Tranny trouble; 94Chev PU

tinknal · #1 12/21/10, 05:32 PM

I'm worried about this one. 4 speed automatic (3 speed w O/D) 460E transmission (yeah, I know). first and second gear are fine. As soon as it tries to shift into third it slips. Have to run very high RPM to get it to a speed where it will go into OD, where it still slips, but will get to around 50 MPH at 3000 RPM. I've found that if I run it to about 40 MPH in second I can skip third.
I put in a bottle of Lucas. It was low which is funny because it has never had a leak and maintained level so well that I got out of the habit of checking it as often as I should (yeah, I know).

To compound matters, right now I so broke that if it cost a Nickle to take a dump I'd have to throw up.

Beeman · #2 12/21/10, 09:39 PM

Does the fluid look and smell burnt? Ther's no fix in a bottle for a bad clutch pack and burned clutches. The good part is the trans are cheap at junk yards, local shop buys them at pull a part for $62 each.
One thing to physically check is the throttle valve cble. look where your accellerator cable attaches to the throttle body(air intake). This cable is adjustable and if it has slipped or off it will cause erratic shifting. Your trans doesn't use a vacum modulator and should be all mechanical except for torque converter clutch.

**Roadking** · #3 12/21/10, 09:58 PM

Constant, or just when not up to temp? Being in MN, you are a bit colder than some...might need a flush of the old and a cleanout with fresh fluid instead of putting some more stuff with the old. Just a thought.
If only when cold, block heater. Does wonders for my 95 'Burban.
Matt

tinknal · #4 12/22/10, 05:59 PM

It is constant. I put this tranny in (used) 2 years ago. It has about 20,000 miles on this filter and fluid. The throttle seems to work fine.

I should add that it is not catching in OD, for some reason when it gets up to about 35mph and I back off the throttle for a second it drops back into second and stays there as long as I keep the speed up. If I drop below 35 it pops back out of second and slips again. I have about a 20 minute ride to work and I have just been driving in second.

Beeman · #5 12/23/10, 10:03 PM

If there is no TV cable at the throttle body it would be an electronically controlled trans, 4L60E. Is the check engine light on? Has it ever been on? The shifting of the trans is controlled by inputs from engine sensors and trans sensors and the vehicle speed. The PCM then controls solenoids in the trans to make it shift.
To diagnose properly I would hook a scan tool to it and look at codes and data then control the trans manually with the scan tool.

tinknal · #6 12/23/10, 11:25 PM

Quote:

Originally Posted by Beeman

If there is no TV cable at the throttle body it would be an electronically controlled trans, 4L60E. Is the check engine light on? Has it ever been on? The shifting of the trans is controlled by inputs from engine sensors and trans sensors and the vehicle speed. The PCM then controls solenoids in the trans to make it shift.
To diagnose properly I would hook a scan tool to it and look at codes and data then control the trans manually with the scan tool.

Yeah, it is 4L60E. The check engine light does come on when it idles warm for a bit, but it always has. Are there any fuses or relays that could affect this?

Beeman · #7 12/24/10, 12:06 AM

Really can't think of a fuse/relay that would cause your problem. Check engine lite is the first place to start.

tinknal · #8 12/24/10, 11:27 AM

Quote:

Originally Posted by Beeman

Really can't think of a fuse/relay that would cause your problem. Check engine lite is the first place to start.

As I said, the check engine light acts as it always has. It comes on when at warm idle for several minutes and goes away as soon as I accelerate, probably O2 sensor or something like that. I'm going to crawl under and check things out today.