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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Transmissions
Satisfied Customers: 44474
Experience:  16 yrs. experience with auto, manual, & CVT drivelines
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Glad you guys are out there helpin' us poor DIY folks out

Customer Question

Hello! Glad you guys are out there helpin' us poor DIY folks out lol... I very much appreciate it! My wife's 06 Nissan Xterra... Trans slipping after 15 miles. Did a flush, replaced filter, replaced radiator (trans cooler section totally clogged), trans external cooler was clear. Still runs and shifts great but now for only a few miles. Then checked fluid at cooler supply hose when running. Ah HA! No fluid except when I let it cool down an hour or so. What does this intermittent fluid pressure mean? Pumps just slowly die Right? Are there any spring valves I can check and clean before going for a trans rebuild?
Submitted: 23 days ago.
Category: Transmissions
Expert:  Chris (aka- Moose) replied 22 days ago.

Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner past midnight.

  • Sorry no one has helped yet for the question fees you have already paid.
  • I can help with this question.
  • Reply and let me know when your able to work on this concern.
Customer: replied 20 days ago.
sir! Please help! I'm hoping there's a gunked-up pressure regulator valve or two accessible from outside the T-case, but I'm without a car lift, working from squeezing myself under the vehicle on jackstands. Kinda hard to know what my hands are grabbing up there. Again, the bands and clutches are functioning fine when the fluid is pumping... but then it stops pumping after a few miles and starts to slip.
Expert:  Chris (aka- Moose) replied 20 days ago.

Do you own a pressure gauge to check the pressure?

Monitoring the cooler flow is not a form of diagnosing unless your trans oil has an overheating concern. Cooler flow is regulated by a thermostat.

In the event pressure is low slipping would be a minimal concern because low pressure would result in it slipping horribly or not even engaging. Also in the event pressure is low, the damage to the clutches and bands is already done meaning you now have a cause and result to address. Based on it slipping I believe overhaul is inevitable at at the least including diagnostics to see if pump line pressure is low.

What now

  1. You have asked a question.
  2. You have paid a deposit and received an info request and or answer(s).
  3. Now it is time to follow up if needed or rate my answer, hopefully 5 STAR EXCELLENT. Sometimes the rating fails, responding with (I am a pleased) will suffice.
  4. You are more than welcome to still follow up. I want you pleased with me and my answer(s).

Thanks for using Just Answer, and rating me so I am compensated, Chris

Expert:  Chris (aka- Moose) replied 19 days ago.

Hello again Chris here,

  • Sorry you were not pleased with my help.
  • What would you like to do regarding your question now.
  • This post is coming up on the 7 day mark where it times out. When a post times out, that means it's no longer on my active list (you reply and I may never know it.)

Thanks Chris

Customer: replied 18 days ago.
Chris thank you for the reply. I've just been busy last two days. I do think there is a possibility I may have mis-worded the symptoms. First, by my staying I checked cooler flow.. I meant the trans cooler line... not the coolant flow in the radiator.. Just making sure. If the trans oil flow is regulated by a thermostat, that's news to me. Also, when I mentioned slipping, I failed to mention that it really just let's go... like bands/clutches not engaging at all. That's when I left it running and pulled the trans cooler line to find no flow at all. After an hour of sitting, it drives and shifts fine again, for a few miles, then lets clutches let go entirely
Expert:  Chris (aka- Moose) replied 18 days ago.

Do you have a scan tool to check the trans fluid temp?

Do you have a pressure gauge to check the line pressure?

Customer: replied 18 days ago.
I have an infrared laser temp gauge, but not an inline gauge, and here at home no pressure gauge. Line pressure is either all or nothing. When I start the vehicle cold, pull the cooler send line, and it just gushes, I reconnect and clamp it, check fluid level, jump in and she shifts fine, and after a mile it completely loses fluid pressure and trans disengages.
Customer: replied 18 days ago.
Its not really slipping as I said before.. It's fully operational, then nothing. The slip-time is literally a half-second, as it completely disengages. I have only test driven it twice that this happened. I know not to run it and burn the clutches and bands, but both times it happened, I pulled the cooler supply line to find no fluid coming out. I wait an hour, walk the block back to the Xterra, start it, pull the line, and it gushes out, reconnect and drove it home, so it seems that the fluid pressure is all or nothing, and the clutches and bands are fine because it shifts fine, and doesn't slip (when it's working).
Customer: replied 18 days ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 18 days ago.
Aaron(###) ###-####
Expert:  Chris (aka- Moose) replied 17 days ago.

I can diagnose this based on it not having line pressure and not knowing the fluid temp via special tool checking. However the diag may be wrong since we are basing it on a test not outlined in the repair guides as needing to perform to get to the next steps.

Customer: replied 17 days ago.
Last few test drives, it disengaged after only a mile or so, after cold startup. Trans fluid hasn't reached operating temp duri g these last few falures
Expert:  Chris (aka- Moose) replied 17 days ago.

So do you want to continue forward on the diag based on assuming its loosing line pressure?

Customer: replied 17 days ago.
that's all I think it is. Hard parts engaging fine, or not at all. Line pressure intermittently all or nothing. Fluid temp cold to like warm at best
Expert:  Chris (aka- Moose) replied 17 days ago.

Based on the pressure test, low line pressure means the pump is worn out or the pressure regulator are the most likely failures.

https://dl.dropboxusercontent.com/u/90220402/pressrg.pdf