No 1st, Reverse is great still... any ideas?

[Brandons]

Got an A4LD in my 94 and it appears the transmission will not shift into drive.

This next part is boring and dry, if you want to skip to a quick summary its below all this crap.... (as well as quick history of the transmission).

Recently i have been driving it with the vacume line off and it was running great. One day i come home and it doesnt work (dad drove it that day into town). He complained it was slipping when going into gear, and hasnt heard any wierd noise when it did act up.

So first reaction "oh crap was it having the vacume line off that did it" (also note i did cap the octapus so no leaky). So i put the line back on and no drive at all. Once i stepped on the gas a little it would start moving (around 3000rpms) enough for me to park it. Once it was almost parked it went into gear just fine as it was moving.

During this time reverse was running just fine, no delay, even when warm. When i took the vacume line off again, the transmission shifted into reverse just great, and drive acted as it would if the vacume line was on (when it was working right). Once warm it delays into 1st and sometimes takes a bit of gas to get it in. Once in gear it works fine... it just shifts when the RPM is a lot higher.

I took a sample of the fluid (from the cooler lines) and you could not see through the fluid as well as it was pretty dark. (i can provide pictures if necessary). The good thing is that i found no shrapnel in the bottom of the pan. So i replaced the fluid and added a bottle of trans fix (lucas) to it. Still got the problem.

For now i have the vacume line off so I can still get drive.

A bit of history on the transmission:
- Rebuilt twice, 2nd rebuild had about $3000 canadian into it
- Driven about 3000km before the explorer was parked (timing chain skipped)
- Sat for two years, purchased truck for $300 canadian
- When i dropped the transmission out of it, the fluid still looked quite healthy, no shrapnel
- Installed transmission into the other explorer and it worked great until now (I replaced the fluid of course)

So to summarize the symptoms
- No drive with vacume line on
- Delayed when going into drive (1st) only with vacume line off
- Wierd fluid (i presume it is from that tranny sitting for 2 years)
- Goes through gears without slipping, just doesnt like going into 1st...

Im at the point were im stuck between ideas. The servo seal leak doesnt really seem to apply to this since it is just 1st gear that is doing it. I was also considering the vacume diaphram but again.. just 1st gear. I am quite lost as to what to do next, can anyone help me figure this out? Thanks guys

 

[jimbo74]

sounds like its time for a rebuild

 

[Glacier991]

I'd suggest you pull the modulator and pull out the tv valve..... (don't lose the pin) clean it up good and clean the bore...then replace the valve and make sure you get smooth movement as you move it in and out. I'm wondering if that valve has gotten stuck or is sticky. Line pressure readings would be a great diagnostic help here too.

Did you replace all the fluid? Levels where they belong etc? often a reverse no forward is a low fluid symptom.... (I'm sure you did it just bears saying).

The worst case scenario is a probably forward clutch that is burned or glazed.

 

[Brandons]

I beleive i got all the fluid, i drained the coolers at the front (i use two) by disconnecting the return line and running fluid through (it seemed to have alot of pressure as well). Im not sure how to get line pressure readings though?

Also with the vacume line off on a cold start (like engine running for about 10-15 seconds), if i wait a couple seconds, put it in drive, and it goes in like it should normally. I dont know if this is of any help or not. I'll look into the modulator/tv valve, since i am not too sure were exactly it is or what it is....

As for the level, i think it may be a bit over... ill check again tomorrow (or at least i plan on it).

Thanks for the help it probably is the worst case scenario knowing me.. lol

 

[Glacier991]

Another case where line pressures would be helpful. The modulator is the rear most thing under the heat shield on the passenger side.... has a vacuum line to it. The A4LD Diary shows it pretty clearly.

 

[Brandons]

**EDIT** I was writing this when you edited the last post now i know what part you mean . I am hoping this isnt the result of me leaving the vacume line off for a bit?


I have no clue how to get the pressures sorry to say.

As well im not very good with transmissions, but reading that diary makes me want to dig into my valve body.

Is pulling out the modulator and tv valve a complicated job? Im afraid of messing something up royally.

thanks for all the help Glacier

Heres a pic of the fluid comparison i had lol..

As you can probably tell, left is from my transmission, right is brand new.

The oil pan just after pulling it off the transmission. I was happy to not see shrapnel for once...

comparing it to my last transmission....

