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  1. #11
    Join Date
    Jul 2015
    Location
    Maryland
    Posts
    18

    Default

    I used an infrared gun as well as just touching the input and output hose of the trans cooler. It's definitely cooler on the output side. Perhaps something is just malfunctioning with vida or the temp sensor. I'd be grateful if someone could check their vida/obd readings to see what theirs says. I searched on the net, but couldn't find anyone who'd checked temps in Vida. There was one post that referenced fluid temps before and after the cooler, but I assume he must have added sensors, as the XC70 only has the one sensor in the valve body, right?

    Could there be a thermostat in the transmission that maintains the temp at 190°f?

    I haven't towed with the larger cooler yet to see if it better keeps the temp from rising.

    I'm confident that the cooler I've installed is keeping fluid temps down, but now I'm just curious as to what's going on with the obd readings and if what I'm getting is an anomaly. Thanks again for your ideas and responses.

  2. #12
    Join Date
    Dec 2010
    Location
    Cumbria, UK. Maine USA.
    Posts
    513

    Default

    I know where the sensor is bolted in the trans, but never saw any thermostat inside the AW's i have dug around inside of.
    Current Junk: Couple of worthless rusty old clapped out Volvo bricks, XC70's 02, 04 & Countless P.O.S's, Rust buckets, Junk cars,( 50W Oily cesspool Sludge) Stolen and other assorted rubbish cars, 1928 Jed Clampett Tourer, (8 hole cast iron lump, original rust and decay, 40W Straight Bacon Grease),

  3. #13
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    4,116

    Default

    My AW-55 rebuilders manual is at my shop. I’m unlikely to see it anytime soon, but I don’t recall a thermostat in the transmission...

    I’m surprised by the lack of noticeable temperature improvement. It may be that’s the best result you’ll get under modest load, where the fluid is relatively cool, and warmed by the radiator.

    My hope would be, that the fluid under heavy load, when it’s quite hot, gets noticeably cooled by the cooler. Yiu would need some before and after data to confirm.

    In any event, I think you’ve done a good thing for your transmission. It still runs at normal temps, but I don’t think it will hit the same highs under heavy use.

    Let me also add that I’ve relaxed my position on fluid. I used to be pretty adamant about JWS-3309 and only used Mobil 3309 or Toyota T-IV. But I’ve used Valvoline Import Multi-Vehicle and AMSOIL Signature Series with good results, so, pick a fluid that’s JWS-3309 among the many available, and change it often.

    https://www.amsoil.com/p/signature-s...ion-fluid-atf/
    Last edited by Astro14; 08-27-2020 at 03:53 PM.
    Current Fleet:
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    2004 XC90 (235K, HPL 0W30 Euro)
    2002 V70-XC (295K, HPL 0W30 Euro)
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  4. #14
    Join Date
    Aug 2020
    Location
    Seattle-ish
    Posts
    11

    Default

    Quote Originally Posted by K_G_1 View Post
    .

    I'm confident that the cooler I've installed is keeping fluid temps down, but now I'm just curious as to what's going on with the obd readings and if what I'm getting is an anomaly. Thanks again for your ideas and responses.
    I am baffled just as you are, 2004 XC70. I installed a cooler last weekend and OBDII shows no change in temps.

    Granted, I did use a cheaper Hayden tube/fin cooler. But still...

    I ran the car with the OBDII installed prior on a specific route. Outside air 85F, temps went to 190F pretty quickly and stayed there +/- 2F. I installed the cooler, ran the same route, at 65F, and the temps were 188F +/- 2F!!! I don't buy it at all. 20F ambient temp difference PLUS a 4-pass tube/fin cooler should make a big difference. My prior experience was installing a more robust and larger cooler (but still tube/fin) on my SUV, and the temps are vastly lower. On that route my truck would have run 160F, max when the ambient was 85F, and it would have run 140F at 65F ambient. In my SUV I have an a-pillar mounted trans temp gauge, and the temp sensor for it is located in the line pressure test port in the bell housing. That would make it reflect fluid temp after it has left the valve body, but prior to hitting the torque converter or any clutch packs. Thus, it should represent pan temps, and thus cooler-output very closely. I'd like to get the Volvo transmission running that temperature, but don't know how at all to trust the OBDII temp reading. When I did the install, I also flushed through 8qts of Toyota T-IV and Mobil 3309 (had both around;l they are the exact same thing), and added some Lubegard red. The transmission works great and should have seen a big temp drop.

    The other thing that is wrong with the OBDII readings in my observation is that if I slow down into traffic, it stays around 190F or just a very few degrees higher. On my SUV, that would create a 10 to 20F temperature excursion depending upon time, humidity, ambient temp. No way should the Volvo OBDII temp stay the same unless it is measuring the AT temp right at the radiator intake or upper 1/2, OR it is corrupted and it's actually giving you a coolant reading by mistake. So I vote pitch the OBDII reading for all intents and purposes. It simply defies all logic and physical reasoning.

