[Epartsman]

Hello all.

Thank you for taking time to read.

So my 2000 Astro AWD started making this noise upon cold start. After a few minutes it will get a bit better. Everything seems to be in order but obviously something is off. Most recent work done was to replace the alternator and the battery. I can't seem to find a connection between the repair and the noise.

Note that I have been getting P0420 DTCs and had not yet gotten a chance to investigate since this appeared.

I've done a little reading and I'm not sure if this could be the worn distributor, or, something much worse. I believe that the disty is original and I'm approaching 300k miles. I'm hoping you'll recognize this noise which will help me find it and fix it. Budget is very tight and we're already down one vehicle.

Astro Noise 20221210 080048

Cold Start noise. Help id.

youtube.com

 

[Malik chams]

this noise sounds like your engine tolerances are worn out and on cold start, it chatters bad i wouldn't drive it anymore the engine might blow

 

[Bikley]

I hate to say it but that sounds terminal. On the other hand have you checked to see if the fan may be hitting the shroud?

 

[bryancraftyhands]

I have to agree with hope it is the fan hitting the shroud. Otherwise, it sounds like a bad case of a rod knocking. Going by how you say it gets better after running some, I'd go with the latter. That would be the oil reaching it helping it to sound better.
When was the last oil change?
You can maybe buy some time by making sure your oil is good, maybe a slightly heavier weight, and run it GENTLY AS POSSIBLE.
It probably won't leave you stranded when it fails completely, but you'll know when it is limping along.
I drove a 4.3 to, from and back to a garage about a mile or two away in an urban setting with 3 cracked pistons and head gasket. First was to confirm what I had thought, brought it back until an engine was located, then back to have it put in. It limped but it made it. I did the damage running high rpms in 4low playing around, not by any actual normal road use.

 

[gwd]

It does sound like the motor bearings are worn but before going that route check to see if there are no loose exhaust covers or tranny / starter shields are loose.
I had one time the flywheel bolts come loose off my SB Chevy motor and were rubbing under the tranny motor cover.
You should lay down on the ground and hear where the sound is the loudest. You will probably need to drag you self under the van to pinpoint the noise more.
You can also attach a stick to your cell phone and video under as you move the phone around with the stick.
The loudest sound will show up on your video.

 

[tungtide]

That rod did not just jump up and start knocking. I would be looking at the shroud area. You replaced the alternator so I would look in that direction. JMO

 

[Bikley]

Coincidence or Google spying? 😃 This just showed up in my notifications.

 

[Bikley]

That rod did not just jump up and start knocking. I would be looking at the shroud area. You replaced the alternator so I would look in that direction. JMO

I spun a main bearing in my Firebird on a normal 1-2 shift. It was sudden, drastic and for no apparent reason.

 

[bryancraftyhands]

Coincidence or Google spying? 😃 This just showed up in my notifications.

Of course you already know the answer to that, and so does google, nsa, cia, secret service, kgb, mi6, the mossad, and your local meter maid.

 

[bryancraftyhands]

Hello all.

Thank you for taking time to read.
Note that I have been getting P0420 DTCs and had not yet gotten a chance to investigate since this appeared.

I've done a little reading and I'm not sure if this could be the worn distributor, or, something much worse. I believe that the disty is original and I'm approaching 300k miles. I'm hoping you'll recognize this noise which will help me find it and fix it. Budget is very tight and we're already down one vehicle.

Astro Noise 20221210 080048

Cold Start noise. Help id.

youtube.com

Your P0420 code is a generic code that says Catalyst System Low Efficiency.
Follow this link for more info:

P0420 - Chevrolet Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis

P0420 Chevrolet Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis

www.dtcdecode.com

bookmark the site for further use.
I know that page mentions diesel, but it applies to gas as well. Based on what you said about your distributor, I'd say this applies:

• Continuous engine misfire conditions, or weak or low coil output

It can be caused by other reasons though. Exhaust leaks, dirty injectors, etc.
With any luck you are just having a knock from a cylinder not firing.

 

[Epartsman]

Okay! Lots of good info. Thank you so much!

To answer some questions.

It is about due for an oil change. Probably 4k on this last change. The strange part is that it had been sipping oil .. about two quarts over a change (3-5k) and now it has stopped. That also has me concerned (crazy saying that you're worried when your engine does not use oil...). I believe the oil loss was due to external leaks though, valve cover gaskets, etc. most everything has a nice coating of oil underneath.

I did replace the disty cap and rotor, the wires and sparkplugs this summer. I think the plugs I pulled out were original. I know, they shouldn't have run that long, but after going through the replacement process, my concerns about the near impossibility of changing the driver's side plugs was confirmed. Some Engineers should be shot!

