Loud Clunking Noise Help

[Brian Timmins]

Sorry, but this is going to be a little long winded. I just bought a 94 Yukon SLE two days ago. The previous owner told me that the tranny doesn't shift into 2nd or 1st, but O/D and D work fine. I took it for a test drive and it actually ran pretty good. Engine strong, tranny didn't skip/slip. The only negative thing I noticed is it too a few seconds to engage once I shifted into drive or reverse. Figured that was somewhat typical on a truck that has 278K klicks on it.

Anyway, drove it home from the previous owners shop (side street sand highway) 70 km and again, it drove fine. Drove all around this morning and still fine. Until my last trip. Started out ok then about 5km out I heard a funny whirrling noise. It started out quiet then got louder as I drove. After about another 5 minutes, I'm like, wtf? and turned around. Noise got loader and loader so I made sure to take side streets and drive slow (under 20km/h). Almost back to the house and decided to pull over and let the cars behind me pass. Once I pulled back out on the road again I hear and feel this load clunk. Like load, metal to metal clunk. I'm guessing it's coming from the tranny. For the first little bit I was able to crawl along but the the moment I applied gas I got the loud clunk again, usually every couple of feet. I parked, let it sit for about an hour and tried again. Still was able to crawl at idle but as soon as I applied gas, clunk...few feet...clunk. Then parked and waited for tow truck which took a few hours. When tow truck arrives, even at idle crawling to the back of the i go the clunking.

I first thought it was a broken u-joint so i got underneath and checked. Nope. Loose driveshaft, nope. Had the tow truck driver inch the truck forward while I peeked underneath and it's definitely coming from the tranny. I'm thinking either torque converter/flywheel/flexplate or teeth on the gears broke off.

Any help would be appreciated. Need to try and get this running pdq and would like to hopefully have an idea of where to start.

Thanks in advance

 

[Brian Timmins]

Well, took it into the shop (towed) and it wasn't the tranny at all. The rear diff basically blew up. So that's getting rebuilt. Can't remember how they explained it but the rear diff, but I'm guessing a bunch of teeth got knocked out) and once I started driving it would slip causing the loud banging up near the tranny.

 

[iLikeEggs]

Similar thing happened on my 98 Blazer. It started with one tooth coming off followed by a bunch more. At first the noise sounded like the muffler blew out. Sure enough though, new rear end. That was only at around 70k miles too.

 

[ThinBlue82]

If you don't mind disclosing...what was the damage on that repair? Was it costly?

 

[iLikeEggs]

At the time I was traveling around my market and I rolled into a shop at the far end of it so I was kind of stuck there. Labor was reasonable and they found used rear end. I believe it was around $600. That was around 2003 though.

 

[Brian Timmins]

In regards to my situation, not only were the gears missing a bunch of teeth, but the side bearings were blown to pieces as they say. They had to buy a used diff and rebuild a basically new one form the two diffs. They also but in new rear shoes, e-brake linkage, new rear shocks, u-joint, u-bolts, seals, wheel cylinders, etc. Basically have an entire new rear-end minus the leaf springs. Cost was around $2,500 Canadian and they had it about a week. They actually had it longer than I did lol.

Now onto re-building the rest of this beast. Getting excited again!

EDIT: Oh, I should mention that everything was rusted together. They had to cut the shocks and u-bolts off with a torch.

 

[iLikeEggs]

Wow! That was a lot of work.

 

[Brian Timmins]

Yup! Just the start of it. Bought the truck for $800 knowing it needed a shit load of work. Wanted a driving project which this one is as long as the tranny holds out until I swap it out for a remanufactured one. The engine runs good, good compression and no blue smoke, just everything else needs replacing. I can do most of it myself, but rebuilding diffs is not something I can do. Hoping to bring it back to stock and keep it for 10+ years. Frame's straight and solid, body and interior are actually really good. Again, just drivetrain stuff needs replacing.

 

[Brian Timmins]

Our junkyards out where I am have lot of Yukons, Tahoes 1500 and suburbans so parts are going to be easy to come by...hopefully.

 

[1998Suburban]

A bit pricey but it sounds like they went well above & beyond, sourcing another diff, breaking out the gas axe, etc. Any pics of the carnage? I just finished my first 10 bolt rebuild (for a 69 GM A body, sourced the donor from a 71-72 A body) and I spent $1120 on conversion/installation. I went from a 2.56 peg-leg to a 3.42 posi. It was a lot of work but I learned a TON. Definitely wouldn't want to do it when I was under time constraints so I can see why you'd farm it out. Took me WAY longer than a week but could probably do it again in 1/2 the time. Would still be longer than a week though...