8V92 & HT755 - Transmission temperature question

PCC · November 28, 2012, 07:06:43 AM

I noticed recently that the transmission temperature seems to be creeping up close to the engine temperature, and that has never happened before.

The dipstick (not referring to a person this time) tells me that the fluid is up, and low fluid is the only reason I know to effect this change.

The oil is bright (not burned), and the shifting is just like it has always been; runs all day. I do not use my transmission retarder.

I also noticed that both temps (engine and transmission) are running higher (both proportionately increasing above normal when traveling at speeds above 60 MPH), but the engine radiator is full (50/50 mix distilled) - Engine oil is up, and is 40W (low ash).

These changes are new and I want to be sure it is just because the weather is cooler ?!

lostagain · November 28, 2012, 07:13:21 AM

Thermostat (s) sticking closed?

JC

PCC · November 28, 2012, 07:18:59 AM

No, I think not the thermostat, because I can run all day at 55 - 60 MPH and never get over 180F

I think the problem is stemming from something in the transmission, but I have no idea so I ask (here) the experts.

TomC · November 28, 2012, 07:49:49 AM

If your engine is at 180, your transmission will always be higher-around 220. Up to 275 for short periods on the transmission isn't bad. But below 250 is better. 180 is normal for an 8V-92TA. I don't think you have anything to worry about. Good Luck, TomC

PCC · November 28, 2012, 08:16:41 AM

I have just never seen it, in all the years I have been driving this vehicle, over 160F for the transmission, so when I saw it going up . . .

Climbing a long grade, the engine gets to 200F, but the transmission went there too, and I am not used to seeing it so high.

Thank you - maybe the sensor started working, and I now know the truth.

Proves I look at the dash - at least once per trip !!

luvrbus · November 28, 2012, 08:50:37 AM

Normal operating temperature for the transmission is 160 to 220 at the sump not the converter the converter can reach 300 degrees max keep it between the lines and you will have no problems fwiw low or high fluid level will cause one to heat also

good luck

PCC · November 28, 2012, 01:54:12 PM

So then allow me to extend my query to the engine temp which runs warmer than (my) normal as I increase the speed over 60, it gets up to 195, when it never used to get over 180.

Am I still within boundaries there, considering 2 stroke 8V92. I went over the Rockies and never got up to 200F, so I am still wanting to be sure - just my breakdown concerns !!

Thank you for your patience with me. I have not changed the overall weight since the Rockies trip.

Lin · November 28, 2012, 03:03:47 PM

Is there a possibility that your radiators are dirtier than on your Rockies trip? It is not a bad idea to clean them out once in a while. Are you talking about the same speed, outside temperature, and toad (if any)? What bus is this (you may have posted the info, but I missed it)?

PCC · November 28, 2012, 05:22:33 PM

Radiator was just dipped and cleaned, but I will pressure wash it, as that may be something I can do to be sure that something did not get missed - Thank you.

I am an H5-60 Prevost. No significant weight has been added since the Rockies trip, but dust and dirt can be added anywhere along the way.

buswarrior · November 28, 2012, 08:08:32 PM

Go easy with a pressure washer around the radiator!

You don't want to damage it with high water pressure.

Pressure washers are also good for ruining older double pane windows by forcing moisture where you don't want it.

happy coaching!
buswarrior

Ace · November 28, 2012, 11:04:39 PM

You said your 8v-92 runs normal at 180•? I'd be checking the gauge! Mine never runs that here on a cool day in Fl.
190+ depending on speed and thats with a new radiator, hoses and such!
Sounds like your situation is more thermostat than anything else!

Sent from my iPhone using Tapatalk

PCC · November 29, 2012, 07:18:43 AM

Gauges are accurate, so maybe I have just been fortunate that my vehicle has been running cool, and now it is normal, unlike me.

Thank you to all for easing my concerns.

Hope to cross paths someday as we travel the highways of the greatest country on earth.

HB of CJ · November 29, 2012, 11:33:54 AM

Could your gages be giving off bad readings? Wire connection continunitunity over time will do it? Are you using a cooolant lube/pH reducer along with the antifreeze and distilled H2o? You want a very alkaline coolant reading. If it is not, buildup in the radiator(s) may occur resulting in decreased cooling? Delo 40 in the Detroit? Curious how your temperature reading would climb/stabilize at maximum contineous warp speed. (wide open) I'm concerned that your normal (?) Allision temps may be too low and why. HB of CJ (old coot)