Question:

 

I have a 1990 Nissan Pathfinder. The original transmission failed after about 35,000 miles, and then the second transmission failed after about 59,000 miles. I saw in Consumer Reports that Nissan Pathfinders built from 1990-1992 had an abnormal number of transmission failures. Do you have any more information on this problem? Nissan says there is no problem.

 

Answer:

 

There are quite a few transmission related Technical Service Bulletins pertaining to the 1990 Pathfinder. But I can't pinpoint just one dealing with your problem without knowing the exact failure.

 

Your transmission went at 35,000 miles for whatever reason, and then again at 59,000. If it was the same part that failed there's a good chance it was more than a coincidence, and you should have received assistance from the manufacturer, dealership, or transmission repair shop, depending on warranty status. If the two failures seem unrelated, then the best bet is to go over the basics. The normal life span of a Nissan transmission is obviously well above the mileage we're looking at.

 

Here are a few important questions: Were the replacement transmissions new or factory rebuilt units? If not, was it a qualified technician doing the repair or overhaul? Also, was there debris in the first failed unit, and if so, was anything done about it?

 

Often times a transmission failure leaves behind fragments and particles of steel, aluminum and clutch materials inside the system, and then the transmission cooler and cooler lines must be back flushed with a cleaning solvent and compressed air before installing the new transmission. This is to prevent the contaminants, or a blockage of the cooler, from causing damage to the new unit.

 

This applies to most vehicles, but your particular SUV may be a little different. Conventional cleaning methods will do the job properly on a "tubular" type transmission cooler. Your Pathfinder may have a "fin" type cooler which makes cleaning impossible and requires replacement of the radiator after the entry of foreign material. If that's the case, and you are driving around with insufficient transmission cooling due to an obstructed transmission cooler in the radiator, you will be working on transmission number three real soon.

 

Check with Nissan parts to see if you do have the fin type cooler. Either way have the cooler and lines checked for proper fluid flow.

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