2004 Transmission Slipping Uphill

[AppleTech]

So if I back down my very steep driveway in reverse, when I get to the bottom and put it in D, it doesn't go forward. I have to rev or put it in park for 30 sec until it will drive again. I also noticed going UP the driveway today that it lost fluid pressure and slid back down. Fluid level seems OK, but I am going to check it again - I only cursory looked when I bought the truck. Haven't noticed this before but it has been noticeable colder the past few days (in the 20-30's). I do not notice any leaks under the truck.

Any idea what the cause would be if the fluid level is OK? It also seems to only be right after I start up the truck but admittedly I haven't had the truck but 2 weeks and have only driven it a few times.

Thanks,
Phil

 

[AppleTech]

Well it looks like it may be low fluid. I let the truck idle for 30 minutes up to operating temp, ran it through the gears a couple times and checked the dipstick. Fluid is just on the bottom of it, not near the crosshatch. Also looks like the PS line is weeping. I also noticed the coolant is brownish and foaming, not sure if there is internal contamination. What's the fix for leaking at the top of the trans cooler line, new radiator?

-Phil

 

[AppleTech]

And when I loosened the radiator cap this came out. I did an oil change right when I bought it and have driven it about 300 miles since. Oil level seems static and clear (hasn't dropped and doesn't look contaminated). Does that point to internal leaking on the radiator meaning the trans fluid and coolant are mixing? Is that even possible on this radiator design? Am I looking at a headgasket? I would suspect HG but I'm not seeing an oil level drop or contamination...

 

[swshawaii]

ATF (Mercon V) is leaking from the transmission cooler inside the radiator. No leak repair possible without replacing the radiator. Before driving again, check the transmission fluid for coolant contamination. Mercon V transmission fluid has a
clear red to pinkish color.

 

[AppleTech]

Yeah luckily it looks like it was going from the trans lines into the coolant and not vice versa since the transmission is low. I'll inspect the ATF when I drain it but I'm hoping it was just a one way street for the most part. The transmission still drives fine strangely other than the symptoms above, so hopefully I caught it early.

Ordering a new radiator and transmission filter now. I'm 99% sure its not a headgasket. Previous owner said the truck was sitting for a year with only intermittent use so it does make sense that the internals of the radiator probably deteriorated.

 

[shucker1]

Safest bet is to quit driving it until the radiator is replaced and the transmission fluid and filter are changed out.

Also safe to assume that you will need to flush the cooling system to get all of that old transmission oil out of there.

 

[AppleTech]

Agreed - it has been parked and I've got a radiator and transmission pan gasket and filter on order.

 

[AppleTech]

My Ford factory manual says has two procedures for vehicles with and without a torque converter drain plug... to the ST's have a drain plug on the TC or not?

So far as fluid exchange, my goal was to drop the pan and replace the filter, refill, then disconnect the line going TO the transmission cooler and use a clear tube to direct it to a bucket. I was then going to start up the truck and watch the fluid coming out. Once it starts to look clear I was going to shut it down and then fill to spec. My thought is this method will flush out any contaminated fluid using the built-in pump without running it through my new cooler. I've done this kind of swap on my Toyotas with good success but wanted to run it by y'all.

Thanks in advance!

 

[shucker1]

If you do that you will need to keep a few quarts on ready to drop back into the pan while the engine is running.

Don't let that pump run dry. That's bad news.

Might be a good idea to flush the line from cooler to transmission as well.

Best idea I can come up with is to hand pump mineral spirits into the line into the transmission disconnected.

Flush until the junk is out and then blow the line COMPLETELY clear with compressed air.

Reconnect both lines and try and run.

 

[AppleTech]

OK update. Trans fluid was drained and did NOT look like it was contaminated, just old. I didn't see any water bubbles or mush in it, so that's great. I've done the following:

1. Dropped pan, replaced filter, refilled, flushed out lines with pump, ran truck for a bit and checked level.
2. Replaced radiator
3. Removed tstat and flushed out cooling system. Removed all hoses and flushed through them. Burbed it for about 45 min and truck is running on temp and heat is hot. Coolant looks pretty good. There is a small amount of gunk floating to the top. I'm going to pull it out with a turkey baster. Its not foamy and creamy like it was.

Took the truck around town for a bit and its driving great and shifting normally. Ran on temp. One thing I did notice when I parked it was some coolant dripping down from that looks like the top of the bellhousing. It is dripping down both sides, collecting on the bottom, and dripping on the xpipe making a nice burny sound. I noticed it after my first test drive but has seemed to slow down or stop. It COULD have been some water that collected when I pulled the heater hoses? I don't see any leaks anywhere visibly on the motor, but obviously I can't see the back side.

I'm going to watch coolant level and keep an eye on the leak... any idea what it could be on the back of the motor just above the bellhousing? Perhaps a freeze plug?

 

[swshawaii]

Has the lower thermostat housing ever replaced? Extremely common failure with ALL 4.0L SOHC's. Possibly caused an issue when replacing the thermostat? Torque spec for lower and upper is only 89 inch pounds, or 7-8 foot pounds. Use a small mirror and strong flashlight and inspect the REAR of the lower housing closely for leaking seams. For better visibility, carefully pulling the upper radiator hose over the oil fill neck helps. Did you reuse the upper housing o-ring seal?

 

[AppleTech]

I checked it when I took the tstat out and found no signs of leakage. I didn't see any today when I checked but I can't see too far back. I'll see if I can find a mirror. There is no leakage around the tstat housing. I re-used the existing o-ring as it was very pliable and seemed in good shape. Replacements at local parts stores all had really bad reviews so I chose to re-use it.

 

[AppleTech]

Just an update on this - the heavy coolant leak stopped. I think it was trapped coolant from when I flushed the heater core just sitting on a framerail or something. Now what I do have is a very slow drip from the front of the motor... coolant. Definitely coming from the tstat housing - top of housing is wet looks like it is coming from the upper radiator connector. Ordered a new o-ring. Weird since the one that came out looked to be in fine shape and I lubed it up with soap before installing. Weird thing is it is dripping even when the truck is sitting. I haven't driven it for a week and there are little pancake-sized puddles on either side of the suspension - looks like it is dripping down the block on either side and dropping off the bottom of the crossmember at either side.