4th to 3rd downshift trouble for Volvo V70XC 2000

Richard99 · Post by **Richard99** » 10 Aug 2020, 16:56

Hello,

When it is above about 80 degrees F, my 2000 Volvo v70xc won’t down shift from 4th to 3rd up hills and the engine will get bogged down. If I come to a stop, it will shift up through all the gears perfectly fine. Just seems to be that 4th to 3rd downshift. As soon as I come into the city and the temp dips below 70F, there are no issues. Also important is that I can manually put it from 4th to 3rd just fine. Any idea what this could be?

Post by **FLXC90** » 10 Aug 2020, 17:16

Is yours a 5-speed auto?

Post by **abscate** » 10 Aug 2020, 17:33

Sounds like a sticky solenoid. Definitely worth a series of three drain and fills of correct ATF to see if it will unstick

Richard99 · Post by **Richard99** » 10 Aug 2020, 18:14

FLXC90 wrote: ↑10 Aug 2020, 17:16 Is yours a 5-speed auto?

I have the 4 speed. Aisin 50-42le.

Post by **FlyingVolvo** » 10 Aug 2020, 19:48

How many miles?

As abscate suggested, if you haven't already done so, do several drain & fills with some good ATF (it's a bit pricey ~$10 quart, but I recommend Mobil 1 Syn ATF). When you drop the drain plug, it dumps about 3.5 quarts. Replace the same amount that came out thru the ATF dipstick. Do some driving, and then maybe another drain and fill. After the first one, I would also disconnect the battery for a bit and try to get the transmission learning to reset.

Richard99 · Post by **Richard99** » 12 Aug 2020, 00:16

Hi Ed,

Mine has 128k miles. I have done a thorough drain and fill a few months back. I installed an oil cooler from a C70 that I thought would be useful for the heat and hills in CA. Not sure if that has caused anyone problems or not.

Post by **FLXC90** » 12 Aug 2020, 15:40

Richard99 wrote: ↑12 Aug 2020, 00:16 Hi Ed,

Mine has 128k miles. I have done a thorough drain and fill a few months back. I installed an oil cooler from a C70 that I thought would be useful for the heat and hills in CA. Not sure if that has caused anyone problems or not.

You are referring to an aux trans cooler? Like Abscate said, sounds like a sticky solenoid, try adding a trans flush additive, running for a few days, then doing a pump and dump servicing. The main cause and effect I would see in the cooler and your situation is if there were gunk in the cooler that broke free and got into your system. Your mileage and the robust nature of the trans wouldn't normally indicate, especially if you previously changed the fluid by drain and fill. Had it been power flushed then yes. But not by a gravity or self pumping routine. Also, the solenoids are an electronic item (electric really) and they can be fickle. You draw a correlation between ambient temps and the issue, a hydromechanical problem or many intermittent internal electrical gremlins would more likely be fluid temp related. Were the addition of the cooler and the onset of the problem near in time? Also, did you add the cooler to the system, or did you re-route the flow, bypassing the cooler in the radiator.

Richard99 · Post by **Richard99** » 12 Aug 2020, 16:44

FLXC90 wrote: ↑12 Aug 2020, 15:40
Richard99 wrote: ↑12 Aug 2020, 00:16 Hi Ed,

Mine has 128k miles. I have done a thorough drain and fill a few months back. I installed an oil cooler from a C70 that I thought would be useful for the heat and hills in CA. Not sure if that has caused anyone problems or not.
You are referring to an aux trans cooler? Like Abscate said, sounds like a sticky solenoid, try adding a trans flush additive, running for a few days, then doing a pump and dump servicing. The main cause and effect I would see in the cooler and your situation is if there were gunk in the cooler that broke free and got into your system. Your mileage and the robust nature of the trans wouldn't normally indicate, especially if you previously changed the fluid by drain and fill. Had it been power flushed then yes. But not by a gravity or self pumping routine. Also, the solenoids are an electronic item (electric really) and they can be fickle. You draw a correlation between ambient temps and the issue, a hydromechanical problem or many intermittent internal electrical gremlins would more likely be fluid temp related. Were the addition of the cooler and the onset of the problem near in time? Also, did you add the cooler to the system, or did you re-route the flow, bypassing the cooler in the radiator.

Yes, I installed an aux trans cooler from a C70. When I bought the car about 6 months ago, the owner sold it to me for cheap because it had a hydraulic solenoid fault. I did a pump and dump service to it, as you mentioned and the problem went away. I installed the aux cooler a few months back. I added the cooler to the system, keeping the flow through the radiator. I'm guessing that the problem that I originally had when I purchased the vehicle is creeping back up on me. I'll do another drain and fill to see if that can fix it. Like you said, maybe something from the cooler or residual bad oil is making it act up again.