The Black Flower of Transmission Death

[SkiMachine]

See the attached image. It's from my 94's RE1R01A. That it so clearly demonstrates the magnetic fields is really cool. The black stuff looks like metal shards, end-to-end radiating outward like hoar frost. I'm not sure what the grey stuff is - it has the consistency of sludge/jelly. I'm also not sure what this means for my goal of rebuilding this thing. Tearing it down now, so we'll see...

 

 

Debris in filter...

 

This is not rum, though i could use a drink right about now...

[AndyC]

Dang! (But that image is really cool!)

How many miles on the tranny and any signs of it failing leading up to this?

[Precise1]

That doesn't look good, but at least it is small pieces. What happened to the ATF though?

 

B

[Slartibartfast]

Looks like Hershey's syrup in that bottle!

[SkiMachine]

That fluid is basically black without a light right on it. When it's shallow it still looks red-ish, maybe.

 

So far the only thing I've seen that is suspect (other than the fluid and that magnet) is the edge of the front low/reverse clutch housing where it mates up with the rear housing of the same clutch pack. It's rough and appears to have impacted with something. Some of the needle bearings are also not as smooth running as they should be, but that's most certainly more symptom than cause.

 

The reason for all of this is that reverse stopped working suddenly.

 

The warning sign that something was amis was that the transmission would randomly decide it didn't want to shift into second anymore - after reversing. This problem occurred very occasionally, and wasn't reproducible which didn't help my troubleshooting attempts. Then suddenly, blamo, no reverse at all..

 

The history behind this is in this thread: http://www.nissanpathfinders.net/forum/index.php?/topic/null-VG30-Timing-/-No-Power-Issue In other words, I'm one of those "I drove it for six months without reverse" types. Though the metal dust on the magnet suggests I should not have.

 

There is currently about 220,000km on the clock for the truck, not sure about the tranny. There is clear evidence this beast has been off the truck before. Newer, non-stock (non removable) zip-ties on wiring that needs to be removed to get the tranny out, a missing (if the FSM is accurate) oil tube clip on the valve body. Plus the loose crankshaft pulley bolt - which could have easily been loosened while someone was tightening torque convertor bolts on to the drive plate.

 

 

 

 

[SkiMachine]

It looks like that magnet really was the black flower of transmission death.

 

Something clearly did some bouncing around in this tranny, and it did some damage. Ultimately what ever it was tore a chunk of the first of two reverse clutch sealing rings out of its grove on the oil pump cover's snout:

 

 

Looks like a part of the missing piece got wedged up on the other side:

 

 

Note that's not debris on the edges of the seal seats - they're ground up and jagged. Thus the oil pump cover is a lost cause. Coupled with the suspect clutch pack and I'd say this transmission is toast. Any thoughts?

 

FWIW, the friction plates in both the reverse clutch and high clutch are in like new condition - they measure in at standard, nowhere near the wear limits. It had to have been rebuilt not too long before I bought the truck.

 

 

[Towncivilian]

That magnet looks neat for sure. But not all of the fluid passes over the magnet, so I don't even want to imagine what other ferrous wear material was still floating around. That's why I run a Magnefine in-line filter; all fluid passes over the magnet, and much of the non-ferrous wear material will get caught in the filtering media, which is in the range of 35 microns; even the best in-pan strainers don't go lower than about 80 microns. Strainers are more like rock catchers than real filters.

 

Installing an in-line filter is especially beneficial after a rebuild, since there will be new break-in wear, plus any debris that may have entered through the rebuild process... transmission shops aren't exactly clean rooms.

Edited November 18, 2013 by Towncivilian

[SkiMachine]

Yeah if I get this thing back up and running a inline filter will be installed for sure. I already have a Hayden cooler ready to go on the truck. The stock rad cooler was still in use, and judging by its condition, pre-dates the previous rebuild. It's unfortunate that someone went to all that work/expense for a rebuild and didn't pay attention to that detail.

 

I think I can get this back on the road if I replace the reverse drum and the oil pump, along with that drum's bushing, which came in the bushings kit from Rock Auto. Everything else seems fine, except some bearings. Speaking of the rear drum's bushing - metal shards were apparently being gouged off of it.

 

This seems to be a common cause of this common issue, judging by the description in this post here (off-site), and the photo of the reverse clutch in this post

 

[Precise1]

What a mess! Thanks for documenting it though, we can always use more info about these trannys.

 

Make sure that you have proper flow through the stock radiator cooler, sometimes they clog. Many of us run after market cookers to avoid this or a combo of filters and tranny temp gauges so you can reduce likelyhood of insufficient cooling and monitor things.

 

B

[SkiMachine]

Documenting it is kinda the goal. It's surprising how little info there is out there on this subject, despite a loss of reverse being the typical failure mode for these transmissions.

 

Here are some somewhat better photos, with annotations:

 

Front Drum:

 

Front stator (on oil pump):

 

Both of the above as they would sit together in the tranny, for clarity:

 

Stator/Drum bushing. The diagonal grooves should spread oil evenly across the surface. The new one has grooves facing the same direction, where the old one had opposing groves pushing in opposing directions, I'm not sure if the change is intentional. The stator has lube circuit ports that inject oil "under" this bushing (into the diagonal grooves) to keep wear to a minimum. The inside of the bushing (and only this bushing) is copper or brass. Any loss of lubrication due to plugged fliters, bad seals, cooked/old oil, or abrasive material in the oil, etc would be disastorous for this bushing given the softer metal on the wear surface.

 

If you take a good look at edge of the worn bushing, you'll see a shard of metal coming off of it (top of photo)... not good at all. Difference in thickness was about 0.25mm, or .5mm inner diameter. I'm pretty sure the stator has worn down by a mm or so diameter as well which adds up to quite a bit of play.

 

 

Edited November 21, 2013 by SkiMachine