Transmission Flush - Do or DON'T??

[crystalworks]

Originally Posted by mejim707

Yes, in fact I have ISTA and scanned the entire car and there are no fault codes whatsoever in the transmission module.

My thinking was that this additive won't do harm to the transmission if it is in fact performing properly. But, if it's not performing properly, and the fault is with the clutches or torque converter, it will be an immediate and apparent improvement in drive dynamics and I'll know at that point that the transmission / clutch are at fault.

If I add it and nothing changes I'll continue to dig. But if it makes an improvement or "fixes" the issue then I would target my efforts on a fluid change followed by a transmission replacement if needed. I can do the work myself.

This car is so smooth and feels new. This is the only issue I'm facing. Low speed -> Mild throttle -> Shift -> Shudder -> Hesitation

The additive could "fix" the trans, or it could grenade it. No way to tell before doing it. It shouldn't... but we all know how that goes.

No codes at all eh in the EGS? If you are sure the trans is the source, and you are comfortable doing the work, and you really want to keep this X5, then I'd follow:

Step 1: Replace tube seals, bridge seal, mechatronic sleeve, trans pan/filter, and fill with Valvoline Maxlife multivehicle. Clear adaptations.

Step 2: If the above doesn't help. Or it hurts and makes it worse. I'd have the valve body rebuilt w/ Sonnax zip kit. ~$750 service, or $300 in parts if you do it. I paid WorldWideSpecialties to do it for me. Clear adaptations.

Step 3: If above fails. Source low-mileage transmission w/ torque converter. Found mine for $800 shipped with 88k on the clock. Confirmed by getting VIN of vehicle it came out of and running it. Install your rebuilt valve body into it with original EGS (so no coding involved). New seals, pan, etc and clear adaptations.

Those are the steps I went through with our 35d and it shifts/drives like new. All in with PM parts (motor mounts, trans mount, vacuum lines, DPF cleaning, rear main seal, etc) I think it was ~$2000. We have 168000 on the truck. Remember, logically your truck is only worth $4000 at that mileage and with that issue. With a totally crapped trans... worth even less. So make sure to factor that into the value proposition. Ours is pretty nicely equipped and I couldn't send it to the scrap yard. But holy crap did it cost me time and back aches.

Note: Anytime you clear the trans adaptations it will drive like absolute dookie for 10-20 miles while it figures things out again. Mine bucked and even failsafed once. Just restart and keep driving. After a few miles it will get smoother and smoother.