Photo of timing chain guides

[peterwells]

All,

I'd posted previously on overhauling the timing chain/tensioners/etc on our 2008 Expedition, 170k miles. The vehicle has been back together for a few weeks and so far all seems to be good, no more clattering on start up.

Today I got around to cleaning the garage and thought I'd post a picture of old guides. The driver's side had a couple of cracks but was basically there, the passenger was a series of bits either resting down by the crank sprocket or for the smaller parts in the oil pan/oil pickup.

I'm surprised this didn't cause more problems. I replaced with OEM parts and they were the same revision as the broken parts. I'm not aware of anything that would have caused this damage. I'd be interested to learn if others have explanations.

Peter

 

[JExpedition07]

Bad tensioner seals can leak oil pressure down after engine is turned off. Chain then slaps on startup until tensioners build oil pressure. This slapping busts up the guides over time.

It seems for most the problem is most pronounced at startup until it tensions the chains.

 

[peterwells]

Thanks for the reply, you're probably right. For sure it made some awful sounds on start up and there were some pretty deep gouges in the timing cover. The tensioners have both spring and hydraulic biasing, maybe the springs grew weak over time.