Diagnosing a Transmission Problem | Subaru Outback Forums

Hello everyone, entry post here

I am hoping to get some help diagnosing my transmission problem so I can make decisions on what path to take with the repair. I have searched a lot on this forum, google, facebook etc and found a lot of valuable information. I would like to make as much progress as I can with the diagnosis before spending $$$ on a mechanic. The transmission is a 2010 TR690.

The basic symptom is harsh stalling (highly reported) that feels like the clutch has dropped into a manual (or perhaps, like upshifting into third). It is not safe to drive in traffic. I have no error codes or peak lights. Apart from this single issue, everything else is fine.

Since the issue came out of the blue, it seems to me that something has gone wrong. The possibilities that I am aware of are:

  • Bad battery / ground
  • Throttle body problem
  • Valve body solenoid failed
  • Torque converter coil failure (leading to metal particles leading to one of the other problems)
  • Valve body worn / blocked
  • Trans fluid pump failure
  • Internal broadcast failed
  • A failed driveshaft seal, causing the diff to release fluid and overheat, leading to damage to the trans pump seal / or other internal part, leading to the two fluids mixing. I have no evidence that this is the case, but I haven’t ruled it out.
  • (I think this is unlikely, but can’t rule it out) Some ATF fluid in the CVT. When I replaced the radiator last year, I also replaced the power steering fluid at the same time. The service receipt does not mention cvt fluid, only ATF fluid, which I am very confident would have been used only to replace the PS fluid. Apparently they weren’t worried about losing CVT fluid with the radiator change.

As mentioned below, I still have a few things to test or retest.

If I can prove that the problem is likely to be one of the cheaper ones, I’m happy to continue down that path. If I can decide that a whole transmission replacement, or for that matter, a new VB AND TC is the most likely outcome, then I’d rather not spend too much money to find out.

I’m open to draining the trans fluid or dropping the pan to check for metal fillings but note that by doing that I’m on the $$$ to refill so I can then move the car or do more beyond (directed) diagnostics, fluid that is then likely to be lost in the eventual repair. It looks like I may have to drive the car to determine if any of the possibly simpler repairs have fixed it or not – but I don’t want to cause further damage.

I will try to give as much information as possible without being long.

Background: In early February, I pulled over on the highway (hills) for 3 hours and at the end of this trip I first noticed the transmission symptoms (note that I pull over at least weekly). The only difference on this particular ride compared to normal is that I drove the bike a little harder than usual up the hills. I usually keep it at ~3000rpm when towing to limit fuel consumption, but this time I ran maybe 4500rpm at times.

At my destination, I did a short hop forward while backing up the trailer and that’s the first time I definitively noticed the transmission problem. It is possible that I noticed the symptoms slightly in the week before this trip, but if so, they were minor. My wife drove up the next day and called me to say there was a problem. We had the local dealer take it around the block for a quick appraisal. Their advice was ‘it’s a transmission issue, don’t drive it, we can’t look at it for 6 weeks’. We drove the car for another 10km that day and then put it on the flatbed at home. I drove it for a while. It’s scary. It seems to be deteriorating rapidly.

Steps I’ve taken: I’ve seen the car in short bursts over the last few weeks.

1. Charged the battery After it had been on the road for a week or two (before I looked at it), I noticed that the battery status indicator on the battery was showing that it needed to be recharged. So I charged it for a few days until it showed fully charged. The battery is approaching 3 years still under warranty. There were blue crystals around the positive battery terminal.

2. Checked for fluid leaks I have never noticed any oil leaking onto the road. Given the age and mileage, I’m not surprised that there are some leaks, but nothing significant to me. When I investigated the transmission, the first thing I noticed is that the bottom of the car, the RH side, especially the drive shaft, was covered in oil photo photo2 photo3 photo4. So was the front differential housing. The oil itself looked clean / like fresh oil. The LH side was not covered with oil. I can see some areas further up that have oil as well. All RH side. Given the location I was wondering about the rear main seal or drive shaft seal. When I cleaned the oil I smelled it and it smelled like gear (diff) oil. Oddly, and perhaps unrelated to everything else, there is also a small weep at the rear of the transmission that appears to have blown forward.

3. Controlled solenoids I tested the solenoids in the webinar and all the solenoids tested at or very close to range when cold. I warmed the car up a bit and tried again, again everything seemed fine except maybe the lock/ignition solenoid. Two caveats: 1) At that stage I had no way of reading the trans fluid temp other than feeling the coolant pipe temp (and from later experience, I know it would have been in the “cold” range of Temps of operation); and 2) my readings weren’t necessarily great. I will have to buy some new test strips as mine are not giving consistent readings all the time.

4. I have not yet tested the lock operation solenoid under actual load as described on p.14. I tried, but then I realized that I had previously blown the fuse in my multimeter and by the time I replaced it, I was having problems with the battery (below).

5. OBD codes checked I got a bluetooth obd reader and confirmed there were no codes, ran the car to raise the transmission temperature so I could check the fill level and recheck the solenoid resistance values ​​when it warmed up. I couldn’t get the fill port open and didn’t get reasonable readings with the multimeter, so I’ll have to repeat this exercise.

6. Flat battery I left the obd reader plugged in. When I returned to the car a week later, I realized the battery was only reading 3v. It was too flat for my charger to handle so I need to pick it up and charge / test / possibly replace it. I suspect the obd reader drained the battery but that could indicate a battery problem.

7. Checked the basics The resistance in the main ground cable to the block is ~ 0.1 ohm.

8. Front differential fluid With the car cold, I managed to loosen the front diff leveling plug and after loosening it just a little bit, some fluid drained out (see on my hand). I thought that meant the diff finally had the correct fluid level, but then I read somewhere that made me think maybe I should open it up right away to get a reliable fluid level check. Some of the liquid was clear, some was black. The diff oil was changed <12 months ago / 25000km.

9. Trans fluid level With the car cold, I was able to open the fill port on the transmission. (it is worth saying that the car is close to level). I was very surprised that the trans fluid came out with the car cold. Is this unusual? Given the requirement to have the transmission at the correct temperature when filled to get the correct fluid level, I would expect the fluid level to be below the fill port when cold. The fluid didn’t look new (it isn’t!), but it still had its blue color with some gray particles. The gray particles settled quickly. It felt different than the oil I found leaking. Vaseline is the closest thing I can think of to that smell.

10. Throttle body I have never cleaned the throttle body. I noticed when I went to start the car that with the ignition on, engine off, there was a noise from the throttle servo. Google tells me it’s normal. But I noticed it wasn’t doing this on other occasions. (If anyone could kindly point me in the direction of a good TB cleaning guide I would appreciate it).

11. I haven’t cleaned the ground connections yet.

Next steps:
1. I will charge the battery, test it and repair it. I will clear the grounds.
2. I will double check the solenoid resistances with new test leads, cold and hot. But without a code, this seems impossible?
3. I will clean the throttle body.
4. I might go for a drive in manual mode and see if that fixes the problem. If so, what does this mean for repair?
5. Would a line pressure test verify that the pump is working properly? Will any mechanic be able to do this, or do I need a specialist? I may also buy the DIY kit if someone can point me in the right direction as to what exactly I need to buy.
6. If the conclusion is that I need to replace the VB and torque converter, I think I’ll drain the trans fluid next to assess the condition of the internals (looking for large metal parts), to help set should I repair this trans or get a refurbished replacement with new TC and VB.

Summary questions:

  • Am I on the right track?
  • What else can I do to diagnose?

Thanks, John

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