Hi guys,

I've been having issues with the auto tranny in my UCF10 after I brought the car to a mechanic for a fluid flush and torque converter install. During every cold start, the tranny will not shift into second until the engine reaches 4-5k RPM or the throttle is open fairly wide (which I assume increases tranny fluid pressure via the trans kickdown cable). There is no slippage, it just hangs in first for a couple of seconds before slamming (very harshly) into second. The remaining shifts seem to be fine. After a few starts and stops it will begin to shift normally, although the shifts remain slightly harsh till after about 15 mins of driving. It will shift as normal until the car has had a couple of hours to cool down. Occasionally the tranny also makes a low pitched whirring noise when cold.

About 2 months ago the tranny started slipping. I couldn't cut through the sealant on the trans pan to check the filter so I had to bring it to a mechanic. I got him to do a flush and also got him to swap torque converter just in case. I supplied the fluid (Mobil 3309/Toyota Type-IV) and TC as I was once told by a "transmission specialist" that it would be ok to use Dexron. The mech said the filter was stuffed (as I expected) but the pan and magnets were apparently very clean. He did a drain and refill, not a power flush. The delayed shifts started immediately after I got the car back. I have a suspicion that the the issue may be caused by fluid drainback due to incorrect installation of the torque converter as I left the car to sit for 48 hours once and the fluid level on the dipstick rose by about 6 inches (with the vehicle off). I rang several transmission shops and some have told me that drainback is a probable cause while others have said that the trans should circulate fluid quickly enough to avoid fluid drainback being an issue. Some have also said fluid drainback will cause the auto to slip, which mine doesn't - it just hangs onto first.

The tranny was overfilled by about 2 inches (trans fully warmed up and running) when I received the car back. My rear mains seal also started leaking immediately after getting the car back, causing an oil leak near the bellhousing. I spoke to the mech and he said there were no traces of oil when he took the trans off. They deny any responsibility for it, and instead quoted me $500 to drop the trans and change a $30 seal.

The mech also didn't bother cleaning or checking the trans solenoids and tried to BS me that getting to the solenoids would require removal of the valve body. Two weeks later I dropped the pan to clean the solenoids to see if it would make any difference. The pan looked pretty clean, and the fluid was still fresh. The shift solenoids (1 & 2) tested fine, but I couldn't test the remaining 2 solenoids (3 for T/C lockup, 4 for accumulator pressure modulation/controlling shift shock) as I didn't have equipment to simulate a duty cycle.

I've also played around with the throttle position sensor and trans kickdown cable and even tried a new ECU to see if it will fix the problem. I suspect that the issue is caused by either fluid drainback or a faulty solenoid (#4 in particular), or possibly a dying oil pump.

Has anyone come across a similar situation? Some advice would be greatly appreciated.

Thanks!