C6 transmission problem

1987moneypit · Sep 5, 2007

my 1987 bronco (5.0)302 4x4 is slipping in 1st gear between 1700 and 2400 rpm's and then will shift to 2nd. i have changd the filter, modulator,used lucas additive and sea foam. when i changed the fluid out, there was a sludge in the pan(not metal shavings) is there a linkage that i can adjust, or a vacuum besides the modulator? any suggestions will be helpful. thank you

gatorbronco · Sep 6, 2007

Sounds to me like a more serious mechanical problem. Had the same type of problem with my AOD and it was a cracked housing and blown torque converter. Granted I did take a turn on two wheels to cause the problem... :-"

1987moneypit · Sep 9, 2007

did it cause a leak on the seal where it meets the engine?

mine has a very slow leak, and it drives very sluggish in anything other than 1st.what little bit of 1st that i can use....

thanks for replying.

miesk5 · Sep 10, 2007

yo, I had written a lot in a reply here, but this lousy lap top shut down.....am on road now. so look C6 tech Links page

http://www.broncolinks.com/index.php?index=786

miesk5 · Sep 10, 2007

miesk5 said:
yo, I had written a lot in a reply here, but this lousy lap top shut down.....am on road now. so look C6 tech Links page
http://www.broncolinks.com/index.php?index=786

will hit Reply button after a few secs to ensure I get you info before this effin lt shuts down

C6 Trouble Shooting Flow Chart Source: by jasperengines.com via web.archive.org

miesk5 · Sep 10, 2007

C6 Modulator, Diagnosis & Replacement in an 89; The different color bands indicate the diamater of the rubber diaphragm inside the modulator. The two COMMON colors from auto parts suppliers are PURPLE and GREEN. These are for CARS. TRUCKS like OURS REQUIRE the BLACK banded modulator, likely from a transmission shop or dealer. This is reguarding the mid/late 80's models, maybe more... Id venture to say any C6 with a slip in modulator. Again, PURPLE and GREEN are NOT the correct units to use, BLACK is the intended modulator as was designed for TRUCKS. by MyFullSize

miesk5 · Sep 10, 2007

C6 Vacuum Modulator Troubleshooting; You have a modulator on the rear of the transmission on the C4 / C5 and the C6 units. The modulator is on the passenger's side of the transmission on the C3. Pull the vacuum line off the mod. If fluid comes out of the vacuum line your modulator is not good.

Source: by usatransdoctor.com

http://www.tciauto.com/Products/Components/modulators.asp

C6 Adjustable Vacuum Modulator; The vacuum modulator is a vital component of an automatic transmission. It tells the transmission what kind of load is being put on it allowing the transmission to react with the proper line pressures and shift points. Over time, modulators can develop leaks, get ruptured diaphragms, get bent, etc. Not only can this cause annoying drivability issues, it can lead to premature transmission failure.

Source: by tciauto.com

miesk5 · Sep 10, 2007

C6 Vacuum Modulator Adjustment; Stock factory modulators are pre-set and most are sealed. TCI

miesk5 · Sep 10, 2007

C6 Shift Linkage Parts Break-Out Diagram in an 88

Source: by Dustin S (Dustball, Mellow Yellow, Mr. Laser Boy) at ylobronc.users.SuperMotors.net

1987moneypit · Sep 10, 2007

miesk5 said:
yo, I had written a lot in a reply here, but this lousy lap top shut down.....am on road now. so look C6 tech Links page
http://www.broncolinks.com/index.php?index=786

thank you for all of your help. i am going to re-replace a new modulator and see what that does. so do you think that a modulator would effect only 1st gear though? seems kind of strange. i'll see what happpens. thank you again.

C6 transmission problem

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96 Bronco 5.0

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