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oil temps on downhill grade
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Jon
I have a retarder. But NO stalk. Just a 2 position switch on the side panel.
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Don
No warning light comes on.
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We were out in MT a couple of weeks ago and that was my first experiance with a retarder. I was surprised when my overheat buzzer came on going down hill. I have driven engines with jake brakes for years and never had the water temperature go up that high. It only happened twice and I was close to the botttom of the hill so I backed off I didn’t think to look at my trans temp.
I pull a 24 foot stacker trailer trailer hauling a car I am not sure if that is normal with a retarder.
1999 XLV X-6872, liberty #440 -
I have no experience with a 2 position retarder.
I do, however, go down lots of hills with a 24′ stacker! Turn on your trans temp display and you should be able to find a sweet spot. On my coach, at about 65-70000# gross, I cannot use more than position 3 of the retarder in 5th gear. If that’s not adequate to hold speed with liited brake use, if I slow to under 52ish, I can use position 4 in 4th gear and that gives much better retarding while keeping trans temps under 250.
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So I guess overheating is not unusaul when you are going off a hill and pull the lever all the way down??!!
Guess I have to learn the differances between a retarder and a jake.
Thanks
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Correct. Use of the retarder heats the trans fluid which cannot be cooled fast enough for extreme uses of long duration. I only use position 5 or 6 for extremely short periods of time or under emergency conditions.
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Tony,
I don’t think you have a retarder. Can you send a photo? I think the first step is to figure out what you have, then figure out the 300.
FWIW, I had Jakes on my first coach and they had a 2 position selector, a hi or low position and it was a small pad like the Allison pad. I would see 300 on my pyrometers when they were engaged. Do you have an 8V92?
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no I have a series 60. Premier Coach said I had a retarder. What would you like a picture of?
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Show a photo of the retarder control. Premier has had enough Prevost coaches so they should know, but I have never heard of one without the small stalk on the RH side of the steering column.
2025 Marathon H3 / 4th Prevost
21 Ram 1500 EcoDiesel 4x4 -
Tony,
The usual retarder is the small stick on the right hand side of the steering column under the steering wheel that looks like a turn signal stalk. If you have a two position switch on the dash, it may be a two stage Jake Brake and not the hydraulic retarder that is mounted on the transmission.
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I have a two position rocker switch for my retarder that turns the retarder on and turns it off. Plus I have a short stalk as shown in the picture to the right of the steering column that controls the amount of retarder I can select. Up is little or no retarded, down gives me everything the retarder has. At the end of the stalk is the Allison Transmission logo. I hope this helps.
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Hi all,
I know I’ve been absent for about a year but I’m back on the road again in my XL2. We’re in Steamboat springs this week and headed downhill (Denver) later today. I thought that I’d share a bit of my retarder experience that I had with my 1997 Liberty XL.
My first trip in the Liberty was from Phoenix to Flagstaff and there are a lot of grades between the two, along with a 6000 foot elevation change. To be honest, I didn’t know enough about the retarder when I started and I pretty much used it as a brake to hold the speeds in the 55-60 mph range along the trip. By the time I was nearing Flagstaff, the transmssion would not shift out of 4th gear, limiting my top speed to around 50-55 mph. We knew something was seriously wrong, but not much more. The trans temps were spiking into the 300 degree range over the downhill legs.
We decided to overnight in Flagstaff an made the decision the next day to drive to Las Vegas where a Detroit/Alison shop could have a look. The trip to Vegas was without incident and the transmission performed flawlessly in all gears. The shop in Vegas said that the oil “looked and smelled” normal, but they replaced it anyway with Transynd and I was back on my way northbound, a day late and $750 poorer.
I learned from the experts here (formerly at the other web site), that retarder use requires a keen eye on the transmission temp gauge and I watched it like a hawk thereafter. We completed our summer trip, about 5000 miles, without further incident. I felt like we had dodged a bullet.
Next year, we took off on a similar trip and this time, while in Montana, the transmission started acting up badly. We had been crossing a lot of mountain passes, etc., and although I never let the temps go above 250 or so, the transmission would suddenly act as if it were in neutral. We would coast to a stop, wait 20 minutes, and then take off again. This was the drill for the next 125 miles until we reached Billings where another Detroit/Alison shop was found.
To make the story short, we had a rebuilt transmission installed in Billings. It took about 12 days of downtime (a week waiting for the replacement), and I was out about $12,000 for the experience. The bus ran fine after that and I had all of the retarder knowlege that I would ever need.
So in closing, when the trans temps are 300 or more, you are certainly in the danger zone and the damage may already have been done. Try to avoid it!
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This would be a great application for one of those new gauges I see on the NASCAR cars. It appears they are blue or green when things are normal, then they go yellow, then red, and flashing red. Or maybe they flash fives times or so the new color when they first enter that color range.
Does it make sense that green ends at 250, yellow is from 250 to 300, and flashing red starts at 300? Or if the trans temp gets to 300 is it too late?
I’ve mentioned this before … when I was in the airplane business we ran Pratt & Whitney R-985s developing 450hp on take-off in a Beech 18 and DeHaviland Beaver. The various engine temp and pressure gauges in the aircraft had yellow and red ranges (they might have been hand painted in the field) so that pilot could easily tell if he or she needed to reduce power, land, or take some other corrective action. I am disappointed our Prevosts don’t have the same thing. To make matters worse, I believe the transmission gear lube temp gauge in our Prevost is identified as “Oil Temp” and we apparently have no real “engine oil temp” gauge which I think is really, really stupid. Its something I would expect to see in a small cheap car, not Detroit Diesel powered, Allison Transmission equipped Prevost motor coach.
Do any of you other Prevost owners have an engine oil temp gauge on the dash?
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I do have a guage on the dash that says oil temp…I assume it is the engine oil temp..I do notice that it usually is very close to water temp guage…when the water temp rises so does the oil temp and when it comes down so does the oil temp?
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My Telltale has both oil and transmission temps.
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