Yesterday my 93 XL 3.0 decided it didn't want to shift into second gear. It would run first up to almost 30MPH (I backed off at that). I stopped and checked the fluid, but it was full. I turned back toward the house and it shifted, but not until above twenty. By the time I got home, it had shifted on up through the gears. I went back out, and it shifted a little late out of first, then I had no problems. It seems like after it warmed up, I had no problems the rest of the day. This morning, it did the same thing. What gives? I've got 235,000 miles on her. I've only had it for about 80,000 miles, and haven't serviced the tranny. Is it as simple as changing the fluid and filter, or am I looking at bigger problems? When I checked the fluid, it was full (maybe even too full) and still red, not brown or otherwise burnt-looking. Please help.

 

I suspect a modulator problem for two reasons:

1) It's cheap to replace

2) You have a 3.0L where the modulator sits unprotected next to the Catalytic Converter.


Also, is the engine pinging when you go uphill or when the car is under heavy acceleration? If so, it's almost definitely the modulator. If not, check the vacuum line going to the modulator. Open the doghouse panel inside the van, pull the vacuum line at the vacuum tree and apply vacuum there to see if you have a leak.

Good luck

 

What is the "vacuum tree" and what does the modulator look like? Also, how do I "apply vacuum"? I hate to sound clueless, but if the shoe fits . . . .

 

The vacum tree is where all the vacum hoses for the van meet its a cluster of rubber hoses together.

The modulator is a round metal can mounted near the cat that has a vacum hose connected to it.

Why you should apply vacum to the hose is if the hose has a crack and its leaking the engine vacum isn't getting to the modulator and this could also be causing your problems.

 

i think you can also pull the vaccuum line on the modulator and see if it is sucking up any fluid into the line, if there's fluid in the line(on the bottom end) it's toast

 

And don't forget to change your oil and filter afterwards its not good for the engine having that tranny fluid in there.

 

I'm still confused. HOW do I "apply vacuum"? And, what if the modulator and vacuum lines all check out okay? Can I "apply vacuum" to all the other lines to check them? How difficult is it to replace all the vacuum lines. I assume most of them are original. 12 years and 235,000 miles might be too much for a cheap rubber/plastic hose.

 

I agree with the modulator theory, but now its my turn to sound "Clueless"... If the tranny fluid was getting sucked through the modulator hose into the intake plenum, how would it end up in the engine oil??
Am I missing something?
Seems to me it would end up getting burned up in the combustion chamber.

 

Hi Aerocook:

Some of it will leak past the rings and end up in the oil pan. Actually, someone here reported that he gained a quart or two between oil changes just from the modulator leak. I can't find the thread, but that's what I remembered.

CharlstonSC:

You apply vacuum with a hand vacuum pump you can borrow from Autozone or purchase for perhaps $20 from any autopart stores. Instead of checking the vacuum, it might be easier to just replace all the rubber vacuum lines in the engine compartment if your engine has such a high mileage. The modulator has two segments of rubber lines at the two ends and they are connected by a steel line. So, as far as the modulator is concerned, you must replace the rubber on both ends of the steel line. Even then, the diaphragm on your modulator may be broken, in which case it must be replaced.

 

Thanks! I've got a good idea of where to go and what to do. Now I just need to make the time to do it. You guys have been a big help.

 

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Good luck. Keep this in mind, too, about vacuum lines, rubber. Certain types of lines get brittle, in which they become porous, so if they have a small curve in them (new) when they are old, that curve can become a partial "kink", causing engine problems. Some vaccuum hoses, become weak, after heat and 210,000+ miles. They actually will collapse, causing restriction, when hot. You have no clue, because you are driving, not inside a hot, dark, engine compartment! Some of these hoses, after cooling, will then appear normal. But what it's doing, with age, is actually the same thing as if you took your thumb and index finger, and squeezed the hose. It only takes one hose doing this, to cause problems. The solution, as others have said, replace all of the vaccuum hoses. Take your time. Don't make this a hurried job, for obvious reasons. It is also a good idea, to have a hose routing diagram. Why? You might be surprised, on high mileage vehicles, I have seen where a small vaccum hose (1" - 1 1/2") might come off, completely, and you don't even know it's missing! But a proper diagram, will show you where everything goes, and what hoses you should have. Some California certified, vehicles, are slightly different too, that Federal vehicles. Same with if you have a "high altitude" or "Low altitude" certified vehicle. Lastly, when changing your vacuum hoses, buy one of those "Hose T" assortment packs. Nothing is worse than finding your "three into one" nylon plastic connector has suddenly snapped, or cracked, from 200,000 miles of use, and you don't have a spare. Many of those small "T" connectors are as important as the vacuum hose itself! Again, good luck...and take your time! It isn't a hard chore, and then you'll be good for another 200,000 miles, with your nice running Aerostar! ED