    I may get an AF33/AW55 manual from ATSG so I can figure out what is inside this thing. Or if the AW55 has a line pressure test port, maybe I'll just install a separate transmission temp. dial/"steam" gauge. Or maybe I'll just trust the cooler is working OK and ignore the OBDII temps, as your experience and mine are identical. I know Astro14 is very knowledgeable and reliable as I have seen his posts and interacted w/him for years on BITOG, but something's wrong with these OBDII temps, no disrespect.

    As an aside, I will say for those who argue to plumb the cooler upstream or downstream of the factory cooler, I am hugely in favor of downstream for maximum cooling. A) otherwise you'll re-heat cooled fluid, and B) I have found there is an acceptable "floor" to temps on downstream coolers despite what armchair nay-sayers suggest. As I said, my SUV cooler is over-sized (it is class B motorhome rated and actually 1/2" diameter, not 3/8"). On a highway at 65f, it will give me ATF temps coming out of the valve body at ambient +75F in all temps down to about 30F. Around there, it hits a floor of 110/115F and no lower temps ever register, even if ambient goes down to single digits (lowest I have experienced is high single digits). This is an outstanding temp range and stability IMO.

    I hope this helps the OP, as his time to explain his experiences has helped me. I am new to this car and this forum. Thus, I am not expert on it's unique systems at all, though have a lot of other mechanical experience.

    I am currently on a "shake down" run with the car on the Oregon coast. I spent a few weeks poking/prodding/fixing/etc. I've put about 800 miles on it since Monday (and I think I'm still 400 miles from home) coming down here from Seattle, a run down to the northern California Redwoods today, poking on to forest roads and beaches. What a great vehicle for this kind of use. The one I settled on has relatively low miles and is cosmetically very nice; I could see making friends with this car and keeping it a very long time.

  5. #15
    Join Date
    Jul 2015
    Location
    Maryland
    Posts
    18

    Default

    I had been using Mobil 3309 in previous changes, but used Valvoline import multi vehicle in my most recent flush after reading that it was equivalent, and since it was available locally for a good price at Wal Mart. Good to know that I wasn't going too far out on a limb with that choice.

    I'll report back with temps when I tow the camper again next weekend.

  6. #16
    Join Date
    Jul 2015
    Location
    Maryland
    Posts
    18

    Default

    Somehow I missed Oro-o's reply confirming my experience when I posted last, so thank you to him for taking the time to respond. After towing with the trailer, I did see somewhat lower temperatures, but nothing that couldn't be explained by the fact that ambient temperatures were ~20 degrees cooler than the last time I towed. The more telling detail is that again transmission and engine coolant temps stayed pegged to one another at all times, and never dropped below the expected 188-190 F. This leads me to believe that the OBD transmission temp reading is actually just a repeat of the engine/coolant temp, which is regulated by the thermostat. The fact that the OEM thermostat on the XC70 is set to open at 87C, which is 188.6 F seems to confirm this.
    I'm ok with just trusting that the transmission cooler is doing what it needs to, however, given that it seems pretty universally accepted that the transmission in the XC70 is fairly sensitive to proper fill level, and that the fill level is quite sensitive to temperature, how is one supposed to reliably fill the transmission to the correct level? Based on the Volvo chart, a difference of 30-40 degrees F (a reasonable temperature drop to assume with a cooler installed) could put one pretty far out of the proper fill level. Am I over thinking this??

    Click image for larger version. 

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    Last edited by K_G_1; 09-08-2020 at 07:38 PM.

  7. #17
    Join Date
    Nov 2018
    Location
    CT
    Posts
    76

    Default

    I installed my cooler hours before a trip to NH from CT, basically at any time I stopped I checked the fluid level and slowly added more bit by bit until I was comfortably within 1/8”-ish from the top of the hot range. Hasn’t budged since.

    I know that’s risky given the sensitivity to levels, but I’m doing another fluid flush (Gibbons method) in a couple of weeks and the transmission has been stellar ever since. I plan on flushing out the fluid every 30K or so for longevity, car shifts better today than it did when I first bought it (fluid never had been changed at 106K miles).

  8. #18
    Join Date
    Aug 2020
    Location
    Seattle-ish
    Posts
    11

    Default

    Quote Originally Posted by K_G_1 View Post
    =Based on the Volvo chart, a difference of 30-40 degrees F (a reasonable temperature drop to assume with a cooler installed) could put one pretty far out of the proper fill level. Am I over thinking this??
    Yes, honestly, I think so.

    What I do is rely upon the cold level. I started to have to do that with an Aisin U151e transmission in a Lexus ES. It could not read reliably hot - splash from the pan from any amount of driving would get into the tube and smear the stick well past the "hot" level. So I got in the habit of just checking them cold, with no "splash error." No problem.

    Also, I've done some math using thermal expansion co-efficients for oils the viscosity of ATF. The expansion rate is just really not that big. It has been a while since I did it (and I put it in a post/thread at BITOG), but IIRC you *might* get a an expansion of 12 ounces on a 10qt sump between room temp and full hot. And there's plenty of room inside any transmission case/pan I've seen for that much difference.

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