Mitsubishi AYC Failure in cold, fluid related?

[calgaryevo]

In the last week we have been delating with air temperatures of around -30º C in Alberta. A huge number of Mitsubishi Evos in our local owners club have had AYC Pump failures at these temperatures.

Doing some research, and a little bit of speculation it appears to be fluid related, the AYC uses Diaqueen (or Diamond) SPIII ATF to drive the hydraulic action of the pump. Members are noting that the fluid in the reservoir does not pour or is pouring very slowly (reservoir is stored in trunk/boot so does not gain heat from the engine bay).

As the pumps are upwards of $2000 plus very expensive Western Canadian labor of another $2000k for replacement, and bleeding, we are trying to find a solution that would allow us to use our vehicles in what are relatively normal winter temperatures.

I was planning on moving from the BP made OEM SPIII with an official pour point of -40ºC to Redline with -60ºC.

My next thought was to use a inline heater connected to battery with a thermostat to kick in at temperatures below -10. Any thoughts on weather a heat blanket for the pump, an in reservoir (plastic oem) heater, or inline heater would be most beneficial?

Is there anything else you would consider to improve the flow of the fluid?

 

[The_Jeff]

Whatever does this do?

Found this thread: http://www.evoxforums.com/forums/showthread.php?t=87010

 

[cchase]

Active Yaw Control? Basically uses hydraulic fluid to move power to different wheels.

 

[calgaryevo]

Thanks for that link, I came across this too, they never really ventured back to viscosity and temperature issue.

The AYC pump also has another issue of location (behind rear wheel, and it suffers from corrosion issues on salted roads). I have protected against corrosion already, more concerned about pump failing as it physically cannot push the heavy almost frozen fluid.

The AYC is part of active differential system in the EVO that applies torque to the wheel with the most grip. It is electronically controlled based on the inputs of a bunch of accelerometers.

Back to viscosity and heating the oil, any advice would be appreciated!

 

[vssjim]

wow if it's to cold for atf maybe you should not run that part of the system during the really cold parts of winter and live with warning lights if that is possible.

 

[calgaryevo]

I was considering that and still might, two things are holding back.

1. Half the fun of the Evo is snow driving and getting a nice drift going.

2. More importantly, I have heard pulling the relay to the AYC system turns the rear diff into an open diff and greatly decreases safety, and messes with other parts of the stability control system, prone to great amounts of oversteer, and unpredictability in cornering.


I understand our winters are extremem, but Its a little frustrating that they sells these vehicles in our market that are not fit for purpose.

 

[JHZR2]

They probably sell Corvettes and Ferrari convertibles in your market too.

While I often belittle the wife's tale of pao being so important in pcmos, when conditions get that cold is exactly when one should consider such metrics for their fluids. I would definitely have swapped over to a more cold temperature capable fluid for this application.

 

[Rand]

Definitely something ester or pao based.

Alot of the more boutique brands might be much more suited than the generic SPIII which IIRC isnt syn.

The redline product would be D4 ATF.
PP of -75!!

TYPICAL PROPERTIES

Vis @ 100°C, cSt 7.5
Vis @ 40°C, cSt 34
Viscosity Index 198
Pour Point, °C -60
Pour Point, °F -76
Flash Point, °C 225
Flash Point, °F 437
Brookfield Vis @ -40°C, P 52

 

[calgaryevo]

I was leaning towards Redline Atf SP III as I saw the pour point was a much lower -60ºC, are there any other metrics I should be looking into, do any better cold weather appropriate SPIII compatible fluids exist?

 

[Rand]

Originally Posted By: calgaryevo
I was leaning towards Redline Atf SP III as I saw the pour point was a much lower -60ºC, are there any other metrics I should be looking into, do any better cold weather appropriate SPIII compatible fluids exist?


use redline's application finder.

it says D4 for mitsu EVO AYC

at least on the random model year I picked.
(IIRC 2007) since you didnt list a year.

 

[calgaryevo]

I will go this route, thanks Rand.

Any thoughts on the best way to add some warming to the equation? I was considering the following:

1. Heat Blanket on pump.
2. Move the reservoir to the engine bay to gain some warming - this may be counter productive in the summer with too much heat being generated.
3. In line heater between pump and reservoir.
4. In reservoir heater.

I would prefer something to work off the battery as sometimes getting a plugin can be tough.

 

[jrustles]

SPIII ATF? WOW! That's equivalent to DexIII no? Talk about an afterthought!

Definitely use something synthetic, ideally the lowest PP stuff you can find. DexVI even, if you don't want to shell out for true synthetic fluid. But I wouldn't recommend leaving the SPIII in there much longer at these temps, you could actually ruin the pump permanently.

 

[The_Jeff]

Pick up some of this maybe: Mag1 from amazon with a pour point of -60'F:

http://mag1.com/ProductDetails.aspx?id=d97f9a91-b8b5-4334-b42a-55f0b5c590fe

If'n they'll ship to

of course.

The heat blanket on the pump sounds like a good idea, but "they" say the pump will overheat if you look at it wrong.

 

[RF Overlord]

Maybe try a battery warmer on the pump...that shouldn't cause it to overheat.

 

[artificialist]

I brows Evoxforums.com and many people state that those units fail from road salt. I didn't think about that, and I simply but universal synthetic ATF in my ACD pump.

Also, they have links to rebuilders and rebuild kits. A rebuilt unit might sell for $500 USD.