Manual Transmission Grinding

[McClurgM]

Hello all. I tried searching and did not find what i appear to be experiencing.

 

I am starting to get a grinding sound/feel when shifting 1st to 2nd and 2nd to 3rd. not 3 to 4 or 4 to 5. It just started yesterday. I am wondering what is making this. not enough transmission fluids. worn out clutch. etc....

It grinds for a sec then slips into gear. clutch pedal is fully pressed when it occurs.

 

thanks

 

matthew

[unccpathfinder]

check your fluid level...if its low check the slave cylinder boot...you should have noticed a change in pedal stiffness if it was that...since it was sudden and in all gears I would be willing to bet that you have a leak in the clutch system or possibly moister and maybe just need a flushing...

 

I would also find the harmonic RPM's somewhere between 2500 and 2000 rpms to shift without using a clutch if you cannot find the problem right off the bat to help save the syncro's as much as possible

Edited August 22, 2007 by unccpathfinder

[McClurgM]

check your fluid level...if its low check the slave cylinder boot...you should have noticed a change in pedal stiffness if it was that...since it was sudden and in all gears I would be willing to bet that you have a leak in the clutch system or possibly moister and maybe just need a flushing...

 

I would also find the harmonic RPM's somewhere between 2500 and 2000 rpms to shift without using a clutch if you cannot find the problem right off the bat to help save the syncro's as much as possible

 

Fluid level of transmission or of clutch cylinder.?

I did not notice any change in pedal feel.

 

Just did a flush of the fluid in the clutch cyl. tonight. no difference.

 

thanks for the feedback....any other ideas:?

[mws]

I hope it's not, but it could be the synchros...

 

Have you changed the fluid in the last 25K miles? If not, give that a try.

 

May I suggest Redline Oil? Expensive, but worth it.

[unccpathfinder]

if you did change did you get the right amount of fluid back in? if you fill from teh fill plug I believe that will be the wrong fill level...

 

when you flushed it you did bleed the system correct? if so then...

 

it could be syncro's but I dont think all gears would go at the same time (my 95 has a bad syncro for 1st to 2nd and sometimes into 4th if the clutch isnt all the way...and if you know how to shift it right it wont grind)...I just reread and it sounds like it could be them...what is your pace of shifting...I usually have a pretty quick throw and I found out it would not grind from 1st to 2nd if I stayed on the gas a little shorter after pushing the clutch in to go to 2nd and then let the RPM's start dropping b4 going to 2nd it would not grind...so you may want to change the force and speed of the shifts...mine would not grind all the time just now and then usually when trying to pull some1 off the line from a light...I can also RPM shift it without grinding and that helped me gage my shift points and speeds...its been doing it for at least 2 years and i have not had it drop out on me...but as i mentioned it is periodic and mainly on the driver and how well they adapt to the truck... (my 87 in the cold you have to go towards 4th and drop into 2nd or it wont go..its never ground but it just simply wont go unless that is the shift path and its only when its like 45 and below...so i have different driving styles for both trucks)...I also noticed if you go to N at stops to get it in 1st without a grind if it was grinding, I'd push the clutch in wait like a second or 2 then shift to 1st and that would keep it from grinding if i did it normally it would grind...

 

it could also be that your clutch is starting to go...does it ever slip...go find a steep hill get it in the highest gear possible and get it up to about 4500RPMS and see if you feel any slipping (if you cant feel it or dont know what ot feel for watch the tach if the speed remains constant but the tach still increases without any acceleration the clutch is slipping

Edited August 22, 2007 by unccpathfinder

[88pathoffroad]

An easier way to check for clutch slippage is to put it in fourth gear from a dead stop and see if it will let you take off that way. If it stalls out, the clutch is holding and should be OK. If it goes, it's likely slipping and needs a new one.

 

Definitely make sure you put in 5.1 liters of fluid and NOT 3.6 as per the FSM and other service manuals. The fill hole on the manual FS5R30A transmission (V6 5-speed manual tranny) was located too low for proper gear lubrication, the fix is to add more gear oil either by tipping the truck to one side and adding fluid or by removing the gear shifter and pouring it in through there. Use brass-friendly GL-4 gear oil only, NOT regular GL-5, just in case. Martin has more info on specifics of gear oil, I think. I know not the oil weight ratings and interchanges due to synthetic oils and reformulations at the moment.

 

Nissan supposedly corrected the case design in 1996.

[spotana98]

When you say tilting the Pathfinder to add that extra bit of fluid, is there a particular side to tip it. My tranny is making that hardcore growling/whining sound except in 4th. I already bought a tranny and have yet to pick it up, I wonder if making sure the tranny is full would stop that bearing noise. Any ideas?

[Simon]

It's possible. Rather than trying to tip the truck to get enough fluid in, just remove the shifter. It's really easy, and you can be sure you'll have 5.1qts in there. That's the way I always filled my MT.

[mws]

May help quiet it down, but if it's whining, the damage is done.

 

To tip, raise the right side (passenger in US) about 8-12". I jacked it and slid cinder blocks under both right side wheels.

[spotana98]

May help quiet it down, but if it's whining, the damage is done.

 

To tip, raise the right side (passenger in US) about 8-12". I jacked it and slid cinder blocks under both right side wheels.

 

Thanks for the reply guys, I'll probably just throw in the other one after I go pick it up today. Anyone want a tranny for rebuild :-D

[unccpathfinder]

When you say tilting the Pathfinder to add that extra bit of fluid, is there a particular side to tip it. My tranny is making that hardcore growling/whining sound except in 4th. I already bought a tranny and have yet to pick it up, I wonder if making sure the tranny is full would stop that bearing noise. Any ideas?

 

you sure its not the throwout bearing growling I'd hate that you would replace a tranny for that...