Recently Ford acknowledged that the 2.3-liter turbocharged engine in the 350 horsepower Focus RS has an issue with burning coolant. Some owners report coolant burning at cold start up and this has resulted in everything from a Ford replacing blown head gaskets, complete cylinder heads, and even complete engines as recently highlighted in our last article on RS engine problems.
With an issue like this on such a popular car, its normal for many theories to pop up. Some believe the lack of upper cylinder wall strength associated with an open-deck block design is causing the head gasket to move and wear out. Some believe the cylinder head-integrated exhaust manifold could be producing too much heat that's causing the coolant to boil and eventually lead to a warped head. The folks at Road & Track, however, believe they have figured this all out and that the entire issue could be the wrong head gasket being installed from the factory.
According to the Road & Track article and the article we posted last week, it seems that Ford has updated the head gasket in the RS with one less coolant passage hole. They believe that since the eco-boost in the Mustang and the RS are similar, that Ford may have accidentally installed the incorrect head gaskets on early RS engines.
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The 2.3 liter EcoBoost in the Mustang has a V-shaped passage cut into the block in between cylinders in order to transfer coolant. This necessitates two holes to be cut into the head gasket to facilitate the transfer of coolant. The 2.3-liter EcoBoost in the RS uses a completely different design where the coolant is routed through a passage below the deck surface.
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Without the v-shape passage on the RS engine, coolant gets trapped in the passageway and boils. This destroys the head gasket and can lead to coolant entering the cylinder.
The image of the bad gasket clearly looks exactly like the EB Mustang gasket but what's even more interesting is that the part number on the gasket (EJ7E-6051-HA) does not match the Focus RS gasket part number at all. pic.twitter.com/XXKmSdhvpT
-- Bozi Tatarevic (@hoonable) December 28, 2017
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Road & Track speculates that both gaskets come from the same supplier, and they accidentally sent Mustang Ecoboost gaskets to the team building the RS engine.
Ford is yet to come out with an official repair, bulletin or recall so at this point we don't know for sure what the fix will be. Ford is covering all repairs under warranty as expected, but it still doesn't take away from the fact that RS owners are worried. Unless this is as simple as a head gasket, the value of these cars will be affected. Ford announced earlier that 2018 would be the last year for the Focus RS.