s is by any chance the plug that helps your transmission shift smother disconected. that would make shifts kind of ruff.)


Modified by sxcoupe at 11:13 AM 5/5/2006