2001 Chevrolet Silverado HD transfer case np263hd problem
I have repaired and replaced the transfer case np263hd in a 2001 Chevrolet Silverado HD to fix a leak due to the pump rubbing a hole in the case. While I had the case disassembled, I also replaced the range shift fork, the hi-lo range hub associated with the fork, the mode shift fork, the chain, and most bearings and seals. When I put everything back together, I ran into a problem. The unit seems to work okay in 4-high and 4-low, but there is a problem with 2-high. The gears seem to barely be engaging, and when I accelerate anything much more than an idle, I hear a grinding/chattering noise in the transfer case. It sounds like certain gears are barely making contact, and are slipping under load. I suspect I may have installed something upside down or backwards perhaps the mode selector? Also, while the truck will shift from 2 hi, to 4 hi to 4 lo, it seems to have trouble doing it sometimes. Help?
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You either have a switch problem or the shift shaft seal is leaking oil into the shift motor(encoder motor) on the transfer case(t-case). A switch is an east fix but if it's a seal leak you have to remove and disassemble the t-case in order to replace the seal then you have to replace the encoder sensor and get it reprogrammed by a dealer. Not easy or cheap.
I had a similar problem with
the Service 4 Wheel Drive light which came on intermittently then became more
consistent in the message center display. It would go into 4 wheel drive if the
message center did not display the Service 4 Wheel Drive message in the message
center, but not when the message was displayed. I found the transfer case
switch module in the dash was defective, and it has been working with no other
problems for three years.
I just had my transfer case rebuilt on my 2002 2500 silverado duramax. They told me that the spring that holds the pump inplace in the transfer case wore a hold through the case. He said this was common on these transfer cases. Chevy has not acknowledge the problem. He designed a steel plate, with flanges that holds the pump in place and will not wear a hole in the case again. And as far as the post to engage it once a month, the chain turns even when in 2WHL drive.
You mean between the case halves? It is just silicon, no gasket. These are good for the pump wearing a hole in the rear housing and leaking oil. The cure for it is a new rear housing and a piece called a case saver that keeps the pump from doing it again. Taking the transfer case apart to fix it is easy, I can tell you how to do it.