Rex Marble

The trailer is 4800 lbs. The transmission temps topped out at 248 degrees. I have been told after getting home that the transmission temperature should not have been over 224 degrees. I thought that the tach should move some also when surging. The brakes could possibly be an issue, because the sensation was similar to what I think the fill would be hitting the hand brake while in motion. After purchase and before getting on the road we did check the hand brakes to be sure that they were working, and they were. Is there something on trailer brakes that is activated when not on level roads? I did read on a post where someone disconnected the cable to the trailer to test the possible brake activation; their results were negative but something I should check. I will check the brakes and see what the results might be. Thank you for your response and suggestions. My son is out of town for about two weeks. I will post the results of the after the test.

First time pulling a trailer with 1/2 ton GMC suv. When starting to climb rolling hills the GMC starting surging. The surges were quit noticeable and concerned that the truck to stop but it continued to run while surging and speed reduced. Once on the top of the grade the surging stopped but engine didn't seem to have the normal power. The tach did not vary during the surging. Does the issue sound to be more engine or transmission issues?