Hissing noise after transmission rebuild

familyhauler · Post by **familyhauler** » 02 Mar 2011, 09:09

I have a 2004 XC90 T6 that just had the transmission rebuilt. When I got it back from the shop (Aamco), I noticed the steering wheel was squeaking and there is a hissing sound when accelerating.

A member of another forum had mentioned that the hissing sound could be caused by a metal collar or bearing at the base of the steering shaft. I did notice a metal collar just sitting in place at the top of the boot covering the steering shaft at the floor board. I was wondering if that collar is out of place and if there is a simple fix to get it back into position.

I was able to get rid of the squeak by spraying some WD40 around the base of the shaft, but the hissing sound is still there. I even had the repair shop check all turbo plumbing, vacuum lines, hoses, etc. and found nothing. The only thing we noticed was an air vacuum inlet for the brakes (located near the air filter box, a round disc shaped part) was loose, but I tried taping that in place to seal it off to no avail.

Everything else seems to be working fine, and the transmission is shifting smoothly and engine is getting plenty of power. No error codes lighting up on the dash.

Any ideas?

Post by **jimmy57** » 02 Mar 2011, 10:30

If the noise is present if you are sitting still and maybe sitting still if you increase engine speed, then you could pack a rag around steering shaft where it passes through floor and see if the noise is just the normal noise getting through an imporoperly fitted or broken steering shaft seal assembly.
There are lot of noises that are normal and present in our vehicles we never hear due to the sound insulation and seals in firewall.
I had to take complete seats and carpet out of a car a few years ago due to an open window and a severe storm (DUH!).
I drove the car a short distance with all the floor coverings and seats out and the scary noises I heard were amazing! Put it all back together and all was well and nothing was really wrong.

familyhauler · Post by **familyhauler** » 02 Mar 2011, 18:28

Thank you. I will give that a try.

trstjohn · Post by **trstjohn** » 03 Mar 2011, 10:21

my car sounds like this occasionally, is this what you hear? This was right before I changed my air filter, it's not as bad now, but I still occasionally hear it.

From my carfax, I know that the transmission was replaced, also at an AAMCO station. Also, my steering wheel does squeak. It's not as bad now, since I put in some more steering fluid.

familyhauler · Post by **familyhauler** » 04 Mar 2011, 07:52

Thank you for the feedback!

I'm happy to report that with the help of another forum member I was able to fix the issue.

I wish I would have taken photos, but let me give you a quick write-up:

On the XC90s, there is a metal collar or bearing that fits just underneath the boot where the steering shaft goes into the floorboard. Mine was actually resting on top of the boot. I guess during the transmission disassembly/reassembly the steering rack was moved around and that caused the bearing to pop out of place.

What I did was use a plastic pry tool, like the kind you use to remove a bicycle tire, to gently pull open the lip at the top of the boot and work the bearing back in place, and then work the lip of the boot over the bearing to cover it.

It's also a good idea to work a little grease along the inside of the bearing before putting it back into place so it's well lubricated. You may need to spray a little cleaner (WD40) to remove any debris that collected on the inside of the bearing while it was dislodged before applying the grease.

No more squeaking and no more hissing! I alerted the guys at Aamco so they can double check that the next time they service another XC90.

marcas73 · Post by **marcas73** » 02 Feb 2012, 16:37

Thankfully I have found this forum. I have transmission courtesy of AAMCO as well. Since picking up the car, there is a hissing sound upon acceleration. The hissing sound seems to be coming from the driver's side. Are you saying that the noise is caused because of the steering bearing? Do you think AAMCO will check and fix that for free seeing as how they must have hit it?

Thank you again!

marcas73 · Post by **marcas73** » 15 Feb 2012, 06:50

Well I'm back from AAMCO and they fixed it. The metal ring was in fact out of the rubber thing at the floorboard. AAMCO did fix the problem for free and it only took them about 20minutes. Hard to believe all of that extra road noise and hissing was all from that little problem. Car now runs and sounds great. Thanks so much to this forum.

superglide9375 · Post by **superglide9375** » 15 Mar 2018, 21:15

thank you for this answer

Post by **SuperHerman** » 15 Mar 2018, 23:04

When one drops the tranny the steering column needs to be disconnected. This is done by removing the rubber boot and pulling it up to gain access to the disconnect point. This pushes the bearing up.

When putting it back together, after attaching the boot, one can just push hard on the bearing twisting it or the boot until it starts to enter the boot. Then push it all the way down and you are good to go. It takes 5 minutes. A little silicon spray on the bearing and boot would help.

For me the harder part was getting the boot to properly sit to the firewall because there is just no room for a human down there. Pull up on the boot and make sure it is seated and fold back the rubber flap to visually assure. If the rubber boot is not properly seated water can enter the foot-well.

Any noise from the boot and or bearing should only occur when the wheel is turned as the movement causes friction noise.

BerndReini · Post by **BerndReini** » 20 Sep 2019, 22:36

Thanks to this thread, I was able to get the same issue fixed. I had the valve body replaced and had the same hissing noise. My mechanic said everything was normal, the sound came from the turbo, but I insisted that I had never heard that sound before. I read about the collar here and saw that mine was sitting on the boot as well. I went back to my mechanic and told him to fix it, and lo and behold, the sound was gone. The turbo sits right behind on the opposite side of the firewall close at the back of the engine compartment and the noise came through the opening for the steering column.