Let's play guess that noise! (help...lol)

Hey guys/gals I need to borrow some of your wisdom here in helping diagnose a little problem I've just run into. I posted this in the 5.0 forums, but sadly did not get much in the way of a useful response.

So here it is. Starting last night, after driving about 5 miles in my '89 GT, I started to hear a rattling (like metal on metal) sound coming from the front of the car. Luckly I was almost home so I pulled in shut it off decided to deal with it today. So I take it out and run it around the block and nothing happens, no sound, not untill I've been out drving for 10-15 mins. Then, the rattling starts again, it is occuring when the clutch is first engaged and upon acceleration up to about 1800 rpm, then it goes away. Usually it starts out quiet, but within a few more minutes of driving it is scathing loud enough to get the attention of other drivers, old ladies walking down the street, small furry animals, etc. The sound does not exist when the clutch is in, or during in-gear deceleration, it is ONLY when I'm letting the clutch out or have let it out and am accelerating under 1800 or so - and the noise stops the second I let off the gas.

What am I looking at here? I'm assuming it is relating to the t/o bearing or retainer, but it is not doing the characteristic t/o bearing "squeal" - and also the fact that it appears to be heat related is throwing me off. Could this have something to do with clutch pedal alignment? Also, the rear main seal has been leaking for a little while now, could oil slop have anything to do with this?

Oh BTW - the clutch and bearings (t/o and pilot) are relatively new, replaced them about a year ago and have only put maybe 7k on the car since.

Any insight you can give me would be great, I have a few other questions too, but I'll stick to this one for now

Thanks

Thanks guys...alright well, the fluid level is fine, the sound is not a "gear noise" - it sounds like it is outside the case, but somewhere in the bellhousing.

I'll check the bellhousing and see if the all the bolts are tight, I'm pretty sure they are, when I was under there everying looked solid. As far as clutch adjustment, I'm not really sure what I can do besides pull up on the pedal with my foot and pump it back down and let it adjust automatically. I was told that there was supposed to be an adjustment on the end of the clutch cable (where it attatches to the fork), but the cable was replaced by the PO and has no provision for any changes on that end.

My phone doesn't take sound bytes, but, I might be able to digital video the occurance. I'll try to describe it a little better. I'm not sure if you have experienced this with manual tranny cars, but I've noticed in several that I've driven that if you let the clutch out too fast and the rpms dip way down the motor will lug, and if it lugs enough I usually hear a slight little rattling sound from the front of the tranny as the rpms come up. Actually, it makes this almost sound anytime the motor is bogged in gear...like shift it from first into fourth and it'll drop to like 400 rpm - were you to stay in fourth and try to accelerate back up to normal speed, you will probably hear a little rattling sound along with the lugging of the engine geting less prounouced as you get back up to the normal speed/rpm range for that gear. Has anyone else experienced this????...lol....well if you have, then you will understand that it is THAT sound I'm talking about, just REALLY loud, and regardless of how I let out the clutch.

I would take it to Jeff, but he is a looong ways away from me, I took it to one tranny shop, and the guy gave me the "well, I dunno, could be a lot of things....will have to take it apart to be sure..here sign this......"

I'll check the cable, seemed tight last I had the dust cover off, but will look again. The cable was replaced with a non-stock cable, and that is why the adjuster isn't there. It could have stretched in the last few thousand miles, I'll look into it.

As far as the sound, it is DEFINITELY not detonation, it is 10 times louder, and, theoretically, the detonation would get worse as the rpms climb. And as stated above - it is the same rattling sound you get when you bog the motor (same mechanical action taking place - I think)...BUT..it is much louder and it happens everytime I engage the clutch, and everytime the motor is under about 1800 rpms when I am accelerating at any rate. I find it hard to belive you guys don't know what sound I'm talking about! Everyone I know who knows NOTHING ( so they can't help me..lol) about cars all are like: "yea, that little rattle sound it makes when I accidently leave it in third to start, goes away when I get up to speed....." The motor is barely running, so there is a vibration through the powertrain, and something rattles against pretty hard against something else - i think. I always assumed it was the t/o bearing wiggling.

My thoery was that it is the input shaft bearing retainer that is possibly wearing out, and that leaves more wiggle room for the throwout bearing to bounce around when the car is in gear, when I get up above 2k it will go away, because at that engine speed it is centrifically held more solidly to the springs on the clutch. Does this make sense to anyone? I was hoping someone with a T5 would be like "yeah my tranny made a similar hideous rattling sound on acceleration/engagement too...turned out to be the ( t/o bearing, clutch cable, vibrating input shaft, a pack of mischievious little monkeys putting marbles in my bellhousing, fill in blank) "

I'll test all your suggestions when I get a spare moment - keep the suggestions coming, it seems we're narrowing it down some.

Thanks

I'm over by the Haggen on Meridean - (360) 738-7710, I'll be around pretty much all the time till friday, working on a research paper tonight and tomorrow - but can break away if you want to meet up and give a listen, maybe you can think of a better way to describe the sound...lol (or at least help push when the thing finally blows up)

Frankenstang65 is also my AIM name if ya got that...

Gimme a ring man, ask for Scott

Skoobie said:

Well If I knew anything about cars I would stop by...as it stands I could bring beer, point at stuff, and say usful things like "Hmmm..." and "I think its the muffler bearings"

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Muffler bearings, yeah, you know you might as well just sell it when those start acting up......

I'll keep you posted on what we figure out, and as far as the beer, well, that just might be the best solution I've been offered yet . We definitely gotta have a little meet-up at Boomers or something one of these days - get our own BM type deal going up here. Also, I'm moving to a place with a better garage in the next month - sooo, I'm thinking house warming party...lol. We shall see.

You ever get prices on the rear main seal change?...Mine's leaking more than typical 5.0 normal too, figured I'd just pull the tranny (again..lol) and do it myself in the next month or so, but would be curious to see what kinda $$ you were quoted around here.

-Scott

Frankenstang65 said:

As far as the sound, it is DEFINITELY not detonation

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ummm....did I say that???

Ok, well, the very knowledgable Driftin4 came over and hooked me up with a diagnosis, it WAS the muffler bearings!!....In all seriousness though, it turns out that it was detonation all along!! GAH!! So thanks Scooby5.0Doo - you were right after all. I've experienced detonation in my '65 and it sounded different, and only came on when I put the hammer down. The reason the car was detonating was because it the motor was extra warm - I've had a slow radiator leak for a while now- and have been thinking that I was topping it off full when I refilled the resevior, well, I was wrong...lol...it was waaay low.

So I want to thank driftin4 for being cool and helping me out, and everyone else who weighed in on the problem, best fix in the world - like they say on monster garage - FREEBIE!

-Scott

I'll start warming people up on my end, next week will be a busy one for me but after that I'm in the clear...Keep me posted if ya got any ideas or dates, we'll get a cruise together for sure

-Scott