I recently got an 03 G35 sedan for really cheap thinking the transmission was bad. This is really the only major thing wrong with the car. What happens is sometimes the transmission will slip in the higher gears. Would you guys think putting a new transmission filter and fresh fluids would fix it? Or is it time to find a donor trans? Car has 180,000 miles.

 

Welcome to G35 Driver Tyler! Question is, how often have you changed the trans fluid in all those miles and when was the last time fluid levels were checked? Our AT's operate on line pressure, if it's low that would be the cause of the high rpm slippage. Do a drain/fill, maybe that will solve your issues...couldn't hurt!
Again Tyler, welcome to Driver...enjoy the ride!
Gary

 

Hi Gary!
Thanks for the reply. I actually got the car last night and I don't know the last time the trans fluid was done. I will take the pan off sometime this week to take a good look at everything and get fresh fluid in there as long as that won't cause any bigger problems. I tried to check the level last night, but the trans dip stick is missing! the rubber cap was there, but the metal stick that slides down the tube was gone.

Thankfully I have other cars I can drive until i fix this. I hope its just fluid so I can put away my other cars for the winter.

 

Drain the fluid into a very clean pan and drag a magnet through it to look for metal shavings, if the fluid is not very dark you can let it sit for a day and pour it off into another container and use the "gold panning method" to look for aluminum glitter which won't be captured by a magnet.

Remove the transmission fluid pan and physically inspect the underside, I suspect the dipstick is actually still in the tube but is broken off from the cap at the top and is currently resting on the bottom of the pan. A borescope can be pushed down from the top also if you want.

 

This might sound dumb, but how much is TOO much metal shavings? To the point where it's not salvageable? I just want to know what to look for worst-case-scenario.

Interestingly none of my engine codes are for the transmission.

 

Do you have engine codes popping up? If so which ones?

Consider that metal parts contacting each other does create some wear and you will find the worn particles in the fluid, regular fluid change intervals are for a few reasons, 1. The fluid has a lift expectancy due to the conditions of heat/friction and will break down with time. 2. Fluid also acts to catch these contaminants and worn machine parts and these need to be removed from the system regularly so they don't INCREASE the wear of the part by adding a lot of extra friction. 3. Over time broken down fluid and contaminants can deposit in various places of a transmission to create a sludge that WILL eventually ruin the throttle body, there are a lot of very small passages in the TB that can become clogged or high pressure contaminants starts to remove material at all hydraulic thrust points (corners) within the system.

If the fluid was changed every 30k I would say the first interval you MIGHT see a small amount of glitter but it would be barely noticeable. If however, the fluid has NEVER been changed and has the full 180k on it then it is definitely going to have metal in it, will likely look dark, might smell like it's burned, and will have completely broken down and is actively contributing to more wear.

EDIT: TL/DR, change the fluid but don't be surprised if there is metal, fill it up and change it again in 5-10k since you don't get ALL the fluid out (and contaminants), the torque converter is still full of old fluid, then switch to a regular 30k and hopefully the issue has resolved itself by then.

Fluid change interval for both the hydraulic automatic AND the 6MT is 30k, it is as important to change transmission fluid as it is to change engine oil.

 

^^When you talk about the throttle body do you mean the valve body? If not then I've learned something new today, the transmission has a TB. Who knew?????

 

Lol yeah I meant the transmission valve body, distracted and working while on my phone on the forum

 

I am going to be attempting it tonight. I will post an update. Thanks for all the good information guys!

I got 5 quarts of the matic s from a nissan stealer. I hope thats enough

 

Since it's missing you should also got a AT dip stick, dealership or Rock Auto or bone yard...Gary

 

What exactly do you mean by slipping? When you pull a way from a light? On upshifts? Downshifts? Could just be low fluid if it slips when starting off. On shifts, could be a lot of things, most of them not good.

 

The slipping occurs in 5th gear the worst. For example when heading home after work I have to go up a very long and steep hill. If I leave it in Drive, I can't speed up and the revs go wild. If I use the ManuMatic I have to leave it in 4th to make it up the hill. 5th I have absolutely no power in. It's as if in a manual when the clutch is slipping. 1st, 2nd, and 3rd seem to be fine. 4th is mostly good, but revs higher then it needs to it seems.

I did drain the trans fluid, put in a new filter and gasket. The fluid was burnt and disgusting, but there really wasn't much metal flake. I have serviced my manual vehicles before and those had flake in them. I couldn't really find much in this. The trans seems to be a bit better, but not much. That could just be me hoping its better too. I poured in 5 quarts of the Nissan Matic S. I haven't sourced a dipstick yet unfortunately.

 

The transmission holds 10.5 quarts. Usually when you drain the pan only (we call that a drain and fill) you replace between 3.5-4 qts., usually closer to the 3.5 number. If you refilled 5 qts. you most likely overfilled the tranny and that's not good either, you really need a dipstick to monitor how much fluid you have in there. Most of us don't recommend complete flushes, especially on cars with high mileage because that in itself can cause problems. To replace the most fluid do 3 drain and fills with 200-300 miles in between to replace most of it. You can find Matic S on the internet a lot cheaper than at the dealership.

If it's one gear you are having the worst issues with there's a good chance your valve body is shot and needs to be replaced. Sadly that's not a cheap fix. I'd take it to a reputable transmission shop for a proper diagnosis.

 

Yup next time I will be buying the fluid online. I was just hoping I'd be able to fix it quick. I will be getting a dipstick soon, I haven't driven the car much except to test the transmission. I have other cars to drive until it snows.
For the valve body, is that something I could take off the car and see it is bad by looking at it? I found this guide to change the valve body. Should I follow this?

I would like to do the work myself if at all possible. Unfortunately I am finding Auto transmissions are a bit more complicated than the manuals I am used to. I have done engine swaps and clutch jobs before, so working on cars isn't foreign to me, just automatics are!

 

I found a whole trans with 88k. If the price is reasonable should I just swap out the whole trans?