Williams may be reaching out to Mercedes in a bid to end its 2018 car crisis.
Under the technical leadership of former Mercedes chief Paddy Lowe, Williams's 2018 car is among the very slowest on the grid.
Germany's Auto Motor und Sport reports that a major issue is the cooling system.
"Paddy Lowe wanted to copy the cooling system of his former team Mercedes, but the concept is complicated and apparently Williams made a mistake," correspondent Michael Schmidt explained.
"Now the bodywork has to be opened up completely and that costs a lot of downforce."
A Williams engineer is quoted as saying: "If we solve the cooling problem, we'll gain eight tenths in one fell swoop."
The 2018 championship continues this weekend in Baku.