Relevance. Rating Newest Oldest. Best Answer: DECOMPRESSION LEVER: A decompression lever fitted to the engine enables the user to start the engine easier when it is extremely cold, when the battery is low or when bleeding the fuel system. http://www.marinedieseldirect.com/univer...Source(s): http://www.marinedieseldirect.com/univer...here was a small oil leak shown down to turbo exhaust. I have taken to service, and I have changed diesel separators, airfilter etc. After that I have ran around 200kms, and I found oil drain in my car porch. When I checked, the leakage is from diesel separators, and some other small pipes.