Transmission Issue

[studum]

I'm afraid that I've got a problem that I don't want to admit that I have. It has only surfaced since the cooler weather has started to come around and is only present when the truck is cold.

Issue: Hard shift from 1-2 when accelerating swiftly. Like kick in the back snap your neck hard. Truck will move in first just like there is no problem, no slipping or anything. Then it will rev higher than normal when you think it should be shifting from 1-2, to the point that it doesn't feel right, and it will bang into second gear. For the first second or two after the hard shift 2nd gear will slip if I try to accelerate again too quickly (I usually let off the pedal when it revs high to encourage it to shift).

There are no codes at all, I've checked via my scangauge.

Wierd thing: after a few blocks or the truck warms up everything is a-ok. No driveability issues at all, nada, none, zilch, zippo. The 1-2 shift goes back to it's normal kinda-sorta hard-ish shift which from what I read after adding the Lucas is pretty normal with these trannies and it has done since day one with me.

In the morning I don't usually notice it because I get to drive a few blocks on residential streets before hitting the main road accelerating at a slow pace (most of it is school zone and stop sign every 2 blocks). However when I leave work and the truck has been sitting for 8 hrs to cool down I have to go from my work's driveway onto a pretty busy 80km/hr speed limit road and 9 times out of 10 I'm forced to accelerate near full tilt. This morning I tested leaving home and it indeed does happen on the residential streets as well as long as the transmission is cold.

I've had the truck for 14 months now, and one of the first things I did was change all of the fluids - including getting the transmission flushed at Mr. Lube. Then in the summer I put in a bottle of lucas tranny stuff (drained some of the tranny fluid out too) to see if it would do anything for the normal 1-2 shift and it did not. That's where the truck is sitting right now. I haven't had a chance to checkthe fluid level when cold, I understand that's the most accurate way to check it. But when warm the fluid is full, maybe even a bit too full. The fluid is still a bright pink on the dipstick, and smells like oil.

What should I do? Another tranny flush? A drain and fill? Some sort of transmission cleaning treatment thing? Give up and take it in to Milton Nissan?

I don't want to spend another 2g's on this truck right now, but I feel as though this is going to be expensive Any advice would be greatly appreciated - even if it is a simple give up and take it in.

[amplifire]

I don't know, but could this have to do with the torque converter not locking up when the fluid is cold?

[studum]

I don't think so. I believe the torque converter only locks up in 4th gear anyways, maybe 3rd too under the right conditions. From what I can tell it still locks up when it's warmed up, and it won't ever lock up when it's cold in an effort to warm up faster. I could be wrong though...

[Simon]

studum, you're right about the operation of the torque converter. It won't lock until warmed. However, it could be that it's not maintaining fluid pressure when cold, causing the slip condition you're feeling. The Torque converter is a fluid driven part, so it's a possibility.

The other thing is possibly a shift solenoid sticking when cold, and the fluid thickens up. This would explain why when the truck warms, as does the fluid, it works properly.

[Adam]

My truck used to do this, but from 2nd to 3rd. You'd be waiting for it to shift and it would go up a few hundred rpms higher without moving, and then it would slam into third. Honestly it stopped doing it shortly after I changed the fluid and added an external filter to the transmission, did mr lube do a drain and fill on the trans or did they flush it with a machine? If they did a drain and fill that only takes out like half of the old fluid.

[studum]

studum, you're right about the operation of the torque converter. It won't lock until warmed. However, it could be that it's not maintaining fluid pressure when cold, causing the slip condition you're feeling. The Torque converter is a fluid driven part, so it's a possibility.

The other thing is possibly a shift solenoid sticking when cold, and the fluid thickens up. This would explain why when the truck warms, as does the fluid, it works properly.

I wonder if the TC is having trouble maintaining pressure due to the fluid (me adding the Lucas...) I had thought about a sticky solenoid for that reason too.

Adamzan, your condition sounds exactly like mine, just different gears. I would have done a drain and fill myself, I went to Mr. Lube specifically to have the flush done. They hooked it up to the machine and you see the old fluid come out and new go in. Just as you say I had read this is the only way to get all of the fluid swapped. To stop yours did you flush it or do a drain and fill?

I don't believe I have an external filter, I couldn't see one anyways. I believe it's just a screen in the pan.

[Adam]

The external filter is something I added, as transmission failure on the older pathfinders is common from debris clogging the cooler passages. It is a 3 micron filter, so far better than the factory rock strainer. The last time I changed the fluid I did the backyard mechanic flush, where you take one line off and let it puke into a bucket while having someone top it off with new fluid.

My tranny fluid was purple as well, and when bigbird changed the filter I remember seeing quite a lot of gray paste looking stuff in the pan.

[Morpheus]

Are you sure your scanguage will do transmission codes? most cheaper ones will not, unless you spend $500-$1000 on a scanner.

You may have codes in there for shift valves, etc.. bring the truck by and let me scan it for you with the consult, there may be codes there you can't see with your scanguage

[studum]

Not sure if it reads tranny codes. I'll do my best to pop down for a visit this evening.

