'91 grinding sound

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bueller

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crosspost from the "problems" thread. thought i'd check in here too.


hey guys,

i did a search but didn't have any luck finding anything related to my problem.

my auto '91 has about 235k miles and the transmission was rebuilt about 30k miles/5 years ago.

the problem:
there is an intermittent and seemingly unprovoked grinding sound coming from beneath the driver's floorboard. the grinding is not a sharp sound but almost like a tire rubbing sound. i hope that helps you understand the type of sound. the tires do not rub.

i believe it is something with the 4wd transfer case. we have it at our mech's shop who's tranny guy says in order to diagnose the problem, the transmission must be opened as well since the differential/transfer case/transmission are all related. they want $1000 just for labor before any parts. he thinks it could be a bad bearing but won't know until it's apart. also, we have a slow leak on the main rear seal that we're waiting to address. could the seal relate/cause anything with this grinding?

any suggestions are welcome and tia.

matt in denver
 
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How did you determine that the sound was coming from your transfer case/transmission? It very well could be, could also be something else so for me to be sure you have pinpointed the sound I have to ask these things.
 
Here's what I just learned with my 91. I did front brakes and bearings because it needed it. Repacked both front bearings and replaced the right side because of a similar noise. I then just yesterday replaced the front differential because it needed it. The PO ran it dry of gear oil (don't know why or how) and the bearings trashed themselves because I didn't check the oil when I bought it. So all new front end components and the same sound. I finally tracked it down to the CV shaft I just replaced about 3 months ago; it was from Checker (Schucks/Kragen), supposedly new but had axial play and was making the noise in question.

Long story short, I guess, is check your CV shafts up front, along with wheel bearings and diff fluid. Easy enough to check yourself and costs but a little time in the driveway.
 
There's a few things you could do before spending 1K on a tear down (sounds like an AAMCO or Cottman ploy). An a really good tranny guy would be able to narrow it down better w/o tearing it down (although most have seen few Toyota auto w/4wd's).

Unless you drive around in 4WD you can pretty much eliminate the front diff too.

What happens if you put the t-case in N and the trans in gear?
 
thanks for the quick responses guys. i'll try to answer as best i can on my limited knowledge.

turbosr5: i thought it might be the transfer case because, like 401jeeper, we recently had the front brakes and bearings done. also, i was trying to eliminate any possibilities like suspension or brakes or whatever. i'm not the most knowledgable about cars in general but i'm trying to learn.

401jeeper: good information. thanks. i don't really have any tools nor any jackstands. is checking the cv joints something i can do just sliding under? what should i look for? i have a haynes manual somewhere to see what parts i should look for. but any pics you guys can post to point me in the right direction would be awesome.

fourwd1: the tranny place is my trusted mechanic's trusted friend. so i trust them. but yeah, $1000 just to tear things open = suck. the tranny guy said there are three sets of bearings/gears and sometimes one of the bearings can go bad. i don't know. and yeah, auto 4wds are weird with it all combined. he said he was able to duplicate the sound by going to higher revs manually shifting the gears. interesting.

something of note---when i shifted into 4wd the other day after a snowstorm that rolled through, the sound came back loud and just as bad as it ever did.

again...thanks guys.

matt
 
Can the noise also be reproduced by "power braking the engine in either drive or reverse?
If so you may just have a motor mount or exhaust rubbing condition. I am a Toyota Master Diagnostic Technician, and I only say that to qualify this statement.... I always make sure I know where my noise is coming from before tearing down beacause how else can you fix it without replacing every worn looking (albiet expensive) part in the transmission. Oh BTW while the transfer case is bolted to the transmission it is NOT incorporated and disassemby of both to find the problem is what we call in the field "Throwing Darts" If there is a problem in the driveline it is usually only in one of the components not all of the components.
 
define "power breaking in drive or reverse" and i may be able to duplicate. do you mean slowing down by downshifting like what one would do coming down a mountain pass to save the brakes?

btw, the noise has been dramatically softer to non-existent since the tranny mech manually shifted through the gears at his shop.

thanks,
matt

ps-motor mounts are on the long-term list of worn parts that will need done eventually as said by my mechanic.
 
I recently had a similar problem with my 91. The sound was coming from the front driver's side. It was a grinding sound along with what sounded like rubber rubbing something. The front end was in need of maintenance so I started with bearings, brakes, and calipers. This did not solve the problem, so I went ahead and changed the cv half shafts. It ended up being the driver's side cv shaft that was causing the problem at the point where it knuckles and goes through the spindle. Hope this helps.
 
bootheel said:
I recently had a similar problem with my 91. The sound was coming from the front driver's side. It was a grinding sound along with what sounded like rubber rubbing something. The front end was in need of maintenance so I started with bearings, brakes, and calipers. This did not solve the problem, so I went ahead and changed the cv half shafts. It ended up being the driver's side cv shaft that was causing the problem at the point where it knuckles and goes through the spindle. Hope this helps.
Click to expand...

was your sound louder and more likely to happen during cold temperatures? that's the case with mine, but perhaps that has something to do with the vehicle getting up to operating temperature and getting everything to that point?

thanks guys for the input. i'm going to call my mech today and see if they checked the cv halfshafts.

matt

EDIT: the halfshafts were done and then looked at again and adjusted to see check if they were fitting to spec. all seemed okay. he was going to see if anything could be done on the fluid side of things to tide us over until we can afford a rebuild. ughh.
 
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Just to reply to your question, it did seem to happen more often if the temperature was around freezing or below. Also it was more evident that something was going on that wasn't quite right when I was at lower speeds like pulling up to and away from a complete stop. It would normally clear itself after increasing speed above 20 mph or so.
 
Any update

So it's winter again, just wondering if this happen again. Mine started up again. I live in the northeast - DC to be specific.
 
My bets are it's the spindle bushings. I'm surprised none of you guys said that yet.

You can either replace them with the updated needle bearing way:

http://www.yotatech.com/~corey/tech/jimrockford_spindle/jimrockford.htm

Or replace with new bushings. Apparently the needle bearings require more maintenance, bit more of a pain in the butt but then I've seen guys say that they've done needle bearings and had no trouble since they've switched.

You can tell a wheel bearing is shot by jackin' the front up and grabbing the tire top and bottom and wiggling it back and forth. Have someone watch the CV; if it doesn't move you know it's the wheel bearings. A shot CV should make a clicking noise if I'm not mistaken.
 
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haven't had the money to really diagnose and fix the problem. I'm working in Eagle, CO and getting this thing over the passes is not fun. but I did notice when the temps dropped to single digits, not only is the driver's side doing the noise, but now the passenger side as well, although not nearly as loud or as often. And what's also weird is the the sound is not speed dependent, nor is does it happen more or less under braking, nor does it matter if it's in 4wd versus rwd. i'm still baffled. this winter season, it's so bad, you can feel it vibrating in the steering now. i'm pretty sure the tranny has nothing to do with the noise. When I do come to a complete stop, the sound will "slow down" right before completely stopping. even just going 1 or 2 mph the "rpm" of the sound is has high as when cruising at 40mph or more.

yay!

the next time i'm in Denver with the runner, i'll check with my mech about the spindle bushings. are those costly to replace? how long for labor?

Thanks guys,
matt

btw, i'm pushing 260k on the clock now. :) hopefully within 2 years we'll be able to replace this old guy with a newer runner. i like the smaller more squared body style. was the last of that type in 2000?
 
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