I've had Mercon V in it for about a year. Before that used what Mercon III I had left because was told "Use what the mfr suggests". With that fill tried an additive. Finally bled it out and ran Mercon V thru. It makes the same buzz no matter what is in it. Ford service is reluctant to comment but told me they only get a quiet job about 50% of the time. In other words, no guarantees. I'm having trouble accepting that I'm the only one up against this problem......
Changing PS fluid over to Mercon V has worked for a lot of noisy pumps.
Instead of a full flush and having to bleed air out I did mine by sucking out the reservoir a couple times and refilling with the Mercon over a few weekends. Sort of a slow flush the lazy man's way.
" slow flush the lazy man's way"
Wow did not I was 'lazy'.
I have done that and will do that for my 3 Fords every year. If I suck out the resivor and replace each fall, it will always be reasonably fresh.
As for noise, one should be sure it is not air in the fluid. The only way I have been successful is to suck the fluid our, replentish it, run it few minutes min, repeat. You can usually see foam on top of the fluid in the resivor if it has any air in it.
I will do my trannys inbetween the 30K filter change also. It does not cost that much, takes a little effort for the tranny. For that, I measure what I take out, and put back just what I removed. That assumes I have checked the level recently before.
I have a 96 sable. I had the cooling system flushed and new radiator and heater hoses installed. After I had the work done I would smell antifreeze and see wisps of steam coming from under the hood. Took it back where I had the work done and the guy said it was my soft plug seeping. He also said he might have used too much pressure when he flushed it but he would only charge me 300.00 to fix it. WTF! I went the cheap route. $3.00 for bars leak or $300.00 . It's my work car with just under 134,000 miles. I've owned it since 1998 and it's been a great car.