Transmission slip / gear won't engage

Vaximily · Aug 30, 2015

Yesterday it started losing power, maybe a dead injector... Also had a big smoke cloud for about 2 minutes while parked slightly downhill, from the exhaust pipe under the main engine compartment.

This morning it won't properly engage drive, overdrive, or reverse... Orf i rev the engine it'll eventually catch and give me some movement briefly but then it slips again and i lose all drive power.

Any quick ideas? It's sitting in my sisters driveway at the moment, I'm about half an hour drive from home.

1989 Ford Ranger 4x4 XLT Automatic 2.9L V6

Thanks in advance!

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Vaximily · Aug 30, 2015

Forgot to mention, I've had it parked downhill now for over 5 minutes while writing post, no smoke yet... Yesterday i assumed it was from an oil leak dripping on to the exhaust but wouldn't that mean it should do it now?

Oil pressure was reading 60 when i first started it, now back down to 5 (which is normal when it's idling from what I've seen in the past, it jumps up to 20-40 when accelerating usually)

Not sure what that means.

Going to keep testing it in this cul de sac to see if it improves as it warms up.

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Vaximily · Aug 30, 2015

Got it up to 45 on a side street, seems to have helped with the slipping, gears engage almost normally now, but instead the smoke is back and billowing heavily from the tailpipe and engine compartment, roughly from what i think is below the intake manifold, in the area shown in the bottom half of the picture.

At this point afraid to drive it anywhere...

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Vaximily · Aug 31, 2015

Managed to get the truck home last night... it would slip out of gear periodically (scary thing at 55mph when the engine suddenly redlines) and I'd have to play with it to get it to catch again.

I replaced the PCV Valve based on info found in other posts, and noticed oil in one of the vacuum lines running into the intake manifold.... Smoke seems to be less since replacing the PCV valve, but not completely gone even after a ~20 mile drive.

I'm completely stumped at this point... don't even know where to start.

Andy D · Aug 31, 2015

What does the ATF look/smell like? I have zero knowledge of this particular trans. But I had 727 behave like this from a clogged filter. A leaky line could be running it out of ATF .

Vaximily · Sep 1, 2015

Andy D said:
What does the ATF look/smell like? I have zero knowledge of this particular trans. But I had 727 behave like this from a clogged filter. A leaky line could be running it out of ATF .

I put half a quart of ATF in it before driving home yesterday, now the dipstick is virtually dry again, so I'll start digging into those possibilities.

The smoke seems to be gone. . . even reconnected the suspect vacuum line that the oil appeared to be coming from and it still didn't start smoking again, so hopefully that means the PCV valve fixed that problem after all.

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Vaximily · Sep 1, 2015

OK, I've been digging around online for about an hour now and I can't seem to find any good diagrams of the overall Transmission setup (even the Autozone repair manuals are lacking on this one).

Can someone point me in the right direction so I know what I'm looking for and where to check for leaks / bad parts? That fluid has to be going SOMEWHERE.

Big Jim M · Sep 1, 2015

If the fluid ain't on the driveway then you are burning it! The only way to burn it is thru a vac line.
Big Jim

Vaximily · Sep 1, 2015

Big Jim M said:
If the fluid ain't on the driveway then you are burning it! The only way to burn it is thru a vac line.
Big Jim

I slid a piece of plywood under to check for drips, added the last 6 ounces of ATF i had left and haven't noticed any drips yet...

Would the PCV Valve going bad cause ATF to be pulled into the vacuum lines and burned in the intake manifold (maybe using the wrong terms here)?

If so, in theory, now that I've replaced the PCV Valve, the burn off should stop and all I'll need to do is refill the ATF once i pickup another quart. (How much ATF does this thing even take?)

But surely it can't be that simple... Can it?

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Spott · Sep 1, 2015

There's another possibility; perhaps the ATF is leaking out of the "oil" cooler. The cooler is like a little radiator for the transmission fluid, and it's located inside the end of the actual radiator, so that heat from the transmission is dissipated into the coolant and cooled by the radiator.

If the oil cooler leaks then ATF will get into the coolant system, or coolant into the transmission, and cause problems.

