Tranny Slipping or the Snow?
 

Hello all, before I start may I issue the disclaimer: I have done as much searching for this topic as time may allow, and have found nothing useful at all.

Ok then, now to the problemo. So we just got about an inch of snow on the ground, and as usual I have been out and about trodging around in it (gotta love AWD). So as i go up hills, the rpms flare up, as though the wheels were spinning and not getting any grip in the snow, which is a perfect possibility. So finally I get very close to home, where there is a small hill, that i am forced to stop in the middle of. I open the door and hang my head out to watch the tires. When I give the car gas and look at them, there is nothing happening with the wheels. Plenty of gas, and engine activity, no wheel movement, slipping, nothing! So i turn the car off, let it 'chill' for a few minutes and then manage to limp the last mile home at like 5 mph in the snow. I tested it again this morning, to the same result. I also checked the tranny fluid, and it looks completely nice and red, although it smells funky, but not burnt. I get this lack of movement in 1st, second (force it into manual mode) and reverse. Does anyone have any idea what this could be?? I really need to find out quickly what kind of problem im looking at. Thanks so much for your help in advance! -Andrew Robb

Low/Reverse brake?

Only the wheels on the passenger's side are spinning?

The other possibility is that you haven't given it enough gas. If the speedometer doesn't move then the wheels aren't turning. The speedometer is hooked up pretty directly to the wheels. If it shows speed, then the wheels (at least one of the front ones) are turning.

Well from speaking with Andrew...
 

...and trouble-shooting the problem it appears that two things could be at play with his car.

1) He didn't mention a constant ticking sound that's coming from behind the engine but infront of the transmission. Appears the flexplate on his '92 LS-L with 146K miles has a crack in it. However, his car has had this noise for a couple of weeks and was driving like normal despite it.

2) Even now Andrew's car drives like normal when cold, but once the car warms up it doesn't move. It's almost as if the engine cannot be engaged with the trans.

Now in a different post, I think it was Earthworm that mentioned to Nik Fu S. that when the trans is cold, the atf flow doesn't go to the trans cooler to allow the fluid to come up to operating temp as quickly as possible. Once operating temp is reached, the flow map then changes to incorporate this 'cooling loop'.

Since Andrew's car runs as normal when cool (power going to all four wheels btw), something is causing his trans to not work when it reaches operating temp. I'm guessing that his '92 trans cooler (in the radiator) has a clogged screen, which was removed in later model years by Subaru. However, as a stroke of good luck, the previous owner of Andrew's car installed an aftermarket trans cooler. ;)

For basically $1 (hose clamps), I'll be cutting the lines going to his cooler in the radiator, and only hooking up the lines to the aftermarket cooler. Svxfiles is also suggesting that we drain the atf as this will help to get rid of any other debris floating around in his high mileage trans, which is a great idea! :)

If all goes well, Andrew's car should be back on the road in less than a week.

-Chike

P.S. I'll report back and let you guys know if my hunch is correct. Once his car is drivable again, Andrew plans on fixing the flexplate problem asap.

Re: Tranny Slipping or the Snow?
 

Hi Andrew, as it does it in D, 1st, 2nd and R, it looks like it may be a lack of line pressure. I woud check for a code first, to rule out the A solenoid, throttle position sensor.

As it happends in 1st position of D, the low/reverse brake is not active, to rule it out. The cooler is not the cause as the oil flow through it is constant, and plays no part in line pressure.

I would suspect it is a lack of line pressure as too any things are affected. I think the fault could be caused by the screen filter in the pan may be blocked.

Harvey.;)

Re: Re: Tranny Slipping or the Snow?
 

Harvey, understand that Andrew's description left out several details. I did think of the internal screen, but if that was blocked, the line pressure would be low whether the trans was cool or up to temp. When his atf is cool, all of his gears work properly according to Andrew. Everything just ceases to work once things warm up.

Either way, dropping the transmission pan and replacing the screen would probably not be a bad idea, but I'm not sure if Andrew has the funds to cover the parts (trans pan gasket & filter screen).

Hopefully, when we drain the trans enough debris will become dislodged to allow some atf to pass through his screen.

-Chike

could the ATF temp sensor be playing a roll in this? It seems that the temp of the trans is crutial in this problem so why not think of the sensor that detects that. Maybe the sensor is not reading properly or not at all and is allowing the TC to freewheel when it is warmed up. It was just a though that i have already passed by Amazonparrot. Let me know what u think Harvey.

As far as I know Tom the over temp signal, only forces Power Mode, to run the pump faster to circulate the ATF through the cooler, to reduce the temp.

According to Andrew, he said he tested it the next morning, and had the same results. So it would seem that the problem was still there when, 'stone cold'.

I feel that it is a lack of line pressure. (though I would not rule out the forward clutch). This could be caused by a number of things. Depending on the model, it could be the pump gasket, the A solenoid stuck open, the pan filter blocked, a ball plug blowen out of the valve body, or any number of other units leaking. A test of line pressure will tell, but as he is stuck at home, the pan filter is the most likely and something he could check.

Hope it goes well for him.
Harvey.;)

well if he still has the problem at a cold temp also, I am at a loss. I would say replace or rebuild. Easiest and maybe most cost effective. But do as Harvey says first cuz he knows a lotl more than I do

That's the confusing thing with Andrew's post, it reads like the problems persists when it's cold, but it doesn't. After speaking to him on the phone for a total of 2 hours, he claims that the car drives as normal when cold, but as soon as it heats up - the problem comes back. He even has a video he took of the car driving around a barn at his place and then all of a sudden the car stops working.

Oab_au is basing his inferences on the limited info Andrew provided in his initial post. Maybe Harvey is correct that the internal screen is blocked, but I need to figure out a way to get Andrew's car back on the road.

-Chike

#1 thing I would suggest and also goes along with what Harvey said is to drop the pan. This way you can see exactly what the fluid looks like and what kind of shavings are in the pan. Also you can clean or replace the screen filter. A little time consuming but well worth it if that ends up being the problem.

Tom

Agreed. Makes good sense.

-Chike

What is the year model of the car? The screen filter could be full of lining chips. Or it could be the pump gasket, depends on the model.

Harvey;)

Andrew has a '92 LS-L with slightly over 146K miles.

Another thing which he didn't mention in his initial post is that he had a torque converter completely rebuilt and got his car back last summer (took 8 months). I'm not sure if there's debris in his 4EAT from when the trans just sat on a bench at the repair shop, or if the rebuilt torque converter had metal shavings in it...

Basically, there are a lot of details that were left out. Svxfiles also spoke to Andrew for ~45 minutes and couldn't conclusively isolate the problem. That's why we think there are multiple things at play with his '92.

-Chike

A very early 92 can have the pump gasket problem. As a 92 It would have the lining problem. This problem affects the TC lock-up clutch linings to do the cooler blockage and gear set burn -up. It also sheds chips from the other clutches and band, in the trans to block the screen filter.

Did he say why the converter was rebuilt?

Harvey.;)