89 B2 Auto grinding in reverse gear.

[McWillies]

I recently installed a new starter solenoid in hopes of fixing my starter issues. It didn't fix the issue so I went on to install a new starter. I now have the new starter installed and it starts better than ever. The issue now is that reverse grinds like hell, but it still moves when given gas. All other gears work just fine, but when I put it in reverse it makes this godawful grinding noise. I have done a lot of googling but 90% of the stuff I find is for a manual transmission, I have an auto. I have already checked and it's not in 4wd. I don't have reverse in 2wd or 4wd. What do you guys think it could be?

 

[McWillies]

Please help if you have any insight to what could be the issue. I found one thread that said the torque converter may be bad. Supposed to have it in a shop by Monday, but I would like to know if it is something I could easily fix myself instead of wasting time. I need the vehicle to be usable as soon as possible. One thing that I haven't looked into is the brakes. My brake lights/anti-lock rear have been coming on for some time now, mostly in the morning though, when the weather is colder. Could that have something to do with it growling at me like a bear when I try to use reverse?

 

[Tedybear]

Torque converter won't care what gear you are in. At least it shouldn't. I would carefully jack up all 4 wheels onto jackstands. With all 4 tires off ground, then you can have a helper CAREFULLY put into drive and reverse. From there it's just crawling underneath CAREFULLY and trying to pinpoint sound origins. I've had 3 different A4LD. In our former b2. Never had that issue with reverse. But I find it unlikely a torque converter would be at fault. Sorry couldn't be more help.

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[McWillies]

Thanks for the insight. I don't have the tools to jack it up on all 4s, unfortunately. I should have mentioned the trans was rebuilt about 3000 miles ago, when I got it. I've also been wondering if there is anything underneath the truck that I could have accidentally bumped that could cause issues like this? I was basically pulling on my socket wrench with the force of a trillion baby gorillas to get the bolts loose down there.

 

[McWillies]

Recently found this post:
http://www.bimmerforums.com/forum/showthread.php?1708997-Grinding-noise-when-engaging-Reverse-gear-in-automat

If you read through it you will see that the motor/trans mounts were causing the engine/trans to move while shifting gears, causing reverse to grind.
It's currently 10 PM so I will wait until the morning to check it out. I'm supposed to be leaving the truck at a shop tomorrow for who knows how long. I would really like to avoid that as I need a vehicle, but I guess I gotta do what I gotta do.

P.S. If anyone has any engine/mount diagrams for the 2.9l, I would really appreciate them. After about an hour of googling I have come up completely empty.

 

[JerryC]

In the way back days in auto shop we had a couple of cars with bad motor mounts and of the engine torqued hard enough the engine fan would hit the fan shroud. Since reverse is geared higher you could see the problem there first.

 

[McWillies]

I'll be sure to give that a look-see too, thanks Jerry.

 

[McWillies]

Brought it to the mechanic yesterday but the shop was closed so we just left it out front with a note. He took a look at it today and it turned out to be something with the starter (I had my suspicions all along that it was the starter, seemed like too big of a coincidence). Anyways, supposedly the starter was trying to engage when I put it in reverse. He got it all fixed up, I should have it back later today.

 

[Tedybear]

Brought it to the mechanic yesterday but the shop was closed so we just left it out front with a note. He took a look at it today and it turned out to be something with the starter (I had my suspicions all along that it was the starter, seemed like too big of a coincidence). Anyways, supposedly the starter was trying to engage when I put it in reverse. He got it all fixed up, I should have it back later today.

Interesting. Not sure exactly what would cause that. Maybe the engine being 'torqued' just right and a bad wire? I really don't know? But yeah, that would really make that gear grind sound!

Maybe something in the steering that when put into reverse it's moving the ignition switch?

Please let us know the cause if you find out. It's an interesting one!

S-

 

[McWillies]

Interesting. Not sure exactly what would cause that. Maybe the engine being 'torqued' just right and a bad wire? I really don't know? But yeah, that would really make that gear grind sound!

Maybe something in the steering that when put into reverse it's moving the ignition switch?

Please let us know the cause if you find out. It's an interesting one!

S-

I thought the same thing. Supposedly some frayed wires were contacting something. He put a ground on the starter to stop it from engaging but even he didn't really know why it was in the first place. He said he had never seen anything like it before. Maybe if the transmission shifts when changing to reverse just enough for the wires to come into contact? I'm not sure, I'm a novice when it comes to electrical stuff.

 

[Tedybear]

Sounds reasonable. Never know whatcha find wrong some days...

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