Rod Knock -Replace or Repair?

[ViolentBlue]

I just bought a 2007 GMC Envoy with 150,000 Miles. it has been babied all its life, previous owner had the oil filter collapse and oil starve the engine (he managed to get some money from the filter company for this)

oil was full of sparklies, oil changed and everything clean but has a rod knock on start up and under load.

is it worth pulling apart and changing out all the rod and crank bearings?
I keep hearing that these engines are cheap and plentiful but I've not be able to find a suitably low mileage engine, or even a reasonable priced high mileage engine.

 

[Mooseman]

Until it's taken apart, there's no way to know what is salvageable. Likely the crank and a rod are done, possibly the block if it spun a main bearing, the head may have been smacked by the piston, cams may be damaged. Check out this video of the teardown of one of these (actually a 5 cyl. variant) that has suffered a complete self destruction event.

Even though yours is still running and knocking, metal has been pushed through the whole block and a lot of stuff has likely been damaged.

I'd keep searching for a good used one. Try car-part.com or even eBay. Maybe find a good running rust bucket. Be aware that you can swap in an 02-05 engine as well with a minor modification to the coolant sensor wires so look at those too.

 

[rchalmers3]

I just bought a 2007 GMC Envoy with 150,000 Miles. it has been babied all its life,,,,,,

is it worth pulling apart and changing out all the rod and crank bearings?
I keep hearing that these engines are cheap and plentiful but I've not be able to find a suitably low mileage engine, or even a reasonable priced high mileage engine.

If the vehicle is as nice as I imagine it is, and you wish to keep it for some years, then I might suggest doing a light rebuild on that engine. Crank kits are available from RockAuto, and you will probably find the engine does not require much more than a good cleaning and re-assembly.
The cost for the engine repair will be a hard pill to swallow, but I find these trucks to be a really nice ride and comfortable. I like them!

Rick

 

[TollKeeper]

And I am on the other end of the spectrum. The 4.2 are such a pain to rebuild. Find a used engine, and rock.

 

[ViolentBlue]

found an '04 trailblazer with strong engine but bad trans. but the 2 arent directly interchangeable.
it was cheap enough and I found a replacement trans easy enough.

I'll probably take a poke at doing a bottom end rebuild on the '07, maybe replace the timing chains.
thanks for the tip on the rock auto kit, I'll take a look at it.

 

[Mooseman]

found an '04 trailblazer with strong engine but bad trans. but the 2 arent directly interchangeable.

Like I said earlier, they are interchangeable after a minor change to the wiring for the temp sensor.