'97 Taco V6 4X4 5 speed R150F whining noise in 5th gear

Hey guys,
I have a '97 Taco V6 4X4 5 speed with only 135K on it. The R150F transmission is making a whining noise in 5th gear. 1st thru 4th gear is fine. So I run it on the highway in 4th gear to get to where I am hunting then lock the Aisin hubs for the mud. The Taco has been used primarily as a hunting vehicle here in MS in deep mud/water. I am of the opinion that 5th gear/bearings are worn and it is just time to send the transmission to Marlin for rebuild. Any one had the same problem? Thoughts? TIA!

 

These transmission go 500k plus,
Put redline in

 

Putting Redline MT-90 in the transmission is worth a try. The Amsoil

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 I used for many years was WAY better than Mobil 1 gear oil in the R150F 5 speed manual transmission. So I am firmly of the opinion that the type of gear oil used can show a big difference in manual transmission function. Will change the Amsoil 75W-90 gear oil in the transmission out to Redline MT-90 and report if it made any difference.

 

I keep a few used Amsoil oil bags on hand,
I fill the empty Amsoil oil bag up with the redline oil and it makes it a breeze to fill the transmission and Tcase, NO oil pump needed, FYI

 

OK,
I ordered the Redline MT-90 online since I could not find it locally. It arrived and was put in today. I test drove the Tacoma on the Interstate with the Amsoil

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 GL-4 Gear lube in it, changed the transmission lube to the Redline MT-90, then test drove the Tacoma over the same course at the same speeds. The Amsoil in the R150F had been in there for 3 years with probably 6-7K severe OFF-ROAD miles on it. 5th gear is noticeably quieter especially under full throttle with the Redline MT-90 and the synchros are working noticeably better thru all the gears. I am sure some of this is simply due to having fresh high quality GL-4 gear lube in the transmission. But I have to give the Redline MT-90 a thumbs-up. It made a noticeable difference in the overall function of my 24 year old gear box. Will take the Taco OFF-ROAD this coming week then make a final decision as to whether to pull the R150F, separate the transmission from the transfer case, then ship the transmission to Marlin for rebuild this summer or let it go a bit further.

 

Looks like some crush washers there. Where can I look up the parts I'll need to do the trans, diffs, and transfer case oil changes? I didn't see anything about it in the owner's manual. Also what diameter tube will I need to pump for the brake flush?

 

I use clear vinyl 3/8" tubing.

$6 Rexka 12pcs Transfer & Differential Service Gasket Kit Compatible with Toyota Lexus 4Runner Land Cruiser Tundra Tacoma FJ Cruiser Highlander RAV4 Sequoia Sienna 1215710010 9043024003 90430A0003

https://www.amazon.com/dp/B07CJHTDVV

Replace the rear differential breather while you're down there. 13mm box/open wrench

$14 Dorman 924-262 Differential Vent Valve Compatible with Select Lexus/Toyota Models

https://www.amazon.com/dp/B00NF1SLT8
@TheloniusDrunk

 

I got the washers from the dealership.
I had the dealership flush the brake system when I had stainless steel lines installed front and rear

 

I did not have a good experience with Red Line MT-90. Within 250-500 miles, I started hearing a whine that sounded like a WWII dive bomber coming in hot.....it got worse and worse until I drained it out and refilled with Royal Purple 75-90 again. I would not use GL4 even though it says it can take it.

 

I have 665,000 miles most of those miles with redline and Supercharged that adds another 100 hp to the transmission, zero issues

 

Yeah...I have read that others have not had any issues with the MT90. I can say that this manual is a transplant from some other Tacoma into my 04 DBL Cab...not sure what year though. Im assuming its an R150F. I was stoked about the MT90 at first but after about 500 miles had a significant whining noise...no...it wasnt the kids....so I went back to the RP 75-90. I say if it works for ya then do it.

 

Ok, so this is not your original transmission and you probably have no history on the maintenance?

I change my running fluids every 75-100k like clock works

 

Yeah....no history. So...other than an R150F...what would it be that its not compatible with the GL4? . The RP works well. No issues AT ALL after swtiching back so.....????