Open up your rad cap and see if there's any discoloration of the coolant. Also, if you're losing pints and quarts of ATF, you'll see your overflow tank filling up noticeably (unless it leaks). Also look for "snot" in the transmission fluid or on the AT dipstick.

If everything I mentioned is clean then your ATF isn't leaking into the coolant.

Vaximily · Sep 1, 2015

Spott said:
There's another possibility; perhaps the ATF is leaking out of the "oil" cooler. The cooler is like a little radiator for the transmission fluid, and it's located inside the end of the actual radiator, so that heat from the transmission is dissipated into the coolant and cooled by the radiator.

If the oil cooler leaks then ATF will get into the coolant system, or coolant into the transmission, and cause problems.

Open up your rad cap and see if there's any discoloration of the coolant. Also, if you're losing pints and quarts of ATF, you'll see your overflow tank filling up noticeably (unless it leaks). Also look for "snot" in the transmission fluid or on the AT dipstick.

If everything I mentioned is clean then your ATF isn't leaking into the coolant.

This doesn't APPEAR to be the issue, nothing looks out of the ordinary, but I'll keep an eye out.

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snake · Sep 1, 2015

Does this have a modulator valve on the transmission? If it has a vacuum line going to the rear of the tranny pull that line and see if it has fluid in it. it should be dry so replace the mod valve if so equipped and not dry. Past that the transmission can leak from the rear main seal at the driveshaft, the pan, lines, front seal or front pump seal or even the dipstick tube. Running it low on fluid will destroy it so keep it topped off until you can find the issue. Why the engine was running crappy the day before is a clue but I can't think of how they could be related unless the transmission was horrifically over full and it finally blew the excess out of the pressure relief valve

Vaximily · Sep 1, 2015

snake said:
Does this have a modulator valve on the transmission? If it has a vacuum line going to the rear of the tranny pull that line and see if it has fluid in it. it should be dry so replace the mod valve if so equipped and not dry. Past that the transmission can leak from the rear main seal at the driveshaft, the pan, lines, front seal or front pump seal or even the dipstick tube. Running it low on fluid will destroy it so keep it topped off until you can find the issue. Why the engine was running crappy the day before is a clue but I can't think of how they could be related unless the transmission was horrifically over full and it finally blew the excess out of the pressure relief valve

I don't even know what a modulator valve is but I'll start investigating lol. Just added an entire quart of ATF and no change, so it's either tremendously OVER full (which i don't think it is) or was very very low.

The dipstick is hard to read but it looks like it's finally starting to get up near where it should be. Taking a break for dinner and then I'll check it again.

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enjr44 · Sep 3, 2015

According to the tech section this truck has a A4LD transmission. So, being hyd controlled I would bet it has a modulator valve.

Look at the pictures here http://www.therangerstation.com/tech_library/AutoTrans.shtml and I think you can see the modulator valve on the right side of the trans. That valve will have a vacuum line connected to it.

Now if that valve fails, the engine will suck trans fluid out of the transmission and burn it (smoke sometimes, sometimes not). And depending on how big the hole in the valve diaphragm it can suck a hell of a lot of fluid. It will also mess up the way the transmission shifts.

Don't let this go. Fix it. If you keep jacking around you can expect a $2000 dollar trans job in your future!!!

Vaximily · Sep 3, 2015

enjr44 said:
According to the tech section this truck has a A4LD transmission. So, being hyd controlled I would bet it has a modulator valve.

Look at the pictures here http://www.therangerstation.com/tech_library/AutoTrans.shtml and I think you can see the modulator valve on the right side of the trans. That valve will have a vacuum line connected to it.

Now if that valve fails, the engine will suck trans fluid out of the transmission and burn it (smoke sometimes, sometimes not). And depending on how big the hole in the valve diaphragm it can suck a hell of a lot of fluid. It will also mess up the way the transmission shifts.

Don't let this go. Fix it. If you keep jacking around you can expect a $2000 dollar trans job in your future!!!

It did indeed turn out to be the Modulator Valve! I guess the PCV Valve either wasn't bad or was just another of many issues. Got it replaced last night, added somewhere in the range of 4-5 quarts of ATF, and now it's running and shifting better than ever! ?

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Transmission slip / gear won't engage

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