Horrendous noise after sitting for a week...

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jhdeval

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[ame="http://www.youtube.com/watch?v=qDnjiYEQRfw"]20130825_225821.mp4 - YouTube[/ame]

I am not getting much response at slantsix.org so I am hoping someone here may have some suggestions.

So what I have so far is a horrendous noise while the engine is idling. If I accelerate past idle the noise goes away. The engine is a fresh rebuild less than 500 miles on it. I have done nothing mechanical aside from burning out the wire from the starter relay to the ignition switch. I replaced the wire and the engine started but you can hear the noise in the video. I have checked the valves and they are adjusted 15 and 17 as per the OCG 791 cam card. When I held my hand on the starter I could feel grinding. I brought to autozone and let them hook it up and I could hear a light grinding in comparison to the new one. I also tested with a screwdriver against my hand and the starter and I could feel the vibration in the screwdriver. I used that same technique on the block and just felt the consistent rumble of the engine.

All of the valves are opening and closing. Each exhaust runner is hot to the touch which tells me I am getting both intake and exhaust strokes. The engine appears to be idling fine except the horrendous noise.

I believe it could be the starter but when it was tested the gear engaged and disengaged correctly. The other thought I had was maybe the flexplate to converter bolt came loose? My other idea is could the starter stick and knock while under load? I need some guidance at this point I do not want to tear down the engine just to find out it was something small.
 
Check the flexplate bolts and inspection cover for wear marks.

Doesn't sound like it's coming from the motor.
 
Anyone recommend a little threadlocker on the flexplate bolts?

I tried to inspect them from the starter hole but it is hard to tell for sure.

I am glad to hear others believing what I was thinking. It is hard to tell where the noise is coming from because it is SOO loud. If it is hitting the inspection plate that would explain why. It covers both sides of the motor.
 
Flex plate is brand new from Pioneer. I installed when the engine went in but I will check.
 
Run the engine as little as possible. Get your self a convenient scrap of about any hose from 5/16 through garden hose 2- 3- 4 ft, whatever is needed to reach, and probe around with on ear at one end

Also, start the engine cold, and run with NO belts on the engine.

Probe around with the hose and listen. I would pull off the lower dust cover as it may be hitting, and also to access the bell area. Be careful and probe up in there

Since you seem to already suspect the starter, pull it off and examing it, the bell, and the ring gear for damage. Examine for things like junk/ debri stuck in the rear "socket" where the end of the starter nose fits.

If none of that proves anything, stick your test hose down the PCV hole in the valve cover as well as the oil filler and listen, see if it gets worse.

If nothing else shows results, remove the distributor boots. Use a grounded clip lead and screwdriver, and pull out individual plug wires, and slide your probe into the distributor tower to ground the spark. Listen for a change in the noise.

As bad as that sounds it should not take long to run down.
 
Well thankfully I was right the flex plate bolts were ALL loose some worse then others. Since I had the starter out I went ahead and tightened down from there after a drop of thread locker. Then marked each bolt with a spot of paint so I can inspect movement later.

Started the car and listened and it was all gone. The starter is still grinding a little but I am going to troll the junkyard tomorrow and see if I can find a spare.

Thank you guys for allowing me to bounce these ideas and your responses. It is always helpfully to hear others ideas.
 
jhdeval said:
Well thankfully I was right the flex plate bolts were ALL loose some worse then others. Since I had the starter out I went ahead and tightened down from there after a drop of thread locker. Then marked each bolt with a spot of paint so I can inspect movement later.

Started the car and listened and it was all gone. The starter is still grinding a little but I am going to troll the junkyard tomorrow and see if I can find a spare.

Thank you guys for allowing me to bounce these ideas and your responses. It is always helpfully to hear others ideas.
Click to expand...

Glad you found the problem.
 
pull the inspection plate off and fire it up. my ram mad that noise after I dropped the oil pan to change the oil pump, ot it all back together and it made that same horrendous noise, pulled the inspection plate off and you could see where it was rubbing, fired it up and no more noise
 
spikekid999 said:
pull the inspection plate off and fire it up. my ram mad that noise after I dropped the oil pan to change the oil pump, ot it all back together and it made that same horrendous noise, pulled the inspection plate off and you could see where it was rubbing, fired it up and no more noise
Click to expand...

Read post #8, fixed it.
 
pauly said:
Check the flexplate bolts and inspection cover for wear marks.

Doesn't sound like it's coming from the motor.
Click to expand...

2x... i dont know what it is with these slants but they like to loosen converter bolts when you start to build them up... and ONLY after letting it sit!

mine has done this twice since ive built it, both times i brake cleaned out the holes, wire wheeled the bolts, and used blue lock tight... and both times they have loosened up its been after sitting, worst feeling in our stomach when you hear that sound...

pull the starter and clean each bolt/hole and use red locktite.

and if you have any kind of stall converter i would leave the cover off, helps keep it cool
 
If the flex plate moves under the bolt head just a fraction they will work loose. You wont hear hear them working loose while its running. The noise appears at restart. Doesn't matter if its a minute or a month. Bottom line... they didn't magically back out while sitting. LOL
Mating of metals, underside of bolt head and flex plate need to be clean and dry.
I have to wonder if the cadmium plating found on reproduction flex plates is a factor in some cases. Regardless... I'll wire brush or lightly sand all those mating surfaces including backside of flex plate and any paint from the bolt blocks on the convertor.
I tighten, loosen and retighten while holding the torque convertor bolts rotated clockwise against the bolt holes in the flex plate.
Lock tight might be easier but... Even if it prevents the bolts from backing out, the flex plate could still move and egg shape those bolt holes over time. Then a knocking noise results at start and shut down.
 
I've heard a broken connecting rod make a really similar noise.
 
Take the starter out and tighten the flex plate bolts after putting a drop of red loc-tite on them. Mark the bolts so you can keep an eye on them. More then likely this could have damaged the starter. you will need to go to a u-pull-it and get another one. Hope this helps Steve
 
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