Hi,

I tried to do a DIY transmission flush today and disconnected one of the lines going into my trans cooler and started the engine. (I disconnected it through the grill at the point where the lines connect to the cooler.) I got only a dribble of fluid out of the cooler and none from the line going back to the transmission. I tried putting it in drive and reverse, added some gas to get a few RPMs up with my foot on the brake and nothing...

I don't know if I pulled the return or feed line to the trans. It was line going into the top of my cooler on my 2002 Tribute. I assume I should get flow one way or another by separating either line he cooler, but perhaps that's a bad assumption.

Any thoughts?

I ended up doing the dilution-style flush instead but would like to understand if I have a problem with the trans not pumping thru the cooler...

Thanks
Rob

 

Are you having transmission problems?

 

The fluid should pump out, not dribble. If it doesn't flow enough, it will not dump enough heat from the heat exchangers, and the fluid will overheat.
If the previous fluid did not smell burned, I'd expect that the level was low, or you had the vehicle tilted for access, and the pump pickup was exposed to air. But then again, I don't do this for a living.
tom

 

Until the temperature rises it probably bypasses the cooler. These cars were buit with some pretty modern technology.

 

The trans fluid has been burnt around 20K miles ago and flushed by a dealer. I started smelling burnt fluid again, that's the reason attempting another a flush. It's a 2002...

 

Unless the transmission is slipping, you should not have burned fluid in 20k miles. If you tow a trailer, or drive in 'extreme' conditions, such as stop and go traffic in hot weather, or in very hilly terrain, the fluid would have more chance to get burned.
I think you may have found why your fluid got cooked so quick. No, I don't have any good recipe to fix it. A good transmission shop may have more of a clue. There are a lot of articles on the CD4E out on the web, and one may give a hint as to the cause.
tom

 

We don't do any towing or even hard driving, mostly just running around town. I suspect that it's slipping due to earlier damage we had done to it. 20k ago, we drove through some mountains not knowing about the overdrive issue and cooked it pretty good. It was overflowing fluid all over the place and made a real mess. If it's not actually flowing through the cooler, that would explain a lot. I need to see if it will flow when it's up to temp. I had initially tried to flush it while it was fairly cool...

 

I was on a level surface and I got nearly 4 quarts out when I opened the drain plug so I think it was full. Hopefully the cooler flow thermally controlled. Might be best to run it through all the time.

Thanks!

 

I'll try to test that this week end... Thanks!

 

I checked the trans cooler after a long drive and it was not even warm so I'm pretty sure there is no flow going through it. Any thoughts on why that might be?

Thanks,
Rob

 

Could be a cloggged line or someting wrong with whatever 'pumps' the fluid around the system. I know next to nothing about transmissions so I don't know if there is a pump in them like some transfer cases have or not.

It would be worth asking a transmission guy though. If he is even alittle credible he will tell you what moves the fluid around. But I am willing to bet there is someone here that knows.

 

The same pump that pressurizes the components provides the flow for the transmission cooler. A quick test is to disconnect the lines from the transmission AND the cooler, and check the lines them self for blockage. Then, re-attach the outlet line and point it at a bucket, and start the engine. At idle it *should* flow, not dribble. If it doesn't flow then, you likely have an internal blockage or the pressure regulator or flow 'director' may be not working correctly. I read that the output of the pump is re-directed back as the input of the pump if it is not needed to operate the gizzards, thus staying 'pressurized' and readily flow through the pump. Something allows fluid to flow to the cooler, in a limited amount, but I don't remember exactly what it is. I do not think it is temperature activated or limited.
tom

 

Wouldn't have to reach a certain temperature first to open a valve?

 

Thanks for the recent posts Tom, Scott and Bill.

I'll check the lines for blockages next. It's hard to imagine how a line could get blocked unless it's kinked, but it's work a look. I bought this vehicle with a blown engine and had replaced it my self. I may have messed something up on the trans side during that operation.

Thanks!
Rob

 

Well, I figured out the problem... It's nothing related to the design of the vehicle. I'd neglected to hook up the flow through the trans cooler when I had put the engine and trans back in the vehicle a couple years ago. Dumb mistake on my part but glad I figured it out before more damage had occurred.

Thanks everyone!
Rob