Engine knock question
 

I noticed wife's 07 Sienna van knocks when she backs up. It also does it from a dead start going up hill. It has 200k on the odo but I have been thinking about on and off for a few weeks and can't come up with an answer. Can't be cheap gas.

Bad engine mounts?

Engine knock or you just hear a knock? Possibly driveshaft U joints.

Also check the drive shaft hanger bearing, if the noise is from behind the engine.

Can you do a video with good sound, post here?

OK, never thought of that. Will check it out.

are there any driveshaft bearings on a front whweel drive van?

CV joints .

If the knock is coming from the engine - Probably the timing chain (if it has one) tensioner.

Timing chain tensioners are notorious for developing faults over time and a slapping loose chain can sound like a knock or rolling marbles.

I'm on board with slop in the drivetrain somewhere.

You replaced the front hub bearings not long ago?

CV joints kind of click when failing. Backwards as well. If you can get a recording that would help.

Just have the boss drive it backwards and you stand outside with a cell phone.

If you cant post to youtube, send it to me and I can, i'm pretty sure.

^^^ Those were my first two thoughts. What I would check first depends on when the noise appears.

I was thinking Savana not Sienna, wrong van. Yup, check CV joints.

On my El Camino after about 260,000 miles I started hearing a knock if the temps were cold, the engine was not warmed up, and under a load. It sounded like a ball bearing bouncing in the piston. Once fully warmed up, or with medium grade gasoline, no knock. It would only knock with the lowest grade of gasoline.

It went another 40,000 miles and after 300,000 miles on the old 305, I swapped in a crate 350 and took the old 305 to the metal scrap yard and got 20 bucks for it. I never did find anything inside that looked that bad, but I did not care much. It was running fine when I turned off that engine for the last time.