I will look into the shroud. Maybe something is a misaligned. I thought I would have recognized that sound.

Would this symptom come on suddenly? It just started happening within the last couple of days it seems mostly due to the colder weather. Before that, nothing hinting at a problem even after the alternator change. This sort of goes with the rod theory.

Thanks for the clarification on the P0420.

We did have a no-start situation happen about 10 days ago.. it was one of those humid days / light rain.. sometimes it doesn't start in those conditions right away. I was suspecting the coil needed replacing but had not yet gotten to it.. dogbox and all..

Wouldn't a worn disty gear cause misfires too? Maybe the gear finally gave up? I'm pretty nervous about checking that because I'm afraid I won't get it back in in time once I pull it out.

Thanks for the video link.

I'll report back with more info.

 

[bryancraftyhands]

the near impossibility of changing the driver's side plugs was confirmed. Some Engineers should be shot!

A bit extreme but understood. I always just wanted to go and smack a few.

 

[sixsix]

OK... you're parked next to a diesel graveyard where noisy shit goes to die...

 

[mdconvert]

That could be the belt tensioner.
I recently had the ac compressor replaced and we think the diameter of the new compressor pulley is smaller than the original, causing the belt to be too large. On each half of the tensioner there's a tab that will hit each other if the belt gets too loose. When the mechanic drove the van up to hand over to me I immediately told him that the noise wasn't there when I brought it to him. We looked around and saw the 2 tabs hitting. I replaced the belt and noise hasn't returned (after a month). At the time I took some pictures. If I still have them, I'll post later.

 

[Epartsman]

Just a quick update.

So I was finally able to get underneath and check things out. The noise got worse then changed character, sorry no recording of that since I shut down the engine immediately.

After driving it (before the noise change) I noted that it seemed to be a different noise if I was in reverse versus a forward gear.

This lead me to thinking about a broken flex-plate.

With hopes that it was the flex-plate I pulled the inspection port on the transmission bell-housing. After getting my head around what I thought I was seeing, I think that at least the flex-plate / torque converter area is suspect. I can spin the torque converter freely with my fingers through the inspection port.

Obviously, this isn't how things are supposed to work... I have no idea where the bolts are that hold the two parts together. Presumably they are somewhere in the bell housing. The one really odd thing is that there is a rubber plug near the inspection port. It sort of looks like a rubber hose hanging out the bottom of the joint between the bell-housing and the block. The internal end of that plug is wedged in between the flex-plate and the block and the bell-housing. I've not yet developed a theory on how that happened...

So, once I get things apart I'm going to run the engine just to make sure I don't also have an engine issue.

Time to go do a lot of reading on how to pull the trans out with common tools and on the ground.. or sitting on jack stands.

I will report back here with either a link to my saga in the transmission forum, or with more info about any engine noises..

Thank you all for your ears and suggestions.

More to follow...

 

[Rod's Trucks]

Epartsman...I think that is great news ( finding suspicious stuff in the flexplate area) .
The bolts that hold the flex plate to the torque converter may still be screwed into the torque converter, holding pieces of the broken flex plate to the torque converter. If that is the case, new bolts, a new flex plate and possible even a new torque converter may be needed ( much better news than a broken motor !) .
Pictures will be expected!
I would definitely like to see what damage has been done to the various pieces. I have never seen the results of a similar thing, but have seen what happens when a clutch disc and pressure plate decide to slowly disintegrate. It is not pretty.

Mmusicman and others have some excellent experience and good information on pulling trannys, specifically with respect to heights needed. I recommend renting/borrowing a transmission jack if possible. Being able to control the tilt angle of the tranny while on a jack is a huge help, but it might mean a bit of extra height for clearance.

Rod J
Issaquah, WA

 

[Epartsman]

Well, since you asked for photos.. at the risk of running this thread completely off topic for the forum.. here are the discovery photos. Not the best, but it illustrates what I currently see...

Flex plate and converter where a bolt should be installed.. Note some small metal shards (out of focus)..

The rubber plug jammed between the bell housing and the flex plate ..

Shot showing the flex plate bolts.. and from this angle the flex plate does not appear to be fractured.

I've spent the better part of a day reading through the relevant posts in the transmission section. The folks you mentioned appeared there often.

I'll probably start a thread in the transmission forum and put a link here..

I wonder what fun awaits...

 

[Epartsman]

A link over to the Transmissions / Automatic thread where I've posted my questions and some photos of the aftermath.

Flexplate Bolts Came Loose

Hello, Initially I had posted my 'strange noise' in the engine forum believing that it was coming from the engine. As it turns out, the noise was apparently coming from the flexplate bolts coming out of the torque converter! By the time I had this figured out, all three bolts had come out. I...

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