You can get carbon build up in the heads...
around the valves and spark plugs and on the valves..
its Not normally a problem with VW engines these days...
VW Engines do not get carbon build up inside the engine
as they used to in the 50s 60s because of the Detergent oil We use now...
when detergent oils were first introduced..
many engines rattled and lost compression
as the carbon was keeping the engine tight and oil pressure high... this was with All old car engines...
and caused major problems..
I wouldn't waste $180 on Your VW engine...
You can buy additives You add to Your fuel tank to clean Fuel injectors... Wynns NULON etc..
You used to be able to buy a spray to spray down the carburetor throat to clean the engine inlet exhaust etc
but this is hard to find now as Carburetors have Not been on New cars for many years....
Lee
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