6M Cold Weather Clutch - Realllly slow. Anything I can do?

[theKurt]

In a bit of a deep freeze at the moment (-28C), but I noticed a big change at about -15C and the clutch gets heavy and slow on a cold startup. I don't recall this big of a change in my previous manual vehicles. Might be the fact that I'm in a new vehicle rather than one with lots of mileage.

It will eventually behave normally, but it doesn't warm up as quick as the coolant or engine oil and can feel heavy for quite a while.

Does anyone know of anything I can do to improve the clutch warm up or reduce the viscosity (OEM is DOT3) or something? I don't know if its the fluid or a greased bearing or whatnot that's causing the feel. I'm being very careful to engage it slowly and reducing the number of shifts to give it time, but I can occasionally smell it slipping.

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[32spoke]

Brake fluid: Dot 4 LV is “low viscosity” is designed to work better for ABS servo assemblies in cold weather. You could bleed out the dot 3 brake fluid and try this dot 4lv fluid. It is 100% miscible with dot 3 brake fluid and therefore safe to use in your clutch hydraulic system.
https://www.napaonline.com/en/p/AIC1224116

 

[scottiev]

In a bit of a deep freeze at the moment (-28C), but I noticed a big change at about -15C and the clutch gets heavy and slow on a cold startup. I don't recall this big of a change in my previous manual vehicles. Might be the fact that I'm in a new vehicle rather than one with lots of mileage.

It will eventually behave normally, but it doesn't warm up as quick as the coolant or engine oil and can feel heavy for quite a while.

Does anyone know of anything I can do to improve the clutch warm up or reduce the viscosity (OEM is DOT3) or something? I don't know if its the fluid or a greased bearing or whatnot that's causing the feel. I'm being very careful to engage it slowly and reducing the number of shifts to give it time, but I can occasionally smell it slipping.

In a bit of a deep freeze at the moment (-28C), but I noticed a big change at about -15C and the clutch gets heavy and slow on a cold startup. I don't recall this big of a change in my previous manual vehicles. Might be the fact that I'm in a new vehicle rather than one with lots of mileage.

It will eventually behave normally, but it doesn't warm up as quick as the coolant or engine oil and can feel heavy for quite a while.

Does anyone know of anything I can do to improve the clutch warm up or reduce the viscosity (OEM is DOT3) or something? I don't know if its the fluid or a greased bearing or whatnot that's causing the feel. I'm being very careful to engage it slowly and reducing the number of shifts to give it time, but I can occasionally smell it slipping.

In a bit of a deep freeze at the moment (-28C), but I noticed a big change at about -15C and the clutch gets heavy and slow on a cold startup. I don't recall this big of a change in my previous manual vehicles. Might be the fact that I'm in a new vehicle rather than one with lots of mileage.

It will eventually behave normally, but it doesn't warm up as quick as the coolant or engine oil and can feel heavy for quite a while.

Does anyone know of anything I can do to improve the clutch warm up or reduce the viscosity (OEM is DOT3) or something? I don't know if its the fluid or a greased bearing or whatnot that's causing the feel. I'm being very careful to engage it slowly and reducing the number of shifts to give it time, but I can occasionally smell it slipping.

I wouldn’t mess with the fluid. DOT4 is more hygroscopic - will take in moisture.
The smell of slipping is concerning though. Being careful and limiting shifts is smart, but if it persists, there could be binding in the release mechanism or additional wear happening from cold-related issues.

 

[theKurt]

I've been reading more into the DOT 3 vs 4 vs 5.1. It would seem that for lower water absorption, DOT 3 is the best of these three compatible types. 5.1 can have a lower viscosity in cold temps but absorbs water like DOT4, albeit at a slower rate. Going to a 5.1 might mean changing the fluid more often to prevent water damage of the components, but maybe its worth it.

By being slow and careful with letting out the clutch and reapplying throttle, combined with enabling the iMT, I think I've gotten better at preventing slip. I think my usual timing of the clutch-shift-clutch-throttle was thrown off with the slower engaging of the friction disc causing the slippage. No problems of note this morning so maybe I'm just getting used to it. Weirdly, perhaps, using the block heater does help slightly with reducing the cold viscosity of the fluid. I can't find any diagrams explaining how marginally higher coolant temps could affect the clutch fluid, but I'm due for a service anyways so I'll try to get some info from the techs while I'm there. Maybe the whole engine bay becomes a few degrees warmer overall.

I have an UltraGauge hooked up, so I'll watch the sensors and temps and see if I can find a correlation. I like data.

 

[32spoke]

Brake fluid is recommend to be replaced every two years whether the vehicle is driven or not, therefore… not a problem for someone that maintains their vehicles. Dot 4 low viscosity is designed to operate on colder climates: If the
Clutch hydraulic system is proven to be a problem in extreme cold temps, and if the Dot 4 LV, does indeed allow for better clutch operation, then it is a matter of inconvenience of changing out clutch fluid more often, vs either not using the vehicle or risk damage, if that smell is from the clutch disc. Silicone brake fluid is not hygroscopic, but prone to cavitation and therefore hardly used. I don’t even know if the dot 4 low viscosity fluid would solve the issue, but seems like an easy enough project for process of elimination to verify if it works. If the slave cylinder is integral to the clutch release bearing/throw out bearing, then it won’t be fun to bleed the system.

 

[32spoke]

Good news, I just verified- the clutch slave cylinder is mounted to the outside of the bell housing on the driver’s side, so not a PITA to bleed the clutch hydraulics.

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