HELP WITH ENGINE NOISE / ISSUE...:(

[64crew4x4]

Hey guys been a while since I got to play on this forum...

So my 98 AWD Astro has been doing super good for me up till may.

My Wife and I did the road trip to LA and back in it back in Feb. with no issues....

Came home did oil change and all looked well...It's been getting used almost dailey since with no issues...

Went to a wedding in may, and it drove 45 miles from Home with no abnormal noise. Shut it down for about 4 hrs...
Came back out to head home and on start up I get a Very metallic sound coming from rear area of engine....To me it sounds like Bottom end bearing failing or Flex plate cracked out....Very tinny and metallic like a flex plate issue....
Oil pressure is Good, no drop in it....I drove it about 3 miles to Oil Can Henry's Had them change the oil to be safe...looked at oil coming out and saw no metal in it at all.....

I then drove the thing home the 45 miles back with the noise there the entire trip but getting louder then quieter depending on Load I was giving the motor.....

I put it on my lift at home and had the Mrs. run it in gear both forward and reverse...Everything I heard said Flex plate....
So I bought and just replaced the flex plate....when I pulled the old one down and out everything was tight and there is nothing wrong with it.....

So with new Flex plate bolted onto crank, and transmission pulled back 6" from bellhousing, I fire the motor back up, and Noise is still there......

I can feel the Hard parts clanging internally on the motor in the rear as near as I can tell....?? And the noise still sounds like it is in the very rear of the motor....If I put my hand on either the Starter or the Oil filter housing the Clanging that the sound is, can be felt.....

Motor still runs smooth as silk, even though it is due for a tune-up....Oil pressure is 50-60psi cold and around 25-35 hot at idle.....No over heating, coolant is clean and clear of oil residue....Oil is clear of Water as well.....???

I am at a loss for words on it at this point....Has anyone had a similar issue....?

This is the Second Astro to fail on me in 2 yrs.....in a similar fashion.....

All info is appreciated.
Thanks , John.

[64crew4x4]

Not good when Nobody posts anything....:(

I will be pulling the oil pan on Saturday to see what I can see.....Wish me luck...

[LiftedAWDAstro]

Good luck. I would say something about the noise but I don't do engine internals so I can't help. We do have a couple "know - it - alls" here who should be helping!

[Kidhauler]

Your sure it isnt lifter knock? I sure hope for your sake it isn't bottom end noise. Good luck.

[Smiliesafari]

You're right...........no posts are not a good thing. The only thing that comes to mind is maybe the oil pan has a dent in it. But that's not likely because these pans are cast aluminum. If the bottom end is still in good shape there is one thing you might try. There is knock generated by carbon build up on the top of the pistons. A simple (sometimes) cure is to pour water into the throttle body while the engine is running. The combustion heat turns the water into super heated steam and it will clean the carbon off of the pistons. Hold the engine RPMs up to about 3000 and dribble the water in slowly. Slow enough to not kill the engine. About a beer can full should be enough. Good luck.

[1Gary]

Oil pressure is crated by main and rod bearings.Soooo in order for it to have good oil pressure and have a knock,piston wrist pin(s) could be the issue towards the rear of the engine.Still run ok,but have a knock never the less.It would change in the sound of it given a RPM change.Might actually disappear somewhat at a higher RPM.

[64crew4x4]

Thanks Guys...I am actually going to try the Carbon clean this friday...I had already been thinking and reading on that one.....
I am a Mechanic and have been doing engines for 20 yrs now, but this Noise is a new one for me....

I know Lifter noise....I know Rod Knock, I know piston slap or wrist pin slop/slap......

I do not have a good book for pics, but is it possible for the internal parts of the oil pump to jump around and still be ok with oil pressure...?

The noise comes and goes with engine rpm's, but not like a Normal rod knock or wrist pin noise will come and go....and It is a very tinny sounding metallic sound different from your normal wrist pin or piston slap.....????

I'll let you know if I blow it up friday.....

Thanks, John.