2nd blown modulator

Angie · Dec 30, 2012

2 months ago I changed the modulator because it was blown. the vac line was plugging up with fluid and white smoke billowed and i mean you couldn't see 10 feet behind the tail gate for smoke.

The parts shop only had adjustable ones so I got 2. I redneck fixed it by cutting open the floor boards (92 truck who cares) swapped in the new modulator and plumbed in a small clear line fuel filter to keep an eye on the colours for future references.

couple days back she started to show signs of white smoke again... by the time I parked at home and checked under the hood... sure enough the filter was solid red with pooling fluids....

Question...... what causes the modulator to screw up? and is there a proper way to adjust these for the shifting? she shifted nice and smooth through all the gears so I was guessing she was set up ok...

any thoughts and advice will be greatly appreciated... thanks

pics to follow when i get motivated today....

Tedybear · Dec 30, 2012

Forgive me for saying this: Most of the time if a part fails fast? Cheap China Crapola.

Not made anywhere near the standards they should be.

As for the white smoke? That's normally a sign of coolant leaking into the engine. Can someone else get ideas on this? I've not seen white smoke from an engine ingesting oil before?

S-

kimcrwbr1 · Dec 30, 2012

+1 one the cheap modulator unless you have problems with the valve body in the tranny. Being it shifts good get a new modulator if it happens again you need to check the control pressures or have a tranny shop do a diagnostic.

Angie · Dec 30, 2012

definitely smoke.

i swapped in a new one and it still smoking so will need to see what happens. will be calling a trans shop in morning to see what they suggest... if anything over a couple hun i will just by a different truck and swap motors.... lol

thanks guys any other suggestions will be great.

Angie · Dec 30, 2012

kimcrwbr1 said:
+1 one the cheap modulator unless you have problems with the valve body in the tranny. Being it shifts good get a new modulator if it happens again you need to check the control pressures or have a tranny shop do a diagnostic.

how do i check the control pressures? ya it was shifting nice till this. even now it is not nice but i need to check oil level i think it is low and i think it sucked in a ton into crankcase so i might need to change motor oil too... had to do that last time also.

White smoke is 100% burning transmission oil, not steam/smokey from coolant

alwaysFlOoReD · Dec 30, 2012

I just finished watching a car repair show and on the first start the vehicle smoked like a sonabitch. It ended up being a bad modulator. This is the first I've heard of this so when I found your thread I was kind of dumbfounded. The explanation they had is that the modulator uses engine vacuum to work. If the seal in the modulator breaks the trans fluid works its way into the combustion chamber and burns, causing LOTS of bluish white smoke, just like you're experiencing. It may take a while to burn all the trans fluid off as there are pockets in the manifold that will hold fluid until it gets hot enough to vaporize off.
As you mention, you should check the trans fluid level. I don't see it getting into the crankcase, unless I misunderstood the explanation the show gave. But that engine was a mid '50's cadillac.
As far as your other questions I can't help, sorry.
Good luck,

Richard

Angie · Dec 30, 2012

hey floored, yea it is a bit of a head scratcher for sure. the first one i replaced was for sure blown. i could suck and blow bi-directional into it after i had it out. on the second one i did today it seemed fine in that regards. only 1 way direction... i will let it run for a while tomorrow and plumb in a new filter to see if this one is also letting fluid through it. did they say on the show if there was anything in the tranny that could have caused the oil to flow into the vacuum? or is all from the modulator?

alwaysFlOoReD · Dec 30, 2012

From what I understand it's from the modulator. They pulled the line from the modulator and trans fluid drained out, a sure sign of a bad modulator. I think the line goes to a manifold vacuum source. That's how it gets sucked into the manifold and then into the combustion chamber. I'm not too familiar with transmissions but I think that would be the only route in to the motor.

Richard

Tedybear · Dec 31, 2012

It's a quick way to suck transmission fluid into the intake of the engine. The rubber piece inside the modulator cracks/splits...and the vacuum of the engine slowly sucks it up the tube into the intake. It normally should last a long time, but do we REALLY know where our parts come from anymore? Most of the time the stuff I purchase either says "Made in China" or "Assembled in Mexico". Disgusting.

I can see where that smoke would be white/blueish. Might be just as easy as driving it/running it for a short while and seeing if it stops on it's own, given that it probably still has fluid left in the tubing and intake. Kinda like being flooded out with gas--but this time it's trans fluid.

S-

Tedybear · Dec 31, 2012

Angie said:
how do i check the control pressures? ya it was shifting nice till this. even now it is not nice but i need to check oil level i think it is low and i think it sucked in a ton into crankcase so i might need to change motor oil too... had to do that last time also.

White smoke is 100% burning transmission oil, not steam/smokey from coolant

There is a plug port (a port with a plug stuck in it). You can purchase an oil pressure tester that is made for testing transmission pressures as well as oil pressure in the engine. (make sure it states transmission on it...much higher possible pressures) Unscrew the port and attach the hose extension. From there the gauge normally has a quick connect that hook to the extension.

There are a number of how-to sites that list the pressures expected under conditions around. However, if the fluid is at the correct level--and the transmission is shifting normally and strong? I shouldn't worry to much about it.

S-

Angie · Dec 31, 2012

but do we REALLY know where our parts come from anymore? Most of the time the stuff I purchase either says "Made in China" or "Assembled in Mexico". Disgusting.

Don't get me started on the made in china sh!t..... I am fed up with returning things that don't work or crap out after a month..... I would list it for the last 6 months but i think you probaly have the same length of lists.... lol mexico isn't that bad ( we been buying mexico for years if you give it some thought) china is a new ball game of junk.....

i will look into the plug and tester you stated about. will see what happens tomorrow and if it is acting up after rechecking fluids and letting it heat up and burn off old oils.

thanks for that

kimcrwbr1 · Dec 31, 2012

I`m not sure on your tranny but on the C3 auto the control pressure port in on the drivers rear part of the main housing. You should be able to find the plug to the guage up to. My book shows a pressure line for control pressure a vacuum line for vacuum pressure (modulator tee) and watch the speedometer. You can watch the relationship between control pressure and engine vacuum as to how it shifts up and down. Adjust the spring pressure on the modulator to sync shift points. Another thing to be aware of is the cat will burn up from oil. once the smoke stops and it should you may need a new cat?

kimcrwbr1 · Dec 31, 2012

BTW how did your Pinto turn out I wonder about that once in a while when someone brings up the late 70s 2.8 issue?

Angie · Dec 31, 2012

BTW how did your Pinto turn out <<<<< wow, been gone for a while haven't we? lol thanks for asking

the car turned out nice. here is the last page of the thread. she is about 95% finished. the motor is strong and runs nice. we had a large move a couple years back so that set everything on hold before.

check it out. cheers

http://www.fordpinto.com/your-project/project-'78starsky'/60/

Tedybear · Dec 31, 2012

Pinto? Okay....

Haven't seen one of those in a long time.

S-

2nd blown modulator

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