Whining Transmission

nippodriv · Oct 16th, 2007, 11:09 PM

Hi all...like so many others, I have a help question...

I have a 5-spd 2WD '90 truck, (many miles) and the transmission whines in forward gears 1,2,3 & 5, as well as Neutral, when the clutch pedal is in the released position (clutch engaged).

I replaced the clutch almost 2 years ago (it was still barely worn!) If I remember right, I got confirmation that the throw-out bearing doesn't have a problem, or I replaced it.

A relative who's a mechanic told me that mixing synthetic and non-synthetic gear oil can sometimes cause this. Also, a poster in the thread "Tranny Problems...... Maybe?" was very explicit about using only GL-4, and not GL-5 --why?

In any case, since it seems common, I thought it might help to ask what is it exactly that causes this whine? Is it simply shaft gears meshing with ring gears in a "loose" way? Or is it other worn parts like synchronizers or bearings, or an erosion of part surfaces from a bad oil mix? Assuming the tools are at hand, is it a decent project to tear down and fix, or should the whole transmission be replaced?

Thanks to any of you that can answer.

thorn87d21 · Oct 18th, 2007, 07:18 PM

I use synthetic 75-140 fluid in the trans and I myself also have a whine that comes from something under the hood. Not sure if my whine is coming from the trans but I do know it almost seem's to have started after I started using the new 75-140. Hmmm I might just have to drain it out and see what happens noise why if I replace with gl-4.

airdevil85 · Oct 20th, 2007, 09:23 AM

I have a 97 hb with the 4 cyl and 5 speed... the truck has 77,000 miles on it, My dad is the original owner and gave it to me at 50,000k so I know the truck was taken care or... how often should I change the trans fluid??

nippodriv · Oct 21st, 2007, 03:12 PM

Quote:

Originally Posted by airdevil85

I have a 97 hb with the 4 cyl and 5 speed... the truck has 77,000 miles on it, My dad is the original owner and gave it to me at 50,000k so I know the truck was taken care or... how often should I change the trans fluid??

For 1990 through 1995 models, Nissan requires only inspection every 15000 miles, or replacement every 30000 miles if driving in sever conditions (towing a trailer or driving on rough or muddy roads). Chilton's (repair manual) says to replace it every 30000 in all cases.

airdevil85 · Oct 21st, 2007, 05:37 PM

Quote:

Originally Posted by nippodriv

For 1990 through 1995 models, Nissan requires only inspection every 15000 miles, or replacement every 30000 miles if driving in sever conditions (towing a trailer or driving on rough or muddy roads). Chilton's (repair manual) says to replace it every 30000 in all cases.

thats for a 5 speed and not the automatic right? and which type of fluid?

nippodriv · Oct 23rd, 2007, 10:33 PM

Quote:

Originally Posted by airdevil85

thats for a 5 speed and not the automatic right? and which type of fluid?

That's for both the manual and the automatic. Manual tranny requires GL-4, 75W-90 or 80W-90. (Automatics use Dexron ATF).

jmills62 · Nov 7th, 2007, 12:57 AM

My trans just went out today.. All I have now is 4th.. did you have to replace the tranny or was it something else??
thnks

**88pathoffroad** · Nov 7th, 2007, 01:11 PM

GL-5 gear oil typically has a formulation that eats brass synchroes and ruins them. GL-4 does not. Hence the use of GL-4 ONLY in Nissan HB and Pathy manual transmissions.

99% of the time whining in a manual trans is caused by underlubrication. The 5-speed manual transmissions from 87-95 were manufactured with a defect: the fill plug is located too low on the case. Therefore you can't add enough lube to keep it lubed effectively internally and it needs either a revised design transmission or more lube(1.1L more than originally required). You can jack up one side to allow more lube to be added or remove your shifter and pour it in from the top. They fixed this design problem in late 96, so every 5-speed before that has the incorrect fill plug location.

thorn87d21 · Nov 7th, 2007, 06:37 PM

So just filling it from the shifter area would allow you to put that extra 1.1l in or should you do the jack it up on one side thing to add more in? I would think if you added fluid to it through the shifter from sitting in the vehicle it would be the same no matter if you filled it from under say the truck and got it in there with a pump of some sort.

jmills62 · Nov 7th, 2007, 08:57 PM

Do I need to replace my snychros in my tranny or am I better off with a whole new one?? I carelessly put gl-5 before after gears 1,2,3,and 5 started whining and now all I have is 4th.

Same problem as nipppo (89 instead) and only 4th...