V V V V

Hehe were still using the same floor matt. It seems to last longer than our transmissions...

I also dont beleive the fellow rebuilt our transmission right the first time we had it rebuilt. It blew up the reverse planetary (6 pinion) and pretty much totalled the core of the transmission. I was dealing with it through a friend of mine who swore by this guy, and he showed us the planetary with half the pinions just gone, let alone half the cover that holds them in. I started thinking he screwed it up when he also happened to "misplace" a $600 part my friend got him to put in his tranmission. We found this out when the part that broke was a stock part, rather than the part my friend bought for it.

Anyways i may have thursday off work to have a looky. Im curious if i will need to drain the fluid for this (checking the tv valve), which i probably will have to do, but im not sure.

Thanks again for the help.

 

[Glacier991]

You do not have to drain anything to check the tv valve. A pair of tweezers or needle nose pliers can be handy to get it out. If it leaks plug the modulator back in once you have it out.

 

[Glacier991]

As for pressures, there is a thread on using a transmission pressure tester on the board, maybe I should sticky IT too!

[edit: it is stickied, for now]

 

[Glacier991]

And the fluid has a slight look to it of moisture. Is it strawberry milkshake looking close up? That is a sign of coolant mixing in it and VERY BAD news.

 

[Brandons]

im not exactly sure what a strawberry milkshake looks like (Damn its been too long.) but i presume it is a lighter color? This stuff is basically black. I cant even see through it in a small 1/2" container.


Ill try and get some better pics because im not too sure how to describe it..

How could coolant get into it though?

 

[Glacier991]

the transmission runs a line up to a "cooler" in the radiator... like a radiator within a radiator. If a leak occurs there it can mix coolant into the trans fluid.

 

[Brandons]

I see, i totally forgot about that... in fact i think i will take another sample of fluid tomorrow just in case its back to its old state. I have an extra rad in the parts truck if it is a problem.

The fact i use two factory coolers up front wont have caused any harm will it?

 

[Brandons]

I was looking over the rebuild writeup (excellently done i must say ) and i think i found the part you saying i should check.. I decided to put a couple pictures up here to make sure that im looking at the right thing.

Again thanks a lot for all the help :cheers:

Im considering looking into getting the new part you used. the vacume modulator on mine is probably toast anyways.

 

[Glacier991]

That is IT ! With the heat shield in place it is a b**ch to get out....might want to take off the heat shield first. That blue nut stud with a nut attached to hold the shield and a couple clips are what holds it in place.

 

[Brandons]

Well sounds good, my task for tomorrow Thanks again glacier, ill post again when i find out how things go with it. Perhaps pics if its bad or something. the heat shields no biggy for me, changing the oil and dropping the transmission ive gotten used to it.. lol

 

[Brandons]

Alright so today i just, and i mean just, about 15 minutes ago, took out that vacume modulator. There was nothing else that came out, just it and the pin that lives in it.. Unlike the photos, there does not appear to be anything that can come out. The pictures that were in that thread had another rod as well as a spring on the new one. I didnt pry at anything or try pulling anything with the needle nose pliers just in case. so..

Heres a couple pics of what im stuck at.. (sorry for the crappy pics, not a lot of room to take em )

And the Vacume modulator thing itself. At the top it looks like theres a little adjuster thing for a screwdriver.. not too sure until i clean it up.

Im currently at a loss of what to do.. Also while im in the process of this, im fixing my exhaust leaks . So i was able to get that heat shield off pretty easy. Im stuck though on what to do next... even having doubts i got the right part im looking for...

 

[Brandons]

Now that i really pay attention here (i didnt notice how small it really is), it looks to me that it possibly does come out.. though when i pushed it or did anything to it i felt no play.

 

[Brandons]

Finally got it out,... took quite a bit to pull it out. Doesnt look very dirty or anything... there was also no spring that came out.

Nonetheless I shall clean the parts and reinstall them. Im also thinking something is wrong with the vacume modulator,... at first when i tried to get it to pull in nothing would happen, tried again later and you could feel it suddenly move and its been fine since.

 

[Brandons]

OK no difference... you can feel it move a bit now with the vacume line on..

 

[Glacier991]

The end spring was an aftermarket mod. What is important here is that the TV spool move freely in the bore and the modulator will hold a vacuum and not leak.

And maybe your modulator actuator had siezed up? I'll be curious to hear the road test.