Transfer Case Issues / replacement

I have been complaining of a grinding/vibration in my driveline for a while now, bith with my dealer and several posts here. It occurs most at higher speeds 60 -70, but is apparent at lower speeds as well 40 - 50. Very loud and noticable. It only happens when there is no load on the driveline, neither accelerating or decelerating, only when just barely holding throttle (somewhere in the middle). Step on it, noise is gone, back of the throttle, noise is gone. To me it sounds like severe gear lash or something, and when there is a load, the gears mesh and you get no sound. Many have mentioned similar noises when lifting the VX. Mine is lifted, but it made this noise before that. Anyway, dealer had the VX for 4 weeks, used chasis ears, everything to try and narrow it down, so they say. The acknowledge the problem, but cant fix it. They narrowed it down to the transfer case. My luck, there was and Isuzu engineer as they described at the dealer, and he handed them and letter issue in March 2001 to descirbe slight driveline noise and groan on 4WD Isuzus with automatic transmission in 4th gear, when in 2wd mode "as normal". Thing is, the VX is never in 2wd mode, it does it in any gear, and is not a slight groan. So they say there is nothing they can do. I called the 1-800 Isuzu customer support number and am waiting for a resoponse. Ill keep everyone posted.
But has anyone else had tranfer case issues, noise, replaced or repaired??? I have been using Royal Purple synthetic auto tranny fluid since 30K, is this bad? Is the synthetic maybe too slippery? I was thinking of going back to normal tranny fluid to see if it helps.

I'm not a fan of Royal Purple but read the packaging carefully and make sure it meets the specs outlined in your owner's manual for TOD lubricant (same as tranny). The TOD is pretty easy to drain and refill, so if you think that's your problem it would be an inexpensive experiment to try a couple different lubes, such as Mobil-1, AMSOIL or regular petroleum products.

My IronMan has been producing gear whine under the circumstances you describe, but I know it's just normal gear wear so it doesn't bother me. But if yours is really loud then you've got some other issue likely and it should be identified correctly. If you have a local shop that specializes in 4X4 vehicles then that would be a good choice for a more enlightened opinion. These types of shops usually have experieced mechanics that do all kinds of swaps and transplants which gives them a good deal of practical troubleshooting skill.

Thanks Joe, I picked up some regular valvoline dexron III atf and will try the swap soon, to see what happens. I can also try a local 4wd shop too, thats a good suggestion.

I bought my Vx in Vegas and on the drive home, had the same problems that you have... Still under warranty, two dealers tried to fix the problem. One dealer replaced the front dif and the second replaced the rear dif. After two different reps checking the problem out, they said the noise is normal but is very loud. After the last visit, I noticed something that the dealer did not do... rotate the tires. When I purchased the car, the original owner had to buy a new tire because of a blowout which made the originals slightly smaller because of tire wear. The originals were worn to a point that I bought 3 new tires. After the last dealer visit, I measured the tires and the (now) older tire was about 1/8 to 1/4 smaller. By rotating the older tire on all hubs, I have different sounds. If on the front right, 60-70 on accel has noise on decel, on right rear, 60-70 has noise on float or decel. On right left, I get noises at 40-50, slight grind-whirl with traditional rear end noises, with the older tire on the front right hub, I get harsher noises at 60-70. The least noise was when I put the smaller tire on the right rear and pumped up the pressure to about 45psi. This made the diam. of the tire the same as the 3 new ones at 30psi. Now the noise is very slight when the tires are cold but after about 20 minutes, some of the whine comes back at about 65 (slight on decel)... I think I am going to cough up another 180.00 and buy a new tire next week and will let you know the results. I think if there was a way to disconnect the TOD and just run on 2 wheels on the freeway, the noise would be gone, but I dont know if that is possible.

Isuzu won't do anything warranty at all..if they can get out of it and you are stupid enought to walk away without Legal representation.

Serious. That is the only way they will honor their warranty that I have experienced. Even when it is in plain black and white that it is a warranty issue. Once when I was about out of warranty and in California and on my way to Idaho they ordered the wrong parts then said sorry don't know what to tell you you are going to be out of warranty when you get to Idaho and they will not be able to help you.
I asked if they could call ahead or to Isuzu America to get the proper parts to be able to get the right parts but, they said that they could not...that I must wait in SanDiego or no warranty at all.

This is the typical warranty help I received. Some weiseling out of Warranty service on anything. Another time when my VX was bone stock...except I changed out the air filter inside the airbox to a K&N, they said I moddified the VX and they could not honor the warranty cause I had an after market air filter.

That is like saying my tires went bad and I put different kind of tires instead of Firestone Dueler HT's so they couldn't honor warranty the PITTING Chrome on my 18's.

The list goes on and on.

Eventually I just moddified the VX like crazy. Tearing out the Airbox and actually installing the Calmini cone filter which is like a K&N or same thing almost. then cranking Tbars, 34x12.5x17"wheels, Rock sliders, 4:56 gears...the list goes on and on.

I have already changed out one Tcase. PITA. Tedious bolts. They say GM on them. I guess that is why. They are standard size where the VX is suposed to be Metric. I made my own tools too in order to reach the bolts, as they are not exactly in a good location. Probably because Isuzu or GM sells special removal/Installaion tools and they costs an arm and a leg. Even with my own made tools I could only get them to move like 1 mm at a turn. a simple Tcase change out turned into a two weekend job, with turns on the bolts on spare time inbetween.

I took in for Warranty and Isuzu said they only honored it for internaly lubicated parts. But, when it was internaly lubricated parts once it was torn apart, they changed their story to something else. Also, something weisely.