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I’ve been working on this Blazer here and there for the last month or so. When I started working on it, it had been sitting for at least a year and a half before I got it running again. It’s a four speed automatic with four wheel drive, so I’m guessing it’s a 4L60 transmission. Any time when shifting from park to drive or reverse to drive, the engagement into drive is slow. Reverse will always engage within a half second, but engagement into drive is at least a second and a half to two seconds. In normal driving, I will always let it engage, I can feel the engagement, the engagement feels strong, and I get no slippage on take off. I feel no flares during any upshifting and no slipping in any other gears. In testing for this concern, I did shift into drive and throttled a couple times without waiting for engagement. The gear bangs into engagement and the truck launches hard like this.
I have my bottle of snake oil sitting on my desk in front of me while my conscience is chewing on my face telling me I know better. So, I need some advice and opinions about how to fix this the right way and return the snake oil.
Thanks in advance.
**Edit: I went back out and tried shifting from reverse straight to manual one, two, & and three gears. Manual one engages right away and feels great. Two and three feel better but still kinda iffy.
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Not yet. The fluid is really clean on this one so I’m not ready to go in this time without probable cause.
This says it better and faster than I can… Essentially, pump pressure may be an issue…
http://www.hotrodders.com/forum/4l60e-slow-engage-1st-reverse-175284.html
-Karl
It’s funny ToyotaKarl mentioned pump pressure because I was thinking something with the pressures might be causing the problem. I think you can rule out the shift cable adjustment because the other gears seem to engage normally. That leaves a pressure problem as a possible cause. It sounds like it needs to build up pressure before it engages. This could mean there’s a leak somewhere inside the transmission causing this problem. You might try the ‘snake oil’ as you probably don’t have much to loose at this point. More info on solving transmission problems here.
http://www.ericthecarguy.com/faq/solving-transmission-problems
Keep us posted and good luck.
So I did find a time and place to test line pressure on the Blazer. Here are some numbers for you to chew on.
Drive, park, & nuetral spec is 55-189 PSI. Actual pressure was 65 PSI in all said gears including manual one, two, and three. Manual two has a wierdness I’ll tell you about in a moment.
Reverse spec was 64-324 PSI. Actual pressure was 90 PSI.
Manual two flashed a 90 PSI reading at me once & I didn’t stop to pay more attention right away. I cycled through the gears a few more times and all my forward gears held 65 PSI. I decided to power brake the gears and they all started to gain pressure in the twelve to fifteen hundred RPM range and then I decided to cycle through the gears again unloaded. This time, I could consistently get 90 PSI out of manual two.
Does this help anybody explain the root problem?
Here’s the next problem with this pile of disappointment. The pressure tap is about halfway up the side of the case and it’s a little tough getting the gauge hose threaded into that tap. I had to pull off the transmission range switch so I could get my fat hands up to feed the hose in. There was no stress on the cable or the shift linkage in removing or reinstalling any parts. Yet at the end of this testing, I lost park. I figured out that the shift cable will pull down through all the gears just fine, but it can’t quite push the shift linkage all the way back into park. The shifter inside the transmission is just fine and the end of the cable is fully extended without a fight when I shift the truck into park by hand from underneath. There is no feel of binding within the cable. I was using a friend’s shop for this and he told me he’s experienced the exact same failure with another piece of GM junk. A new shift cable resolved his problem.
What I’m wondering is if anybody knows exactly why that cable, without feeling broken in any way, can pull the linkage all the way down, but can’t push the linkage all the way back up?
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