When is it too hot

[Klbrown53]

Phone Dude,

I can't tell from your picture where you mounted your scan gauge? I presently have mine on top of the steering column but I do not like it there.


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[Jim Schings]

Originally Posted by Klbrown53

Have you played with the horse power feature any? Curious how accurate it will be.

Interestingly enough, we did some HP testing with the scan gauge and on the chassis dyno. (Two different cars.) It is relatively accurate. Not sure what you would do with the data, but it is there. Using engine RPM and drive train torque it computes HP using HP=RPMxTORQUE/5252. So the resultant number is HP at the engine flywheel. I would say that they were within about 5% of actual measured HP when adjusting for drivetrain losses. So that and a few bucks will get you coffee at Starbucks.

[thestrangebrew]

My F150 usually runs about 203-208 when towing. Ambient air has typically been mid 90s this year so far. On some of the hills, I see it go to about 213, and once coming home recently I saw it get to about 224 going up a 7% grade punching it (I was passing a semi). Stayed ~224 for about 5 mins until we crested and started going downhill. I guess my question would be, how long is too long to run at these temps?

[Klbrown53]

Thx Jim,

No big deal on horsepower. That sounds about right.

However, I do not believe that the data is going to get me anything at Starbucks.

Interesting to know that it is in the ball park though.

Thanks again.

Ken

[Islander]

Originally Posted by thestrangebrew

My F150 usually runs about 203-208 when towing. Ambient air has typically been mid 90s this year so far. On some of the hills, I see it go to about 213, and once coming home recently I saw it get to about 224 going up a 7% grade punching it (I was passing a semi). Stayed ~224 for about 5 mins until we crested and started going downhill. I guess my question would be, how long is too long to run at these temps?

I am no expert... However, ...
I have been told , by a transmission repairman whom I trusted to work on my truck, that for any thing over a few minutes at 225 degrees F can burn the oil and break down it's lubricating properties. ... IMO 5 min would be max. with regular tranny oil.

Two things to help with this is...
1) use semi-synthetic transmission oil, as it can with stand higher temps.
2) add a larger or an additional tranny oil cooler.

I don't know the year of your truck.... but on older trucks (like mine) high temperatures in the tranny can create high pressure and sometimes that pressure has to be relieved, in my case through the vent on the top of the transmission. When it blew (twice) I thought that I had blown the whole tranny...but it was just oil spraying out.

Hope this helps.

Islander

[f5moab]

Living next door to a trans engineer from GM for four years, we got into a fluid discussion after I took my H3 off-roading in the deserts of Southern UT. Per my Scan gauge it was running at or above 230 degrees in the desert heat (105+); especially when doing steep inclines in the mountains at speed.

He told me not to worry, but get it flushed at around 30K just to be safe (schedule showed 50K). Also suggested flush and fill with a full synthetic and add an external stacked air cooler to help cool it down.

He explained, if you ran, even old fluid at around 225 for 30 minutes, it would not be destroyed; however, it would deteriorate faster than if run at a lower temp. Maybe drop its life span from 50K to 48K. However, if running for a period of time over the max temp of around 260 degrees (non-syn) could destroy the fluid really quick. And he said the additives would destroy faster than the actual fluid.

So running at high temps does not immediately destroy the fluid it just makes it wear down faster.

However, if running full synthetic, he said the temp ratings are different and the synthetic fluid does not deteriorate as fast as non-syn. So long it is a good grade of syn fluid.

[Islander]

Originally Posted by f5moab

Living next door to a trans engineer from GM for four years, we got into a fluid discussion after I took my H3 off-roading in the deserts of Southern UT. Per my Scan gauge it was running at or above 230 degrees in the desert heat (105+); especially when doing steep inclines in the mountains at speed.

He told me not to worry, but get it flushed at around 30K just to be safe (schedule showed 50K). Also suggested flush and fill with a full synthetic and add an external stacked air cooler to help cool it down.

He explained, if you ran, even old fluid at around 225 for 30 minutes, it would not be destroyed; however, it would deteriorate faster than if run at a lower temp. Maybe drop its life span from 50K to 48K. However, if running for a period of time over the max temp of around 260 degrees (non-syn) could destroy the fluid really quick. And he said the additives would destroy faster than the actual fluid.

So running at high temps does not immediately destroy the fluid it just makes it wear down faster.

However, if running full synthetic, he said the temp ratings are different and the synthetic fluid does not deteriorate as fast as non-syn. So long it is a good grade of syn fluid.

X2 !!

Islander