Cooling Questions U225

Topic: Cooling Questions U225 (Read 1482 times) previous topic - next topic

Re: Cooling Questions U225

Reply #25 – July 25, 2012, 08:20:50 am

What is the acronym "CAC stand for ?

Re: Cooling Questions U225

Reply #26 – July 25, 2012, 09:11:39 am

The boiling point for your coolant is not 212. It is in excess of 230 because of the coolant additive.

Re: Cooling Questions U225

Reply #27 – July 25, 2012, 09:19:21 am

Don, CAC means Charge air Cooler, the radiator looking device that runs the turbo pressurized boost thru it to cool it down.

Twig, The radiator pressure cap is what raises the boiling point of the radiator mix.

Dave M

Re: Cooling Questions U225

Reply #28 – July 25, 2012, 09:36:27 am

Are you talking about an aftercooler on a diesel engine? Ie: turbo charged and aftercooled diesel.

Re: Cooling Questions U225

Reply #29 – July 25, 2012, 10:14:05 am

Yes, The CAC is a much improved method of lowering the intake temps. on my ISM500, normal intake temp runs 80-105 f with the CAC. ON the older after cooled models the intake temp ran near or above the water temp as the cooling was done with the radiator water so temp was much higher. CAC is a new term to me also, but I am getting used to it. SO much better than the after cooling setups of years past.
Dave M

Re: Cooling Questions U225

Reply #30 – July 25, 2012, 10:25:15 am

CAC= After-cooler= Inter-Cooler.

Different engine manufacturers/different applications call it different things, but all to the same basic thing: The take hot intake air from the turbo (can be over 300 degrees F) and cool it to just above ambient temperature before sending it on to the engine intake. It is an air to air radiator in our applications.

Brett

Re: Cooling Questions U225

Reply #31 – July 25, 2012, 10:31:36 am

An antifreeze mix of 50/50 along with a 15 lb radiator cap give a boiling point of about 265 degrees. Every pound of increased pressure raises the boiling point of water 3 degrees.

So why is this needed? The interior water passages in a cylinder head can be fairly complex. The combustion chamber wall is hotter in some areas, especially close to the exhaust valve. The increased temperature in these hot spots may cause the coolant to locally vaporize with the potential to cause distortion and cracking. Raising the boiling point may eliminate these areas of vaporization resulting in more uniform temperatures in the metal.

CAC, aftercoolers, intercoolers are all terms for a radiator that cools the compressed air after turbos or superchargers have compressed it. They may operate like a car radiator with air flowing through causing the heat exchange or some may be liquid cooled or even a combination of the two.

The more any gas is compressed, the warmer it gets. In a vehicle, this translates to a higher thermal load on the engine with increased combustion chamber temperatures along with less power as the oxygen molecules are further apart. Cooling the air the engine breathes means less heat and the potential for more power (along with more heat produced).

In Porsche's famous 917 race car, two intercoolers were fitted to the 12 cylinder engine with 1100 hp produced. The intercoolers were modified to be liquid cooled and the horsepower was raised to 1200. This was done back in the 1970's but is still the most powerful race car ever to be driven on a road circuit.

Pierce

Re: Cooling Questions U225

Reply #32 – July 25, 2012, 10:36:12 am

Quote from: wa_desert_rat – July 25, 2012, 12:24:37 am

I was getting pretty worried about 200-degree temps and it looks like I was being a little paranoid. It didn't take that much of a hill to get that gauge up to 200; after all, the boiling point of the water that is cooling the engine is just a short ways away.

The boiling point of pressurized water is much higher.

Re: Cooling Questions U225

Reply #33 – July 25, 2012, 11:51:13 am

Quote from: Caflashbob – July 25, 2012, 10:36:12 am

The boiling point of pressurized water is much higher.

Yes... it's easy to know that but when you have your RV on a hot weather trip for the first time and the gauge starts getting close to the temperature of boiling water that you've known all your life then emotionally it's even easier to stress out.

