I have a 1987 JDM HJ-61 with the 12H-T, 263,000 km on the odometer with zero previous transmission issues, and all of the sudden, I'm having a terrible whining/grinding noise coming from my transmission, an H55f-K052, which the search feature on MUD tells me means I have a 37 ring : 10 pinion, w/ open diff. Of course this happens a week before a giant rock climbing/road trip from Denver to Vegas—although I suppose this beats getting stuck in bumf—k nowhere Utah or Nevada with a shot transmission and no cell signal.
I did an extensive search of H55 issues on here, and it seems wildly surprising that an H55 with this few kms would be having this kind of issue. Any pointers on what to try would be hugely helpful—or if worse comes to worse, a great shop to get this fixed in the Denver area
Symptoms:
- nasty whine/grind in 1st through 3rd, although it's inconsistent in 1st and 2nd.
- 3rd has popped out of gear a few times with quite a loud bang. This has happened under both high and low loads and throughout the RPM range.
- 5th makes a nasty sound intermittently
- 4th is perfect, zero sound, zero whine.
- sounds go away as soon as I put the clutch in
What I've tried/checked so far
- checked transmission fluid level (full—immediately some poured out as soon as I pulled the fill plug).
- adding or removing pressure from the shift lever does not change the sound or symptoms at all.
- some fine sparkles in the gear oil that spilled out, but no chunks. I don't have any extra gear oil so I'm not going to do a full drain until it comes in tomorrow,although I have the bypass/equalization hose so I doubt it would be too low without noticing on the transmission as well) (edit: I do not have the equalization hose). I could be wrong about how much sparkle is in (i.e., it might be BAD), but I've never had any amount of sparkles in any kind of oil I've changed so I don't have a frame of reference.
- checked xfer case level (low, but not sure how much. I have some MT-90 coming in tomorrow to check.)
- whine is same in 4Lo as it is in 2Hi
- clutch fluid is full and clean, and no sign of leaks from either the master or slave cylinders. Clutch action seems totally normal.
Other Relevant Info:
- I've had no issues with the transmission or transfer case previously, it's always shfited perfectly with no signs of grinding or hard shifts.
- Just did a new carpet install which involved removing the shift boot for fitment, which I know can occasionally put some pressure on...some kind of spring that I forget what it's called but came up in my searching. But since adding/removing pressure to the shift lever doesn't do anything, I'm doubtful that this is the cause.
- Just did my valve clearances, went great and had zero issues, although I can't imagine how it could be connected. There were only 3 out of spec even after 4 years since the last time they were done.
- Truck sat for over a year (15 mos, IIRC) getting (a f'n saga of) rust repair and a full respray. But I've been through a few tanks of diesel since then with no issues, and as I said, the fluids were all full and no signs of leakage from either the transmission or transfer case.
- I've had this truck for 5 years now, and the mechanicals have been flawless, no signs of poor treatment by previous owners.
- I do most of my own wrenching, but don't have the time or space in my garage right now to undertake a rebuild myself
- AFAIK has never had anything larger than 33s mounted, it's on my 31 winter set right now
Here's a link to a video I just shot driving around my neighborhood. The sound is fairly representative, although it sounds MUCH louder in the video than in real life—I think because my phone was touching the steering wheel.
Someone please tell me I'm a huge idiot and I'm missing something simple and don't have to rebuild or replace my transmission, I just spent a metric
-ton of $$$ over the last year doing a full course of rust repair and a full respray. And then new carpet, full dynamat, new rubbers and seals, all new glass, some electrical repairs, new snorkel, new decals, new emblems, new grille and headlight buckets,...the list goes on.
Even if you can't help, enjoy some miscellaneous pics of my truck
(edit for odometer reading correction)
(edit 2: misidentified breather hose)
I did an extensive search of H55 issues on here, and it seems wildly surprising that an H55 with this few kms would be having this kind of issue. Any pointers on what to try would be hugely helpful—or if worse comes to worse, a great shop to get this fixed in the Denver area
Symptoms:
- nasty whine/grind in 1st through 3rd, although it's inconsistent in 1st and 2nd.
- 3rd has popped out of gear a few times with quite a loud bang. This has happened under both high and low loads and throughout the RPM range.
- 5th makes a nasty sound intermittently
- 4th is perfect, zero sound, zero whine.
- sounds go away as soon as I put the clutch in
What I've tried/checked so far
- checked transmission fluid level (full—immediately some poured out as soon as I pulled the fill plug).
- adding or removing pressure from the shift lever does not change the sound or symptoms at all.
- some fine sparkles in the gear oil that spilled out, but no chunks. I don't have any extra gear oil so I'm not going to do a full drain until it comes in tomorrow,
- checked xfer case level (low, but not sure how much. I have some MT-90 coming in tomorrow to check.)
- whine is same in 4Lo as it is in 2Hi
- clutch fluid is full and clean, and no sign of leaks from either the master or slave cylinders. Clutch action seems totally normal.
Other Relevant Info:
- I've had no issues with the transmission or transfer case previously, it's always shfited perfectly with no signs of grinding or hard shifts.
- Just did a new carpet install which involved removing the shift boot for fitment, which I know can occasionally put some pressure on...some kind of spring that I forget what it's called but came up in my searching. But since adding/removing pressure to the shift lever doesn't do anything, I'm doubtful that this is the cause.
- Just did my valve clearances, went great and had zero issues, although I can't imagine how it could be connected. There were only 3 out of spec even after 4 years since the last time they were done.
- Truck sat for over a year (15 mos, IIRC) getting (a f'n saga of) rust repair and a full respray. But I've been through a few tanks of diesel since then with no issues, and as I said, the fluids were all full and no signs of leakage from either the transmission or transfer case.
- I've had this truck for 5 years now, and the mechanicals have been flawless, no signs of poor treatment by previous owners.
- I do most of my own wrenching, but don't have the time or space in my garage right now to undertake a rebuild myself
- AFAIK has never had anything larger than 33s mounted, it's on my 31 winter set right now
Here's a link to a video I just shot driving around my neighborhood. The sound is fairly representative, although it sounds MUCH louder in the video than in real life—I think because my phone was touching the steering wheel.
Someone please tell me I'm a huge idiot and I'm missing something simple and don't have to rebuild or replace my transmission, I just spent a metric
-ton of $$$ over the last year doing a full course of rust repair and a full respray. And then new carpet, full dynamat, new rubbers and seals, all new glass, some electrical repairs, new snorkel, new decals, new emblems, new grille and headlight buckets,...the list goes on.Even if you can't help, enjoy some miscellaneous pics of my truck
(edit for odometer reading correction)
(edit 2: misidentified breather hose)
Last edited:
. I'm guessing a flush of the transfer case is a must do too since they're sharing fluid? How much would I be risking driving a couple miles to a shop? Any clear causes of an issue like this, or did I just get unlucky?