[Snafu]

Hey Mike, the tranny stores codes separate from the engine, right? So it won't necessarily trip a CEL or store a code for reading unless plugged in or designed to read tranny codes. I am curious to see what information is pulled from your truck (I should check this sometime too).

With another truck I had I never really experience tranny issues until I had the tranny flushed. I then started having 2-3 shift issues (acted like it had a shift kit similar to Adams problem). The flush probably just quickened existing trouble by loosening some of the crude that gets built up. The flush was similar to Adam's backyard flush but with one line pulling new fluid from a full bucket of fluid and the other line dumping old fluid.

[Bow_Tied]

If it were my rig I would do a fluid change without doing a flush, no Lucas, to eliminate the additive as the problem. How much Lucas did you add? pint? quart?

I am kind suspicious of trans flushing machines.

[studum]

Got down to see Mike this evening and he scanned it with the consult. Had one code in storage that the TCU had once lost power, or something along those lines. No other codes present or pending. Cleared the code and will see tomorrow morning if it was a computer glitch or not. Somehow I doubt it, but Mike's seen stranger things before so who knows.

Failing that working next best step it to do a fluid change or flush.

Failing that it's likely the valve body, which has to be replaced as a unit - and is a good chunk of change. But at that point it would have to go to a transmission shop for proper diagnosis.

[studum]

Well, no doubt about it it's still there this morning. I guess next up is a fluid change.

Should I drop the pan and change the screen or not bother at this point? Not sure if I'm going to do it or get it done. At this point I want it done asap and may take it to a shop for the convenience of it.

[Adam]

I would change the screen, it's not expensive and maybe what you find in the pan will lend a clue as to what is going on.

[Snafu]

Although changing the screen is not expensive you would also need to replace the gasket and then there is the additional time involved.

Unless you are going for another flush to replace it all then I would just drain and refill especially if it was flushed out a year back and the fluid smells and looks good. IMO. Mike would provide the best advice.

[studum]

Lol - the 2 shops that I phoned thought changing the screen was expensive! I guess it's all in the labour though, and markup on the kit... (~$300...) To be honest I don't know exactly what good and bad ATF smells like, I'm much more used to looking at gear oils in manual trannies and diffs where fluid swaps are a no brainer. I believe my fluid looks good, but I'm not sure if the smell is good oil or not.

Drain and fill @ shop is $70, regular Dextron III

Full FLush is $130 regular Dextron III, $200 Mobil 1 Synthetic.

Or do my own drain and fill for ~$30 (5L Mobil 1 synthetic, happens to be on sale @ partsource right now).

A filter kit is $40 @ Napa, but I decided I don't want to go through that hassle on my back on the cold driveway in the dark right now for something that most say doesn't need to be serviced.

I'm debating grabbing a bottle of seafoam trans-tune, following the instructions: pour in half bottle then drive for 30 mins, then doing a flush with regular Dextron III or doing my own drain and fill with the synthetic. I'm worried about not getting it all out with a drain and fill though...

During our short chat Mike said to either do a drain and fill or a flush, bottom line get the old fluid out and new fluid in and hope that it washes something out that may be lodged in the valve body somewhere.

Wish I had a spare set of hands to do a backyard flush, argh.

[Adam]

I used the trans tune on mine, right before I did my backyard flush, but I put the whole bottle in. It did seem to clear up some other issues I was having with the transmission at the time.

[studum]

Thanks Adam, that settles it then. I'm going to do the trans tune followed by a poor man's flush. I suppose I'll toss the whole bottle in too, I don't really have much to lose at this point. I'l go grab it on my lunch and put it in right away. Driving it to work and back home after work should do it.

Question about the poor man's flush:

When doing it do you
A) Do a drain (from the pan) and fill first, then puke into a bucket through the cooler discharge line, shut it off, then fill through the dipstick tube and repeat?

Or...

B) Do you skip the initial drain and fill and go to straight puking into the bucket, shut it off, refill, and repeat until the fluid looks fresh?

Do I row through the gears when puking into the bucket? I think they had me do this when I got it done

Truck aparantly take 8.5L, should I only buy 10L of fluid or should I buy extra?

[Bow_Tied]

Do you think the lucas additive was the cuplrit? If so, why add more/different additive? If you change 2 things you won't know what solved the problem. Or am I missing something?

[studum]

Lucas is a treatment for seals etc. I put that in before I knew that the hard-ish 1-2 shift was normal. What I'm getting now is definitely not normal (when cold).

The seafoam trans-tune is supposed to be a cleaner, not treatment. If the problem is from something sticking I figured this was worth a shot at cleaning it up. It goes in before the fluid change and comes out when you change the fluid. I didn't want to flush it, then do the cleaner, then flush it again. Seemed like a waste seeing as the fluid in there seems ok now anyways.

I decided not to use the Mobil multi - ATF because that is actually what I went with when I did the flush last year. Instead I'm just going with regular Dex III as specified.

I have no idea if the cause was from the Lucas being added (well before the weather got cooler), the Mobil 1 semi-synthetic that I used in the previous flush last year, the actual act of the flush itself, or a combination of any of the above.

If it goes back to ok after I flush the fluid this time I'm not touching it anymore. If it doesn't it will have to go into a trans shop for further evaluation.