Groan, vibration, and power loss

[knobbler]

Hey all,

I'm about to lose my mind from trying to track down an intermittent problem that first started about a month and a half ago.  When accelerating up steep grades (though also on flat surfaces at times), my '85 wagon will make a groaning noise (like wet metal being rubbed against) and will bog down. This doesn't always occur, and when it happens on flat road, the behavior is accompanied by wheel hop up front.  The wheel hop is really messing with me, because I have the front driveshaft and CV axles deleted (with axle stubs retaining the front wheels) and confirmed the tcase is set in 2WD.

So far, I've:
* Checked the flex plate & TC bolts
* Changed transmission fluid & filter
* Verified the wheel retaining nuts were torqued to spec
* Checked wheel bearings
* Drained tcase to find that it was incredibly dry; only 3oz or so came out, but it had no metal flakes or glitter.
*  Half-filled tcase, ran around the block, drained it, and inspected fluid.  Found seal chunks, 3 very, very small pieces of metal.  They had no distinct characteristics to indicate what they were once part of, but they were ferrous.  These were accompanied by some small rubber debris, suspected to be from the output shaft spline seal.
* Sleeved output yoke and changed the seals, refilled the tcase.
* Replaced ujoints, greased slip yoke.
* Changed diff oil.

Despite all this, the problem continues to happen.  I've almost run out of ideas.  The only things I can think of that could be causing this are a failing torque converter (though the behavior isn't really consistent with that), or my leaf springs are so clapped out as to cause binding somewhere.  Has anyone run into anything like this and have some pointers they could share?

[mo.eagles]

Well if you have the drive shaft and axles removed it shouldn't be tcase and you don't have leafs on the front. I would check your motor mounts real close . If you are by yourself you can lift the hood (so you can see engine from drivers seat) , put car in gear with your foot on the brake . Mash the throttle and see if the engine torques over too far .

[knobbler]

Well if you have the drive shaft and axles removed it shouldn't be tcase and you don't have leafs on the front.

Yep. That's why I'm really confused about the hop.  I'd treat it as a general annoyance if it weren't for the fact that it appears to be related to the main problem behaviors (but only on flat ground).

That said, I made sure to check the motor mounts as you suggested.  I observed a fairly substantial amount of twist going on (I'd guess about 15°).  Even if that's not the culprit, I doubt it's doing me any favors. . .  Guess I'll be changing out the mounts soon.

[AMC of Houston]

The trans mount is a known issue with the Eagles.  The automatic mount cannot be found.  Luckily, all you have to do is get a standard tranny mount, and cut out the 4 tack-welded bolts; and you have an auto mount!

[amarshall]

I'm all for changing the motor mounts, but I'm not seeing how that would cause a power loss.  You didn't say anything about the brakes,  Any chance that they are binding up somehow and causing some weird oscillation leading to the hop?

[knobbler]

The trans mount is a known issue with the Eagles.  The automatic mount cannot be found.  Luckily, all you have to do is get a standard tranny mount, and cut out the 4 tack-welded bolts; and you have an auto mount!

That's incredibly helpful information.  Thank you!  Good to know that beforehand, for sure.

I'm all for changing the motor mounts, but I'm not seeing how that would cause a power loss.  You didn't say anything about the brakes,  Any chance that they are binding up somehow and causing some weird oscillation leading to the hop?

That's something I forgot to include in my description, actually.  The brakes were one of my first suspects, since I had fixed some problems with the brake system a few weeks before all this started.  I looked through the brakes and everything's good on that front.

There's also some significant forward lift and rear drop when testing the mounts, so I'm suspecting that (if the mounts are to blame) the power loss is due to binding of the drivetrain components (which could explain the sound I'm hearing, as well).

[knobbler]

Well, I set out to change the mounts. Several hours later, I now have the passenger side replaced.  Unfortunately, that one wasn't really that bad. The left mount is in really bad shape, and I can't make heads or tails of how that's supposed to come out.  I tried lifting the engine from every angle I could come up with, but only raised the top mount bracket halfway up the stud.

Since the TSM is. . . less than detailed in the little bit of text that describes removing the mounts, I was hoping someone here had some tips on how this is done without removing the front axle.  I tried searching for some kind of "how to", but didn't find anything relevant.

[amarshall]

Makes sense on how bad mounts might cause binding and power loss.  Wish I had good news for you on the mounts.  I've done mine recently, but I dropped the whole front crossmember to get to the oil pan - and did the mounts at the same time.

Long story, but I did the oil pan twice.  The first time, I lifted the engine up and slid the oil pan out.  I used 2x4 blocks as spacers between the engine mounts and brackets to hold it up.  By the time I got the engine raised enough to slide the 2x4 into the gap, the engine was raised about 6 inches vertically.  It was a huge pain in the...neck.

I've seen pictures of front cross members taken out with the steering still connected.  No kidding, I would think about dropping the crossmember before I tried to move the engine again.

[knobbler]

I had actually come across your thread when researching it yesterday, which pretty much cemented the idea that there wasn't going to be a quick & easy method on replacing the remaining mount.  I'm thinking if I unfasten the left side bolts to the axle, I should end up with enough play to replace the mount.  At the same time, the front diff is sorely in need of a rebuild, so I'm considering pulling the axle off altogether.  Since I don't have the CVs connected, I don't expect that removing the front axle would leave me unable to continue driving in 2WD like I have been.

[Mods: since this thread has wandered a ways from being transmission-related, feel free to move it to wherever you feel is more appropriate.]

[mudkicker715]

Its fine we are not strict

[knobbler]

Well, it's done and I didn't have to pull the crossmember or axle to do it!  If anyone's interested, I posted a write-up of the process here:

https://agremlinateme.blogspot.com/2018/04/eagle-engine-mount-replacement.html

About 90% of the issues are gone (so many, many thanks for the suggestion!) but I'm still experiencing power loss in similar conditions as before.  It doesn't seem to occur as frequently on steep inclines, though, which is good.  With all the noise of the other behaviors taken out of the mix, I've noticed that the loss only occurs during times of sudden, strong increase in throttle pedal pressure when in low gear.

There's an RPM increase, but no corresponding increase in speed, so a failure to upshift.  I'm starting to suspect that this has something to do with my throttle valve linkage, but nothing seems out of whack with it.  Does anyone have a Weber 38 installed?  If so, how do you have your linkage configured?

[vangremlin]

Congrats to you for getting the job done.  I read your write up, and it sounds like no fun at all.  Thanks for documenting this process.

[knobbler]

Thanks!  Hopefully that can spare some people a little bit of hassle in the future. 

I took the Eagle to the only place where I could get the issue to reproduce consistently, and I got the grind'n'groan again.  None of the other symptoms occurred, which was nice, but now I'm completely stumped. 

[amarshall]

I saw your first picture, of all your extensions stacked, and just grinned.  I've been there too, my friend.  Congrats on getting the mounts done.  I hope you find the rest of the problem soon, I know it's gotta be frustrating.

[mo.eagles]

You might check your cat to see if it's plugged . The groan could come from exhaust being forced through the plugged cat when throttle is opened.