Transmission. . . weirdness. Do I need a new TC/ Pump?

linewarbr · **Posted:** Tue Feb 09, 2010 2:59 pm

I was in the drive-thru at McDonalds, with the Jeep in gear and my foot on the brake. Jeep was not yet up to operating temperature, temp gauge was about 1/5 up. As I let off the brake I heard/ felt a pop, and the Jeep seemed to not want to accelerate as normal, like it took a lot more pedal to make it go.

I immediately shifted into neutral, and only shifted to drive when I needed to pull forward to the pick-up window. No CEL at this point. I idle it over to a parking spot, put it in park and set the e-brake and turn it off. First I look closely for fluid leaks both under the Jeep, and in the drive-thru lane, (love having a diesel at this point, because you KNOW diesel oil when you see it on the ground - and trans fluid is red) and see nothing - skid plates are both dry. Open the hood, and the trans dipstick is sticking out about 2 inches.

I push the dipstick back in, go back in the Jeep and hook up my code scanner to find "P0841 Trans Fluid Pressure Switch." I clear the code, start the Jeep back up, and it drives normal back to my office .36 miles away.

I'm thinking that the pop I heard was the trans dipstick hitting the underside of the hood, but I'm unsure what would cause this - maybe a clogged breather? Last week I checked the fluid and it seemed slightly on the low side, so I added ~1/4 quart of fluid, not a whole lot. It is colder today than it has been, but not yet cold enough to fire up the viscous heater. Could this have been caused by having my foot on the brake at idle with the trans fluid cold? Do I have too much fluid in it? Any help appreciated.

flman · **Posted:** Tue Feb 09, 2010 4:57 pm

Those dipsticks always vibrate out, my repair is to squeeze the tube slightly closed with pliers, to keep the dipstick in. As far as fluid goes, get it good and hot, and pull the stick in park, that is the only method to determine the fluid level.

linewarbr · **Posted:** Tue Feb 09, 2010 5:15 pm

I'm hoping it doesn't do the same thing on the interstate at 80 mph on my home from work. I'll check it then, my garage floor is level (yep I checked it). I don't really want to replace my torque converter just yet. . .

flman · **Posted:** Tue Feb 09, 2010 7:17 pm

Have you done any tranny work lately? Maybe it needs some drive learn?

linewarbr · **Posted:** Tue Feb 09, 2010 8:56 pm

Back around Labor Day I dropped the pan and replaced the fluid and filters. Never have been sure I got the right amount of fluid back in it though. 18,000 miles have passed since then, and this is the first hiccup.

Sometimes I look at the dipstick and it seems like my fluid level is good, sometimes it looks low. Either I don't know how to read a dipstick, or the fluid level is just hard to pinpoint precisely.

Would possibly having too much fluid, or too little fluid, cause this?

geordi · **Posted:** Tue Feb 09, 2010 11:04 pm

flman wrote:

Have you done any tranny work lately? Maybe it needs some drive learn?

Please explain... Do we have a fuzzy-logic transmission? How to reset it then?

Silverdiesel · **Posted:** Wed Feb 10, 2010 12:57 am

Disconnect the battery to "reboot" everything--forces the TCM to re-react with the ECU to "learn" shift points, holding on to gears at a given throttle,other transmission activities, etc. It does not change what encryption the F37 factory mods has burned into the TCM but recoordinates the TCM's relation to the ECU hence new learning. Good to let it learn after transmission fluid/filter changes(at least good for me).
IIRC

Roland

Joe Romas · **Posted:** Wed Feb 10, 2010 7:43 am

geordi wrote:

flman wrote:

Have you done any tranny work lately? Maybe it needs some drive learn?

Please explain... Do we have a fuzzy-logic transmission? How to reset it then?

Yes we do. I posted here last week about where to find "drive learn" instructions in the FSM in a post I put in the FAC section :juggle:

flman · **Posted:** Wed Feb 10, 2010 8:21 am

viewtopic.php?f=98&t=49854&p=555198#p555198

linewarbr · **Posted:** Wed Feb 10, 2010 10:52 am

The battery has been out since then, when I replaced it with a Yellow-Top back in late October, so it is not a drive-learn issue.

Would too much fluid cause this? Too little?

LibertyCRD · **Posted:** Wed Feb 10, 2010 11:15 am

Fluid warm, parked on level ground, shift through all the gears, then shift to park and check your fluid and the dipstick should tell you exactly if you have the proper amount of fluid in there or not. I know it sounds dumb but a lot of folks don't realize you are supposed to check fluid that way.

linewarbr · **Posted:** Wed Feb 10, 2010 11:18 am

OK then, I have another dumb question: How, exactly, do you read the dipstick? Is it where the fluid is all the way across the stick, or where it is on the edge of the stick? This is my first automatic, I've always owned manuals before.

flman · **Posted:** Wed Feb 10, 2010 12:05 pm

Mine, will read a level on each side of the stick that is different, I usually pick the side that is lowest, assuming the higher reading is wrong? But as long as it stays between the high and low lines, you should be OK.

linewarbr · **Posted:** Wed Feb 10, 2010 10:53 pm

Well then I may have overfilled it. Like engine oil, I was expecting a solid line across the dipstick, and fluid trapped in the holes for either "hot" or "cold." I like the black oil in the engine - easier to read the dipstick.

Is there a way for the trans to evacuate excess fluid, such as the breather tube?

flman · **Posted:** Thu Feb 11, 2010 7:00 am

linewarbr wrote:

Well then I may have overfilled it. Like engine oil, I was expecting a solid line across the dipstick, and fluid trapped in the holes for either "hot" or "cold." I like the black oil in the engine - easier to read the dipstick.

