NV3550 issues

KieranHurley · Jul 15, 2021

Hey everyone. I purchased a 98 4.0L TJ with a NV3550 transmission around 2 weeks ago. It was good for a few days but recently I’ve been having problems getting into gear. Changed the transmission fluid with redline MTL a couple days ago and replaced the master and slave cylinder a few days ago. It works well sometimes but other times I need to turn it off and on for it to get into gear agaain, makes it a hassle driving around cities. When it’s cold it works like a charm but when it warms up it’s almost impossible to get into first, if first doesn’t work, nothing else does. Previous owner states he threw a new clutch in it recently. Would be nice to drive my first jeep with ease, thank you

AndyG · Jul 15, 2021

That is in no way normal, entire clutch needs checked out, including slave cylinder,etc.

Steel City 06 · Jul 15, 2021

Are there any odd noises coming from the clutch area? Especially when idling with the clutch pedal depressed? It's possible the pilot bearing is messed up, but generally it will make some noise when the clutch is depressed.

If that's the case, you'd have no choice but to pull the transmission to replace the pilot bearing. It's a good 1.5-2 full days of work for the average shadetree.

Superjay5 · Jul 16, 2021

Are you sure you have the NV3550? Because it would have to been swapped in. That is not the stock transmission for that year. Stock manual would be the AX15. The NV3550 didn’t go into jeep until 2000.

machoheadgames · Jul 16, 2021

Not that it matters for this issue, but are you sure it’s truly an NV3550? That wouldn’t be stock. This doesn’t affect the problem though, NV and AX15 use all the same clutch and clutch h release mechanisms so nothing related to what transmission you have affects this issue.

To fix the problem, it’s usually either a hydraulic clutch linkage issue, or a clutch issue. Most likely the hydraulics since it works sometimes and not others. My first move would be to swap the master/slave cylinder assembly with a new one from Mopar.

CharlesHS · Jul 16, 2021

The AX-15 that I had in my '98 XJ 4.0L had problems with 1st gear even after I installed a new clutch, pressure plate, throw out bearing, fly wheel, pilot bearing, hydraulic MC and slave and TOB actuating arm. The problem was finally diagnosed as a bad 1st gear syncho.

geenius · Jul 16, 2021

Give me your reg number an I can check the original box that was fitted.
Aslo syncromesh faults are pretty common

KieranHurley · Jul 16, 2021

AndyG said:
That is in no way normal, entire clutch needs checked out, including slave cylinder,etc.

Plan on taking a look at the clutch this weekend. Slave cylinder was put in by a trusted mechanic but it might be worth a shot to take another peek at it. In cold weather it works fantastic but once it gets hot it’s a nightmare. Turning the ignition on and off to get in gear is a nightmare during rush hour

KieranHurley · Jul 16, 2021

Steel City 06 said:
Are there any odd noises coming from the clutch area? Especially when idling with the clutch pedal depressed? It's possible the pilot bearing is messed up, but generally it will make some noise when the clutch is depressed.

If that's the case, you'd have no choice but to pull the transmission to replace the pilot bearing. It's a good 1.5-2 full days of work for the average shadetree.

No odd noises which is strange, would make it a lot easier if there was. Going to take the clutch out and see what I can find

KieranHurley · Jul 16, 2021

CharlesHS said:
The AX-15 that I had in my '98 XJ 4.0L had problems with 1st gear even after I installed a new clutch, pressure plate, throw out bearing, fly wheel, pilot bearing, hydraulic MC and slave and TOB actuating arm. The problem was finally diagnosed as a bad 1st gear syncho.

Quite possibly could be a synchro. I’m not very good with jeep mechanics, would that affect the ability to downshift into first? Upshifting is smooth

CharlesHS · Jul 16, 2021

KieranHurley said:
Quite possibly could be a synchro. I’m not very good with jeep mechanics, would that affect the ability to downshift into first? Upshifting is smooth

For me... the problem started as an issue going from 1st to 2nd, but after a couple years the problem progressed to where the transmission was difficult to both up shift and down shift between 1st and 2nd.

Cobble Hill Bill · Jan 7, 2023

CharlesHS said:
For me... the problem started as an issue going from 1st to 2nd, but after a couple years the problem progressed to where the transmission was difficult to both up shift and down shift between 1st and 2nd.

To fully understand NV ( new venture ) transmissions go to Wikipedia. It was a joint venture project by GMC and Chrysler. There are no original nv3550 transmissions only remans, theses remans use cheap rebuild parts usually from China, Vietnam, Thailand etc. you get the idea. They have an inherent sloppiness and any decent shop technician will tell you this. Do not get ripped off be informed!!!. Put a AX15 back in. Check out Transzilla. Jeep dropped the ball and they rub their hands together with greed when they see you coming. Don’t believe me ask someone who owns a 3.6 aka ticking time bomb. Shame on Jeep. NOTE …… If you’re buying a new Jeep order it without a motor and tranny have a professional builder put a proper drive train in. Cheers Cobble Hill Bill. P.S. when these issues came up ( early 2003 ish ) a service memo was issued to all Chrysler shops.

Cobble Hill Bill · Jan 8, 2023

g.hayduke · Jan 8, 2023

Almost definitely a clutch issue. The Mopar master and slave comes as a sealed assembly. If PO replaced just the slave, it's an aftermarket part. Replace both Master and slave with a Mopar kit and your problems will most likely vanish.

If I'm right and you go long enough without fixing it, your synchronizers will get trashed as well.

tnjeepguy · Jan 8, 2023

Wrote to OP to see if he was able to fix. Been a while. His answer:

"I don’t have the vehicle anymore but looks like it was the throwout bearing being completely shot. Replaced clutch and everything anyways"

Cobble Hill Bill · Jan 8, 2023

g.hayduke said:
Almost definitely a clutch issue. The Mopar master and slave comes as a sealed assembly. If PO replaced just the slave, it's an aftermarket part. Replace both Master and slave with a Mopar kit and your problems will most likely vanish.

If I'm right and you go long enough without fixing it, your synchronizers will get trashed as well.

What year, engine size, type of transmission, is this a reman transmission?. I CAN’T stress this enough OEM does not mean original equipment manufacturer……. It means made to OEM specifications usually in China, Vietnam, etc. Major parts suppliers ALL !! buy from the same supplier then are reboxed with their label on it. I’m sure there are better manufacturers out there BUT NO true original replacement parts. Bottom line ……. These are old vehicles that for the most part are driven hard and when it comes time to find 20-25 year parts they will be of poorer quality and they new Jeeps have there issues 3.4/3.6 aka ticking time bomb, never ending code trips, you have to be a master technician with access to proprietary Jeep computer to analyze issues. BUY AN OLDER JEEP take out nv3550 replace it with Terminator AX15 , pick your choice of stroked crate motors and save $$$$$$don’t get sucked into the must have new and shiny philosophy.