Siromer 304 (Jinma 254) Three Point Lift Slow in Cold Weather

[aesmith]

Hi,

My subject isn't quite a full explanation, it's not that the lift is slow all the time, rather after starting the tractor the lift doesn't work at all for up to a few minutes in cold weather. For example in -8 C it would only lift the snowblower after the engine had been running for maybe five minutes. The tractor has a spin-on cannister filter down by the injection pump on the right hand side of the engine, I am going to replace that. I've already checked that the fluid level is OK, and the fluid doesn't show any particular sign of contamination. I don't actually know what grade fluid it is, if I had to take a guess I'd guess 46, as round here most places say that put that into everything. Are there any other checks I should carry out at this stage, for example would it be worth changing the fluid just as a precaution? Of course I can't test the effect until next winter, everything works perfectly normally at the moment.

Thanks, Tony S

 

[piper184]

My 284 has the same issue. The problem is two fold. One is the great mass of the cast iron that makes up the hydraulic tank and the axle underneath it compared to the relatively small mass of the fluid itself. The hydraulic pump is the only way to insert energy into the fluid so it takes a very long time to get all that mass up to operating temperature. Now take all of that mass down to 0° F or lower and the poor little pump can't generate enough heat to warm the fluid. The second problem is one of surface area vs. volume. Consider the outside surface of the tank radiating heat vs. the amount of heat being added by the pump. In my case I have a front end loader and the cylinders act like a great big fluid cooling radiator.

To counter the warmup problem I tapped a 110v oil tank heater into the hydraulic tank. Based on the info from the heater manufacturer the smallest one was 150 watts and it was too big for my little tank. In retrospect, it isn't big enough.

Here is the procedure I use in cold weather. Times vary by outside temp but here is what I use at 0° F.
About 4 hours before I need to start work I plug in the hydraulic heater.
About 30 minutes prior to start I plug in the engine heater. That is a 1000 watt tank heater plumbed into the coolant system. I usually toss a little snow on the head to see how fast it melts to determine if the engine is warm enough to start.
Get the engine running and set the idle to about 1000 for a minute or two then increase to 1200 to 1500. This gets the warm (warmer anyway) fluid circulating in the system.
Unplug the engine heater but leave the hydraulic heater plugged in. Any additional energy you can get into the fluid is helpful at this point.
When able, start "exercising" the FEL.
Eventually as things start to warm up things wills start moving and sounding more normal.
At first the 3pt won't lift at all. Then as things warm up it will lift only as the FEL is being lowered I keep at this until I can get the 3 point so that it will lift on its own. Sometimes this takes as much as 30 minutes, depending on outside temp.

There have been many times when things work just fine in the yard but when I get to the top of the driveway or at a neighbors where exposed to the wind at temps below -20° F the hydraulics will loose heat faster than it is generated and the hydraulics will start to slow down. I have to then get out of the wind for another warmup period. I try to alternate the work between areas for both the tractor and me. No matter how much covering I have I chill down pretty fast at those temps too!

I run the lightest fluid I can find in the winter. I did some viscosity experiments with different fluids at -20.
ISO 46 was thickest I had on hand, no surprise there
"all season" (no rating on jug) was next thickest
ISO 22 was about equal to Dextron III ATF
Motorcraft ATF LV was slightly thinner but not by much. I had it on hand but that would be expensive to use in a tractor!

Finding fluid lighter than 22 has been impossible where I live (well at reasonable prices when considering shipping)

Things I have considered but not figured out how to do:
Add a 12 volt oil heater to the tank. Now that I have upgraded to a 60 A alternator it might be possible if I can find a heater.
Get some kind of insulation on the tank and the FEL cylinders. This would need to be removable for summer work to prevent overheating.
A larger capacity "add on" tank that could be insulated and heated so there would be more fluid mass in the system
A larger capacity pump to add more heat to the fluid.

 

[aesmith]

Thanks, it's interesting that you find the same. Typically we don't get down to those temperatures. Although we had -17.5 one night, the coldest that I operated the tractor in was -8 dropping to -12 while I was working. The engine starts OK in these temperatures, just needs maybe 15 or 20 seconds of heat instead of 10.

I might change the hydraulic fluid anyway. The UK agent specifies ISO 32, not quoting a temperature range so I assume this recommendation holds for both summer and winter.

I don't really understand why low temperature would stop it working at all. If I understand correctly I think the hydraulic pump is positive displacement, so should pump the same volume hot or cold. So why doesn't the hitch lift until a certain temperature is reached?

 

[Bob Rooks]

Thanks, it's interesting that you find the same. Typically we don't get down to those temperatures. Although we had -17.5 one night, the coldest that I operated the tractor in was -8 dropping to -12 while I was working. The engine starts OK in these temperatures, just needs maybe 15 or 20 seconds of heat instead of 10.

I might change the hydraulic fluid anyway. The UK agent specifies ISO 32, not quoting a temperature range so I assume this recommendation holds for both summer and winter.

I don't really understand why low temperature would stop it working at all. If I understand correctly I think the hydraulic pump is positive displacement, so should pump the same volume hot or cold. So why doesn't the hitch lift until a certain temperature is reached?

ISO AW 32 is usually the hydraulic oil recommended by most manufacturers for most applications, and equivalent to SAE 10 W. ISO AW 46 for extreme temperature conditions where viscosity loss becomes apparent. For my hydraulic equipment I use a multi-grade hydraulic oil (ISO AW 32/46/68). It performs well through all temperatures. The problem with a higher viscosity hydraulic oil in cold temps is that it causes micro cavitation in the pump suction side, hence poor performance until it works its way out. This can be alleviated by heating the reservoir prior to use with magnetic block heaters or the like. (Yeah, I should have read Piper's post first).

 

[piper184]

besides the cavitation issue at the pump gears, there is also the problem of "sucking" thick fluid through the fine mesh pickup screen in the tank.
Then there is the long trip from the tank to the pump through a thin walled steel tube that is exposed to the cold. Another radiator...
I was a little surprised at the ATF viscosity in low temperatures. It explains the reluctance of the vehicles to move at really low temps. Of course the torque converter can pump a lot more energy into the fluid rapidly.
The backhoe gets higher vis oil to help fight off power loss, but I rarely use it at -20.