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Transmission temps

Yahoo Message Number: 95122
Hi all,

Normally my trans temp and engine temp run pretty close, 198-202 degrees.
Last week while in stop and go freeway traffic the trans temp jumped up to 250 so I pulled off onto a crossing freeway, got up to normal speed and it cooled right down. The other day I was moving the coach about 30 miles and the trans temp only reached 150 when it normally should make it to 200.
Any ideas, similar experiences or offered diagnosis? Thanks in advance,

Jerry Keller

2006 Allure #31347

Re: Transmission temps

Reply #1 –
Yahoo Message Number: 95123
You don't mention which engine or transmission, but I'm gong to assume Allison and ISL 400. But you could be all CAT. If you are the Cummins and Allison like I am the temp sensor is not in the pan of the tranny but at the exit where the hot coolant goes to the radiator and there fore doesn't tell the true temp in the sump. You can get that if you have the silver leaf. Yes every time you do stop and go driving the readings will be wild apart. With the tranny temp being higher. Don't worry even as you get to 275, just use lower gears and switch to neutral while at rest or idle. The only time my transmission reads lower than the engine is when I'm driving in cold/cold approaching freezing weather or on wet cold roads where the moisture sprays up on the trans mission. When I drive in the hills of Colorado, AZ, etc anytime there is a thunderstorm that cools off the pavement and splashes the tranny temp drops. Driving the hills of the coast of Oregon on a foggy wet day gets the same results.
TWI 2004 Intrigue 11731

Re: Transmission temps

Reply #2 –
Yahoo Message Number: 95124
Jerry,

Stop and go driving is the hotest your transmission will ever run. I've never seen 250 but I've not been in stop and go for long.

Thirty miles is not enough distance to get your transmission to full temp.

All that you describe seems normal to me.

George in BIrmingham
'03 Magna 6298
George in Birmingham
2003 Magna 6298

Re: Transmission temps

Reply #4 –
Yahoo Message Number: 95128
Jerry,
I have a Cummins 8.3 (1997 CC) with the Allison six speed Tran. Do you think I should install a Tran Temp Gauge? I did install a EGT gauge and down shift to keep the EGT in the green when needed. I run about 1600 RPM at 58 MPH and get between 9-11 MPG if flying straight-and-level with my GEO tracker (2200 lbs) in tow. I run my CC about about 3000 under GW most of the time and never take on water (8.3 LBS per Gal) when not needed for the trip.

Thank you all,

Randy 32 foot CC

Re: Transmission temps

Reply #5 –
Yahoo Message Number: 95134
Jerry

My transmission consistently runs hotter than the engine and in stop and go traffic I have often seen over 235 degrees. Allison said that you cannot damage the transmission as it will shut down before that happens. They said 235 is nothing I don't know that I have seen 250 but I was told don't worry about the temperature because of the built in controls.

Dan 2006 Allure 31348

Re: Transmission temps

Reply #6 –
Yahoo Message Number: 95135
Check the wire on the temp sender for the trans, sounds like it needs cleaning and maybe tighten up the connection.

Mikee

Re: Transmission temps

Reply #7 –
Yahoo Message Number: 95142
Jerry - I usually put the bus in neutral when stopped and idling. That to include long red lights. The torque converter builds up heat fast when in gear and not rolling. Idling in gear in hot weather I've seen 250F+. Probably not good. As a guide line, trans temps should be less than or equal to 30F higher than the engine coolant. I've also removed my rear flap and leave the radiator fan running constantly. This has made a HUGE difference in cooling everything down. The temps I'm quoting are off the Silverleaf.

My bus like yours is under powered. On long climbs I'll keep the torque between 800-900 ft/lbs and engine RPM at a nominal 1,500-1,700.
Whatever gear it takes to achieve these parameters is what I use. The traveling speed falls and adjusts according to the grade. Sometimes going as low as 15 MPH with 30-40 MPH being more typical. The 4 way flashers work wonders. The drive train is rated for 1,200 ft/lbs but why push things to 100% duty?? A 50-75% duty cycle is more conservative and will undoubtedly reduce the wear and tear factor. It also keeps the heat down. Heat is the enemy of oil, bearings, hoses and electronics.
The less of it beyond normal operating temperatures the better. Do what you can to beat the heat. That said, we'll average about 61 MPH over the road between locations. We just allow a proper amount of travel time which gives the bus enough time for the slow climbs. We also tow an 8K pound van.

This past run (between Ely and Elko Nevada) the engine coolant was 180 - 190. And the trans about the same. Things went up about 10F during climbs. Good luck and stay cool.

Best - Scott

2006 Allure 430 40' #31349

(Bus-Stead Lemon) My Allure Page http://www.muniac.com/Allure%20Page.html

Re: Transmission temps

Reply #8 –
Yahoo Message Number: 95143
Okay folks I have to throw a cravat in this.
A 2006 coach most likely has an engine 2003 or greater, if so it is an EGR engine. Running an EGR engine it has to operate hotter for proper function of the EGR system. Running at 180 will cause issues in the EGR system over a period of time.
An EGR engine usually has a 195 degree thermostat, whereas a non EGR engine uses a 180 degree stat.
The fan controller in most newer truck engines is set op engage at 219 degrees. Cool is great in non emission engines, but not so much in EGR and more emission engines. The engine, electronics, etc are designed to operate in these higher temps. It does not cause failure. Seeing temps of 200 to 210 is normal in an EGR motor.

Your engine, your choice.

Mikee