2004 wrangler 4.0 5-speed NV35505

[Diesel]

When I shift into second both up and downshifting it grinds. I have read to flush with kerosene and and Mopar fluid. Does this work or is there another remody for this?

 

[Bounty__Hunter]

I would not flush with Kerosene. Flush with cheap generic ATF if you're worried about getting out all the old fluid. Inspect the fluid in there now as it drains, looking for any brass glitter that used to be your synchronizers.

I'd recommend a good synthetic like Redline MT90 if your shifting can be improved.

 

[JPNinPA]

If you never changed fluid or did not use synchromesh the syncros are likely corroded.

 

[drewbuddy]

+1 on the redline products. Mt90 is thicker mt80 mtl is thinner mt85 is middle of the road. If you want to play with it you can mix mt90 and mtl for a mixture that works for your trans. I used mt85 and it fixed some notchiness and my not going into 1st issue, sometimes had to double clutch from a stop(syncro has to be worn I think) but it worked wonders. Not an issue since. A friend of mine uses a bottle synchromesh stuff in his mix and said that worked great for his trans. Mind you these are mitsu transmissions. I wouldn't use kerosene to flush, just thinking about it I would be worried about it eating away at any rubber seals. Just doesn't sound right to put that through a transmission, to me anyway

 

[Diesel]

Mix like maybe half and half?

 

[drewbuddy]

I would maybe read up on it a little. I went with 85 so I wasn't having to play with mixtures and did good for my dsm. My buddy just added 1 bottle of syncro stuff with his fluid. Depends on kind of driving cconditions and other factors I guess. If you want to spend the money, have at 'er but if a mix doesn't work you're draining and doing it again. There is a lot of stuff out there so if you don't know you're not making it worse. Check this out and hopefully it helps.

Red Line Synthetic Oil - Gear Oil for Manual Transmissions