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Author Topic: Groan, vibration, and power loss  (Read 581 times)

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Offline knobbler

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Groan, vibration, and power loss
« on: March 27, 2018, 02:06:09 PM »
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?

Offline mo.eagles

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Re: Groan, vibration, and power loss
« Reply #1 on: March 27, 2018, 04:07:40 PM »
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 .
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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #2 on: March 27, 2018, 06:17:43 PM »
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.

Offline AMC of Houston

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Re: Groan, vibration, and power loss
« Reply #3 on: March 27, 2018, 07:50:43 PM »
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!
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Offline amarshall

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Re: Groan, vibration, and power loss
« Reply #4 on: March 28, 2018, 12:40:42 AM »
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?
Wanted:  Any leads on 3.07 ratio front differential

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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #5 on: March 28, 2018, 01:10:50 PM »
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).

Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #6 on: March 29, 2018, 01:49:57 AM »
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.

Offline amarshall

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Re: Groan, vibration, and power loss
« Reply #7 on: March 29, 2018, 10:19:48 PM »
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.
Wanted:  Any leads on 3.07 ratio front differential

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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #8 on: March 30, 2018, 06:57:37 PM »
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.]

Online mudkicker715

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Re: Groan, vibration, and power loss
« Reply #9 on: March 31, 2018, 02:39:00 AM »
Its fine we are not strict



Manitowoc WI

Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #10 on: April 01, 2018, 11:37:51 PM »
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?

Offline vangremlin

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Re: Groan, vibration, and power loss
« Reply #11 on: April 02, 2018, 02:02:09 PM »
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.
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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #12 on: April 02, 2018, 05:04:47 PM »
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. 

Offline amarshall

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Re: Groan, vibration, and power loss
« Reply #13 on: April 03, 2018, 05:24:59 PM »
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.
Wanted:  Any leads on 3.07 ratio front differential

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Offline mo.eagles

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Re: Groan, vibration, and power loss
« Reply #14 on: April 03, 2018, 06:23:11 PM »
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.
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rear window washer /wiper 
tach and gauge package
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rear window washer/wiper
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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #15 on: April 03, 2018, 06:36:55 PM »
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.

I'd thought about that as well, but it turns out a helpful burglar took off with the cat and replaced it with a straight pipe.

I think I'm on to the cause, though; I checked my throttle valve linkage again, and it's way out of whack.  I haven't adjusted it on account of throwing my back out, but I'm about to grab a stick to bite on and get it sorted.  We'll see what comes of it then.

Offline mo.eagles

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Re: Groan, vibration, and power loss
« Reply #16 on: April 03, 2018, 08:37:53 PM »
I'd thought about that as well, but it turns out a helpful burglar took off with the cat and replaced it with a straight pipe   
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power seats ,windows and locks
rear window washer /wiper 
tach and gauge package
A/C
 '85 wagon   power windows and locks
rear window washer/wiper
factory tow package
A/C
 '84 wagon parts

Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #17 on: April 04, 2018, 02:40:42 AM »
Alright, so the throttle valve linkage wasn't way out of whack.  It was completely and totally wrong.  See, when I had checked it before, I still wasn't very familiar with how it should be set.   Combine that lack of familiarity with my failure to solidly parse the TSM instructions, and the result is my completely overlooking the fact that the clamp was rust welded to the trombone slide/clevis pin looking end (I actually had to twist the pin and break it free).

Long/short, my linkage may as well have not even been there, but it's now properly set and Eagle seems to be driving a lot better as a result.  We'll see if it fixed the problem once I get to the testing hill tomorrow morning.

Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #18 on: April 04, 2018, 05:34:40 PM »
Well hot :censored:.  I don't want to get my hopes up too much, but things are looking better.  I went up the testing hill this morning.  At the point where nastiness generally occurs, we actually shifted instead of having any of the unpleasant effects I've described in this thread. 

This is the first time there's been a proper shift at this point since this stuff started happening, so it's seeming as though there were a lot of problems that existed independently, but showed symptoms under shared conditions. 