Craig

Re: Cooling Questions U225

Reply #34 – July 25, 2012, 02:07:52 pm

Quote from: wa_desert_rat – July 25, 2012, 11:51:13 am

Yes... it's easy to know that but when you have your RV on a hot weather trip for the first time and the gauge starts getting close to the temperature of boiling water that you've known all your life then emotionally it's even easier to stress out.

Craig

Without exception in my years of being in the business this was the one thing I made a point to show/mention to every customer. And demo if I was doing the out of state delivery to las Vegas. Up baker grade many times. Pushed the coach on purpose just to show them it would not hurt it. Versus people leaving vegas in the dark to not have the temp gauge move in the summer. Lots of nice dinners were bought for me for making their rving a lot less stressful.

Can't blame them for worrying. Garrett box had a large fleet of garbage trucks and he's the one I remember mentioning what engine and trans temps his trucks ran. Then I talked to Allison bob at S&J Chevrolet in Cerritos, ca. the Allison service guys in my area and he showed me the commercial, fire trucks and such that ran 250 or more trans temp always in use. He mentioned 300 for an hour would burn the fluid. Dip stick would smell burned and red changed to orange if damaged.

Hard to get these that hot. These were four and five speed 643 and 743 and 754 if I remember.

We have desert most users won't have and long grades.

Re: Cooling Questions U225

Reply #35 – July 25, 2012, 04:19:10 pm

Funny seeing Caflashbob's comment, "We have desert most users won't have and long grades."

I have been driving in Texas and worry. I have been looking at temps in places in the US, as it is so hot here in Ft. Worth. Note that the desert out in Moab UT is day after day cooler than here! As an added plus their night temps drop much lower than our's as well.

But sure is good to know I can occasionally top out over 200 degrees on grades.

Re: Cooling Questions U225

Reply #36 – July 25, 2012, 11:44:51 pm

Quote from: Dave and Dolly Cobb – July 25, 2012, 04:19:10 pm

Funny seeing Caflashbob's comment, "We have desert most users won't have and long grades."

I have been driving in Texas and worry. I have been looking at temps in places in the US, as it is so hot here in Ft. Worth. Note that the desert out in Moab UT is day after day cooler than here! As an added plus their night temps drop much lower than our's as well.

But sure is good to know I can occasionally top out over 200 degrees on grades.

The little motors lead a harder life. Wear more. Duh......

No one but me and my customers and a few others ever pushed these at all.

Sure not trying to damage anyone's equipement but put the hammer down. I have bet customers on my money that the temp within reason would harm nothing. Never lost. And I took the same coach in trade with lots of miles many times. More fun to use the equipement within reason versus baby it.

I have hardly ever taken in a nice deisel that the motor was not a full power from never using it hard. I have taken dozens of used diesels rving and almost all were way tight.

Bought a 70,000 mile old giant Cadillac long ago. Floored it finally and red rust came out of the tailpipe. I laughed. The owner never floored it. I did.

The Rv business buys DP's and I bought an expensive used diesel pusher coaches and did not and does not have the motors tested as no one stresses these at all. The bus nuts were different but I never took a old 4104 or 4106 or either eagle as I could not show them enough on paper for the trade. They hotted up their stuff and you needed to bid low as it might have issues.

Re: Cooling Questions U225

Reply #37 – July 26, 2012, 01:27:40 am

Bob, I laughed at your comment about the bus nuts, 4104, 4106 & the Eagle type bus and how most folks have an elevated value on their bus, No way will one ever recover more than 10-20% of the cost. Sure glad I had the fun and experience of the MCI, large HP and all that goes with it including cooling games.
So much happier with my 01, 320 with the ISM500 and all that goes with it, why I smile alot.
Amazing how things change as we get older/wiser/smarter or we think so anyway.

Dave M

Re: Cooling Questions U225

Reply #38 – July 26, 2012, 07:26:18 am

Reading these posts make me laugh as I remember how I was regarded as a wizard for quickly fixing my mom and dad's diesel cars. I'd take em out (without my parents), look for a stretch of road with no cars on it, put em in a lower gear and pin em to the governor. Unbelievable what would come out of the tailpipe

Re: Cooling Questions U225

Reply #39 – July 26, 2012, 02:24:04 pm

Quote from: Dave M – July 26, 2012, 01:27:40 am

Bob, I laughed at your comment about the bus nuts, 4104, 4106 & the Eagle type bus and how most folks have an elevated value on their bus, No way will one ever recover more than 10-20% of the cost. Sure glad I had the fun and experience of the MCI, large HP and all that goes with it including cooling games.
So much happier with my 01, 320 with the ISM500 and all that goes with it, why I smile alot.
Amazing how things change as we get older/wiser/smarter or we think so anyway.
Dave M

I used to kid the bus nuts about switching to store bought. If I offerred 50k I would have got them all....

