Missing Engine Part???

I just inherited my parents 77 MGB that they purchased new. It has always overheated and did so as soon as it was delivered to me. I am not a mechanic but put in a new water pump since it was in bad shape, but it is still overheating.

On the top of the engine over the water pump there is a hole that in looking at pictures should have a bold or something in it. I have looked everywhere trying to find out what this is and what to do but have had no luck. I’m looking for any help I can get on this.

It does not feel like any water is going through the lines when the engine is running. This is also a big concern.

I am attaching a picture of the area I"m talking about.

Thank you for any help anyone may be able to give me.

See if either of these links are of any help:

1977 MG MGB Images, Information and History (http://www.conceptcarz.com/vehicle/z7374/MG-MGB.aspx) and 1977 MGB Engine Images (http://www.google.com/images?oe=UTF-8&gfns=1&q=1977+MGB+Engine&um=1&ie=UTF-8&source=og&sa=N&hl=en&tab=wi&biw=1272&bih=753)

Thank you for your response - I can see the pictures and that is where I decided I needed some type of bolt to go in it. However I need to know what it is and what bold I need. The hold is raggad so I may need to take out something that is there - I just don't know.

The hole your talking about takes a screw on cap, not a bolt! It's for initially filling the cooling system. If the threads are messed up, you need to get a new goose neck and cap. Also install a new thermostat ! You can get them here from Moss Motors. PJ

http://mossmotors.com/

Here's the link for the unit you need. Numbers 4, 5, & 6.
http://mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=28977