naughty automatic transmission

[robogo]

The Car: 1994 geo metro hatch back with 1.0 liter engine and auto
transmission. I've owned the car for only a month and don't know
how it should really run.
The Problem: when in P= slightly rough idle, on shift to R= really rough
and harsh shift, N= seems all ok, D= delayed shift and "seeking" while
at stoplight and slightly rough idle. At speed it seem to run and shift
ok. I've just changed the fluid and filter and the result (after an around-
the-block test drive) are, P- slightly smoother idle, R= ever rougher idle
but no harsh shift, N still ok, D reduced roughness and delay.
The Questions: does the poor transmission cause the roughness? Can I
fix it or is it time to replace or rebuild and what is the least expensive
alternative. Is the transmission problem related to the engine stalling
and not starting until it has "rested" for a while? (Today it wouldn't start
after the fluid change but it eventually started. These were on very
hot days.)
Any wisdom the forum could impart would very much appreciated

[savabuck]

Your problem sounds similar to my 92 Geo Metro w/automatic 3spd. It slips in "drive" gear, but low and 2nd shift just fine. WHEN CAR HEATS UP AFTER 5 MINUTES OF DRIVING...the slipping in high (drive) gear disappears. Transaxle fluid change did not help the "drive" gear slippage (which occurres, apparently, only when the motor and transanxle are cold, but not when they heat up) . Is there a mechanic among us who can explain the fix and if it's expensive? From [email protected] (As for your other problem...the rough idling...could be normal maintenance issues like a tune up, new cap & rotor, foweled air cleaner, weak plug wires, low spark. Check all that first before dragging it to the garage. There are so many "little" things that can go wrong on our Geos, it can be discouraging...but, the high side is...there are a lot of friendly brains in this forum ready and willing to answer these nagging questions. Anyone want to respond to the email address above with an anwer to my transmission problem?...or, to the forum in general?

[hot_sd]

I've rebuilt my automatic transmission so I may be able to help you guys with your tranny issues. I also have the ATSG rebuild manual for the MX17 tranny.

robogo - the rough idle could be the engine rather than the transmission. As soon as you place the car into gear, the engine will be under load even though you are not moving. If the engine has a problem with the fuel system you could get this. On the other hand if something is jamming inside the transmission -torque converter or oil pump - you could place the engine under very heavy load. Another possibility is that the line pressure in reverse could be abnormally high (due to a malfunctioning pressure regulator) - this could explain the rough idle and harsh engagement in R. Also I think you are saying you have delayed engagement when putting it into D. As soon as you put it into D, the forward clutch is engaged. If there is an oil leak in one of the fluid passages in the valve body or if one of the seals in the forward clutch pack is damaged it will take time for the pressure to build up and engage the forward clutch. I would suggest measuring the line pressure as the first step. I have to say I don't really understand the problem in drive as described - don't understand the part about "seeking" at the stoplight.

savabuck - not clear if you are slipping in first or third gear - Low is the same as first. In any case slipping is due to either partial application of a clutch or band (due to a problem in the control body like a shift valve or servo) or due to worn clutch plates or worn friction metarial on a band (the MX17 has only one band for locking the sun gear in second). If it is a worn clutch or band a rebuild is the only way out. If the shift valve is sticking some friction modifier added to the tranny fluid may help. You can try some "Lubegard Red" and see if that helps.

[robogo]

hot_sd:
Thanks for the input. What I ment by "seeking" is while
waiting at a stoplight in D it will shift into 1st and then
release several times, sometimes I have to keep my foot
on the brake to stay in place. I also strongly suspect
that the timing is incorrect. I'm far from a mechanic so
I'll ask a skilled friend to to look at it.

[hot_sd]

OK I understand what you meant. My previous suggestions about what could be wrong still apply in this case. If you are really sure that it is switching between 1st and no drive at all (as opposed to first and some other gear), then the things to look at are the valve body followed by the forward clutch pack. Unfortunately to look at the clutch pack the tranny will have to be removed and disassembled. The valve body can be pulled from below without taking the tranny out. If it is switching between first and say second or third during the "seeking" then I can suggest some other things to try. If not then you can have someone take a look at the valve body. And also you can do a line pressure test in D and R, this may also reveal something. For example do you lose drive when driving or only at stop. If it only happens at stop the pressure may be to blame. If you are lucky it may be a defective pressure reg (as opposed to a faulty oil pump) which is not too difficult to fix.

[robogo]

hot_sd.........
Thanks again for your wisdom. The problem ONLY happens in D
after stopping and to my untrained mind it also seems a pressure thing.
I am now less fearful of the transmission shop.

[hot_sd]

This is what I would suggest. First get a line pressure reading on R and D. This is something you can do yourself. You will need an oil pressure gauge - you can buy one if you don't have one already. The line pressure tap is at the back of the tranny just above the oil pan. The pressure reading you should get are

in R - 78 - 113 PSI at idle, 149 - 199 PSI at stall
in D - 28 - 56 PSI at idle, 71 - 100 PSI at stall

Be careful if you plan to do the reading at stall - take the necessary precautions - although the idle reading should tell you if everything is OK or not.

If this reads OK next step is to pull the valve body and clean everything. If not OK the valve body should be pulled and then the pressure reg examined and replaced if needed. If this step does not fix the problem, only then I would recommend pulling the whole tranny out. If the pressure is not correct but the pressure regs (primary and secondary) check out fine, the oil pump should be removed and disassembled to check for problems. At this time the forward clutch pack should also be disassmbled and checked for damaged seals, piston and all other components.

This would be the logical and cost effective way to investigate this in my opinion. Note that many transmission shops will immidiately attempt to convince you to do a full rebuild and may not explain or investigate the problem in this manner. It will be upto you to decide how to handle the situation.

Good luck.

[hot_sd]

I remembered that I did take some photos while I was rebuilding the tranny so here are a couple for those who have not seen inside the tranny.

[starglitch]

i have a 1992 geo metro and my trans gives me trouble when i go about 16 miles then it starts . it wont move it jurks then i pull over go back turn off then it will catch agian run fine again for another 11 miles maybe then wont go again is that TORQUE CONVERTER or is trans going out or oil pump can any one help me out and where i can get a good price on a TORQUE CONVERTER if thats what i need i changed my trans oil 3 times now trans filter 2 times still the same once it gets warmed up dont know what else to try but TORQUE CONVERTER thought its not pumping trans fuild any one help thx dino