V70XC tranny "thump" before going....

[RookieRoger]

My 2001 V70XC, just over220,000 miles, upon moving forward revs past 2000 rpm and before engaging in gear, produces a very noticable "thump!" As if I have hit something or someone. After this initial "thump" it struggles to reach 60 mph but eventually does. The frequency of this occuring has been increasing the past 8 weeks.
I finally found the transmission fluid check and it appears normal.
But I know this sound can't be normal!?
I have zero experience with auto transmisions.
I'm searching for work meanwhile I'm delivering Pizza part time with this vehicle and will try to learn before it is too late. I know transmission problems can cost big money.
What kind of a problem may I have and what should I do next or did I wait too long before addressing the issue? Thanks for your time, I REALLy appreciate it. Roger.

[oragex]

Has it been doing this for long time before ? The first thing to try would be to replace half the fluid, equivalent with a drain and refill - we refill only through the dipstick tube hole, there is no proper refill plug but garages who don't know these cars try removing a top bolt and bam the transmission no longer works - saying this in case you bring it in, stay near the guy working on it. You need about 4 qts of this https://www.fcpeuro.com/products/volvo- ... -1161540kt
But the partial fluid change would be about the first step. However, realistically speaking don't expect miracles. It may or may not help.
I would also have Volvo check if the neutral stop function was already removed from the transmission software. I would guess it was, but just to be sure.
Other than that, you are really short of cheap options. Some people tried replaced the valve body, but given the miles it's a costly gamble.

[abscate]

This really sounds like the neutral stop feature.

A Volvo dealer will remove that for free, I think the nearest is in San Leandro

[SuperHerman]

With those miles and your budget this is what I would do.

Pick up some Valvoline MaxLife - under $25 for the 4-5 quart jug and a bottle of Seafoam Trans Tune (not the motor stuff by transmission variant).

Drain the fluid that is in there - about 2.5-4 quarts should come out. Replace the drain plug and put in 1/2 of your can of SeaFoam - then top off the fluid based on what came out (less the Seafoam) - check your transmission dipstick while the vehicle is in park and running after a lap around the block to get it up to temperature. Top off as needed.

Then drive the car for 500-1000 miles and repeat the process. It most likely will continue to slam for the short term, but if the Seafoam works you will start to see improvements. It is not an instant fix - the solvent takes time to work (if it works).

It sounds like your solenoids are sticking and then releasing, causing the bang. Sometimes the fluid change and Seafoam will clear them up. Some have had success - others not. On a budget this is your cheapest option which has delivered results for many.

There are more options, but they are more expensive and much more difficult. What I suggest requires one socket or wrench to remove the transmission drain plug, a funnel, and a drain pan to catch the waste - plus the fluids mentioned.