# 97 HB Automatic Transmission Woes



## Oldnissanguy (Jan 6, 2005)

Driving my truck today and it was running fine. Stopped at a stop light and when I pulled away it wouldn't shift out of first until 4,500 rpms. Went to over 5,000 rpms in second and it still didn't shift to third. First consistently shifts at 4,500. No dash lights and the transmission is full and the fluid looks okay. Any clues?


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## rogoman (Dec 16, 2004)

The TPS may be bad.


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## jp2code (Jun 2, 2011)

There should be some sort of vacuum line that lets the automatic transmission know it is time to shift.

If you can find that, take a hard close inspection of it. If that line is cracked or torn, the transmission will have a hard time getting enough vacuum to shift.

All that said, I've never had a Hardbody with an automatic. I wouldn't know where this.

1989 Nissan Truck High Rpm, Delayed Shifting: Transmission Problem...


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## SPEEDO (Jun 9, 2003)

might have a issue with the shift solenoids, there are 4 in the upper valve body and 1 in the lower, they do go out from time to time, has the trans fluid been changed? was/is it dirty?


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## Oldnissanguy (Jan 6, 2005)

Seems to be working fine this morning???? Driving in the neighborhood it shifted into second at 15 mph which is normal and into third at around 20 - 25 mph. Magic truck?

Don't see a vacuum line but the TSM suggests checking some linkage adjustments. I can't see how they would apply due to the transitive nature of the problem. The pressure test might be in order. 

I'll see what happens when I get it out on the highway.

Thanks for your responses and I'll report back with further developments.

ONG


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## jp2code (Jun 2, 2011)

It sounds like something inside may have clogged a line. I'm thinking dirt or a stuck valve inside the transmission somewhere.

I've seen plenty of schematics on automatic transmissions, but I don't understand how all of those little passages translate to the transmission shifting gears.

You might want to think about having the transmission flushed at some point in the future.

???


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## Oldnissanguy (Jan 6, 2005)

I drive it most days but not very many miles. I normally have it on the highway at lease twice a month with speeds 60 - 70 mph. I had the transmission fluid and filter changed (no flush) less than a year ago and nothing noticeable in the pan or on the magnet. It was over 90 yesterday and I drove around with the AC on and idling quite a bit but the gages indicated no issues. Maybe heat related? We'll see.


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## smj999smj (Jan 1, 2006)

Was Dexron III installed when you serviced the trans? Nissan doesn't recommend it for use during servicing the fluid as it has been found to potentially cause sticking of the valves inside the valve body. The factory fill was Nissan-Matic Type "D" ATF, which is actually Dexron (the original formula). Dexron and Dexron II have a thinner viscosity than Dexron III. Other than using Type "D" ATF, most synthetic ATFs are compatible with Dexron/Dexron II applications, including Castrol Transmax-J Multi-import ATF and Valvoline Maxlife ATF. Also, Nissan transmissions use a screen rather than a filter which doesn't need to be replaced except during an overhaul. Nissan believes that if there is enough debris in the transmission fluid to clog the filter, then the trans needs to be overhauled or replaced, not serviced, as this is evidence of an internal failure (i.e. clutches deteriorating or burning up).

FYI, 97 Hardbodies don't use vacuum lines on their automatic transmissions nor vacuum modulators; it's all electronically controlled.


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## Oldnissanguy (Jan 6, 2005)

Thanks smj. Something else to check out.

Additional information: I did add a transmission cooler several years ago.


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## Oldnissanguy (Jan 6, 2005)

Valvoline MaxLife DEX/MERC ATF Full Synthetic.


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## Oldnissanguy (Jan 6, 2005)

Truck continues to shift correctly. Current thinking is that this was a random failure (valve or solenoid) from internal heat buildup due to excessive idling with AC on in very hot weather.


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