99 Silverado weening noise, rpm's jump to 4200
 

So I was driving about 70 pulling a 18' fiberglass boat when I started experiencing some weird problems. When approaching a hill the truck started making a weening noise at the same time the battery low voltage indicator came on and my dash gauges were moving funny and the rpm's jumped up to 4200 which seemd really high. (I had my transmission rebuilt about 8 months ago).

This was a quick wheeen and than everything went back to normal. I continued on for 10 minutes and the wheening came on again and this time the change engine oill light came on also. The voltage's looked fine on the cluster. This time it started happening more frequently so I pulled off the freeway. The truck seemed to have a lack of power and I swear I could hear something knocking but not real noticeably loud.

After turning the truck off and sitting for a while I attempted to start it and it took 3 tries and a lot of "turning" before it turned over.

Someone had mentioned the altenator might be out to lunch. I have a hard time thinking it is the tranny since that shifts smoother than it ever has after the rebuild.

Any suggestions on what could be the problem?

When voltage drops low, the alternator will whine up becuz its tryin to build up more juice. So it sounds like this is the problem. Do a load test on it.