Should I flush my S13's auto trans?

[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.

[40daws]

Flush it all,trans,coverter and lines . I did this on a 90 Maxima and it cured my problems. I did the flush with synthetic trans fluid,but ATF 3 should be good enough.

[HashiriyaS14]

Has anyone here ever had a flush damage their transmission?

[HashiriyaS14]

For what it's worth, I just did a "hot" transmission fluid level check and I definitely have sufficient fluid, and it's a nice light color.

The level was at least up to the end of the cross-checked pattern on the "hot" side, may even have been a little bit over (should have noted that at the time).

Could an overfill of fluid cause this problem?

[SirSilvia]

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.

It shifts hard due to the fact that your motor mounts are bad, it took the shop 10 mins to figure that out. and when I changed my mounts, it stopped jerking into 2nd and was a hell of a lot smoother afterwards

[rogoman]

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.

The 240SX transmission normally shifts a little harder from 1st to 2nd. If the TPS harness connector has oxidation on the pins or the connections are not good for some other reason, then the transmission will shift extra hard and at higher RPMs.

There is a dropping resister for the transmission that's located near the ignition coil; if that resister is bypassed, the shifts will be extra hard.

Always check the ATF level with a fully warmed up transmission while the motor is idling. The level should be at the full mark and definitely not overfull.

The ATF and the filter should be changed at least every 30,000 MI.

Flushing the transmission is not neccessary and may possibly be harmful. If you want to flush out the transmission cooler, disconnect both lines at the transmission; use a power flushing kit with the proper solvent.

If you don't disconnect the lines at the transmission and attempt to flush the transmission cooler, any crud in the cooler will get into the transmission valve body and will screw the transmission up.