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It is encouraging to find the right people .
I have been a Prevost owner for a few months now. In that time, there have been several issues most of which can be traced to previous non use or the current operator. The learning curve is really quite steep when compared to a non bus conversion. I like ergonomics and my conversion (98 Liberty) is not as logical or user friendly as some of my previous coaches but with time I have come to appreciate this riveted chunk of steel. My enjoyment increased when I discovered this group and I am very thankful for the information exchange offered here. Another great help has been a service person that knows the how as well as the why of things – if that makes sense. With his word pictures he takes you inside components without having to take them apart yourself. I thought I had an issue with an oil temp. guage but he quickly indicated it was not measuring oil temp of the engine but rather of the differential and the readings I thought were low were in fact correct. He also showed me the redundancies of the Prevost with a water temp guage on the engine as well as one on the dash. The one on the dash was 23 Degs.Lower than the actual on the engine so the error was in the sending unit to the dash guage but I can add 23 degs. Or go back,and confirm by looking at the engine mounted guage until I can get it fixed. I know many of you read the manuals and know this stuff ( as I should have) but it sure helps to have a mentor with my name in his phone. That came in handy on a Sunday afternoon on a mountain pass in New Mexico a few years ago. Anyway the adventure continues.
Wave
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22 Replies
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Wave,
If you add information to your signature line regarding the coach and model (Elegant Lady or Classic) you will find a lot of specific help from the multitude of owners on this site that collectively have a lot of knowledge and experience with your vintage Liberty.
A valuable addition to your coach would be contact information (phone nos. and email addresses) for other PC members with that knowledge. If anyone is willing to provide Wave with contact information but wants to maintain privacy send it to Tom or I and we will forward it to Wave.
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Wave,
If you change your profile to allow e-mails, all they have to do is click on your screen name and send you an e-mail.
We have had no issues here with e-mails being used for solicitations and when you having a problem or need info, many times members will contact you direct.
Thanks for the kind words about the site.
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Welcome aboard Wave. This board has been very helpful with the purchase of my coach going on 3 years now. Mine came from a small converter that’s been out of business for years and it’s been like finding a needle in a haystack with systems on my 91. You learn something everyday and these fine folks are always there to help you find a solution.
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Wave.
Here’s a quick test 😉 How did you determine which water temperature gauge was incorrect? I ask because my gauges also have about 20 degrees of difference. I concluded it to be the rear engine gauge based on the fact that the transmission and engine temperatures tracked each other very close when using the dash gauge. On my vintage coach, which should be the same as yours, there is a transmission heat exchanger, so my assumption was that engine and transmission temperatures on level ground after both had warmed up would be very close. I also shot several places where engine coolant runs and found the temps to be different but is almost each place closest to the engine gauge.
It’s important that the dash gauge is corerct on our vintage coaches as it’s the reading driven from the ECU, the very same used to turn on the engine fan. You don’t want your engine fan to be activated 23 degrees higher than it should.
I too like that there are some very knowledgable contributors to this board.
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On Wave’s vintage coach he has coolant temp, oil pressure and transmission temp as the three gauges in a line across the top of his instrument panel.
Life is good if all three needles on those three gauges are pointing straight up and down. However what will make Wave’s transmission and coolant temps deviate is Wave likely has a transmission retarder and when that is engaged and working the transmission temp being registered is at the outlet from the retarder ahead of the heat exchanger. But generally speaking if they are all pointing up and down they are likely displaying the correct values.
Gil makes a very good point about DDEC needing to see the correct temps, but Wave can verify that because the 2 cut in temps are around 204 and 208 so if he sees the temps cycling around those temps it is likley his fan is cutting in and out as needed.
When in doubt if there are two gauges, base the decision on what is being shown on an IR heat reading gun pointing as close to the temperature sensor as possible.
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Hi Gil,
It was pointed out to me that the ECU gets its information about temp from a different source than that dash gauge and an inaccurate gauge would not adversely affect radiator fan function.
Wave
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Thanks Wave. Our coaches, although almost the same year, are different. I have 2 water temperature sensors. One is dedicated to the gauge in the engine bay and the other to the DDEC. My dash is supplied water temperature data via the DDEC. Although I have a glass dash and not individual gauges my glass dash is using the Prevost supplied water temperature signal and wire.
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I have changed my profile. Did not realize I did not allow e mail.
Gil, It is interesting how different converters uses the same basic components but do different things with them. I like the looks of the CC dash. Mine is old school.
I am trying to use my coach as much as possible to work out kinks before a trip to N.H. and Maine. Especially frustrating when still working to spend what you thought was a trip in a repair shop.
Wave
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I haven’t noticed a water temp guage in my engine compartment. Where is it located, or do the H3’s not have it?
At cruise, my Prevost computer shows 208, while the guage on the dash shows around 20 degrees cooler?
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Mine is located just right of center and above the engine. Not sure about your H-3.
wave
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Jerry, here is a pic showing the mechanical gauges in upper right on the Series 60 in my MCI. If yours has them, they are likely in the same location. The E series MCI has a tall engine bay like your Prevost H. I think you would have seen them if they are there.
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I don’t know specifically where on the H3 the gauges are located, but on all my XL coaches the guages have been located to the right of the rear electrical box up high on the bulkhead above the 50 DN alternator.
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Jon,
I am still not clear on the temp guage on the upper right on the 98 liberty. You had a 97 as I remember. I think the guage is supposed to determine the temp of the transmission oil – is that correct? The guage starts at 140 degs. and I think half scale is about 190. What should that guage read under normal conditions?
Wave
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Wave,
My 98 XL chassis has two guages to the right of the electrical box in the engine bay. I assume all XL were likely equipped this way. One gauge is oil pressure and one is water temperature. I assume they are there to allow an operator to monitor the most critical engine data while using the rear engine start/stop controls.
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Just to make sure I am understood I will talk only about the 3 dash gauges and my readings. I have the two in the rear by the electric box, one for coolant temp, and one for oil pressure but I ignore them.
The three guages on my 97 were oil pressure, coolant temp, and transmission fluid temp.
The oil pressure I think read about 40 at cruise speeds. It had a jumpy needle so I couldn’t say what the actual pressure was, but despite the nervous needle it never went low enough to give cause for concern.
The engine coolant gauge had a difficult range of readings. I don’t remember what the minimum and maximum markings were, but the marked temperature closest to the needle I think was 190 or 195. The needle rarely pointed to that mark, instead it seemed to reside between 200 and 210 varying depending on OAT and driving conditions, namely hills. Even when it was up to what looked like 210 I did not get concerned because usually I saw that temp when climbing a steep hill on a hot day and when the needle point to 210 it cycled back down to a lower value. The only time it exceeded that was when my clutch started acting up and I just locked up the fan. Then it cycled bewtween what looked like 190 and 195.
The oil temperature gauge was measuring transmission fluid temperature. I learned it was measuring the temp, not at the oil in the transmission, but at its hottest point immediately at the retarder discharge and prior to the oil cooler. Under normal driving the temperature shown on the gauge tracked very close to the coolant temperature. But if the retarder was working, either by assisting when going down a hill, or when I stepped on the brake the tranmission fluid temps started climbing almost instantly. I had a self imposed limit of 230 degrees for the transmission fluid because i believe heat is the biggest factor in shortening the life of oils. That is my opinion only and comes from having a 245 degree red line on oil temps in my plane.
As soon as the retarder was not engaged the transmission fluid temps when right back to coolant temps or thereabouts.
I never compared the front and rear gauges. I couldn’t get my wife to agree to sit back on the batteries while I cruised at highway speeds so I could get normal operating pressure and temp in the rear gauges.
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