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Ugh, if it's not one thing it's another
https://slantsix.org/forum/viewtopic.php?t=23492		 Page 1 of 3
Author:  Jopapa [ Tue Jun 05, 2007 9:28 pm ]
Post subject:  Ugh, if it's not one thing it's another
Well today I finally adjusted my valves (which were WAY off. Each screw got a full turn or more to get tightened to factory spec). It's far quieter now and idles smooth as silk, BUUUUUUT now whenever I rev the engine and release the gas, I hear a really hard rattle (has the same tone as a bad engine knock) that sounds like it's coming from underneath the valve cover. Once the engine's done decelerating the rattle goes away and it's right back to a smooth idle. My timing is set to 8 degrees BTDC initial, and when the valves were way out of whack, it wouldn't make that noise (but damn were the valves clacking loudly). Any ideas what might be going on here? I know I didn't leave anything underneath the valve cover when I put it back on, and it looks like the gasket's still in place and not torn. It's a brand new gasket too, so I know it's not losing chunks.

Oh yeah, and now the bearings in my alternator are screaming too :roll:
Author:  quarter mile heartbeat [ Wed Jun 06, 2007 4:46 am ]
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what did that licence plate say that i saw on the motor home a couple days ago? "if it has tits or wheels, it's going to cost you money"...
the difference is you can sell a vehicle if it starts costing you too much. try that with a woman and it'll cost you more. (why get married? just find a woman i hate and buy her a house)
Author:  Aggressive Ted [ Wed Jun 06, 2007 12:56 pm ]
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How many miles are on this engine?

Some thoughts..........

The first that comes to mind is that under load you may have a rod knock that was being disguised by the rocker arm clatter. No more clatter and things show up. With no load you wouldn't hear it.

A sutler knock comes from the fuel pump. Once the car goes back to idle you don't hear it anymore. Mine does this on a brand new rebuild. Once I bought a stethoscope and proved it to myself, I don't worry about it.
Author:  Jopapa [ Wed Jun 06, 2007 4:53 pm ]
Post subject: 
Quote:
How many miles are on this engine?

Some thoughts..........

The first that comes to mind is that under load you may have a rod knock that was being disguised by the rocker arm clatter. No more clatter and things show up. With no load you wouldn't hear it.

A sutler knock comes from the fuel pump. Once the car goes back to idle you don't hear it anymore. Mine does this on a brand new rebuild. Once I bought a stethoscope and proved it to myself, I don't worry about it.
No idea how many miles are on the engine. Mechanically, aside from being way out of tune, it's in outstanding condition so far.
I did a bit more troubleshooting today. No knock whatsoever under load or when the car is in motion. Only when parked and under a no load condition when I bring up the RPMs and then release the throttle does it make that sound. I probed around with my stethescope and it still sounds like something rattling around inside the valve cover near the #6 cylinder, but it was most intense at the starter. Like for some reason the flywheel was still touching the starter gear and making the starter spin when the engine decelerated with no load. I'm going to pull the valve cover as soon as it stops raining (God I want my own garage so bad) and make sure everything's secure, and if everything's good and I still hear the noise, I'm going to pull the starter and see if I can find any damage. If that is the case, would it be advisable to shim the starter at all to prevent it from contacting the flywheel? If yes, what's the maximum thickness allowable to shim it?

I'll give a listen to my fuel pump with the stethescope and see if there's any racket coming from that as well.

One more question: given how loose my valve lash was and since I have no idea how long it's been that bad, anything I should look for as far as potential damage to the valves or cylinder head?
Author:  dakight [ Wed Jun 06, 2007 4:56 pm ]
Post subject: 
Check your flywheel / torque converter bolts to be sure they haven't backed out just a bit.
Author:  Jopapa [ Wed Jun 06, 2007 5:21 pm ]
Post subject: 
Quote:
Check your flywheel / torque converter bolts to be sure they haven't backed out just a bit.
Can I do it with just the inspection cover removed?
Author:  Aggressive Ted [ Wed Jun 06, 2007 5:55 pm ]
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Yes you can. Just remove ths inspection cover and your in. Having the starter off will help too You can get to the bolts thru either hole. Shims usually are much over .030 to .045.
Author:  Jopapa [ Wed Jun 06, 2007 8:32 pm ]
Post subject: 
Quote:
Yes you can. Just remove ths inspection cover and your in. Having the starter off will help too You can get to the bolts thru either hole. Shims usually are much over .030 to .045.
Cool, I'll get it up onto a lift soon and take a look. Now that I've got my truck running again, I'll park the Duster so I can avoid doing any damage to it (and finish the tune up before it really gets upgraded to daily driver status). After pulling the valve cover and finding the majority or the cause of the high RPM rattle (chunks of the old gasket that I missed when I cleaned up in there before), I was still hearing the knocking/grinding sound when decelerating from high RPMs coming from the starter. This time it was happening when driving and without load on the engine. Just to be sure, I checked several areas of the block and the manifold runners and all that was sounding nice and smooth. So now I'm sure either the flywheel (or TC) bolts are loosening, or the starter's reset spring isn't holding the gear back the way it was until yesterday. It just started making the sound yesterday, and it's much louder than my valve clacking was, so I would've known if it was doing it before, and it wasn't. Poopy timing. I'm out of car money for a while here...
Author:  LUCKY13 [ Wed Jun 06, 2007 11:08 pm ]
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If you dont find nothing there I would supect a rod bearing.


