Uncle volvosenior,

Please verify correct power steering fluid type in your 1991 Volvo 940 owner manual.

While the 700/900 FAQ on Steering at (https://www.brickboard.com/FAQ/700-900/Steering.htm) states:

Fluid Specification. [Editor] Your manual calls for "ATF" which means Dexron. Many people have had outstanding results with synthetic ATF such as Mobil 1 or Castrol. While Volvo does not specify an oil change interval, you are highly advised to regularly flush the system or add a filter.

ATF is an abbreviated acronym for automatic transmission fluid. Many ATF varieties exist. However, the statement ""ATF" which means Dexron" not at all times correct.

While my Volvo 240 factory and owner manuals remain packed up and miles away, I'm very certain your 1991 Volvo 940, like the 1991 Volvo 740 use ATF Ford Specification "Type F" or "Type G". I use synthetic "Type F" in my Volvo 240.

Unless your power steering system (pump and rack) is a replacement by you or a prior owner that does indeed require the use of a Dexron version for power steering fluid, you most likely have a TRW/CAM steering rack on your 1991 940. These power steering racks racks of this vintage on Volvo 240/700/900 use usually the same TRW/CAM gear power steering rack, with form factor variance by Volvo model (inner tie rod length), and these racks, unless I'm really wrong, use ATF Ford Specification "Type F" or "Type G" as my Volvo 240 and 740 owner manuals clearly display, from memory. I do not recall what the 940 owner manual states.

Using Dexron in a power steering rack that requires "Type F" will cause seal and other failure and rather quickly. The rack seals fail first and the inner tie rod bellows fill with the red power steering fluid and leak.

I've seen this happen before and I've done this to myself as the later publishing date edition Haynes manual for 1976-1993 240 call for Dexron III as the power steering fluid when the Volvo factory owner manual for 1990, 1991, and 1993, and I think 1979, and some other years, call for ATF Ford specification "Type F" as power steering fluid.

I replaced the power steering fluid in my 1990 240 DL with TRW/CAM rack with Dexron III and within a short period, maybe some months of daily driving, the rack seals had failed. That 1990 240 DL wagon, with M47 II, has 180,000 miles.

There may be power steering fluid type variation on the systems equipped with the ZF power steering racks. The ZF racks were used on mid 1980s models.

Your 1991 Volvo 940 should use the very same power reservoir and steering pump and a similar TRW/CAM gear rack as my 1991 240. Same should be true of your 1989 740 GLE. I believe Koyo are a type of CAM rack came into use on 900 series 1994 and later and may or may not use a power steering fluid other than "Type F".

Please verify and correct if needed.

After market repair manuals, like Haynes and Chilton, can be wrong in specification, like fluid types, torque, and procedure.

Hope that helps. Apologies if my alarm is unwarranted. No need causing premature failure to a functioning power steering rack!

Thanks,

Buttermilk MacDuffy's Tavern.
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Teh RWD Volvo is forever awesome!