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2006 Subaru Tribeca Limited
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Discussion Starter #1
Hi all, I was referred over to you guys from the Tribeca forum. I'll copy and paste the problem I'm having below, hopefully some of the bright minds here can steer me in the right direction. Thank you!

So I haven't had this vehicle very long. It's a 2006 Tribeca with around 120k on it. Got it with a blown head gasket which I had a Subaru tech repair on the side for me. Now I finally got the car back and noticed a significant dipping in the RPMs at certain times while driving (and letting off the accelerator).

Easiest scenario to lay out is this: Driving down the tollway around 65-70mph if I let off the accelerator the RPMs will drop like the car was put in neutral. As soon as I touch the accelerator it will pick back up right away and read as it should. Doesn't appear to be slipping and don't notice and hard shifts or jutters and there are no indicator lights on...

This happens in multiple gears and seems to happen when cruising with RPMs over 2k. It's just most noticeable at higher speeds. Video below:
https://www.youtube.com/watch?v=r0uXLmc53qc&feature=youtu.be

A friend mentioned it could be trans fluid related due to pressure sensitivity. Maybe the wrong fluid used by previous owner... Not sure if that would be the cause though but another avenue I may have to explore. Not sure if a plug or cable was missed when the car was being repaired for the head gasket either, but that's a thought.

Thanks again,
Nate
 

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2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
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here is that thread on the tribeca forum

Transmission Issue - RPMs dropping significantly when letting off the pedal - SB9T.com

and I agree with tdelker rom raider maybe your best bet at logging and showing what is doing this.

throttle position sensor tricking it into a over reaction maybe,...or just typical EZ30R 5EAT activity
Subaru B9 Tribeca Research Site: price, colors, options and more



this is on the flat,...not going down or up a grade?

was it just the one head gasket that was replaced,...or both sides?

maybe when the engine went back in,...something did not get mechanically hooked up, or electrically hooked up 100%.
@ntippet just got a tribeca

and @plain OM is pretty good at looking at rom raider logs.
 

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2006 Subaru Tribeca Limited
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Discussion Starter #3
The video was indeed recorded on a fairly flat and level piece of roadway.

And yes, both head gaskets were replaced along with all the bells and whistles including sending the heads out to be machined. During the process the engine was removed completely so it very well could be something that is not hooked up or not hooked up securely. This was one of my primary thoughts as to the cause as well.

I have parked it for the time being until I can get the issue remedied as I don't want to have any damage caused from it.



here is that thread on the tribeca forum

Transmission Issue - RPMs dropping significantly when letting off the pedal - SB9T.com

and I agree with tdelker rom raider maybe your best bet at logging and showing what is doing this.

throttle position sensor tricking it into a over reaction maybe,...or just typical EZ30R 5EAT activity
Subaru B9 Tribeca Research Site: price, colors, options and more



this is on the flat,...not going down or up a grade?

was it just the one head gasket that was replaced,...or both sides?

maybe when the engine went back in,...something did not get mechanically hooked up, or electrically hooked up 100%.
@ntippet just got a tribeca

and @plain OM is pretty good at looking at rom raider logs.
 

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Lawn ornament XT
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14,366 Posts
Agreed start with fluid level. Then I might look at a log of the torque converter clutch, engine rpm and turbine speeds.

I don't know if the tribeca has the same built in diagnostics as the rest of the legacy family, but you might try using the link in my signature to see if the TCU has stored any old trouble codes.
 

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2006 Subaru Tribeca Limited
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Discussion Starter #8
Thanks for the help and advice so far!

I did check the levels, should have mentioned that. I don't know how warm the engine needs to be but it was about 45 mins after running during IL winter. The level was OK, a little shy of the top measurement. The fluid did look quite dirty though (brown).

Interesting on the trouble codes, I could give that a shot. I've only put about 50 miles on the car since I got it back from the head gasket repair so not sure if it's had adequate time to "learn" or throw any codes.

The mechanic that worked on it did mention having to replace a vacuum line that threw a code after he had the engine back in. I don't know what line it was or the code that was thrown though.

have you checked the fluid level yet?
 

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The fluid did look quite dirty though (brown)
That alone would be enough for me to suggest fluid replacement.

A) you don't know what kind is in there, car is new to you.
B) whatever it is probably started out pink, so I doubt it's that good now anyway.

Use Subaru HP fluid- it really does make a difference in these 5EATs. Available from the dealer, and apparently also from amazon.

It's not much harder to do than an engine oil change, so you can save a lot of money if you're the DIY type. You will need to do 3 back-to-back drain and fills to get a near-total volume replacement, with a short drive & manual cycle through every gear to exercise the valve body. Approx 3qt per fill cycle, so 8-9qt total should do the job.
 

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That alone would be enough for me to suggest fluid replacement.
+1

if it's a new to you car then you probably want it to last anyway - ATF change is probably the most cost effective preventative maintenance you can do on that vehicle given the cost of transmission repair/replacement.
 

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brown? ....I am thinking it might need a few flushes / drive cycles to flush out all that brown and any solids that maybe in it,

...Edit: maybe even 3x more then rasterman suggests if there is "solids" rinsing around
@MiddleAgeSubie was just doing this as a first time DIY on his Tibeca,...and might want to read through all the posts here.

Do you have maint. records from the 60,000 90,000 intervals?

that 2006 has a spin on trans filter: subaru part number 38325AA032 which is about $25 to buy off a dealer site / amazon /ebay
 

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2006 Subaru Tribeca Limited
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Discussion Starter #12
Not a whole lot as for maintenance records but it was at a dealer (and later an aftermarket shop) based on the Carfax when I purchased it. It was in for overheating and blown coolant tube a couple times before I got it. Thus the head gasket job I had completed. Took it down, replaced all o-rings, had the heads machined and checked, replaced all bolts and items per the TSB. So it should be mechanically sound on the top end.

