1998 E-150 van 4.6l, 240k miles. Started up a week ago and got an immediate metal knock sounding like it was coming from the bell housing. Used mechanics stethoscope checking both valve covers and heads, oil pan, transmission and catalytic converters. The noise was most prevalent from the bell housing. Good oil pressure. Thought it was a cracked flexplate. Pulled trans and flexplate was fine but replaced with new along with a rebuilt torque converter. Noise remained. Removed the serpentine belt, noise remained. Prior to the new noise the only thing we've done is replace the muffler. Thought is might be a rod so changed the oil and added some motor honey, no change in the knocking. No oil in water or water in oil. Runs (no misses) and drives great. Haven't seen anything like this when I search the web. Any ideas??

 

Two things you might check,
First , check the crank pulley (Vibration damper) , sometimes the rubber that separates the inner part of the pulley from the outer part will let go and it can sound just like a rod knock., Also you might check the end play for the crankshaft thrust bearings., That is done by trying to move the crank pulley in and out with a heavy screwdriver or pry bar.

 

Will give both a try. When we had the flexplate off I tried prying on the end of the crankshaft and there was some play that didn't seem excessive but I didn't put a micrometer on to measure it. I'm also going to try disconnecting the VCT solenoids as a wild shot that one or both may be clogged. One thing I didn't do before disconnecting the battery was to scan for pending codes so now that we've run the engine a bit I'm going to check again, but the check engine light hasn't come on yet. I'll let you know what I find out in a couple of days. Thanks

 

Hi Denny,
I have to share something with you.
A long time ago someone brought a 64 Falcon for me to check out due to excessive blow by.
He also tried "Motor Honey" and in the process of dropping the oil pan the inside of the engine looked like someone hung curtains in there. Will never forget that picture.
I can only hope it doesn't do the same thing to your vehicle's engine. By the way , it didn't do anything to correct the problem either, most quick band aids don't.!

 

Thanks Hanky, the Lucas motor honey wasn't meant to be a band aid fix, I was just trying to see if it helped to soften the knock, and if so it would give me an indication that its an internal bearing problem. It didn't seem to help so I'm leaning towards it not being that, but I'm not totally convinced that it isn't. If we can 100% identify the problem, and the fix doesn't involve removing the engine, then we'll change and flush the oil. The van is 23 years old with many rusted undercarriage bolts so I'm not inclined to try and remove the engine. Thanks for the input.

 

Took a 200 Ford 6 apart that the owner used STP with each oil change. Scraped a couple inches of it out of the oil pan. Thick as syrup.

 

Not a proponent of motor honey especially wit VVT/VCT but as I said it was a last ditch effort to try a rule out a bad rod bearing.

 

You can verify if it is a rod knocking by just unplugging the coil for that cyl for a few short seconds. If the noise completely disappears when the coil for that cyl is disconnected
that will usually verify a rod bearing problem.
Just don't run the engine too long without spark because the injector will keep working and ,= excess fuel into cyl unless you unplug the injector also.

 

I disconnected cylinders 4 and 8 injectors and spark plugs since they are the rear most and nearest from where the noise seemingly is propagating from and the noise still remained. It's just so hard to get to cylinders 3 and 7 to disconnect those injectors and plugs on a van. I usually don't like to pull the plug wires at the coil (this has two 4 pack coils) but that may be a last ditch effort. Thanks

 

Something you may be able to use,
If you remove the plug wire from the coil tower and insert a 2 inch piece of vacuum hose in the tower then put the plug wire into the vac hose, now you can connect a grounded jumper wire to a screwdriver and touch the vacuum hose with the screwdriver . That will accomplish the same thing as shorting out the spark to that cylinder to determine if the rod bearing is the cause of the knock.