No warranty,no financing does not help.

Re: Cooling Questions U225

Reply #40 – July 26, 2012, 03:07:12 pm

You would get most of them if you offered $25 K, each conversion is a one of a kind, hard to find a buyer for such as too much change needed for new owner. I gave mine away real cheap and did not shed a single tear, just glad to have it gone, was time to turn a page and move on.
I did have max enjoyment for over 20 years with the MCI, made many changes to engine/s, trannys, all playing and getting a real strong runner, on local mountain on interstate, stock bus would drop to 48 mph, my best was 85 mph+ with light throttle, did burn some fuel, would get rough on drive tires (melted or very gummy, hot), but oh what a joy to play. Too much for words here.
Cheers
Dave M.

Re: Cooling Questions U225

Reply #41 – July 26, 2012, 03:24:27 pm

I hope this will help, but only with the Cummins 230 hp. I had Dave and Dolly Cobb's U225 from 2007 through 2010. During that period I became obsessed with engine temps. It was not uncommon to have 110 degree days in Oklahoma in the summer. After spending around $2,000 with Cummins and others including a new water pump, three thermostats, running straight water plus Water Wetter additive, pulling the radiator and finding it to be if perfect condition, a new temp gauge, two new sending units and finally an auxiliary radiator mounted in the front of the coach and plumbed into the 3/4" HEATER HOSE, I found a Tech Bulletin from Cummins issued in 1994 for the BT 5.9, 230hp engine that said the acceptable operating temperatures for that engine are 180 to 240 degrees. Mine had a 15# Radiator cap. I would still never run hotter than 215 for short periods.

The auxiliary radiator I added was a NASCAR 24" x 24" Aluminum radiator purchased from eBay. It was the only thing that made a difference and dropped the operating temps about 10 degrees on average. It was plumbed so it could be shut off and taken out of the cooling system in the winter.

I have looked several times trying to locate that tech bulletin again and cannot find where I saved it but I will keep trying. I asked many Cummins tech people about the temperature range and seemed to get a different answer from each one but I firmly believe that the temp range I mention here is accurate, not that I ever let my 5.9 ever run that hot. I'm too anal for that. As I said, 215 was my max and only for short periods of time.

I don't recall ever having the transmission temperature run significantly higher than the engine temperature but they ran about equal many times and the transmission temp was slower to come down than the coolant temp once we hit the down hills.

The 5.9 is just a high revving (2600 rpm red line), hot running engine in the summer temps and is slightly under powered on hills which exaggerates the higher running temperature. Relax and enjoy the great little coach and economical engine. We got over 10 mpg frequently.

Re: Cooling Questions U225

Reply #42 – July 26, 2012, 04:30:44 pm

Quote from: Kent Speers – July 26, 2012, 03:24:27 pm

The 5.9 is just a hot running engine in the summer temps and is slightly under powered on hills which exaggerates the running temperature. Relax and enjoy the great little coach and economical engine.

Kent... your expensive tuition has certainly helped me feel better about my coach in hot weather. I am running the Banks Stinger so it's possible that it's exacerbating the tendency for the engine to run wam anyway. I'll have to watch my foot and RPMs.

I do like you idea of the little radiator up front. Did you just plumb it into the heater hose?

Craig

Re: Cooling Questions U225

Reply #43 – July 26, 2012, 05:31:16 pm

We had a '93 U225 that was identical to Kent's (now Dave & Dolly's) coach. We never had an overheating issue unless we were taking a looooong upgrade in hot temperatures and pushing hard. UNTIL ... UNTIL ... we had sold our home and were making the trip from PA to Texas in a warm week in early October with 10 lbs of stuff in a 5 lb motor home AND a fully loaded tow vehicle. We were shocked to have the heat issue, but quickly realized why. I suggest that a very non-technical place to start ... that will cost about $9 ... is to weigh your coach. Just keeping' it simple!

