4r70w acting up...

porky · #1 09-30-2008, 12:42 AM

first a little info, my 2wd 99 F150 has 145,000 miles, the 4.6, 4r70w tranny, 3.55 gears, and i've been running 33s for a year now (finally ordered new gears yesterday). now, on to the problem:

i first noticed problem a month or two when my truck would squeak a little when driving really slow. figured it was just mud on a seal or something, didn't worry about it. now it's back, but louder and more often. if i step on the gas while driving it'll kind of squeal or whirr, i guess, kind of hard to explain. also, if i downshift with the shifter it'll squeal or chirp. other than the noises, it shifts through the gears fine. however, if i accelerate from a standstill and let off the gas and then punch it again it will kind of hesitate, like there''s a little slack or something (u-joints are fine though).

my guess is the torque converter is going bad, but i'm not sure. preferrably, i'd like to do the work myself, so any parts and retailers suggestions would be great. labor costs at shops are ridiculous, and i have a lift and everything at our shop, and besides, i want to learn how trannys actually work. I want to replace any worn-out parts with upgraded, heavier duty stuff, as i plan on keeping this truck a while, and want it to handle whatever i throw at it without having to worry about tearing it apart again.

any help would be greatly appreciated

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shifty_85 · #2 09-30-2008, 02:28 AM

sounds like a belt or a pulley not a tranny. if it shifts fine i think your ok. and i just had my 4R70W rebuilt and it still does that if i go from a stop let off then hammer it it will wait a lil bit. the tranny is getting out of the OD gear and just into 1st 2nd 3rd or 4th thats what you are feeling. turn OD off and see if it still does it.

porky · #3 09-30-2008, 02:36 AM

thanks for the help, i hadn't even thought about that. it sounds like the noise is coming more from the transmission though. i'll look at the belt a little closer tomorrow though, how could i check to make sure that the belt is or isn't what's causing the noise?
and yeah, it does it whether OD is on or off. and it's not that i'm too concerned about the lag, it's just that i don't remember it being as noticeable as it used to be. i dunno though, it may just be that i'm looking for it and so I notice it more.

shifty_85 · #4 09-30-2008, 02:50 AM

u can check by having ur truck on and open the hood lisen under there and see if you can hear it also look at how your belt looks there might just be some crap in there im noticing when its colder my trucks belt will make a high pitched noise for a lil bit till it gets warm.

porky · #5 09-30-2008, 03:04 AM

yeah we have a front-end loader and an old mack truck that will squeal like that, pretty annoying. i don't think that's the problem on my truck though because the "speed" of the squeak is dependent on the speed of the driveshaft, not the speed of the engine itself, leading me to think its coming from in the transmission. for example, if i put it in drive and have my foot on the brake, as i slowly let off the brake it'll slowly squeak as i roll forward and then it will stop as i brake and stop the truck, all the while with the engine just idling.

shifty_85 · #6 09-30-2008, 03:07 AM

humm werid i have no idea what would make that happen. ask a tranny shop...Whats the fluid loook like?

Mark Kovalsky · #7 09-30-2008, 08:45 AM

That sure sounds like u-joints to me. Have you removed the drive shaft and inspected the u-joints?

porky · #8 09-30-2008, 06:38 PM

so here's an update. i looked at the fan belt and it's cracked down the middle of it, so i'm going to replace the belt. hopefully this will fix the noise when i downshift and the belt is just slipping. it's not quite the belt squeal i've heard on other vehicles though, but we'll see, i have my fingers crossed.

then i took out my driveshaft, the back u-joint was binding, which explained the creaking while driving slow, so i'll replace both u-joints. i usually just checked the u-joints by wiggling the driveshaft and checking for play. that's why i never noticed it was bad, because there's no play at all, but it only grinds when you turn it.

But...just when i thought my problems all had easy solutions, i looked at the tranny output shaft while i had my driveshaft out. There's some slack in the shaft and i can wiggle it probably 1/4" side to side and up and down. Is some slack normal, or is this too much? If this is out of the ordinary, i'm assuming it's the bearing inside the tranny for the shaft that's worn out, right?

Also, when i had my driveshaft out, i started the truck and shifted into neutral. I looked underneath and the output shaft was spinning, is this normal? I heard once that some power might get through the transmission even when it's in neutral, is this true? I tried to see how much power was actually going through, so i tried shifting to park from neutral, but the shaft was spinning too fast and wouldn't let me, so i just shut the engine off in neutral. With the driveshaft put back in and the rear tires off the ground, i tried it again and the tires would start spinning in neutral. anybody else's truck do this?

Mark Kovalsky · #9 10-01-2008, 10:29 AM

There is internal drag when the trans is in nuetral. It will spin the wheels if they are off the ground. When it's REALLY cold outside some vehicles will drive a little bit in nuetral when they are first started. Once the trans fluid warms up it thins and there is less drag. What you see is normal.

shifty_85 · #10 10-01-2008, 11:32 AM

the 1/4" play your feel with the output shaft with the driveshaft out is normal. even after i had my trans rebuild it still had some play in it the tranny shop told me this is because the driveshaft stops the play and with no driveshaft in there it has very lil play. Hope the belt and U-joints fix your prob

Darrin Burch · #11 10-02-2008, 08:44 AM

When you replace that belt, get a Goodyear Gatorback. You won't be disappointed.

Darrin