Jess
Author:  slantzilla [ Thu Jun 07, 2007 6:05 am ]
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I've had a couple Slant motors that makes knocking noises like you describe. I never did find the noise on either, but suspect it might be piston slap becuase both ended up having 1 cylinder go dead eventually. :shock:
Author:  Jopapa [ Thu Jun 07, 2007 6:26 am ]
Post subject: 
Quote:
I've had a couple Slant motors that makes knocking noises like you describe. I never did find the noise on either, but suspect it might be piston slap becuase both ended up having 1 cylinder go dead eventually. :shock:
Even if you couldn't hear anything from the block when you used a stethescope?
Author:  79AspenSuperSix [ Thu Jun 07, 2007 6:27 am ]
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I had one doing the same thing your describing. It would also make that same noise going down the road with just a little throttle, push down on the throttle a little more and it would go away. Let off the throttle completely and it would go away. It was most noticably when you completely backed off the throttle after a heavy acceleration. Sounded like a diesel engine rattlin'! I copped out on it and swapped a low mileage 6 out of another car into it. The one that was making the noise ran great and got 22 miles to the gallon! But the noise bothered me. Sounded bad! The motor was filthy inside when I got it, it was so gummed up the oil wouldnt evan flow thru the rocker arms. The engine I swapped in had 34,000 orignal miles, well maintained and spotless inside. I did this two weeks ago and havent tore the motor in question apart yet to see if I could find the "noise" making problem. Oh but I can tell you it wasnt the torque converter bolts. I feel for you because other than the noise it ran GREAT! I did strain the oil and didnt find any bearings chunks or pieces just "glitter". Like Slantzilla I suspect piston slap. I had put new valve stems seals in it and was still getting a little oil smoke on start up. This motor only had 71,000 miles on it but was more filthy inside than the K-member under the oil pan!
Author:  Jopapa [ Thu Jun 07, 2007 12:36 pm ]
Post subject: 
Quote:
I had one doing the same thing your describing. It would also make that same noise going down the road with just a little throttle, push down on the throttle a little more and it would go away. Let off the throttle completely and it would go away. It was most noticably when you completely backed off the throttle after a heavy acceleration. Sounded like a diesel engine rattlin'! I copped out on it and swapped a low mileage 6 out of another car into it. The one that was making the noise ran great and got 22 miles to the gallon! But the noise bothered me. Sounded bad! The motor was filthy inside when I got it, it was so gummed up the oil wouldnt evan flow thru the rocker arms. The engine I swapped in had 34,000 orignal miles, well maintained and spotless inside. I did this two weeks ago and havent tore the motor in question apart yet to see if I could find the "noise" making problem. Oh but I can tell you it wasnt the torque converter bolts. I feel for you because other than the noise it ran GREAT! I did strain the oil and didnt find any bearings chunks or pieces just "glitter". Like Slantzilla I suspect piston slap. I had put new valve stems seals in it and was still getting a little oil smoke on start up. This motor only had 71,000 miles on it but was more filthy inside than the K-member under the oil pan!
Yeah the more I snoop around, the more it's sounding like it's coming from the starter (or the immediate area around it). I'm going to shim the starter to see if that clears up the noise, and if not, I'm going to check the flywheel/TC bolts and make sure they're properly torqued.
Just for laughs, I'm going to run a couple batches of Dan Stern's engine cleaner recipe through and see if that clears out alot of crap (and maybe even helps with the noise). Something's bound to help! I'm just going to go at it one step at a time and try to fix the problem.
Author:  Aggressive Ted [ Thu Jun 07, 2007 12:59 pm ]
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I had an engine do this once and when we tore it down after many, many miles, it was a cracked skirt on the piston.
Author:  Jopapa [ Thu Jun 07, 2007 5:31 pm ]
Post subject: 
Well I just pulled the starter, and there's no visible damage on the starter's gear, but the teeth on the flywheel show a good deal of fresh damage, as if they were hitting the starter gear. Looking at the starter, the gear has a healthy amount of posiive spring tension holding it fully back. I can't figure out why the flywheel would suddenly start hitting it, but it (the flywheel) is definately damaged. I'll snap a pic shortly and post it so I can get you guys's takes on it.
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