Dean_Fuller

Just replaced the TT in my 89 car. New torque converter bearings and new pump seals. Everything felt like it went back together well. Had a little trouble seating the pump but after a little turning it seated well I thought. Replaced the fluid with new and filter as well.

I need to state that the modulator has a very slow vacuum leak. I replaced the main vacuum line and tested the line it self and it holds vacuum well...but the modulator itself does not.

At first the only gear that seamed to work well was reverse. ALL forward drive gears slipped badly...so bad it would not pull the car up an incline.
Adjusted the modulator 2 full turns clockwise and it pulled MUCH better. After a test drive it holds gear too long and the up shift is harsh but it felt smooth at highway speed.

After a longer test drive today ( 30 minutes) ...I get a vibration above 60 MPH on the highway. This vibration fluctuates slightly...almost like a wheel bearing but nothing below that speed. The harsh shifting is still there but now if I hit passing gear the transmission slips badly. Motor RPM increases fast but of "pull" then a catch as the rpms lower.

I noticed the torque converter is from a 87 model ( written on it with paint and the word "good" ) so it was replaced at some point. I have paper work that states a replacement transmission was installed in 2002 at one point. I can assume the converter was replaced then.

Here is my questions...

1) Can a leaky modulator cause all this?

2) Can a bad converter cause this? When a converter goes bad what are the signs?

3) How can I test to see what the problem is?

4) Does the fact that all forward gears could pull nothing after install tell me anything?

5) Could I have screwed something up by removing the converter and pump??? ( the new seals are not leaking so far)

Automatic transmissions are above my head. The fact they work at all is magic as far as I know.

Any feedback will help. not sure what my next move is. The only thing I KNOW is not right is the SLOW vacuum leak in the modulator. I can fix that but I'm not sure that will cure all these issues.

Leon Speed

Dean, are you absolutely sure the bowden cable is adjusted correctly and the trans is filled correctly?

ammonman

As Aryan said, make sure the control pressure cable is properly adjusted and the fluid level is correct. When starting cold the fluid level can not drop below the cold mark (20C) on the reservoir. You are going to need to set the Modulating pressure first as if it isn't right, then all other troubleshooting relative to slip kind of goes out the window. You can get a gauge and adapter kit from Amazon to do this. Once you know the Modulating pressure is right we can proceed. Slip is usually caused by either a) a fluid issue (wrong type or amount), b) a fluid pressure issue (not enough or not enough in the right places i.e. a leak internally) or c) worn friction components (clutch disks/steels and/or bands.) Was the trans functioning correctly before the refurb? If so then it stands to reason the issue is with something that was worked on. Based on that, are you sure you re-installed the front pump assembly in the same orientation as it came out? There are fluid passages made into the mating surface between the case and pump. If they aren't properly aligned you might not be getting fluid to the right places. Are you sure the Teflon sealing rings on the input shaft and the two on the pump assembly got installed correctly and did not get damaged/dis-lodged during the install? This will cause a loss of fluid pressure to the right places internally. If the slip only occurs above 80 KM/h the issue may be bad one way clutch in the torque converter.

Report back once the fluid level is verified, control cable is checked, and Modulating pressure is set.

Hope this helps.

Mike

supercedar

Its real easy to damage the seals putting the pump back together. We used this neat piece of plastic to aid the hub inside the seal.
Thomas

hb4

What Thomas said.
We used this tool to help the larger lip seal slide past the pump as it went together. The first time, without the disc, we tore up the new seal and had to use the old, more flexible one. It worked, but the reused gasket didn't seal and we had to take the trans apart again. Then we used the new seal with the plastic disc and Bob's your uncle.

GregBBRD

An automatic transmission isn't going to slip in all 4 speeds, at the same time, unless there is a pressure problem or the torque convertor is bad.

Quit guessing. Put some gauges on it and test the pressures.

Rare for these modulators to leak. Common for the rubber cap that covers the adjusting "T" to leak. The cap is available as a separate part, BTW.

Dean_Fuller

The cable connections were not messed with other than just reconnected..

The fluid is verified as full while running in N.

supercedar

this tool link not working.

Dean_Fuller

I will take it to a trans shop ASAP as I am over my head on this.

The trans shifted without sliping before...however there was a hard shift and high RPM at times. The vacuum leak at the modulator would do that if I understand it correctly. I am NOT getting any fluid leaks on the concrete after my work was done...I assume the seals I replaced are doing their job. ???

supercedar

Dean,
This is a piece of cake compared to what you have done with this car. You will get it the second time. It took me 2 times also. The pump seal lip gets torn real easy, and I do not believe it will show up on the concrete. You know it worked fine before now go after it.
Thomas

hb4

Fixed it. Here is the correct link.

fbarnhill

Dean, I have a pretty good modulator valve that I removed from an 86.5 4spd auto just last week. If you need it let me know. I believe it will work on yours, not sure when they changed. If I am not mistaken, they are color coded somehow. I am sure ther are others out there who can answer that. It would be a quick easy thing for you to try.

Thanks,
Frank Barnhill

SMTCapeCod

check numbers/applications...just providing the attached refs- not vouching for the info itself!

Dean_Fuller

2-5-13 update


After talking to the trans guy here and showing him what I replaced and how...and then telling him my problem of sliping in passing gear at low spped...he is SURE one of the teflon seals I replaced has rolled out of place. So the trans comes BACK out tomorrow.

Is there a way I can leave the TT in the car??? Or is that too much trouble to align the drive rod up in the replacement ?

BTW...he said if it were a bad torque convertor...it would sound like gravel...???

supercedar

I have left the TT in all three times when I removed the trans. Be sure to remove the air box and filter.
I also have a 2 post lift and trans hoist. On the ground I would get that car up 3' in the air.

Much easier the second time.
Thomas