I posted this over at toyotanation.com but got zero help so I figured I'd try here instead hoping that someone might be able to help with this.

My sister in law just bought a 1991 Toyota pickup truck, 4x4, and I wanted to see if there would be an inexpensive fix to a problem she has.

In 4x4 mode (and only in 4x4 mode), with or without the front wheel locks engaged, you can hear a "tapping" sound. It's rather loud and you can feel it in the truck. You can only hear it during certain loads and conditions while accelerating, not while coasting. Again, this is with or without the wheel locks engaged, and only in 4x4 mode.

I can try to get a video showing the sound and the conditions tomorrow if you guys want. It sounds like it's coming from the passenger side but I can't say for sure. The sound is repetitive and increases in repetition as wheel speed increases. It's like a loud tapping sound.

I cannot hear the sound with the wheel locks engaged with the truck in 2 wheel drive mode, but I can hear it in both 4 wheel high and 4 wheel low. 4 wheel drive does appear to be functional while the truck is making these sounds, so it's not a huge issue, but it is one I'd like to get resolved if possible.

Truck has 163k miles on the dash and appears to have been taken care of very well for the most part. 2.4L engine. Was re-painted once and had the under-body coated. Very little rust given the mileage and age. Bought it from southwestern Michigan for $1590.

Could this be the a CV shaft/joint or the transfer case? I've inspected the truck and I cannot find any evident problems. Although the CV shaft boots on both sides appear to be a tad dry rotted, they do not appear to be cracked or torn. I do not have any maintenance records for the truck.

Any help would be appreciated. Thank you.

Here's the truck looks like (along with my sister in law who bought it)



Update:
I grabbed the base of the CV shafts where they connect to the wheel hubs and shook them. The one making noise had a significant amount of play. You could hear it from 5 feet away. The other side had some play too but it wasn't quite as bad.

I found a tutorial on this site for replacing the steering spindle bearings, so I was wondering if that's what was causing this. I'm not entirely sure so I was hoping you guys could help. Are there any other tests I could perform to determine the source of this problem?

 

I read in another thread here that was psoted several years back, and they said that the trim ring around the front pinion would come loose and start turning in 4wd. It made horrible noises, but was relatively harmless. Anyone know if this might be similar to what I'm hearing? It sounds really bad.

 

Can you tell if the sound is coming from the front, or right underneath the truck?

With the truck not running and in 2wd, and the hubs unlocked, get under and spin the front drive shaft. See if you feel anything that might be causing it. Check that dust ring to see if it is loose and spinning. Also, check to see if your hubs were added to the truck, and if your differential has ADD (automatic disconnecting differential). When you turn the drive shaft, do the CVs spin as well? If so, you do not have ADD in the differential. An example of the sound would be helpful.

 

I totally didn't think of that! Turning the shaft by hand will definitely be the next thing I do. I'll check if the truck has ADD or not. I'll try to get a video.

 

I think I found the problem.


Any ideas on how it can be repaired?

 

Yikes. Obviously, it's the diff. I've got one sitting in my garage, but who knows how far away you are. Let me check the service manual quick.

 

I'm in the Northern IL area. If it would be cheaper to put in a used diff that you know works than it would to tear into this one and figure out what's wrong, I'd rather go that route. I can imagine they're heavy but I can't imagine freight being more than $75. I've shipped 80-pound massive subwoofer enclosures out to that region for less than that.

Thanks for looking into it for me.

 

At the very least, The side gear shaft on that side is having problems. Almost looks like it is snapped. If you spin the drive shaft, does that CV move? Also, check to see if it has ADD, as I asked above. Lastly, let me know what your gear code is, just take a pic of the sticker on the door jamb.

 

If I turn the drive shaft, both CV shafts turn. If I hold one, the other turns faster.



Using car-part.com, where it asks what transmission and engine I have, I was able to find an entire front drive assembly 3.25 hours North of me with 65k miles on it for $95. Sure beats the $650 I was quoted to get the bearings replaced.

 

I'd do a complete swap, for sure. It looks to me on the video that the side shaft bearing is completely gone, which means the seal has probably been leaking for a long time, which means there's likely not much oil in the diff case, which means everything else inside is probably toast as well. The only thing to check carefully if getting a completely different unit is making sure your gear ratios match what's in the rear. Otherwise you'll have to re-gear the replacement after you get it, which will cost a bunch more.

