Transmission thoughts

[Henn28]

Looking for advice on what I think is a slow loos of bottom end power on my e53. I had vaguely suspected that the car was getting a little slower at low RPM (below perhaps 3000 to 3500, but like a frog in hot water didn’t have anything to compare it to until the G05 showed up.

Without the electric motor that car makes 375 hp and has monstrous low end grunt. The 4.6 in my car makes close to 350 and is no where close these days. I realize that the 8hp and final drive could be all, or most of the difference, and that (I think) the 4.6 power comes in later due to it being mostly cams, but I also have had for a long time a very distinct whine coming from the tranny at all RPM.

The gearbox is a remanufactured one I had installed in late 2019 and although this was during the period of benign neglect the car went thru and my records suck from then, it’s probably got 25k or so on it. I’ve changed the fluid once (last year) and all looked good with just a little “mud” on the magnets.

The TC was advertised as new, but it didn’t look new when it went in, so it was likely remanufactured as well. Could a failing TC cause a loss of low end grunt/power without the normal low end shudder that comes with that problem?

I’m thinking of having a full flush and fluid change done since the regular filter change procedures don’t get anywhere near a full fluid change done. Beyond this, I do t know enough about trannys to know why it would be whining like a turbine and if it could be causing a loos of low end power without other problems (slipping, shudders, hard shifts, etc.).

[80stech]

Definitely could be a torque converter/transmission issue. The whining might not totally be related to the power loss but still is a problem. Are you very sure it's coming from the transmission and if so can you tell if it's coming from the front or back of the trans? (and not the front diff) does it change pitch at all ? Your best bet might be to have a transmission shop have a look, they could probably give you a pretty quick idea.

[Henn28]

Originally Posted by 80stech

Definitely could be a torque converter/transmission issue. The whining might not totally be related to the power loss but still is a problem. Are you very sure it's coming from the transmission and if so can you tell if it's coming from the front or back of the trans? (and not the front diff) does it change pitch at all ? Your best bet might be to have a transmission shop have a look, they could probably give you a pretty quick idea.

Whine seems only to change in volume, not pitch with speed. I’m not 100% sure it’s the transmission. Lord knows it could be anything else possible on the car that I’ve messed with (rear diff), or something else just getting old like the front diff, t-case, etc. it does seem to be coming from the middle of the car, not the front or back and diesnt seem to do it when the car is coasting and I throw it in neutral, but I need to do some more troubleshooting.

I will likely take the car in, like you suggest, but need to find a shop experienced with ZF slush-boxes down here in American truck and suv land.

A failing TC wouldn’t be the end of the world and I could swap out the bellhousing and TC for the 4.6 version, rather than the 4.4 stuff. I could also address my tcase chain

[80stech]

I first was going to say "a shop with BMW experience" but the I think the ZF trans is used in a lot of north american vehicles including Ford trucks if I am not mistaken.

[Themoog]

Here are my thoughts.. I don't think it's the transmission or TC.
The M62tu motor torque and power comes on song circa 3500rpm anyway. The lower end power is controlled by Vanos. Mine had (and is happening again) several years ago the same symptoms as yours. I had no codes but a search of Internet pointed to Vanos solenoid. I replaced the one on the right side as you look from the front and it transformed the car.
Another symptom I had was while driving on cruise control then turning it off, the car decelerated like I had applied the brakes.
Something to consider.

[BimmerBreaker]

You can not compare those two cars. Apples and oranges. Drive a well sorted E53 and then see how it stands up.

Typically low end power issues are VANOS related as above poster mentioned but regardless, the comparison to a newer hybrid electric car will make even the healthiest E53 seem like a dud.

[Henn28]

Originally Posted by BimmerBreaker

You can not compare those two cars. Apples and oranges. Drive a well sorted E53 and then see how it stands up.

Typically low end power issues are VANOS related as above poster mentioned but regardless, the comparison to a newer hybrid electric car will make even the healthiest E53 seem like a dud.

I’ll check out the decel characteristics when the cruise control is switched off. I’ve keyed in on the transmission though due to the hydroelectric generator turbine whine from under the car. Not always in normal mode, sport mode definitely brings the whine out.