 

No idea but the input shaft bearing is one of the bearings that does go out.

This transmission IF it’s had regular oil changes will last a longggggg time.

If it’s making noise there might be a problem coming your way sooner than later

 

I change my fluids religiously.....and thats whats weird....it didnt start making the whining until I put the MT90 in....so...been running the RP 75-90 with absolutely no issues since. And yeah since then...Ive hauled 3000lbs of concrete, 15 6x12x16 Doug Fir beams and trailers full of crap all over and moved cross country from Washington to the east coast with all our crap...no problems at all. Love it....like a huntin dog man...it just for whatever reason, DID NOT like that GL4 and nothing against them at all I know Redline's reputation is stellar.

 

loud whiny noise is/was attributed to the input shaft bearing?
this R150F rebuilt at Yota1 from an '02 is exceptionally Whiny in 5th gear
5th gear Also is Very unstable on the shifter stick at certain RPMs
it shakes Violently at highway cruising speeds in 5th gear around 60mph
i take the foot off the throttle the vibration in the stick disappears
gently put the foot back on the throttle and immediately the shifter starts its damned shaking


this R150F rebuilt has about 15k miles and is still under a year warranty in California if this is the issue i really do not know!
it is a 1700 mile one-way trek to the Yota1 shop to have Them Look At It

currently using AmSoil transmission fluid with about 10k of service since changing break-in fluid of what might've been Redline MT50 but not a definite since it was Not a DiY

 

Even a top-shelf synthetic gear oil such at Redline MT-90 or Amsoil will not fix a sick transmission, but the Redline MT-90 definitely helped me limp along in the Taco for one more year/approx. 200 days of hard wheeling while hunting/shooting. In 2022, my R150F 4x4 tranny took the trip to Marlin on the West coast for rebuild. My tranny was much more sick than I realized. Besides all the normal wear items such as bearings/seals/synchros/etc. that were replaced, the tranny needed an output shaft/2nd gear/3rd gear/1-2 sleeve/and 3-4 sleeve. The tranny is still going thru the 10K mile break-in period with LUCAS 80W-90 dino oil and is surprisingly smooth in all gears even with the dino oil. Just returned from a day of shooting/wheeling on our local WMA and my tranny is very quiet and pretty smooth. But I do very much look forward to the day that I can put Redline MT-90 in it. This tranny should be impressively smooth with MT-90 in it. Marlin warned me not to put any synthetic gear oil in their build until the 10K break-in period is over because the synthetic gear oil will inhibit any further break-in.

Marlin rebuilt R150F 4X4 tranny ready to reinstall in 2022:

 

Plenty of good info here but aside from the usual modern manual trans fluids I have found that these transmissions like some moly. The "Liqui-Moly MoS2 Anti-Friction For Gears" makes it easy. I have used it for decades on old BMWs and my 2000 Taco likes it as well. It's an old school trick but the Liqui-Moly additive works great. Syncros love it.

 

I have read about that "Liqui-Moly MoS2 Anti-Friction for Gears" moly additive being used with good results. AAP has it on sale for $7.19 thru July. And I am sold on the idea of using a good moly grease such at Red Line CV-2 on the Taco wherever #2 grease is specified. A little-known fact is that Moly-Graph moly grease was supplied with some high-grade LCA poly bushings and some still use it instead of silicone-based grease. Some of the best CAT greases contain 5% moly as required by CAT. I learned thru experience that a good moly grease will enable parts/bearings I am pressing such as FWBs to go together much more smoothly. Further, some of the MATCH hunting firearm triggers I have specified MolySlide moly grease to keep them running smoothly. Yes, moly definitely has its uses.

 

? how about Whining Noise in Neutral at idle with clutch pedal out

what would be causing this? mine is Exceptionally Loud just sitting there idling and whirring away somewhere, nothing like the '97 R150F that was in there before this 2002 rebuilt

fully push the clutch pedal in and noise goes Away at idle in neutral

i am still trying to educate myself on the underlying workings of the clutch and the R150F
what moves and what does not move and when it moves
have watched a few videos from Timmy Toolman + other gearbox videos and searching these forums
but still find myself confused on how it all works!