Transmission Slipping - Suddenly!

[vedipus]

In January 2020 my 2004 XC70 gave me a "Transmission Service Required" message. Car performed as usual. Due to serious family issues I had to keep driving the car for 2 trips over the span of 40 miles. Again, car ran as usual. Pulled out of a parking spot and immediate slipping. Big time. Like a light switch. Limped the car 5 miles home with small amounts of throttle and under 30 MPH. Parked it. Now it's December. I've looked at many threads here but must have missed this exact problem. I want to make sure a valve body will fix this. Ran the car down the street this week and it seemed normal and message disappeared. I know this isn't going to fix itself.

Transmission History:
-28K dealer fluid change.
-about 160K had less than a dozen flared shifts over the span of 5K.
-166K did Gibbons flush with 16 quarts. Old fluid was dark red, not brown.
-after 16K with no problems, we are at 182K.
-fluid is at exactly the same level as before.

Never had slow garage shifts. Never slipped before 5 miles ago.

I know the valve body will need to be replaced soon, but I'd hate to spend that time and money and still have a dead transmission.

Thanks for your help.

[pbierre]

Don't try to guess your diagnosis. Just to own this car, you should have a Volvo-specific OBD-II scanner (or VIDA / DiCE laptop app). Get a fault-code dump from the TCM.
You need a scanner that can pull TCM codes....not all of them go that deep.

Then, search Volvo discussion boards for the codes you're getting.

Getting a tranny rebuilt on a 16-year-old car is kinda questionable; the money might better be spent on something a bit newer.

[Xfingers]

I'm not sure you can be 100% certain the valve body is responsible for bad shifts until you actually replace it with another and see if your problems are solved. Certainly get your codes read with Vida/Dice as bpierre suggests. I replaced the VB in my 2002 (130k miles) and it did fix my shifting issues. Based on my experience, some telltale signs of a faulty VB exhibiting LOW fluid pressure:

Car shifts fine for first 5-10 minutes until fluid warms up. With my Vida hooked up, I could view the ATF temperature. IIRC, when the temp reached 55-60 Celsius, my shifts started slipping horribly.

Slow engagement in garage shifts. If you move the gear selector to D or R and then you have to wait an unnatural time for the click or engagement. Say you back out into the street and then notice a truck bearing down on you. If you throw the car in Drive and then have to wait for it to engage, low pressure...

[vedipus]

I definitely need Vida/Dice but I need one that is ready to use. Anything other than a straightforward installation is going to throw a roadblock into fixing the car. Not confident about the current Ebay offerings. Would be grateful if people could point to a specific one that works without complications.

I appreciate the suggestions. I just figured that the unique conditions of my car's transmission would lead to a clear way to diagnose? My car does NOT have a shifting problem. It has never had a problem with slow garage shifts. The slipping was from leaving a parking space all the way home. The whole way. It had nothing to do with shifting.

I've read elsewhere here that checking fluid flow at the cooler is a good way to diagnose, but only if slipping is present.

Drove fine -> "Transmission Service Required" message -> Continued to drive fine for 40 miles (2 trips) -> Major slipping ALL the time from the moment I left the parking space to home. There was no time it wasn't slipping. Basically undriveable. Now after being parked for 11 months it doesn't seem to be slipping.

Anyone else have the same condition?

Thanks again.

[FirstVolvo]

My transmission problems began suddenly and it was a clogged filter but about a month prior to it actually slipping, producing codes and the service transmission message I could hear a whining sound when the car was first started (cold), which is a good clue the filter was clogging up and the pump was starving for fluid. Do you hear a whining type sound when first starting the car and as it warms up does the whine go away or at least become less noticeable?

[vedipus]

I posted a few hours ago, but the message is going through the moderator gate-keeper.

I had been hearing a whining noise, but it seems like it is due to a power-steering starvation issue. Only when turning through tight turns at slow speeds. Nothing parked at idle. The information display warning was an obvious signal. I only hear the usual at start-up noise. As for DTCs, they might not show much even with VIDA since the battery has been disconnected for months.

Thank you very much for your input on this. The sudden slipping definitely means something. I'll pay attention for any different sounds. I'll also do some looking into the filter. I know it's a big job.

[perkinscl]

I know you mentioned your fluid level has changed, but the wrong fluid amount could give these exact symptoms. Unfortunately, to get an accurate reading you need to drive for at least 15 min to get the fluid up to temp.

[Astro14]

Always, always, check fluid level first when a transmission is acting up. It can be checked cold (idling, dead level ground) by using the "Cold" marks on the dipstick.

[FirstVolvo]

I posted a few hours ago, but the message is going through the moderator gate-keeper.

I had been hearing a whining noise, but it seems like it is due to a power-steering starvation issue. Only when turning through tight turns at slow speeds. Nothing parked at idle. The information display warning was an obvious signal. I only hear the usual at start-up noise. As for DTCs, they might not show much even with VIDA since the battery has been disconnected for months.

Thank you very much for your input on this. The sudden slipping definitely means something. I'll pay attention for any different sounds. I'll also do some looking into the filter. I know it's a big job.

A whine from the transmission pump changes with engine speed and doesn't matter if in PNDR, it's more noticeable when the fluid is cold. Other symptoms of the clogged filter, transmission service required, P0740 when driving and also the next day (in my case) delay engagements from P-R, P-D, N-R, N-D. I had a delay then a bang engagement shifting to R from P, slipping in D and R. These symptoms didn't occur gradually although the whine had been going on for about a month.

[vedipus]

Thanks for these additional details.

To clarify, the fluid level is exactly the same as when I did the Gibbons flush 16K ago.