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timing belts and engine wear

bradleyheathhays

NAXJA Forum User
Location
Lexington, KY
I bought a 2011 Crown Vic with 300k miles 12 mos ago and I'm wondering how to approach servicing the timing belt. I know very little of it's past maintenance records other than what I've done with it this past year. Basically I'm wondering if I should go ahead and attempt to replace it now, or wait til something starts to go wrong. I don't know how timing belts typically go bad...if they just break or start to stretch or what. If this is an interference engine I'm imagining a fairly bad event so I'd like to get educated and be pro active about it.

Second...Scotty Kilmer teaches that the worst wear an engine sees after changing the oil is before the oil gets pumped back into the filter and then into the engine components during the first engine restart. But he says if you disable the ignition spark somehow when cranking for the first time again, the lack of combustion in the cylinders helps with reducing this kind of wear quite a bit. I don't have an owner's manual and I'm not sure what fuse to pull to disable combustion ignition, or if removing a fuse would be the best way to do this. Any opinions on how this should be done?
 
Millions of oil changes every year and somehow this is a problem? If you are really worried, just fill the filter before you screw it on. It will cut the time drastically.

There is a coating of oil in each bearing that should protect things while the pressure is building up. The first time I start up a new engine, I have already prelubed the bearings with assembly lube, but I spin the oil pump and prime the system before turning over. This is mainly to get oil to the lifters. I still spin the engine with the coil wire removed and the plugs out to allow the lifters to pump up. After breakin I never worry.
 
Timing belt systems have a tensioner that accounts for any stretch over the life of the belt.

I don't know whether your particular engine is interference or not, but if it is, a broken belt will cause significant (if not severe) internal damage to the engine. If it's not an interference type, the belt breaking will cause no damage but the engine will simply stop running, which could be bad if you're on the highway doing 60+ mph at the time.

Timing belt change intervals are specified in the standard year/mileage units, but since they are belts, if you hit the time but not the mileage you should change it anyway - being rubber, the belt does have a finite lifespan like tires. Replacement interval should be listed in the service section of the owner's manual.

Since you have no idea if/when the belt was last done, it should be changed as soon as possible - If it's original to the car (and you seem to have no way to confirm/deny that it is not), it's beyond both the age and mileage limits and could break at any time.

Additionally, given the age of the engine and the unknown service history, don't just change the belt itself. Replace EVERYTHING in the timing belt path - tensioner, all idler pulleys, and anything else the belt may be supplying drive to. That way you have a belt and belt path that's a known quantity.

(Example: my VW TDI has a timing belt, it's an interference engine, and the timing belt also drives the water pump and fuel injection pump. Replacement interval on my belt is 7 years/100K miles; doing the job right means belt, tensioner, all idler pulleys, and the water pump all together as a set.)
 
Ford 4.6 I'm assuming? That engine is timing chains. I've seen the guides break before, and yes they bend valves. It does not however have any recommended service interval. It requires removal of the valve covers and timing cover and then the 2 chains, sprockets and guides and tensioners.
Usually a rattling noise for a few seconds on a cold start means they're getting due for replacement. If a consistent rattle from the timing cover area they need to be done soon.
IDK who Scotty kilmer is but if the issue was that bad wed all be doing something different.
 
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