'94 Q Transmission in a 1991?

[breaksr]

I'm looking at a 1994 Q45 transmission with 150K to put in my 1991 Q. Hollander exchange says the 4/91 (date on my car) can only be exchanged with the '91 and '92 cars. Is it possible to use the '94 transmission in my '91 Q in conjunction with the '94 TCU? I can get the transmission and TCU for $250 which I thought was a decent deal.

[Q45tech]

Used transmissions [even those with 50k] are always a risk and gamble but compared to ~~ $2000 for a decent remanned unit, you can pay a lot of swap and reswap labor [$400-$500].

The worst loser I have ever seen is one junkyard shopper who went thru 4 units before he found a functioning one.

I'm spoiled in that I like my trannies to last 7 years before focusing on another swap.

Too many other things go wrong with old cars to be changing trannies every year or week.

But you can get very good at it when you change them multiple times.

[maxnix]

I can get the transmission and TCU for $250 which I thought was a decent deal.

If subpar short term performance is tolerable and you have lots of time and don't mind repeated labor, it's a great deal. If you want to enjoy your car and life ingeneral, much more expedient to install the Nissan reamnufactured one from Joe.

It's even more cost effective after only 3 years.

[breaksr]

This transmission is not from a salvage yard it was in a running car that overheated. The owner is parting it out so I know the correct mileage and I know the transmission was working before the radiator leaked and the engine over heated. I have a mechanic that will put the transmission in the car for $200. I just want to make sure all of the sensors will work with the 1991 car. I thought there were some additional sensors on the '94-'96 transmissions which makes it impossible to run the newer transmissions in the older cars.

[maxnix]

No, there are no additional sensors. But the ratios will be off for the TCU in gears 1 and 2.

If the previous owner let the car deteriorate into an overheat condition, doesn't that give you pause about his ATF maintenance regime? How well do you know it was shifting? Is ATF pristine?

[breaksr]

Okay good to know it should work. I'll buy the TCU that came out of the same car so shifting should be okay. Is there anything else that effects the ratios?

I agree I am a bit concerned about how well he maintained the rest of the car given it was driven even when it was overheating. The vehicle appears to be in otherwise decent shape but you never can tell how well the internals of the transmission were operating unless you were able to drive the car.

[qship96]

Engine overheat, especially one severe enough to destroy the engine, almost guarantees the transmission also overheated......as the 94-96 dual IN- RADIATOR HEAT EXCHANGERS and thermal coupling of metal transmission case bolted to engine block transfers heat extremely well.

An overheated transmission suffers similar, if not worse decay, as the engine- seals warp and distort, varnish forms from boiled atf,etc

The engines destruction from overheating is a HUGE RED FLAG as to transmissions health!!!!!!!!!

[breaksr]

Okay did not realize that the overheat would have such adverse affects on the transmission. I was told motor would still work but not all cylinders had proper compression so parting the car out seemed more financially practical.

[maxnix]

Engine overheat, especially one severe enough to destroy the engine, almost guarantees the transmission also overheated......as the 94-96 dual IN- RADIATOR HEAT EXCHANGERS and thermal coupling of metal transmission case bolted to engine block transfers heat extremely well.

An overheated transmission suffers similar, if not worse decay, as the engine- seals warp and distort, varnish forms from boiled atf,etc

The engines destruction from overheating is a HUGE RED FLAG as to transmissions health!!!!!!!!!

This is true, hence my caution on the ATF condition as a tell tale. White paper towel test must be performed.

[qship96]

Okay did not realize that the overheat would have such adverse affects on the transmission. I was told motor would still work but not all cylinders had proper compression so parting the car out seemed more financially practical.

You may get lucky and have no problem with this transmission, but good to know the possibilities before you lay down your cash for the part and especially the labor costs!!!! Now you have more info to decide if you want to take a chance on it or not- If you are doing the labor yourself, and seller offers you a 30 day money-back guarantee on the part, it might be worth rolling the dice and trying it?

[BadQ45t]

This sounds like a complete waste of time and money. If you really have a friendly mechanic that will do a transmission swap for 200 bucks (is he your best buddy from high school or something?) and you don't really care about how much longer your Q runs, for $400 bucks, $500 with fluids it would be totaly worth it. However, if you want to knock out another 100k miles and keep the car for awhile, I'd get the Nissan Reman from Joe for probably 2k, $200 bucks installs it, and you know you'll probably get 200k out of the transmission.

So 1 year and out or 5 more years, that is really your choice since this transmission is already at 150k that means maybe 50k miles and a rebuild/replacement is in order again.

[maxnix]

This sounds like a complete waste of time and money.

So 1 year and out or 5 more years, that is really your choice since this transmission is already at 150k that means maybe 50k miles and a rebuild/replacement is in order again.

Spoken by one who knows.

You will only get another 50K if the used transmission has been maintained meticulously with frequent mechancical ATF exchanges while running a auxiliary ATF cooler.

The ATF white papaer towel test will tell you most of what you need to know.