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High Trans Temp
driving near Asheville at 55mph on cruise. Just had bus in shop for a checkup and everything great. 6 hour drive yesterday no issues. Voice synthesizer comes on and won’t stop hacking about high Trans temp. Pulled over and dip stick looks fine. Not even pulling hills yet. Confused.
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20 Replies
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What does the transmission temperature gauge say?
If the transmission was serviced and I got an indication of an over temp on the transmission the first thing I would look for is too much fluid was installed. Excessive fluid, as little as a couple of quarts will drive the temps up. Very hard to see on the stick.
Then there is always the possibility the sensor is in error and the temps are OK. Do you have an IR temp gun you can aim at the transmission? It should track the engine temp, maybe a little higher when pulling hard.
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thanks Jon. The tranny was serviced a year ago and Elite Bus guys just told me it was just fine as-is. I don’t seem to have a tranny temp guage which seems dumb. I took out my books and ready the part about the Allison health check and light on the dashboard. It did not come on at all. I pulled back on 26 and the voice went off again but no Alison or DD lights. I then pulled all the hills with no issue or subsequent alarms. Wonder if it is a bad connection.
i am at Mountain Falls now. When everything settles, I will check fluid level. Can I check tranny level with engine off??
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The tranny temp gauge may read “oil temp”. I had one on my 87 as well as the 97. The current bus has the tranny temp in the message center so Prevost obviously wants us to know the temps.
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Our 1999 Liberty does not have gauges for either trans temp or differential temp.
In 2013 we rented a 1989 Country Coach Prevost and it had both trans temp and differential temp.
Are those two temp gauges provided by the converter? Presuming the gauges are electric and not mechanical, is the wiring for those two gauges sitting under the instrument panel waiting for me to hook up the appropriate gauges?
Pulling the 10,000# race trailer I liked knowing what the trans and differential temps were.
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Liam,
It could also be the CC voice synthesizer that is bad. Some of the dip sticks have a cold setting as well as hot. Best to check it when at operating temp. Your’s won’t have the oil level on the shift pad like the later ones. like Jon said, you should have a tranny temp gauge labeled oil. I’ve not had a bus without a tranny temp gauge.
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my 91 xl doesn’t have trans temp either. Just engine oil. Has a blacked out gauge in one of the holes though. Always wondered about trans temp.
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Dick,
I would be extremely surprised if your Liberty did not have a transmission temp gauge. If it was like my 97 you have three gauges in a row across the top of the dash. Oil pressure, engine temp, and oil temp. The oil temp gauge is the transmission. If you want to verify that engage the retarder and watch it rise.
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Thanks everyone.
Boy was it could at Toxaway Lake last night. Good move having my Webasto repaired!!
I pulled the books and the Oil Temp guage in the upper left is tranny temp. I was actually watching that one during the trip. It normally sits at 200 and this trip was actually a little less.
So that is 2 votes against (guage and Allison indicator) the speech processor.
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Thanks Jon. I will try that next time I’m out. I wonder why it simply doesn’t say “Trans” rather than “Oil”.
So then I can conclude the coach probably doesn’t have an engine oil temp gauge nor a differential temp gauge.
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Dick,
That would be my guess. As to why it is labelled as it is I cannot answer that, except to say that is a Prevost gauge and all I have seen just say oil temp.
I cannot imagine a coach without that gauge or some place to view the tranny temp.
1999 XLV X-6872, liberty #440 -
Liberty #407: My current coach did not come equipped with diff temp and, yes, if you pull a heavy trailer, you should have one. Under adverse conditions (high speed, high load, high ambient temp) it is easy to exceed oil temp design limits.
I found an extra wire running from the back to the dash (can’t remember if it was indeed an extra wire or a wire I re-used from a piece of equipment I felt was unnecessary, maybe radar detector?) and installed a VDO electrical gauge.
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Joel: Was there a temp probe in the differential case that you just wired it into? Or did you have to drill a hole in the differential, weld in a bung, and install a probe? I don’t look forward to the latter. Thanks! Dick
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You know, I can’t remember exactly where we put the probe, but it was into an existing hole of some sort on mine. No welding and no existing probe. Make sure you leave enough slack in the ground wire to allow for full suspension travel…my installation (NOT done by myself) took 2 tries!
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Thanks! One would have to expect there to be bung for a temp probe welded into the differential case when they are made. Where did you put the diff temp gauge on the dash?
I presume your coach is like mine and you have no engine oil temp gauge. Does it bother you not having an engine oil temp gauge? How do the others feel about that?
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I think there is an oil temp sensor. I’m guessing and without looking it up that is my story and I will stick to it. If you do have the sensor DDEC will throw a code if it exceeds some limit.
I strongly suspect that if you have an excessive oil temp your engine is already toast because the coolant temps are likely through the roof.
I learned from flying that when we could fully instrument our engines and literally display every parameter known to man including each cylinder’s EGT, each cylinder head temp, plus all of the various temperatures and pressures that it was possible to spend more time looking at data that meant little than was spent flying the plane.
With DDEC it will alert us when something is out of line, or shut down the engine before it can destroy itself.
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