Offline vangremlin

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Re: Groan, vibration, and power loss
« Reply #19 on: April 04, 2018, 10:13:44 PM »
Good deal!  Glad things are improving for you!
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Offline amarshall

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Re: Groan, vibration, and power loss
« Reply #20 on: April 05, 2018, 10:10:36 PM »
Fingers crossed that the fix holds!  Always nice to get a win.
Wanted:  Any leads on 3.07 ratio front differential

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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #21 on: April 07, 2018, 04:18:15 PM »
I appreciate the hopes and well-wishing!  It saddens me to report that this did not end up fully correcting the problem.  Got the power loss and rubbing groan again today, though it was on a flat road under an attempt to quickly accelerate.  I even went up Intermittent Problem Hill without trouble. 

Eagle's been my daily driver as I work on getting the Gremlin up and running, and as much as it bums me out to think this way, I think I'm going to have to sell it.  I don't want to kick the can down the road, but I just don't have the time or resources to direct towards fixing this wagon up to the degree it needs and deserves.  If anyone's in the PNW region and wants a fixer-upper, let me know.  I'll gladly take a running AMC of pretty much any model in trade.

Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #22 on: May 22, 2018, 09:32:16 PM »
I wanted to post an update on this in case anyone else finds that they're having a similar issue.  In the time that's passed, the situation continued to worsen to the point where Eagle didn't feel safe to drive.  As the condition worsened, I was able to get some more info.

The sounds and feelings were becoming more extreme, so they were easier to pinpoint as coming from the front.  I also started getting a really hard shudder when coming to a stop, which made me look at the brakes again.  When I had checked the brakes before, I saw no indication of anything sticking, warping, or wearing unevenly, but this time I got the IR thermometer out after a particularly rough drive and saw the front wheels were well over 100° on a day of 70° outside temps (at best).

Long short, the calipers have been grabbing, but since the issue had not gotten bad enough, I wasn't catching them in the act.  Corrosion of the pins definitely played a part, but I'm still trying to get everything smoothed out.  Not sure if the calipers have bad seals, if there's particulate getting stuck in the lines, or if it's something more exciting, but I can say that this ordeal has been caused by degradation of the brake system with some other problems muddying the waters.

Thanks again for the help, all!

Offline rmick

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Re: Groan, vibration, and power loss
« Reply #23 on: May 22, 2018, 10:43:11 PM »
I have had the lines degrade on the inside but outside looks good. When it goes bad internally it may allow fluid to flow to the brake but not allow fluid to return acting as a check valve. I have also had brake caliper pistons stick and not release when pedal is released. Fortunately these pats are still available.
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Offline knobbler

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Re: Groan, vibration, and power loss
« Reply #24 on: May 22, 2018, 11:33:28 PM »
Very, very fortunately, they're still modestly priced, too!

The interior of the lines is my #1 suspect right now because of exactly what you'd said.  This wagon is on its 3rd MC since I've owned it- first had a worn piston, second was a really crappy "rebuild" job from a parts store chain, and the current one is a new unit that has been doing what it should, far as I can tell.

Between the corrosion and the 1st MC having a dissolving piston, I'm wondering how much contaminant could still remain in the system (despite the repeated bleedings).  I don't think it's too long a shot for some rust particles to have huddled up together somewhere (like in the prop valve), only to get stirred up when heat, vibration, and fluid flow wakes them up.  I may be wrong, but the fact that my fluid starts going dark really quickly (couple weeks or so?) after a full bleed seems to support that idea.

I think what I may do when time allows is a total flush of the brake system with my buddy's vac pump.  Just keep pulling fluid through until it's clear, drive it around, then do it again.  For now, I'm stopping and going when I need to, so I'm going to just keep an eye out to see what the wagon tells me.

Offline amarshall

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Re: Groan, vibration, and power loss
« Reply #25 on: May 23, 2018, 12:32:22 AM »
Thanks for posting the updates.  Too many of these threads trail off into nothing.  Glad you've figured out which system is causing you problems, at least.
Wanted:  Any leads on 3.07 ratio front differential

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