Somethings chirping and its not pulleys..

[Wishmeluck]

84 Bronco, rebuilt 351w (literally only 50 miles on it) with the oiriginal C6 tranny. This little chirp has developed the last couple days from where the tranny mates to the engine and its driving me crazy. It seems to go away when the rpms are up past 10-1200 (either that or I just cant hear it over the engine rev). Doesnt seem to affect drivability, not that Ive driven it that far yet, but it sure is annoying to listen to when sitting at idle. Ive checked all the bellhousing bolts, flywheel to tc, starter, exhaust, even took a screwdriver and pushed/pryed on a few things trying to locate it. Any thoughts on what could be causing this??

https://flic.kr/p/2pdHzuF

 

[miesk5]

Yo Wishmeluck,
Another Bronco owner had this chirp had this chirp:

 

[L\Bronco]

84 Bronco, rebuilt 351w (literally only 50 miles on it) with the oiriginal C6 tranny. This little chirp has developed the last couple days from where the tranny mates to the engine and its driving me crazy. It seems to go away when the rpms are up past 10-1200 (either that or I just cant hear it over the engine rev). Doesnt seem to affect drivability, not that Ive driven it that far yet, but it sure is annoying to listen to when sitting at idle. Ive checked all the bellhousing bolts, flywheel to tc, starter, exhaust, even took a screwdriver and pushed/pryed on a few things trying to locate it. Any thoughts on what could be causing this??

https://flic.kr/p/2pdHzuF

Hey wishmeluck
Hard to ID from the clip.
This is going to sound weird, but see if it stops when you remove the oil filler cap.
(I have had a weird chirping sound caused by too much vacuum in the crank case. One was a PCV valve that blew apart and the other was insufficient vent side flow caused by aftermarket valve covers.)
It pulls the rear main seal hard against the crankshaft causing a weird chirping noise.
Is it louder beside the truck or under? Maybe try another vid from the side.

Hope that helps, good luck.

 

[Wishmeluck]

Thanks! Its definately louder under the truck. Seems to be the loudest in the area where the transmission meets the engine, almost like the flywheel warped somehow and grazes something everytime it rotates around to that spot. Have a break in the rain the next couple days so I'm going to use a mechanics stethascope and try and see it I can pinpoint exactly where its coming from and tinker with it some more.

Will try removing the breather cap today too and see if that cures it.

Stay tuned.....

 

[Wishmeluck]

Well, started the Bronco and it didnt chirp at all for the first 10 seconds or so, then slowly started chirping again. I pulled the breather and nothing changed. Took the stethoscope and listened everywhere but could not find one thing that sounded off or chirped. In fact, everything sounded great.

Then I got to thinking (very dangerous I know)...and the flywheel has a weight thats welded on but has small seems around it, and I dont have an inspection cover on the trans. I held a piece of cardboard up to block off where the inpection plate would normally be and the sound when almost completely away.

The noise did just start when the colder weather hit, and I'm wondering if its some weird uneven thermal exansion thing thats causing a chirp everytime the air gap from the weight hits the colder air? I dunno...but I'm going to go get an actual inspection cover plate for it today, blow out whatever dirt might have flowin in there, and bolt on the cover to see to see what happens.

 

[Wishmeluck]

Well, I dont think its my flywheel anymore. After taking it for a drive I have a feeling its either my torque converter or the trans pump. After reassessing when I got home it definately sounds like the noise is coming from the bellhousing. I mean, 40 year old tranny and I guess whats to be expected, right?

But now all this leads to a different question...rebuild the C6 or find an AOD for the overdrive? This won't be a wheeler. I plan to take it on random road trips (my dream is a hwy 101 trip from WA to Cali to drive it on the sunny southern beaches a bit), and it will tow a 2-3k trailer very occasionally. Ive heard/read horror stories about the aod behind a 351w, puking out fluid after playing on the beach, blowing up while someone stomped on it, etc, and I will admit theres something very attractive about a straight forward replacement. But 3000 rpms @ 70 is kinda loud and filling that 33 gallon tank all the time isn't going to be fun....Ugh, so many things to consider.

Why couldnt Ford just make a powerhouse mechanical overdrive instead of making all our lives miserable with having to choose???

 

[Tiha]

I would say AOD just for the reduction in noise level alone.

If you want to work it like the old C6 on the beach or at low speeds it will take some upgrades. You can't just slap an old used one in there.

Anytime the torque converter is unlocked it creates a lot of heat. So the lower speeds it what burns them up. Mud, loose sand. Long steep grades.

Trans temp gauge is advised. You will know LOL.

 

[L\Bronco]

Well, I dont think its my flywheel anymore. After taking it for a drive I have a feeling its either my torque converter or the trans pump. After reassessing when I got home it definately sounds like the noise is coming from the bellhousing. I mean, 40 year old tranny and I guess whats to be expected, right?

But now all this leads to a different question...rebuild the C6 or find an AOD for the overdrive? This won't be a wheeler. I plan to take it on random road trips (my dream is a hwy 101 trip from WA to Cali to drive it on the sunny southern beaches a bit), and it will tow a 2-3k trailer very occasionally. Ive heard/read horror stories about the aod behind a 351w, puking out fluid after playing on the beach, blowing up while someone stomped on it, etc, and I will admit theres something very attractive about a straight forward replacement. But 3000 rpms @ 70 is kinda loud and filling that 33 gallon tank all the time isn't going to be fun....Ugh, so many things to consider.

Why couldnt Ford just make a powerhouse mechanical overdrive instead of making all our lives miserable with having to choose???

2 things,
1st, I am thinking your noise is a rear main seal that wasn't fully installed rubbing on the flex plate. (Seen that one a few times)
2nd, they did make a powerhouse auto O\D, its a 4R100. Unfortunately, its not easy to get one mated to a 5.8 and you need a controller to run it.
(Thats why my 79 is a restomod) I had the same inner monolog running when I decided to go big on mine. And...no regrets!


(Its fantastic by the way, tons of work though)
There was a company years ago (Mile Maker) that made a mech O/D that bolted to the trans. They were tough as nails, but no provisions for 4wd.
Tiha is right, heat from the torque converter is what murders most automatics.
An AOD can be built to stand up to "fun" plus I'd add a trans cooler from a Superduty with a torque shift. (Roughly the size of a rad), to help out.
Good luck
Cheers