Could someone explain the circulation path of transmission fluid through our trucks system.

i.e. from the pan, how does the fluid circulate to the TC and then from there through the cooler back to the pan? Interested on "how" the fluid gets to the TC.

Thanks,

Joey

 

I don't exactly know in detail, but there are pumps, or at least one that does it. Also, the valve body directs it as well. There is a series of things working in unisen and it all seems to do good, so I just leave it be.

 

The transmission pump sucks fluid through the filter. The pressurized fluid is sent to the valve body where it is distributed throughout the transmission. One of the places the fluid is sent is to the torque converter. After the fluid has made it's circuit through the torque converter the now hot fluid is sent to the cooler. After the cooler the fluid is sent back to the trans, where it is used for lubrication of the rotating parts. After it passes through there it is dumped into the pan where the circuit starts over.

 

Casey, thanks for the explanation.

A couple more questions. I assume one of the main reasons trans pans don't have drain plugs is because of the internal filter. Naturally, the pan would need to be dropped, either way, to change the filter. Why couldn't an external filter be used? Like, say, a fuel filter? Connected, in-line, from the return to the pan. And why aren't pans equipped with drain plugs, anyway? Seems it'd be easier/cleaner to drain the pan before dropping, regardless of the filter position.

Even if the average owner didn't want to fool with this stuff, the external filter and drain plug would make things easier/faster/cleaner for the mechanics.

Any of you transmission specialists want to comment?

Thanks,

Joey

 

The internal filter keeps any chunks from getting into the pump. It doesn't take a real large chunk of something to destroy the pump, so an in the pan filter is a necessity.

Some transmissions do have external filters to better clean the fluid. The TorqShift transmission that Ford uses in the F250-F550 has a filter in the cooler line from the factory.

Some pans do have drain plugs, but they are rare.

 

OK, thanks.

But is there a good reason why trans pans don't have drain plugs?

 

Same reason a lot of new cars dont even have oil dipsticks anymore.

Come to the dealer for that service...

I feel an external filter bypass setup is a cheap investment to keep the single most expensive part of your truck healthy.

Adrianspeeder

 

Back when I was playing building cars, I would always add a drain plug. Just made sense.

 

Any tranny fluid change requires a filter change. The pan is coming off anyways. If the cost of a pan drain plug was even as low as 50¢ per tranny it would cost ford over $500,000.00 per year (over 1,000,000 transmissions per year sold x 50¢). Having a drain plug would cost them and it would not save them any money becasue we the customers are paying for the fluid change not Ford. Next time you get the fluid changed ask the store what the savings would be if your tranny had a drain plug. Personally I would charge you the same price.

JMC

 

Not trying to hijack the thread, but which new cars don't have dipsticks? My gosh, that's the dumbest idea I've heard of. I would have never checked that if I was in the market for a new vehicle. But, I guess I shouldn't be that surprised, when you need a special tool to remove the fuel lines from fuel filter. What ever happened to simple hose and hose clamps.

 

Simple hose and clamps aren't good enough for the higher pressures of fuel injection. It worked fine with 6 psi that a carb uses, but not 30-60 psi that injection systems use.

There are a lot of cars that don't have trans dipsticks. Many European cars don't, and now some Japenese and American cars don't either.

 

Try to find the dipstick on the new F-150s........

JMC

 

Thanks for the explanation concerning fuel PSI. I guess a new design was required due to increased pressures, I just dread changing out my fuel filter.

You state "trans dipsticks" and the other post states no "oil dipsticks". How is a guy supposed to check anything? Currently, I believe most vehicles utilize the trans dipstick tube as a filler tube. With no dipstick, how do you add? Of course, you wouldn't know you need to add w/o a dipstick? Vicious circle!!

I don't want one of these new vehicles.

Sorry, I'm hijacking again. But thanks for the info, guys.

 

Just because I'm bored and no one else mentioned it specifically, when the fluid leaves the trans, it goes to the rad cooler first (the top line). Comes out the bottom line and if equipped with an aux cooler, goes thru that before returning to the pan...

Mitch

 

"Next time you get the fluid changed ask the store what the savings would be if your tranny had a drain plug. Personally I would charge you the same price."

Hmmmm, let me ask me. Joey, would you rather be able to drain the pan first, or just drop a fully loaded one with trans fluid? Well, Joey, as you know, I'd rather drain it first. Less messy. And you know how I feel about trans fluid in our backyard. Yep, I do know, Joey.

BTW, would you charge the same with or without the plug? Now, Joey, as many times as I've done it for you, you know I'd charge the same. Us being friends and all.

Wow, JMC, just think what Ford could save if they didn't put plugs in oil pans.

What do you think abou that idea, Joey? Don't get me started, brotha!

Joey