Ivan K Posted August 23 Share Posted August 23 I agree with Walter, 14psi should give just over 260F boiling temp at low altitude. We should never ever see it but boiling happens earlier at high elevations, maybe up to 10F lower per 5k ft elevation. This is about a norm for water. Still well in the margins of a healthy engine system and before Stop Engine should come On. Link to comment Share on other sites More sharing options...
cbr046 Posted August 24 Share Posted August 24 @scottknight there's a suggestion to run a lower gear (higher rpm) while climbing long hard hills. Did you do that? - bob 1 Link to comment Share on other sites More sharing options...
Steve P Posted August 24 Share Posted August 24 Thanks everyone. I'll be leaving my expansion tank cap at 14#. And continuing to monitor engine temp, especially in the mountains. The next trip with a mountain is Mt Dora, FL. 😎 Link to comment Share on other sites More sharing options...
tmw188 Posted August 24 Author Share Posted August 24 13 hours ago, Ivan K said: I agree with Walter, 14psi should give just over 260F boiling temp at low altitude. We should never ever see it but boiling happens earlier at high elevations, maybe up to 10F lower per 5k ft elevation. This is about a norm for water. Still well in the margins of a healthy engine system and before Stop Engine should come On. So let me ask “stop engine light” doesn’t really mean pull over and turn off engine does it? I would think it means get pulled over and let it idle down? Link to comment Share on other sites More sharing options...
scottknight Posted August 24 Share Posted August 24 Yeah was using 3rd or 4th gear saw this climb coming road construction single lane behind truck with flashers around 2000 rpm low speeds. The heat shield in the engine area showing its age may be contributing to dusting on radiator been out roaming a few weeks. I think i need better gauge info from scanners like ScanGaugeD suggested on this forum. Homework when i get home. Link to comment Share on other sites More sharing options...
tmw188 Posted August 24 Author Share Posted August 24 Yes at least a ScanGuage, inexpensive it’s plug and play and you’re up and running. Link to comment Share on other sites More sharing options...
Benjamin Posted August 24 Share Posted August 24 1 hour ago, tmw188 said: So let me ask “stop engine light” doesn’t really mean pull over and turn off engine does it? I would think it means get pulled over and let it idle down? If you lost oil pressure, yes, turn off the engine quickly. If the engine is overheated, then pull over, put it in park/neutral and idle the engine, could be medium speed idle. If you don't have dash heat, then you've lost coolant, so low idle for a short time (thirty seconds to a minute?) and shut off. As long as you have dash heat, then you have coolant circulating, so leave the engine running to cool off. Link to comment Share on other sites More sharing options...
tmw188 Posted August 24 Author Share Posted August 24 Yes pertaining to just overheating with no visible signs of coolant loss. Link to comment Share on other sites More sharing options...
diplomat don Posted August 24 Share Posted August 24 2 hours ago, Benjamin said: If you lost oil pressure, yes, turn off the engine quickly. If the engine is overheated, then pull over, put it in park/neutral and idle the engine, could be medium speed idle. If you don't have dash heat, then you've lost coolant, so low idle for a short time (thirty seconds to a minute?) and shut off. As long as you have dash heat, then you have coolant circulating, so leave the engine running to cool off. If no oil pressure loss, pull over when safe to do so, idle up to 2000 RPM in order to allow engine water pump to circulate coolant faster, rear radiator coaches will also have the fan running faster. You will see the coolant temp drop quicker. Also when climbing on a good pull you should gear down, keep RPM between 1900 and 2100 as this also keeps the engine water pimp circulating the coolant faster, this on both rear radiator and side radiator coaches. Good luck guys, Don. Link to comment Share on other sites More sharing options...
Benson K Posted August 25 Share Posted August 25 On 8/15/2024 at 9:08 AM, scottknight said: Last year i changed all engine radiator hoses and thermostate and went with OAT coolant for a mid-summer Family Texas gathering, hoses and thermostat original equipment . I have a 2004 8.3 ISC rear radiator no clutch fan. I do not have any recording or monitoring equipment and have owned this Knight since new. I only have the transmission temp gauge somewhat agreeing with the engine temp gauge. I read somewhere that OAT may help run a few degrees cooler (marketing?) I looked at the radiator cap formulas from some of the cap manufactures fyi info and decided on 7 pounds and also considered mechanical stress and boiling point. I left Bullhead low elevation at 100 plus degrees, normal summer temps using as low as 4th gear when unable to climb with momentum for slow trucks ect. Extended climbs to 6400ish elevation caused no alarms yet........... Amarillo is nice right now. I have always had to be aware on engine temps. Anyone else read or discovered when you turn on the headlight switch the gauges oil, temp, charging become a little deceiving with low voltage after all illuminating load on. Battery compartment passenger rear and front driver bin for a lot of 12vdc distribution. Voltage drop = dash gauge changes. I am not a mecanic rv or diesel just a long-time owner \driver of this rig. I have a 2003 HR Ambassador with an ISC 8.3 engine. When I turn on my headlights my oil, temp, and charging gauges are affected. They all drop about the width of the gauge needle. Link to comment Share on other sites More sharing options...