Is there a way for the trans to evacuate excess fluid, such as the breather tube?

Sounds like you will have to pump it out, the breather is near the top of the tranny, and the fluid level is only in the pan area. Lucky for me, when I over filled I had a plug in my pan to take some out real easy. The problem is the dipstick touches so many surfaces inside the curved tube, that it is hard to get an easy reading, but you have to get it warmed up, and if you pour fluid down the tube, you will not be able to get an accurate reading, due to the residue getting on the dip stick. Now a days, I measure what I take out, to save this type of hassle on refills.

linewarbr · **Posted:** Thu Feb 11, 2010 11:25 am

Man I hate to beat this thing like the veritable dead horse, but this is where I'm at. Yesterday, with the trans warm, I cycled through all the gears, checked the fluid level, and found it VERY hard to read. I ended up adding ~ 1/2 qt of fluid because I thought it was reading low.

This morning before I started it, I checked the fluid again. It had been sitting all night, 8+ hours, and had plenty of time for all the fluid to drain down into the pan. It measured about 2/3" to 3/4" above the Cold holes. I feel like this is a more accurate reading than what I got yesterday.

Should I worry about that much extra fluid? Or drain it off ASAP?

flman · **Posted:** Fri Feb 12, 2010 12:29 pm

linewarbr wrote:

Man I hate to beat this thing like the veritable dead horse, but this is where I'm at. Yesterday, with the trans warm, I cycled through all the gears, checked the fluid level, and found it VERY hard to read. I ended up adding ~ 1/2 qt of fluid because I thought it was reading low.

This morning before I started it, I checked the fluid again. It had been sitting all night, 8+ hours, and had plenty of time for all the fluid to drain down into the pan. It measured about 2/3" to 3/4" above the Cold holes. I feel like this is a more accurate reading than what I got yesterday.

Should I worry about that much extra fluid? Or drain it off ASAP?

Get the fluid low again, and add 1/4 quart per day till you get the right level. It is real easy to overfill these things. Overfill is far worse then a little underfill.

linewarbr · **Posted:** Mon Mar 01, 2010 2:37 pm

So, it happened again today but this time the engine stalled and quit. I was in the drive-thru of a restaurant, not up to operating temp yet, idling in gear, and I noticed that when I let off the brake, it didn't feel as "ready-to-go" as usual. I get my food and pull out (luckily not on to a busy street) and when I let off the accelerator for the upcoming stop sign, it starts bucking and then stalls out - it startled me, I thought it was going to explode or something. Opened the hood, trans dipstick was still in place. Checked it with my scanner, no codes. After a few minutes I crossed my fingers and tried starting her - started right up, no problems. Didn't stall when I shifted back into Drive - she acted like nothing happened.

I have just over 69k miles, 45k of those are mine. I know the fluid level is now correct after the above posts. This only seems to happen under these conditions - not up to operating temp, extended time of idling in gear.

Any ideas of anything I can do to better diagnose what is causing this?

linewarbr · **Posted:** Mon Mar 01, 2010 3:56 pm

Just talked to a guy at a local tranny shop whom I was referred to by a trusted mechanic. He didn't think it was the TC or the pump, he thinks the anti-drainback valve in the trans filter collapsed - possibly while the tranny was overfilled with fluid.

danoid · **Posted:** Tue Mar 02, 2010 10:25 am

First, stop going to drive thru resteraunts. Your stomach (and evidently your KJ also) will thank you.

Seriously, I had a problem with the pump and the symptom was the opposite of what you seem to be experiencing. Mine would stall like it was a manual that I forgot to push the clutch pedal.

If you're slipping and aren't grossly low in oil, yes the filter could easily be the culprit.

Quick rundown on how to check transmission oil.

Oil needs to be hot. 180°F - or slightly hotter than most people can touch for a second. This means you have to drive the car some distance. This is also important for filling all of the cavities in the transmission that are higher than the pan.
Truck on a level surface.
Engine running - transmission in Park or Neutral. (I prefer Park so it doesn't roll away.)
Remove dipstick - clean with lint free cloth.
Insert dipstick all the way, pull out after about a second, hold dipstick horizontal so oil doesn't run up or down.
Read level. Read the lowest point that there is oil completely across the dipstick. (If there's an angle or curve read the lowest point.) Reading should be in the hash marks.

If you are having trouble reading the oil THAT'S GOOD. It means your oil is relatively clear and free of debris / contamination.

If the oil is black don't worry. Then you apply your nose. If it smells burnt or like rotting fish you should consider changing it.

If the oil is frothy (lots of bubbles) you could be overfilled. Turn the engine off and remove some with a pump/siphon. Let the truck sit an hour or two, then take it for a drive to warm up again and start over.

If the oil is pink and frothy you have water in it. Change immediately.

If the dipstick is dry. Double check. If it's still dry you need to add more.

The red dye disappears rather quickly (a couple of thousand miles). Clear oil is not an indication of a problem.

If you have to add some oil, take it for a drive around the block before checking the level again. This mixes the oil and gives it a chance to completely run down the filler tube.

The oil should last forever if you don't:
Tow a trailer and heat the transmission.
Go off roading.
Drag race.
Drive only short trips and never properly get the transmission up to operating temperature.
Have a leak.

If you do one or more of the above, again don't worry. You'll probably have to change the oil every 60-100k miles.

Transmission. . . weirdness. Do I need a new TC/ Pump?

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