I'll pursue the transmission fluid cycling then next friday. Also will replace that filter. I assume I should wait for the final fluid change to swap the filter? Also how long should I drive it between drain and fill?

Thanks for all the advice!
 

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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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I'll remind everyone you can use the transmission pump to do a full exchange with little extra effort. Detailed here: http://legacygt.com/forums/showthread.php/diy-5eat-atf-flush-197248.html?t=197248&highlight=DIY+transmission+fluid

Done it twice myself, once in my XT, once in my Tribeca.

"I repeated this recently on my 08 tribeca (same 5EAT). I had a messy surprise. The line that comes off the bottom of the transmission cooler is NOT the return line. It's the supply. This is different than my XT. Had the bucket all set up for it to come out of the bottom, but it came from the other side of the line and made quite the mess! I also tried the predrain and fill to see if I got clear fluid out sooner. However, that didn't seem to save anything, I could have easily just done it the original way of never opening the drain plug. Used 10 qts and it was clean at the end. Guestimated the spills and was about a 1/2 qt low (this is what I determined was the difference between full and low lines - interested if others found the same)."
 

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Not a whole lot as for maintenance records but it was at a dealer (and later an aftermarket shop) based on the Carfax when I purchased it. It was in for overheating and blown coolant tube a couple times before I got it. Thus the head gasket job I had completed. Took it down, replaced all o-rings, had the heads machined and checked, replaced all bolts and items per the TSB. So it should be mechanically sound on the top end.

I'll pursue the transmission fluid cycling then next friday. Also will replace that filter. I assume I should wait for the final fluid change to swap the filter? Also how long should I drive it between drain and fill?

Thanks for all the advice!
it seems you got to swap all the fluids that have not already been done with the HG job....(front / rear diffs, brakes)

trans fluid flushes from what I have read (please do some reading too, and maybe someone else will respond): some people make a minimum of a 20 minute ride varying speeds, and maybe shifting the automatic by hand some. then drain, measure off what you get out and add that much back in....with the cost of the High Performance fluid I don't know if it is permissible to use some cheap old dextron 3. mixed in to make the repeat flushings cheaper.

some people run by the day or by the week on a fluid flush just based on their own schedule of time it takes to drain and measure.

If you look at your capacities,...there might be 2 gallons or more in there,...and some report only getting 1/3 -1/2 of that volume to drain properly in one go....hence the need for many to drain and flush again carefully measuring each time and looking at the color of what is drained as it gradually turns to the color / viscosity of the clean fluid from the factory.

some here have added a product called "trans X" which I think helps remove some deposits. "seafoam" also makes a similar transmission flush product in their line of cleaners,...although it as a brand is known as a gas/ intake/ cylinder cleaner.


@middleagesubie got a extractor to pull the fluid up,...as some previous owner / tech ruined the drain plugs. (which maybe big 3/8 or 1/2" (mm) recessed square plugs),...and I think he put a thread up on the tribeca forum on it.

If you are going to DIY, you might consider one,...although at this point I would think you would get better flushes by getting the plug open.....this is something I borrow from a friend when I need it.

 

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On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
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I'll remind everyone you can use the transmission pump to do a full exchange with little extra effort. Detailed here: http://legacygt.com/forums/showthread.php/diy-5eat-atf-flush-197248.html?t=197248&highlight=DIY+transmission+fluid

Done it twice myself, once in my XT, once in my Tribeca.

"I repeated this recently on my 08 tribeca (same 5EAT). I had a messy surprise. The line that comes off the bottom of the transmission cooler is NOT the return line. It's the supply. This is different than my XT. Had the bucket all set up for it to come out of the bottom, but it came from the other side of the line and made quite the mess! I also tried the predrain and fill to see if I got clear fluid out sooner. However, that didn't seem to save anything, I could have easily just done it the original way of never opening the drain plug. Used 10 qts and it was clean at the end. Guestimated the spills and was about a 1/2 qt low (this is what I determined was the difference between full and low lines - interested if others found the same)."
that remind me of the couple of horror stories here with people (including dealers) draining and filling and opening the wrong drain plug/ filling the wrong fill tube.

and then getting thin trans fluid into the front diff,...and running around with too little trans fluid.

tdelker,...please check out what I typed out,...never did one, by myself and never had such brown fluid problems....ever. (and I wonder how long happy cranberry red fluid takes to get brown).
 

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I think that a fluid mistake is unlikely and would probably be shifting problems not TC lockup issues. However it is pretty common to crack the pump when installing the engine if the torque convert isn't properly seated. I'm not sure of the symptoms of when that happens.

My used tribeca had brown fluid that had been changed 30k before by a quick lube place (grease monkey). Smelled like gear oil.

My XT I changed my trannie fluid for the first time at 90k and it was black but no smell.
 

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I think that a fluid mistake is unlikely and would probably be shifting problems not TC lockup issues. However it is pretty common to crack the pump when installing the engine if the torque convert isn't properly seated. I'm not sure of the symptoms of when that happens.

I know ATF pump damage is a hazard in the 4EAT but wasn't aware of the same risk in the 5, hadn't heard of that yet anyway.
 

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Okay, I suppose I can't say I've seen a 5EAT with that exact issue. I assumed the 4EAT issue also applies to the 5EAT.
 
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