ISO Transmission advice

[dnudelman]

Hi Guys.
I have a 94 Q45 with 163K miles

Need some transmission advice.   My car won't shift into 3rd. Fluid was dark and burnt.  I did the complete drain/fill, filter and drop pan.  No metal shavings in pan. This was the result of  the fan cutting the trans oil cooler hose at a shop that replaced the radiator last summer.  (boy do I wish I did the job myself).  Can't make a claim, shop has been sold to new owner.So now I have a very nice 94Q with everything working well except transmission.  I only drive it in the summer  so I'm not under pressure.
I could:
1.  Try to sell it as is.  Don't see many for sale,  I have no idea what the value is.
2.  Take it to the dealer and pay $300 for diagnosis.  No ecu codes now.
3.   Buy a used transmission from a running car 151K miles at a wrecking yard, $495.  Pay a shop $900 to install.
Your thoughts?
Thanks
David

[3Q Jay]

Hi David-
Any clutch material in the pan (thick gray/brown slime or particle chunks)?
If not, then I'd say most likely the problem is 1) TCU not commanding solenoids properly, 2) a weak solenoid or two or 3) (most likely in my opinion--again assuming not a lot of friction material loss) would be varnish from overheating causing valve body spools and or clutch pistons to not properly actuate.
Does 2nd gear disengage, but 3rd never engages? Recall that this particular shift (the 2-3) unlocks one clutchpack near simultaneous with locking a different one. If second unlocks, you will get a flare (overspeed) as the trans tries to engage 3rd, but doesn't.
No guarantees of course, but consider starting with multiple chemical flush and fills. I've had pretty good success at removing varnish with the two-part BG products kit. You get the trans nice and hot (30ish minutes of light to moderate, but not heavy driving, and drain HOT. then partially refill, run briefly, and drain again. Q45tech used to quote running for exactly two minutes after the simple fill for circulation to get 'the most' old fluid back into pan for a subsequent drain--but I have no scientific basis to prove that is the correct or at least optimised duration. After the final drain/fill, put in the BG ATF "conditioner"
I use basic Valvoline Dex/Merc replacement fluid from chinamart. The RE4R03A (at least mine) likes this fluid much moreso than M1 ATF.

[dnudelman]

Hi Jay,
I'm afraid I described the problem incorrectly, its the 3-4 shift that does happen. Stays in 3rd, at 60 mph engine speed is about 4000 rpm or so.
No difference in D or 3, except engine braking in 3.

Does not upshift, disengage or flare. Does not try to upshift, just like driving in "3" on the gear shift.

When I dropped the pan, there was some slime but mostly brown fluid. The slime seemed to be on the magnet mostly.

Would this change your recommendation to flush with BG?
Thanks
David

[dnudelman]

UPDATE
Transmission shop determine that clutch is trashed based on the fluid that came out of the transmission
I have found a used transmission at a local salvage yard with "80000 miles" Been sitting in storage for over a decade.
They will allow me to pull the pan and examine before purchase.
Suggestions?

Car listed on craigslist. Not much response.
Rebuilt transmission, $3000 to $5000.

[3Q Jay]

I didnt really understand your second post. 3-4 Doesn't happen, but 1-2 and 2-3 are ok?
60 mph in SECOND would be about 4000 rpm.
As for what to do, I'd be careful with a used box, even if they let you pull the pan. You can certainly eliminate some candidates by looking at filter/magnets/residual fluid, but even if everything is sparkly kleen, that wont guarantee a good box.
It certainly *could* be worn clutches, but that usually manifests as slipping as opposed to complete lack of shifting.
If you trust the shop you went to, what do they want to rebuild YOUR trans?
You might PM "No 1 Dad"--He rebuilds trans for a living, and also has an early RE4R03A (wide ratio gear set) I believe.

[dnudelman]

Thanks Jay,
If I am driving at 60 mph, engine is reving at about 4000 rpm
I have the nico ecu, so I can feel the 1-2 shift and the 2-3 shift.
There is no slipping, just no upshift at around 60mph where it should.
When driving at 60mph, I can move the sector from D to 3 with no change in rpm.

Do I trust the shop, Hell no
Do I want to do a junk yard transmission, Hell no also.

I will PM No 1 Dad, thanks for the suggestion.

The car is up for sale should anyone be interested. https://seattle.craigslist.org/est/cto/ ... 52173.html

[Q451990]

I think the car will lock out 4th gear under really cold temperatures. Maybe it just locks out torque convertor lockup. I'd check to be sure the transmission's internal temperature sensor is reading properly.

[98_Q45]

Not a transmission expert but: have you tried over the counter remedies? I know Lucas, seafoam, bars leak and blue devil all make transmission fixes in bottle. I know that’s frowned upon sometimes, but something is better than nothing.

What I would do: run seafoam transmission gunk cleaner thru it, see how it responds after 100-200 highway miles. Drain only again, Then switch to a transmission fix product. High mileage fluid.

Might have a hard time selling it with a bad shift. Especially now, economy sucks (I have 3 vehicles and been struggling to maintain repairs and even pay for insurance because work is slow and shops are more expensive than ever: not because of Biden, but because of ECONOMICS lol) so people are being kinda frugal with things. Even if you have to buy one sitting for years, a good stop leak additive like Lucas will help rejuvenate seals…but first work with the one you have.

90s Japanese transmissions are pretty die hard. My Nissan maxima 97 had a shift solenoid that gives me crap every so often: but I deal with it by allowing it to warm up before driving, and in the summer it doesn’t seem to give issues at all. Done all the fluid and pan drop previously also.

[90dsdreamin]

Solenoids usually fail first which leads to burnt fluid from slipping clutches. Sounds too late for a fix in a bottle. I have a factory service manual I can photograph any trans tech for you.

If you sell it as is it’s doomed for a short life of being driven till it won’t go anymore.

[dnudelman]

Thanks everyone for all the help over 2 decades of ownership. Car is sold to a young man with a wrench in his hand.