 

Based on your sticker, you've got 4.56 gears. Make sure the gears match on your replacement. The one in my garage is 4.10, so won't work.

 

Well, the situation changed a wee bit. For starters, I bought the truck off of her when we discovered there was a discrepancy with the mileage. The truck actually has 323k miles on it, not 163k miles. The good part is that it runs just as well regardless and is a clean body, so I'm not complaining.

I went up to Wisconsin yesterday and picked up a new differential for $95 that had 65k miles on it. That should do the trick. However, I suspect that my passenger side axle is probably scored pretty badly. Does anyone have an axle they'd be willing to sell me for...say...$40 shipped? I found a place nearby that would have it but I have to wait for them to pull it and they want $40 for it locally. It's a bit difficult to find those axles. I checked the driver side and it seemed fine so I probably won't need a new jack shaft and axle for that side but it wouldn't hurt if they're not too expensive. I don't suppose anyone would be willing to sell me just the axles?

I had to use 4x4 today while carrying some lumber around the yard. The rear tires started spinning so I put it in 4 wheel drive low and locked up the hubs and took it very slow and it made it just fine, so I know everything still works.

In other news, I also need advice on a radiator. Mine is seeping transmission fluid from the joint between the aluminum and plastic.

I found a few online including this one:
http://www.ebay.com/itm/1-Row-w-o-EO...af8a7d&vxp=mtr

The rockauto ones have this as an option also: "4WD; PLASTIC TANK ALUMINUM CORE; W/MAX COOLING; W/H.D. COOLING" made by VISTA-PRO. Not srue which one would be better. Any suggestions?

 

So, you've got a leak at the radiator? Any way of putting sealant on it?

Or, the joint might be loose.

 

I could put sealant on it, but I wouldn't mind just replacing the radiator. That is, unless you have a suggestion as to the kind of sealant I could use to stop a radiator from leaking. I don't know how much pressure the ATF lines are under while operating.

The actual seam between the plastic and the aluminum is what's leaking. It's toward the front of the car, at the bottom. Confused the heck out of me at first since I was expecting the line joint to be leaking.

 

Ordered this radiator since the alunimum one wouldn't fit:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290961991024
I'll let you guys know how it works/fits.

 

Alright. I'm still looking for that shaft. Basically, what I need is #4, but for the passenger side.

 

Wait, you said you drove to Wisconsin and bought a new diff. The new front diff should have included that side shaft (both side shafts in fact).

Can you post a picture up of what you got?

 

It did not in fact include those two shafts. I guess that's why it was $95 instead of $200 or $300 like many of the others. I didn't exactly know what I needed or what it would look like since I didn't have the truck with me, but basically the differential does not have any shafts or anything connected out of the sides. There are two red plastic plugs on each end where you'd slide a shaft through and that's that.

Here are the pictures:
http://imageshack.us/a/img27/6589/c8w5.jpg
http://imageshack.us/a/img855/4043/lpqw.jpg

I have no issues with the jackshaft as far as I can tell, and it should be in decent shape. I'm guessing the other side is scored pretty badly if the bearing got destroyed.

 

I see. Well, it would be a much easier fix if they were already there.

To swap that new one in, you'll need a slide hammer that will connect to the side shafts, so you can pull them out. You'll also need two new snap rings, and two new oil seals to install them in the new diff.

I've never tore one down that far. I would pull the old diff out, and see what those shafts look like. If the bearing went on that side, it may not have done anything to the shaft.

See what you've got going on there. Worse case scenario, I can see if I can find something to pull the side shaft out of my diff, and I can send it to you. My diff has ADD, so the drive side would be no good to you. But, my passenger side should be the same.

EDIT: I guess you have no choice but to swap the side shafts, considering that your gear ratio is a fairly rare one.

 

Wait, so you're saying that I have to get shafts that are also the same gear ratio? That doesn't make sense. I can't imagine why the actual shaft that goes into the gear would be any different.

I'll see if I can find a slide hammer at a store somewhere since I don't actually own one.

I don't mind paying for a new shaft if it means I can get the differential in and out in the same day and have the truck usable. Otherwise, it has to stay parked until I gather the parts.

I don't mind installing new oil seals. Those looked fairly easily to remove and fairly easy to install. What do I need the two new snap rings for though?

Thanks a bunch for the help.