scottknight Posted August 25 Share Posted August 25 16 minutes ago, Benson K said: I have a 2003 HR Ambassador with an ISC 8.3 engine. When I turn on my headlights my oil, temp, and charging gauges are affected. They all drop about the width of the gauge needle. mine really jump..... but under most driving conditions, non-headlight switch illuminating load, it is really clear when the thermostat opens at 180 degrees the dash gauge shows correct numbers, tranny temp gauge mostly agrees, boost and oil pressure look at operating range. Voltage drops and those connections could use some attention\rework. I am cautious and concerned with plastic and all electric or board connections. Fix what i touch and break. Avoid Knight night driving as a good way to travel. It's nice being planted as the sun goes down. Upstream post improved gauge wiring, from daisy change to individual DC ground returns Lots and lots of wiring behind dash gauges. I am real careful what i touch. Link to comment Share on other sites More sharing options...
GringoScot Posted August 27 Share Posted August 27 scottknight, are you sure that your Knight ISC does not have a fan clutch? I only inquire, because you mentioned that your temps at specific speeds are about the exact same as I record (earlier post above). I have a little easier access to the top of my Cummins as I have the rear office area floor plan. I was concerned that after all of the radiator cleaning, slobber tube bypass, coolant/t-stat/top temp sensor swap outs, that I may be overlooking something else. Again, your similar temps to travel speeds made me think that perhaps this is the normal Knight behavior. However, I recently discovered the presence of a fan clutch and think that perhaps an "aging fan clutch" may be to blame for the higher than normal temps....and the only thing I have not investigated to date. The stabilizing support from the engine block to the fan clutch appears to shroud electrical cabling. I will need to investigate further, but I may have an electronically activated fan clutch and the aged internal hydraulics are no longer "in their prime". (Oh, and I found a photo of the JB Weld Marine epoxy fix to my coolant reservoir neck that I mentioned a while back.) Link to comment Share on other sites More sharing options...
scottknight Posted August 28 Share Posted August 28 a couple things on fan clutch, i have a spacer no clutch and using a mirror i see a bolt pattern similar to pully bolt patterns securing fan to pully and, i cannot turn the fan with belt connected. what i may be able to improve is on both sides of the radiator structural frame acts like a dam blocking some fan cooling, mathematically blocking 5% cooling(?). Maybe double thickness of those black metal brackets to retain structural strength and carve out the section that blocks some of the fan cooling. The cac is not blocked by those black c channels. Cac is not cooling. Link to comment Share on other sites More sharing options...
Malewis11 Posted September 3 Share Posted September 3 I have 2006 Monaco Windsor ISL 400 and I would like some input of knowledge and experience, especially for those with my twin. I ran a little hot this summer pulling hills in Arkansas when it was 98. I started digging into this and my 16# cap looked like it had seen better days. Manual say 7# min so I went with 9#. I now notice some weeping from the brass screws (highest temp I saw was 193 when driving) in the surge tank. I just dropped it off to have the radiator flushed and steam cleaned. I’m looking into the steel tank but should I consider canceling my 3 hour trip this weekend? I haven’t seen any reports of catastrophic failures but I don’t want to become a statistic. Several have gone to a 7# cap. Maybe with my clean radiator and new thermostat it’ll run cooler. Link to comment Share on other sites More sharing options...
tmw188 Posted September 3 Author Share Posted September 3 (edited) I wouldn’t cancel your trip, you did some good preventative maintenance. I have a 14# on an aluminum tank. Edited September 3 by tmw188 3 Link to comment Share on other sites More sharing options...
scottknight Posted September 3 Share Posted September 3 Just completed 2500-mile round trip Dodge City to Bullhead City thru Amarillo month of August. No issues with 7 lb. cap, not more than an inch of missing OAT coolant. I have to manage my summits with down shifting to at least 5th. I use a pipe cleaner to check coolant level. The caps are tight to reinstall so i enhance their slight lead-in bend with plyers, don't want to break my tank top reinstalling cap. I have mental plans to improve air flow thru radiator that i have not acted on . The c channel on both sides clears the CAC but air dams the radiator....... save for future custom work on list of things to do. 8.3 330hp. 1 Link to comment Share on other sites More sharing options...
