More like a broken valve head, the critical junction being closest to wear the valve head meets the valve stem and is at its thinnest point. Improper metallurgy/tempering/heat treating can result in a brittle valve which hardens further under multiple heat cycles, eventually leading to failure.
This all makes sense. The service manager told me today that he saw two revisions to the part number when he put in the order for the replacement engine. Interestingly, he also said that Ford told him to order a new fuel pump. Has anyone else with a failed engine also had their fuel pump replaced?Recent Changes - 2.7L Bronco V6 (Nano gen2)
- over the past 6-months there were at least three changes
1) New Valves
- 'Nano valve supplier issue was resolved with more robust design and material changes at the supplier.'
- Timeframe: ~ Summer/Fall
2) Head Assemblies - New Part#'s
- Left
-- Engineering# ML3E-6M099-DB --> new rev -DF
-- Service part# ML3Z-6049-G --> new rev -K
- Right
-- Engineering# ML3E-6F093-DB --> new rev -DH
-- Service part# ML3Z-6049-D --> new rev -J
- Timeframe: prob along w change# 3) below
3) 2.7L V6 Engine - New Part#
- Engineering# MB3E-6007-AA --> new rev -AB
- new part# prob coincident w new head assemblies
- Timeframe: appears ~ Nov/Dec ebd's
Blown Engines
- in B6g tracking, the bunches of dropped-valve failures appear to end w ebd 21224 (Aug 12) - Since then we've only seen one blown engine (21281), which could be an isolated random failure
- so far we have not seen blown engines w new part# rev -AB
- engine rev -AB still fairly new, many still low mileage
Diagram of Head Assemblies w Service part#'s (6049 overall)
. New Engine and starter.
Did he say which fuel pump? They have 2...an electric in tank pump, and a cylinder head mounted DI pump. My guess is he was talking about the DI pump, which I could see as possibly being damaged in the failure
He didn't say but I'll ask next time I speak with him. The DI pump makes more sense.
Consider this, poor fuel management due to a faulty fuel pump results in loss of power in the cylinder/cylinders resulting in a knock, or other destructive valve piston interaction? Reduced cylinder pressure during the exhaust cycle might result in early arrival of the piston at TDC, resulting in exhaust valve piston impacts.
No that can't happen
Well that is good news then.
How do you know he's not sitting in front of his computer wearing a cape?Joseph, not all heroes wear capes. Thanks for all of the hard work you are doing here, staying on top of this information, and maintaining a level head.
Yep, detonation was one of the possible failure modes that I suspected was a possibility early on... But that was ridiculed too.
It sucks that competition is limited to just Wrangler and Bronco in the topless off-road department. And only one of those two is really available for purchase right now for most people.
