I just had the engine completely rebuilt in my 72 240z. After about 100 miles I noticed coolant seeping along the head gasket down the side of the block (oil filter side). It also runs a little hotter than before the rebuild but not too hot (just a little past 1/2 on the gauge, on the M). Could it just be a bad gasket? Or could the head be cracked? I had the head done at a good machine shop. I had no problems before. The engine ran good it just smoked badly and used a lot of oil. Should I replace the gasket or get the head checked again?

Try re-torquing the head again. Hopefully the gasket will be OK, it may be the head was not torqued exactly when it was installed. It is always advisable to re-torque the head after a couple heat cycles when an engine is first put together.

Good luck. If it still leaks a new gasket will be the next thing to do and make sure the head is straight and torqued correctly.