Bill R Posted September 4 Share Posted September 4 @Malewis11 I upgraded last year to SS tank, and it came with 7# cap. Just returned from 2,600 mile round trip to Wyoming. For most part running 195F on flat terrain through Texas with 102F outside temp. On up and down decent hills through Colorado ran between 195F and 205F, outside temp still 95F. After climbing from 5,000 ft to 8,000 ft into Wyoming on 287, and one long 6% grade topped at 210F and then went down to 200F while continuing to climb. All that to say, after the trip, no coolant loss at all using 7# cap. 1 Link to comment Share on other sites More sharing options...
96 EVO Posted September 4 Share Posted September 4 11 hours ago, Malewis11 said: I have 2006 Monaco Windsor ISL 400 and I would like some input of knowledge and experience, especially for those with my twin. I ran a little hot this summer pulling hills in Arkansas when it was 98. I started digging into this and my 16# cap looked like it had seen better days. Manual say 7# min so I went with 9#. I now notice some weeping from the brass screws (highest temp I saw was 193 when driving) in the surge tank. I just dropped it off to have the radiator flushed and steam cleaned. I’m looking into the steel tank but should I consider canceling my 3 hour trip this weekend? I haven’t seen any reports of catastrophic failures but I don’t want to become a statistic. Several have gone to a 7# cap. Maybe with my clean radiator and new thermostat it’ll run cooler. Unlikely your cap change had anything to do with the brass screw-in fitting beginning to leak. 1 Link to comment Share on other sites More sharing options...
Malewis11 Posted September 4 Share Posted September 4 They finished cleaning and flushing my radiator. Said the outside was the worst they had ever seen. At least I’m #1 in something. They even cleaned it twice. I’m sure cooling is much improved so I think I’ll go to 7# cap. Does anyone have an opinion on whether I should try to seal those brass fittings? I turned them but never met resistance. They appear to not have a stop. I would be afraid of any kind of tape but I have read that some used a spray sealant on cracks in these tanks. I plan on going steel or aluminum but that will be at least a couple of months. Link to comment Share on other sites More sharing options...
96 EVO Posted September 4 Share Posted September 4 Seem to recall reading some had good luck using JB Weld on the brass fitting threads. Link to comment Share on other sites More sharing options...
Malewis11 Posted September 12 Share Posted September 12 Question for the group. They just did a great job of cleaning my radiator and flushing it out. Returning from the shop on a very hot day the engine temperatures were down 8 to 10°. It was running in the 183 to 188 range. Also got a new thermostat and fuel filters. Fast forward to today as the remnants of the hurricane were passing through with temps in the 60s, I drove the Coach to have the tires checked and wheels re-toqured. My temperature stayed in the 175 to 177 range the entire trip and I started noticing a hesitation or a shutter, as I would start to go up inclines. I’m not sure that my fan is working properly so it may be running wide open. Now that my radiator is clean I wonder if I’m running too cold now? Could running that temp cause some sluggishness? I don’t notice any difference in the way of drives until it gets to about 40% load and then the sound changes and I get a little bit of vibration. Acceleration from a stop is normal. Link to comment Share on other sites More sharing options...
96 EVO Posted September 13 Share Posted September 13 Probably in your drivetrain. I've felt it occasionally. Manually drop a gear and get your rpm's higher and I'll bet you won't feel it. You are greasing your driveshaft about every 5,000mi right? Link to comment Share on other sites More sharing options...
Malewis11 Posted September 13 Share Posted September 13 @96 EVO I tried downshifting but there was no change. Greasing once per year which is probably less than 5k. The complete timeline is that I replaced the chassis battery then drove to the radiator shop. I didn’t notice anything bringing it home and the temps were in the high 180s. The next day it was cooler and I drove it again and noticed the hesitation as I was going to get the fuel filters changed. Even cooler today with new filters and hesitation was worse. Maybe I’m connecting two unrelated things but the only things that have changed before this started were having the batteries disconnected and a clean radiator. Always something. Link to comment Share on other sites More sharing options...
96 EVO Posted September 13 Share Posted September 13 Hmm, air filter? Other thing would be your CAP'S pump leaking, or failing. Others more knowledgeable on that system would have to advise you on that. I don't have that fuel delivery system. Link to comment Share on other sites More sharing options...
cbr046 Posted Sunday at 02:42 PM Share Posted Sunday at 02:42 PM On 9/12/2024 at 9:37 PM, Malewis11 said: I noticed the hesitation as I was going to get the fuel filters changed. Even cooler today with new filters and hesitation was worse. Are you sure they changed both primary and secondary filters? Does your engine reach full boost? (If so ignore above) - bob Link to comment Share on other sites More sharing options...
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