Re: Cooling Questions U225

Reply #44 – July 26, 2012, 10:31:38 pm

I do like you idea of the little radiator up front. Did you just plumb it into the heater hose?

Craig
[/quote]

Was looking at the extra front radiator just today, and yes Kent plumbed it into the heater hoses, with a gate valve for shut off. It is mounted behind the AC cooler, and has a bracket that supports the new extra unit that bolts to the vacuum pump mounting base. I had that vacuum bracket out to install the new vacuum pump today.

Re: Cooling Questions U225

Reply #45 – July 26, 2012, 11:01:22 pm

Quote from: wa_desert_rat – July 26, 2012, 04:30:44 pm

Kent... your expensive tuition has certainly helped me feel better about my coach in hot weather. I am running the Banks Stinger so it's possible that it's exacerbating the tendency for the engine to run wam anyway. I'll have to watch my foot and RPMs.

I do like you idea of the little radiator up front. Did you just plumb it into the heater hose?

Craig

Craig as Dave said, yes I just used two T's, one before the heater and one in the return line. I then installed a gate valve in the hose from the engine to the new radiator so I could take the Aux radiator out of the system during the winter. I completed the loop from the outgoing side of the radiator to the return heater hose that goes back to the engine. The NASCAR radiators cool the oil rather than antifreeze. Their outlets are smaller, usually 5/8" to 3/4". I just had two 3/4" nipples welded to the radiator tank for maximum flow. I also washed out the oil in the radiator with multiple applications of Dawn Dish Soap and water. I pop riveted 2" aluminum L's to make a channel for the radiator to rest on. I lined the channel with inner tube rubber to stop any abrasion. I attached the channel to the A/C condenser brackets. It would work even better if the Aux radiator was in front of the A/C condenser but it would also reduce the effectiveness of the air conditioner and it works OK behind the condesner.

If anyone doubts the efficacy of the Auxiliary Radiator, just try turning on your heater the next time your engine heat gets too high. You won't believe what that little heater core can do to reduce operating temperatures, at least for a few minutes until it too heats up.

Also, I had worked pretty closely with Banks on what I considered my "Heating Problem" before I found out that I didn't really have one. Their engineers claimed that their stinger system would reduce my engine heating by at least 10% by giving me additional exhaust flow and lower turbo temps so I doubt that the Banks is a problem unless it was not installed properly or a complete system was not installed.

If all else fails, going slower does reduce engine heating. And as Carol say's carrying 10 pounds of crap in a 5 gallon pail reduces heating also. But I gotta have my stuff. I am seriously considering doing the same thing to my U300 to keep things cool for these mountain passes. We are in Montana right now. I guess I will never get over keeping one eye peeled on the heat gauge.

Re: Cooling Questions U225

Reply #46 – July 26, 2012, 11:12:30 pm

I remember a u225 owner that had installed a 24x24 rough sized radiator next to the engine itself facing right to left between the fender and frame. They say it worked well.

Shorter antifreeze run. Less chance of leaks?

Re: Cooling Questions U225

Reply #47 – July 30, 2012, 03:20:35 pm

Quote from: wolfe10 – July 21, 2012, 07:03:07 pm

But, that's really apples and oranges.

The U225 and U240 have COMPLETELY different cooling systems.

U225: rear radiator with solid driven fan. MUCH more prone to clogging the CAC.
U240: side radiator, with hydraulic fan-- on the 1995 U240 two fans with a two speed controller. And if the controller fails, it can stay on low speed and will overheat. Unplugging the controller puts the fan speed to high.

Brett

Is there any easy way to check if the controller has failed, other than running till the engine is hot and getting out to see if the fans are at low speed? Maybe as you say, disconnect the controller to see if the speed changes. If so, the next question is can you tell me where to disconnect the controller on a 2004 ISL? (assuming the set up is the same as you describe for the 240)

Thanks much.

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