I had a bug come in that had stopped running. The owner bought it a from a local car dealer a short time ago. After I pulled the engine out, I discovered that the engine had over heated and blew a rod. There was a small hole right below the oil cooler.
First thing that was apparent – the cylinder tin had been cut away over #1 piston. Then the engine compartment was not totally sealed. This led to the engine overheating.
Someone had put some time and money into it. It had EMPI valve covers and a big merged exhaust. Unfortunately the buyer of the bug was not familiar with the function of the engine compartment tin. Luckily I had a good used engine for him. I was able to get him up and running in no time. I think it is irresponsible to do things like this, or it is a lack of knowledge.
I have another customer that has been running her baja with no cylinder tins. This is unbelievable to me. I thought for sure the engine would burn up in no time. I suppose being a baja with the engine exposed is the only savior for the engine and keeping it cool.
So if you are new to working with VW engines – The engine compartment, which includes the tinware surrounding the engine, is a closed system designed to keep air flowing around the oil cooler and cylinder and head fins. So cutting anything away or leaving off pieces will defeat this system and make the engine run hot. It is important that all of the tins is in place, in good condition, fits properly and will secured to obtain the closed system since Air-cooled VW engines run quite close to their heat limits to begin with, so the margin of safety is small.