Manual trans whine

[dodgy71]

My 87 has a noise/whine when clutch pedal released, goes away when depressed. Guy I bought it from said he researched it and found it is a typical thing for these, is this true? If not what's wrong?

[geezer101]

My synopsis is - if it whines when off or on throttle, it would probably be an input bearing. If it only does it on the clutch pedal, my bet is it'll be the thrust/throw out bearing on the clutch fork. If it sounds like an old roller skate, the throw out bearing is most likely worn out.

[dodgy71]

He seemed to think if it was the throw out bearing it should stop when the clutch pedal is released. It makes noise when released goes away when depressed, I guess I have no idea what it would be. if it's the input bearing that's on the engine side, yes?

[geezer101]

When I say the input bearing, I mean on the input shaft in the transmission. There's the spigot bush/pilot bearing in the end of the crank but you wouldn't hear any imminent sounds of failure from it, more feel it through the transmission. If you aren't experiencing any other symptoms and the whine matches engine rpm, it might only need fresh gearbox oil (GL4 is recommended due to the bronze alloy synchros in these trucks and GL5 reportedly is destructive on the bronze due to it's sulphur content) Synthetic gear oils do not normally contain sulphur as an extreme pressure additive (EP) If a gear oils' got molybdenum in it, don't use it.

[xboxrox]

geezer is right quality synthetic gear oil might very well reduce the noise level ~ it did on my truck ~ bunch of work to replace that input shaft bearing ~ replacement is available a seal too ~ maybe later I can post the Mitsu part # ~ I bet its common on these trucks ~ drive 'n enjoy the sounds ~ replace it ONLY if it prevents the truck from being driveable
Respects ~ George

[dodgy71]

With it being cold outside will buzzing around town for a 1/2 hour warm up the oil enough to get it to drain when I replace?

[dodgy71]

... And what's the opinion on Lucas products?

[dodgy71]

Also...what I could find, fluid capacity is 4.6 pints/ 2.5 qrts?

[geezer101]

Half hour of driving should be enough to get it flowing. Amsoil site claims/states 4.6 pints.

[dodgy71]

You'd recommend going w/ the Amsoil?

[geezer101]

You'd recommend going w/ the Amsoil?

I would lean towards taking the advice given by other members on the forum. I'm a little off the reservation to be familiar with amsoil products as I live in Oz. I only pulled their site up as a reference as it was one of the first ones that actually had listings for fluid/oil levels directly related to these trucks.

[SubGothius]

My '87 owner's manual says 2.3L / 2.4 qts. of gear oil for the manual transmission, "GL-4 or higher" but that was before GL-5 was developed and found to be unsuitable for earlier trans designs, so stick to GL-4 oils and avoid GL-5.

I'd recommend Redline MTL gear oil for your Nebraska climate, maybe their MT-85 since I grew up in Lincoln and remember summer days got above 100°F there pretty frequently even back then, or their MT-90 for even hotter climates like down here in Tucson. The heavier weight might also help with transmission noise due to wear, so maybe just go with the MT-90 in your case.

[camoit]

Ok. First change the oil. It never hurts. Any 80-90 or there about. Don’t waste money on synthetic or expense because there might be an underlying problem yet. Just fill it tell it comes out the side hole. Be sure to remove the full plug before removing the drain. Sometimes it can be stuck and then you don’t have anything in the box.
now to find the the noise.
#1: it goes away when pushing on the clutch?
#2: how high off the floor does the clutch disengage when pushing on it?
#3: how high off the floor does it start to grab? ( 2” is the sweet spot.)
#4: does it make the noise in in all the other gears but 4th, or is it gone?

im sure the other members know where this line of questions are going.

[xboxrox]

My truck's bearing noise happens when clutch out & neutral gear ~ clutch in no noise ~ I bought Royal Purple 90W gear oil at NAPA when they had it on sale ~ draining the 5 speed manual transmission, the fluid looked fairly clean but tinted brownish ~ the new fluid lowered the transmission input shaft bearing noise by about half ~ I don't worry about a little noise any longer; it's too time consuming & too expensive & too much work to fix a bearing that still works ~ I need the truck to get groceries, it's my only ride ~ here is a list of Mitsubishi OEM parts still available in USA ~ Amayama and others might have more parts (?) hope you can read the print (?)
EDIT: I just received all these parts in a box at my place; so I know they are available...

[dodgy71]

My '87 owner's manual says 2.3L / 2.4 qts. of gear oil for the manual transmission, "GL-4 or higher" but that was before GL-5 was developed and found to be unsuitable for earlier trans designs, so stick to GL-4 oils and avoid GL-5.

