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Hello all.

I am new here, I just bought a 2006 Commander 3.7 litre with 175K on it. It sounds excellent mechanically and cosmetically its in great shape as well. I am the second owner and no leaks notting like that, I checked it when car was on the lift, and it drives nice as well.

But once a week it gives me hard time from shifting 1st to 2nd gear. And I don't know why. I spoke with Staten Island Jeep and they advise me not to change tranny fluid but its good to top it off if its less than normal value. COULD tranny fluid level be the issue with the shifting problem.

Also, I want to know what other preventative maintance I should be thinking about. (front end is nice and tight and I can see shocks and other suspension stuff was changed recently.

I will post some pictures of it once I have some time very soon.

Thank you for your help
 

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Don't listen to the guys at the dealership! Go ahead and change the fluid and filters it should help out a lot! And if it doesn't at least you have some fresh fluid in there!


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The 3.7L has the Mercedes tranny, IIRC, which doesn't have a dipstick supplied. You'll have to do some searching hear to find out the details, especially if this is something you want to do on your own.

Personally, I think there is no such thing as having fluid that's too fresh. It never hurts to put in fresh fluids to help rule out possible issues.
 

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I work at a transmission shop on the side for extra money and agree 100% with the dealer when they say not to do a fluid and filter swap on that transmission. With 175,000 miles on that transmission all the clutches are spent or pretty close to it. Transmission fluid has a detergent in it that will take whatever material is left on the clutches off and the tranny will start to slip. Now if the tranny is rebuilt with all new clutches obviously there wouldn't be an issue of having all new fluid in it. Just my .02

My buddy's 05 3.7 liter Jeep Grand Cherokee WK had a dipstick tube but it had a black plug in the end of it. He took out the plug and got a dip stick for it . I'm not sure if different years have the dipstick tube installed already or not and just capped off like his was

Sounds like you will be rebuilding your transmission soon. I hope you didn't pay much for that jeep.
 

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But once a week it gives me hard time from shifting 1st to 2nd gear.
Could you be more specific? Does it delay the shift, does it slip in the shift, does it shift back and forth?

Low fluid level can cause shifting problem, but very low fluid level, NOT just a bit low. Almost all of the 3.7L Commanders have the Mercedes NAG1 trans, it is very sensitive to fluid level, do NOT overfill this trans.

The fluid doesn't evaporate, so if you're low on fluid than you likely have a leak. A slow leak from the fittings on the tranny cooler lines is common. As well, if you've lost 2 qts over 175k miles, yea, you can consider that a case you have to add a quart every other year or so, I wouldn't be in a rush to fix it either.

Yes the Mercedes NAG1 trans does NOT have a dipstick, you will have to find the right dip stick off ebay or another source, then you have find a way to measure the fluid temperature (there are several ways) and you check the fluid level against a chart for what temperature the fluid is.

I disagree that a trans is surely worn out at 175k miles. Sure it might be true, but it is also just as likely the trans has lots of life left in it.

I also disagree a shifting problem means a rebuild is needed, it could be a bad sensor. There could be nothing wrong with the trans at all, and the shifting is being caused by a problem with the Drive by Wire system or the Stability Control System.

I also disagree with the attitude of changing the trans fluid and filter will cause a trans to fail. The clutch material is designed to be compatible with the trans fluid.

I see more posts on other vehicle forums saying "I changed the fluid and filter in my trans, and it solved the problem" then I see posts saying, "I changed the fluid and filter in my trans and it failed and needed rebuild shortly after". If your fluid and filter change actually causes your trans to fail, which I doubt, but if it does, then your trans was on the razor of edge of failing any day or mile anyway. Whats the alternative, have it rebuilt without trying to change the fluid/filter? If the worst happens, the only thing you've lost is the time and money to do a the fluid/filter change.

Changing the Fluid & Filter on the NAG1 is no more difficult than any other trans, checking the fluid level is more difficult than other trans, and that is the problem. The reason why they made the NAG1 "Professional Service Only" is because its so sensitive to fluid level, they don't trust the average owner/shade tree mechanic to do it right. Getting the dip stick tool is a bit difficult, measuring the level with the tool is a touch more difficult than your average trans, reading the chart to know the correct level for fluid temp is easy, BUT measuring the fluid temp is difficult, you need an expensive electronic tool or innovate in some way to measure that fluid temp.

One thing I did, I had a clean pan to catch the fluid I drained from the trans, I marked a jug by the quart and then I poured the collected fluid into the marked jug and measured how much I drained. Then I added the exact same amount I drained. Sure enough, when I measured the level it was dead on where it should be. Of course this assumes the trans was at the proper level to begin with, and if you suspect it might be low, you won't be fixing the problem this way.

Stability Control System - Every once in a while, I try to pull out on the road with my front wheel turned all the way to one side at a stop, on a wet inclined surface or dirt or gravel, and the engine seems to almost stall, I realize its NOT really stalling, the power just halted a little above idle and it isn't increasing no matter how far I push the pedal. Once I get the vehicle on the road and straighten the front wheels, the power comes roaring back. I think to myself, something must be wrong with my vehicle, then I remember, gee, if I just done the same thing in one of my older vehicles (without Stability Control) I would have been spinning wheels like crazy for those conditions. Then I remember the Stability Control System, how it utilizes the drive by wire to back off engine power the moment it senses a wheel spinning, and realize there was nothing wrong with my Commander, that was the stability control system working like advertised and prevented me from pulling out with a wheel spinning like crazy. Something to consider.
 

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I never said that the transmission surely needed to be rebuilt and that it's at the end of its life at 175,000 miles. Like you said it could be a bad soleniod or what not. But does he know if the transmission has been maintained properly in its life? It should have had two drain/fill/filter swaps by now.

Also it is a proven fact new tranny fluid will take off clutch meterial and with 175,000 sure those clutches have had better days. But what do I know, I just work at a transmission shop
 
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