Using tranny fluid - no leaks

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Jun 15, 2009 | 08:42 AM

Red92Ranger4x4

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Using tranny fluid - no leaks

I'm stumped. My '92 Ranger 4x4 (2.9L V-6) is using transmission fluid. I follow the dipstick recommendation and put in Mercon but after a couple of tanks of gas I notice the tranny fluid is low.

I haven't noticed any leaks in the driveway or any other signs of leaks but it seems to me it may be burning(?) tranny fluid somehow. What I thought could be old valve stem seals - it 'puffs' white smoke when I start it up sometimes - has me thinking may be tranny fluid somehow. The truck doesn't 'use' oil between changes and shifts a little hard but with 250,000+ miles I'm not complaining, except when I notice it starting to slip and check the tranny fluid to find its down a quart or so.

Could it be sucking tranny fluid through a vacuum hose into the intake somehow? I can't see where there would be anyway where tranny fluid could be burned, if thats the case.

I'm stumped!

Last edited by Red92Ranger4x4; Jun 15, 2009 at 08:43 AM. Reason: spelling error

Jun 15, 2009 | 10:19 AM

Bear River

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From: Salt Lake City, Utah

'94 and older systems use a vacuum modulator to help control shifts based on engine load. If this diaphragm ruptures, the fluid will be drawn into the engine to be burned. No visible leaks will be found. This is why the diaphragm is listed as a maintenance item and should be replaced every other fluid change.

Jun 15, 2009 | 11:33 AM

Old93junk

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From: McKenzie River

Yep, the white smoke at start up should be a dead give away! The modulator is on the way out, easy replacement job....Its burning the trans. fluid all the time, just not enough to see in the exhaust except at occasional start ups.

Jun 15, 2009 | 08:36 PM

pawpaw

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From: SW Va

I agree, with no visable leaks, it sure sounds like the tranny vacuum modulator.

To confirm, remove the modulators vacuum hose at the intake manafold fitting & see if it's wet inside with tranny fluid, if so, the modulators diaphragm is ruptured & engine vacuum is pulling tranny fluid out through the vacuum line & the engine is consuming it.

I'd also have the O2 sensors switching speed checked, as having the engine process tranny fluid isn't good for them.

More thoughts for consideration.

May 18, 2011 | 01:39 PM

nd925

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I know this is an old post but I found this post and it seems my Ranger is doing the same thing. Could this same thing happen on a 98 Ranger 3.0? I have similar symptoms. Oddly enough my sons 2000 Taurus is doing the same thing. He is actually blowing smoke all the time though. Oil is clean so I don't think it a head gasket. I can't find a vacuum modulator at Auto Zone.com for either vehicle. Could it be something else?
Thanks in advance.

May 18, 2011 | 02:32 PM

pawpaw

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From: SW Va

Quote:

Originally Posted by nd925

Your Ranger & your sons Taurus have computer controlled transmissions, so no they won't have a tranny vacuum modulator.

A clogged up PCV valve can cause an over pressure condition in the engine crank case that can push motor oil past seals & into the combustion chamber.
Worn valve stems or stem seals, worn or broken piston rings, using the wrong viscosity or service grade motor oil, or overfilling the crank case can cause smoke problems too. I'm assuming your problem is engine smoke, but not dropping tranny fluid levels.....right????

So we need some more clues to make a more focused guess as to whats likely wrong.

May 20, 2011 | 06:01 PM

nd925

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Yes engine smoke. I'm not dropping any trans fluid. I'm going to check on the PCV valve, maybe I inadvertently did something to it when I was changing the back 3 spark plugs on his car. Just changed the oil too but checked the level and it was right on. Thanks for the feedback pawpaw. Any other info I can give to help figure it out?