I'd recommend Redline MTL gear oil for your Nebraska climate, maybe their MT-85 since I grew up in Lincoln and remember summer days got above 100°F there pretty frequently even back then, or their MT-90 for even hotter climates like down here in Tucson. The heavier weight might also help with transmission noise due to wear, so maybe just go with the MT-90 in your case.

I appreciate all that! I'll try to find some when I get to the city, im not really set up for mail order rn.

[dodgy71]

Ok. First change the oil. It never hurts. Any 80-90 or there about. Don’t waste money on synthetic or expense because there might be an underlying problem yet. Just fill it tell it comes out the side hole. Be sure to remove the full plug before removing the drain. Sometimes it can be stuck and then you don’t have anything in the box.
now to find the the noise.
#1: it goes away when pushing on the clutch?
#2: how high off the floor does the clutch disengage when pushing on it?
#3: how high off the floor does it start to grab? ( 2” is the sweet spot.)
#4: does it make the noise in in all the other gears but 4th, or is it gone?

im sure the other members know where this line of questions are going.

It goes away in 4th

[dodgy71]

#4: does it make the noise in in all the other gears but 4th, or is it gone?

im sure the other members know where this line of questions are going.

You seem to have wisdom as why the noise goes away in 4th gear, would you care to share? I get the feeling it's not good news.

[dodgy71]

Change the oil today in the transmission, no change, no improvement

[Pengineer1]

I also had a noisy transmission with my '86. It also only got quiet when I pushed the clutch in AND in 4th gear. Last year I pulled the engine myself and rebuilt the engine AND did a full clutch kit because I was hoping my noise would go away after changing the throw out bearing...no such luck, still noisy in all gears but 4th and when sitting idling. I had my trans pulled and rebuilt at a reputable shop and yes, my noise was coming from the big input bearing in the transmission. The guy gave me the old bearing, and yes, spinning it and playing with it you can tell it had been noisy and wearing for a long time...its pretty sloppy. Let me know if you have any other questions but it sounds like our trucks are similar enough I'm afraid you have the same problem I had. I'm in N Colorado if you want to come look at this sloppy old bearing!!
Bill

[dodgy71]

So I have begun the quest to either get my trans repaired or find a different one, I'm not having any luck. Is there a source for any internal parts for these?

[geezer101]

There are full rebuild kits available and there should be part # references in the manuals/tech section.

[dodgy71]

I had my trans pulled and rebuilt at a reputable shop.
Bill

I appreciate all that! I called a reputable shop this morning, the guy seemed to have knowledge about these, he told me internals are impossible to get and that getting a used trans complete and hoping for the best is about my only option. I've called all over 5 states and found 1 supposed lower mileage one in Florida, I need a better solution.

[dodgy71]

There are full rebuild kits available and there should be part # references in the manuals/tech section.

I'll do some digging, thank you!

[dodgy71]

It doesn't make sense that if it's a bearing that the noise goes away in 4th year

[xboxrox]

KM132 M/T 5 Speed Transmission (what digging I've done so far...)

https://norcaltransmissionparts.com/...esult/?q=KM132 <---- REBUILD KITS
https://www.youtube.com/watch?v=h0zwDMJIBtY&list=WL&index=64
itsubishi Parts Central
Mon 7/5/2021 7:13 AM

If you are not going to take the transmission out of the truck, here are the gaskets and seals you can replace while the transmission and transfer assembly are still in the truck -
Trans pan Gasket - MD703796
Filler Plug Seal - MF660036
Drain Plug Seal - MD016339
Back-up Light Switch Seal - MF660034
Shifter Gaskets (2x) - MD704190
T/F Case Rear Driveshaft Seal - MD712012
T/F Case Front Driveshaft Seal - MD712012
T/F Case Filler Plug Seal - MB001294
T/F Case Drain Plug Seal - MB001294
T/F Case Output Shaft Bearing Cover - MD704138
T/F Case Shifter Gasket - MD704159
T/F Case Hi-Lo and 4WD Indicator Light Switch Seals - MD660034
Also, one thing I recommend, if you are taking the shift lever off to replace the 2 gaskets - on the bottom of the shift lever is a plastic bushing you may want to replace. It wears our and eventually breaks, making it impossible to shift. If it is not broken, but worn, replacing it will tighten up any looseness in the shifter. - Part number MD701577

OEM Parts for KM 132 Mitsubishi 5 speed M/T

NOTES:

MD725209 is the input shaft bearing

These parts still available through USA suppliers

Amayama.com supplies parts for Mitsubishi Gen1 Strada truck which has a 5 speed M/T on a 2.5L diesel engine ~ maybe it is a KM132 transmission..?