C-13 NMR T-1, NOE, and T-1rho were measured for two entangled polyethylene melts (M = 16K and 37K) at 5 and 75 MHz C-13 Larmor frequencies from the melting point up to 530 K. Two models for entanglement dynamics are tested against the experimental data. This comparison shows that entanglements not only stretch out those relaxation times longer than the entanglement time tau(e) but also have a spatial effect in restricting the motion of entangled points on the time scale of tau(e). For polyethylene, the amplitude of residual orientation on the time scale of tau(e) is lower than the theoretical prediction fox a Gaussian chain of the entanglement length with both ends fixed. The opposite conclusion was drawn from recent double quantum NMA experiments on polybutadiene. The magnetization decay curve for the T-1rho experiment is nonexponential, indicating that the loss of orientation on long time scales depends on position along the chain backbone.