Taurus SHO 3.5L Ecoboost Timing Failure

Last Modified : Mar 30, 2021

A customer recently showed up to the shop with a check engine light on his Taurus SHO. Very nice car by the way even with the 90K miles on it. He complained that it ran a bit rough for the last month or so, with diminishing fuel mileage and a glowing yellow light. Upon running the codes, we discovered he had a code that stated Bank 2 over-retarded. After checking the VCT error pids, I determined that Bank two did not respond to VCT commands and showed it was off by 33 degrees...

", I priced him out to tear the front of the engine down and see what was going on. Likely would need timing chains, tensioners, the works. He figured it would be safe to drive for now since it's been doing this for the last few weeks at least.

You should not rotate these engines backwards in any case, but of course I decided to try it with this engine. Rotating it backwards put force on the tensioner, retracting it, causing major chain looseness in my situation. So much looseness, that the cams would not turn and the chain would skip right over the teeth on the crank. I am assuming that the chain jumped time when the engine was turned off, likely kicking back as it showed down and fought cylinder compression.

Once the heads were removed, you could clearly see where all the intake valves kissed the pistons. Upon removing the valves, all the intake valves were bent. It appears as the the pistons were ok, the cylinder heads and valve seats were ok. The customer opted to go the cheaper route (since it was customer pay) so we just lapped in new intake valves and threw it back together with new gaskets.