jatco oil temp answer

gstuart · Mar 30, 2015

just for ur info I've always wondered why the oil had to be checked between 35-45 c

got an answer and makes a lot of sense , as I assume then if u checked the oil level cold , filled it up it could then blow seals as the oil expands

just wished to pass the info on to u guys

got this back from a jatco specialst

Hi Gary

The reason the oil has to be checked at this temperature, is due to
expansion.
At this temperature the oil can expand. Meaning if its filled full when
cold, it will actually have too much fluid once the transmission warms.

Hippo · Mar 31, 2015

That's what our guess was a while ago but we didn't know for sure.

gstuart · Mar 31, 2015

Hippo said:
That's what our guess was a while ago but we didn't know for sure.

oh sorry mate didn't see that

nice to get it confirmed though and does make sense

Hippo · Mar 31, 2015

gstuart said:
oh sorry mate didn't see that

nice to get it confirmed though and does make sense

No problem.

I'm still not fully convinced it's the reason thgouh. Reason being the oil doesn't expand noticably if you heat it yerself out of the auto. We did wonder if the cooler activated above a certain temp but I don't have one to take apart to see.

Hippo · Mar 31, 2015

One other thing is that 35 to 45 degrees may be the ideal time from cold for the auto to correctly refill itself via it's pump. This is normally the case within seconds of switching on the engine. I often tell peeps not to drive straight away and let the auto lubricate itself propper for say 20 to 30 seconds. The time to get to 35-45 could be the time to ensure any air bubbles are circulated out of wherever they may be hiding. Thats just a guess. 35-45 degrees is an ok temp to work on, as opposed to 80 degrees where you could burn yerself.

freelance · Mar 31, 2015

Also if the oil is warm it means the transmission has been run to get to temp which means everything is charged, ie, nothing has drained down, no empty oil galleries, clutches etc.

gstuart · Mar 31, 2015

Hippo said:
One other thing is that 35 to 45 degrees may be the ideal time from cold for the auto to correctly refill itself via it's pump. This is normally the case within seconds of switching on the engine. I often tell peeps not to drive straight away and let the auto lubricate itself propper for say 20 to 30 seconds. The time to get to 35-45 could be the time to ensure any air bubbles are circulated out of wherever they may be hiding. Thats just a guess. 35-45 degrees is an ok temp to work on, as opposed to 80 degrees where you could burn yerself.

ref the cooler i did think that something like a thermostat shut off the cooler so it could warm the box up quicker until it reached 35-45 c then opened around the cooler

not got enough mechanical knowledge and was just a theory

I normally allow the engine to warm up for a minute or so before setting off , if it requires all the screen etc to be cleared wait at least 5 mins so it's all nice warmed up and all the windows are clear

suprising how many people try and drive down the road with iced up windscreens and can hardly see out of them

Nodge68 · Apr 1, 2015

gstuart said:
ref the cooler i did think that something like a thermostat shut off the cooler so it could warm the box up quicker until it reached 35-45 c then opened around the cooler

not got enough mechanical knowledge and was just a theory

I normally allow the engine to warm up for a minute or so before setting off , if it requires all the screen etc to be cleared wait at least 5 mins so it's all nice warmed up and all the windows are clear

suprising how many people try and drive down the road with iced up windscreens and can hardly see out of them

There's no thermostat in the oil cooler circuit. The I suspect the reason for checking the level at this lowish temperature rather than at running temperature is as Hippo pointed out, one of safety. The fluid will have expanded to some degree but isn't hot enough to cause burns.

gstuart · Apr 1, 2015

Nodge68 said:
There's no thermostat in the oil cooler circuit. The I suspect the reason for checking the level at this lowish temperature rather than at running temperature is as Hippo pointed out, one of safety. The fluid will have expanded to some degree but isn't hot enough to cause burns.

yes i realise that now, didn't know at time till I was told about the oil expanding

got the two jatco books now , heavy reading

Hippo · Apr 1, 2015

I think making sure pipes like this is full of auto oil and everything is lubricated as it should is part of the reason for 35 to 45 degrees from cold.

DSCN3009 Ktlfqpv

gstuart · Apr 2, 2015

Hippo said:
I think making sure pipes like this is full of auto oil and everything is lubricated as it should is part of the reason for 35 to 45 degrees from cold.

thks and expect ur right

Nodge68 · Apr 2, 2015

Hippo said:
I think making sure pipes like this is full of auto oil and everything is lubricated as it should is part of the reason for 35 to 45 degrees from cold.

That's why all gears are cycled before checking the fluid level

Nodge68 · Apr 2, 2015

gstuart said:
Hippo said:

I think making sure pipes like this is full of auto oil and everything is lubricated as it should is part of the reason for 35 to 45 degrees from cold.

thks and expect ur right

Click to expand...

It's better to use a safe known temperature for fluid measurements. If say ambient or room temperature was used, what is ambient or room temperature? This This would be different from location to location. The fluid measurement could have been done at running temperature, however this would be very dangerous. I suspect this is why 35 to 45°C was chosen.

Hippo · Apr 3, 2015

Nodge68 said:
That's why all gears are cycled before checking the fluid level

The gear level positions can only give you 1, 2 manual, n, and r. I often wonder if cycling the lever covers everything, as not all gear combinations are engaged (3, 4 and 5). Perhaps it's the most you can do so that's it.

Hippo · Apr 6, 2015

Was reading the Freelander 2 manual today and it's auto gearbox temp needs to be approx 60 degrees. It's a different auto to the Freelander 1. LR get round this by advising you to use gloves to undo the level bolt at this temp. That kind of makes me think the Jatco temp of 35 to 45 degrees being a devised safe working temp could be ruled out. So that just leaves the volume of the oil at that temp, and running from cold would have purged all air out of the channels/pipes inside, or at least given it it's time to do so if it's working correctly (no pipe splits etc).

jatco oil temp answer

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