Okay guys, back for more help. Thought I fixed my last problem, new problem popped up. Background: 5.9 Limited (46RE tranny). Recently rebuilt, custom valve body from APS, lots of goodies, etc, etc. I was dealing with an issue where it wasn't shifting until 3000 rpm, a new Mopar TV cable fixed that.
The other day I was enjoying my Jeep again running errands, and I noticed a very weird sound. Whenever the tranny is in any range OTHER THAN park, it makes a hydraulic noise. Best I can describe it is the moaning sound an old ford steering pump used to make when it was getting old and you turned the wheel. In fact, at first, I actually thought my power steering pump was going out. Popping the hood proved I was wrong. This sound is RPM dependent, doesn't seem to sound any louder or quiter in any particular range than another. As mentioned, it doesn't make this noise in park, but it does make it in neutral. It sounds like it is coming from the bellhousing area.
Another interesting twist. The sound is RPM-dependent, meaning it gets louder with engine RPM. However, about a half-second before the tranny shifts, the sound goes away. It comes right back after the shift is completed, and will go away immediately preceding the next shift. And during the 2-3 shift, it feels like the tranny is momentarily letting go.
Lastly, it sounds like there is a mild mechanical sound (scraping and banging) noise in the mix, too.
Now, my research has yielded a couple possibilities, which I will list here:
Can anybody help? Any ideas? I'm sick of dumping money into this transmission!
The other day I was enjoying my Jeep again running errands, and I noticed a very weird sound. Whenever the tranny is in any range OTHER THAN park, it makes a hydraulic noise. Best I can describe it is the moaning sound an old ford steering pump used to make when it was getting old and you turned the wheel. In fact, at first, I actually thought my power steering pump was going out. Popping the hood proved I was wrong. This sound is RPM dependent, doesn't seem to sound any louder or quiter in any particular range than another. As mentioned, it doesn't make this noise in park, but it does make it in neutral. It sounds like it is coming from the bellhousing area.
Another interesting twist. The sound is RPM-dependent, meaning it gets louder with engine RPM. However, about a half-second before the tranny shifts, the sound goes away. It comes right back after the shift is completed, and will go away immediately preceding the next shift. And during the 2-3 shift, it feels like the tranny is momentarily letting go.
Lastly, it sounds like there is a mild mechanical sound (scraping and banging) noise in the mix, too.
Now, my research has yielded a couple possibilities, which I will list here:
- Torque Converter - Heard this as one of the most frquently cited reasons for sound coming from the bellhousing area. However, most things I've read say that this sound disappears in Park AND Neutral. I did a stall test and RPM was normal (about 2500 - it's an APS converter, nominal 2500 stall).
- Flex Plate - Heard these can crack or the bolts can be loose. In all my years of wrenching I've never seen it but okay. That would certainly explain the mechanical sound but I don't think it explains the hydraulic sound. Also, wouldn't it be making noise in park if this were the culprit? Easy enough to check, just pull the inspection cover.
- Plugged Filter - I've heard this noise can be caused by insufficient fluid flow, caused by a plugged filter. I fear this one not because changing the filter is difficult or expensive, but because that means my new tranny is generating enough debris to plug a filter = no bueno.
- Cooling System Restriction - similar to the filter problem above. Heard this can be a problem. I figured a somewhat easy test would be to take like a two-foot piece of tranny hose and "short-circuit" the cooler ports. Take the inlet and tie it to the outlet. If the sound goes away, hope a flush will clear it. If not, new radiator time.
- Valve Body Problem - I've heard a buzzing valve inside the VB can cause this sound. The fact my sound goes away right before shifting somewhat supports this. My VB has the no-buzz PR valve and TV and all the other fancy valves known to buzz. However, I've heard crap can get into one of the valves and cause it to buzz. The VB was assembled by Wayne at APS. Again, my concern here would be how the crap got in the valve in the first place.
- Internal Damage - God, I hope not. I just don't know what would be making noise in N but not in P. However, internal damage might pollute the tranny with debris, possibly contributing to 3) or 4) above.
Can anybody help? Any ideas? I'm sick of dumping money into this transmission!