PROBLEM The factory PTU on certain Ford, Lincoln and Mercury SUVs and sedans often fails when extreme temperatures cause internal lubrication issues. When the lubricant overheats, it can cause catastrophic failures, also making it nearly impossible to salvage and rebuild it. In extreme cold, the factory seals fail and cause oil to leak from the unit.
FIX Dorman’s engineering team made the following improvements:
Patented Heat Shield Protects gearbox fluid from thermal breakdown by reducing heat transfer by 30 o F
Drain Plug Allows routine fluid service (OEM design is sealed)
Upgraded Seals Improved seal material designed to withstand temperatures as low as -40 o F
Next, we addressed the fluid heat by installing Dorman's patented aluminum heat shield near the exhaust, which is routed very, very close to the PTU when installed. In testing, temperatures on the surface of the PTU dropped by no less than 24 degrees at any point in the test, and often more— nearly 50 degrees in some circumstances. Finally, we also addressed dealing with fluid that had been heated beyond its maximum working temperature by installing drain and fill plugs in the case. Astonishingly, Ford did not fit these vehicles with simple drain plugs, permitting fluid level checks, changes, and addition as necessary. Rejuvenating the fluid from time to time with quality lubricants was the final step in helping to ensure our PTU would perform where originals failed. Initial demand certainly has been aggressive for our upgraded solution. We’re proud to have applied what we consider to be the ultimate bevy of fixes to this part. The 600-234XD will keep all four wheels turning for motorists wanting a vehicle as reliable as it is sure-footed.
As Dorman engineers analyzed failed units from the field, we actually
found these problems were related. When the PTU lubricant level fell below recommended level, it overheated. The compromised fluid could no longer properly lubricate the gears, which would audibly voice their disapproval. If the fluid got very hot, it became gaseous. As the PTU vented it, the distinctive odor entered the passenger compartment. To solve the problem, we had to address the low fluid level and the fluid quality. The low fluid levels were caused by seals that were failing in temperature extremes—both hot and cold. Careful examination of the seal lips showed the problem: the embrittled material began suffering repeated microtears that would lead to very slow (but certain) fluid migration. We selected a new seal material that outperformed the OEM.
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