Greetings,
After deciding a Fuso FG fit my needs for a work truck I lurked hard on this forum and learned much. I found a '98 FG with 77k on the odo, took a risk on the rust situation and flew to Ohio to buy it. I live in Washington state and drove it home. 2500 mi. PO was using it as a service truck for his excavation company and I guess it was frequently parked on jobsites for long stretches, thus the low miles.
The drive home went great until we hit some snow in Wyoming and needed to run in 4wd for about 30 mi. I got out, locked the hubs, got back in, shifted transfer case into 4hi and away we went. The roads were pretty slick and dark so top speed was about 40mph, several times we hit stretches of dry pavement and I slowed and shifted transfer case back to 2hi and then back into 4hi when it got snowy again. After about 3 cycles of this and about 30mi we dropped a bunch of elevation and hit some dry pavement, I coasted down to about 30 and shifted out of 4hi, dash light went out, I got back on the gas and started to accelerate and *POP* BANG* ohF*&k*. I coasted over to the shoulder and stopped. Got out, no visible breakage, had my girlfriend get behind the wheel and creep the truck forward a few feet while I watched. I could see the front driveshaft spinning and heard some un-desirable noises. I turned the hubs to free. Same result. Dejected and tired(it was late) we crawled into our sleeping bags and passed out. In the AM I called for a tow. A shop in Jackson( I had few tools as we had flown out to get the truck) pulled the front driveshaft and gutted the hubs so we could drive home.
Today I stripped the front axle to see what I would find. Halfshafts look fine, splines on both ends look good. Differential is TOAST. Roughly half the teeth on the final drive gear and pinion are smashed off or chewed up. Planetary gears all look ok, bearings all feel fine. I drained the appropriate quantity of fluid from the case, and it was changed in December/ 500mi ago, though it is now black and burnt looking. So now the question is how and why would a front diff on an otherwise solid truck with under 80k on it go out like that? I have a working theory but I'd be very curious to hear what the "locals" here think about it. Thankfully it sounds like the previous owner is going to work with me on this.
So here is my theory; During inspection the PO pointed at the hubs and said "Ive never used those, I just left them in free, it still goes in and out of 4x4 just fine". I guess he didn't really understand what manual hubs do despite being an engineer and an equipment guy. When I heard that I thought, hmmm better cycle those and see if they engage. On my test drive, I did just that and they spun smoothly and seemed to lock in and un-lock though I did not jack up the front axle to really confirm engagement/disengagement. After we concluded our deal we drove at highway speeds for two days straight and made it about 1700 mi before we needed the 4x4 and ended up losing the diff. While attempting to determine what had broken I noted that even with the hubs un-locked and the transfer case in 2hi the front drive shaft was still turning if we moved the truck. The shop in Jackson also confirmed that the hubs were not engaging from the halfshafts. So Failure path in my mind is; Hubs went 15 years without being cycled => I cycled them during inspection => they appeared to unlock however the drivers stayed on the ends of the shafts probably due to corrosion or spring fatigue? => we drove 1700 mi at highway speeds spinning the front diff without noticing => it was nearly cooked and when we used the 4x4 and put some torque to it that was the last straw.
Does this make sense? would spinning the front diff at 65 mph because the hubs were locked really cook it even though it was properly lubricated? Thanks in advance for the input. I of course have many of my own should have/would have lessons learned already here, but welcome yours.
After deciding a Fuso FG fit my needs for a work truck I lurked hard on this forum and learned much. I found a '98 FG with 77k on the odo, took a risk on the rust situation and flew to Ohio to buy it. I live in Washington state and drove it home. 2500 mi. PO was using it as a service truck for his excavation company and I guess it was frequently parked on jobsites for long stretches, thus the low miles.
The drive home went great until we hit some snow in Wyoming and needed to run in 4wd for about 30 mi. I got out, locked the hubs, got back in, shifted transfer case into 4hi and away we went. The roads were pretty slick and dark so top speed was about 40mph, several times we hit stretches of dry pavement and I slowed and shifted transfer case back to 2hi and then back into 4hi when it got snowy again. After about 3 cycles of this and about 30mi we dropped a bunch of elevation and hit some dry pavement, I coasted down to about 30 and shifted out of 4hi, dash light went out, I got back on the gas and started to accelerate and *POP* BANG* ohF*&k*. I coasted over to the shoulder and stopped. Got out, no visible breakage, had my girlfriend get behind the wheel and creep the truck forward a few feet while I watched. I could see the front driveshaft spinning and heard some un-desirable noises. I turned the hubs to free. Same result. Dejected and tired(it was late) we crawled into our sleeping bags and passed out. In the AM I called for a tow. A shop in Jackson( I had few tools as we had flown out to get the truck) pulled the front driveshaft and gutted the hubs so we could drive home.
Today I stripped the front axle to see what I would find. Halfshafts look fine, splines on both ends look good. Differential is TOAST. Roughly half the teeth on the final drive gear and pinion are smashed off or chewed up. Planetary gears all look ok, bearings all feel fine. I drained the appropriate quantity of fluid from the case, and it was changed in December/ 500mi ago, though it is now black and burnt looking. So now the question is how and why would a front diff on an otherwise solid truck with under 80k on it go out like that? I have a working theory but I'd be very curious to hear what the "locals" here think about it. Thankfully it sounds like the previous owner is going to work with me on this.
So here is my theory; During inspection the PO pointed at the hubs and said "Ive never used those, I just left them in free, it still goes in and out of 4x4 just fine". I guess he didn't really understand what manual hubs do despite being an engineer and an equipment guy. When I heard that I thought, hmmm better cycle those and see if they engage. On my test drive, I did just that and they spun smoothly and seemed to lock in and un-lock though I did not jack up the front axle to really confirm engagement/disengagement. After we concluded our deal we drove at highway speeds for two days straight and made it about 1700 mi before we needed the 4x4 and ended up losing the diff. While attempting to determine what had broken I noted that even with the hubs un-locked and the transfer case in 2hi the front drive shaft was still turning if we moved the truck. The shop in Jackson also confirmed that the hubs were not engaging from the halfshafts. So Failure path in my mind is; Hubs went 15 years without being cycled => I cycled them during inspection => they appeared to unlock however the drivers stayed on the ends of the shafts probably due to corrosion or spring fatigue? => we drove 1700 mi at highway speeds spinning the front diff without noticing => it was nearly cooked and when we used the 4x4 and put some torque to it that was the last straw.
Does this make sense? would spinning the front diff at 65 mph because the hubs were locked really cook it even though it was properly lubricated? Thanks in advance for the input. I of course have many of my own should have/would have lessons learned already here, but welcome yours.