C6 shifts at 4500rpm.

Sycostang67 · #1 (**permalink**) 10-26-2009, 03:01 PM

I've only recently been able to drive my 86 F-250. I'm not a fan of autos and haven't had to work on one in a long time. I have noticed that when driving, my C6 wont shift until it's about 4500rpm under mild accelleration. If I release the pedal, it will shift. It just seems like it's waiting a long time to shift during regular driving. The trans only has about 60k miles, I did verify the vacumn lines were intact to the modulator and the kickdown rod is still in place. Stupidly though I still haven't checked the fluid level. I need to pull the pan anyway as it has a good dent in it, gonna put in a new filter in as well. Would a low fluid level cause this? I was also wondering which way to adjust the modulator to make it shift sooner.

Lazy K · #2 (**permalink**) 10-26-2009, 04:32 PM

Pull the vacuum pipe off the modulator and look for signs of Fluid in it. If you find any replace the modulator.
Low fluid may be a cause.

Sycostang67 · #3 (**permalink**) 10-26-2009, 09:21 PM

I did check that, and the hose was dry. I was going to check the fluid today, but the weather sucks and I got lazy. If the weather changes tomorrow, I will check the current level before I drop the pan.

fatboyf150 · #4 (**permalink**) 10-27-2009, 10:14 PM

sounds like you need to adjust the modulator. pull the vac line off and look down the tube. you should see a little turn screw.

Sycostang67 · #5 (**permalink**) 11-03-2009, 03:16 AM

Which way do I turn the screw to bring the shift points down?

I finally changed the filter, the fluid didn't smell to bad but was a little browner that I hoped. The pan was clean as was the old filter, no shavings of any kind. I wasn't able to drive it yet as I had to pull the alternator to get it tested. Should have it going again tomorrow.

Lazy K · #6 (**permalink**) 11-04-2009, 08:55 AM

Have you definately got vacuum at the pipe? With trans in Park and engine running pull the pipe off at the trans, does the engine note change? If so vacuum is good and modulator is not leaking.
Next I would be thinking of pulling the vacuum modulator and applying a vacuum to it and see if it is working.

Sycostang67 · #7 (**permalink**) 11-04-2009, 11:17 AM

Ok, I'll check out the vacumn and the modulator. I did drive the truck today, fluid level is now verified but it drives the same as before.