trans and engine temp - scare me or reassure me

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trans and engine temp - scare me or reassure me

June 09, 2011, 09:09:36 pm

We bought our coach in the cool weather. When we drove it, the engine would stay about 180, and the trans would barely get a reading, maybe 120 on a long, not steep hill (not many big hills in East Texas).

Today engine and trans hit about 220. We are towing a small car. The outside temperature is 103-104, and the roadway is probably more like 120. The CAC was flushed thoroughly several months ago.

Is all "cool," so to speak?

BTW, we are in Lubbock, to visit the Buddy Holly Museum.

OldMattB

Re: trans and engine temp - scare me or reassure me

Reply #1 – June 09, 2011, 09:39:55 pm

Matt,
We've got the 5.9 Cummins and four speed. Week before last we were in New Mexico. The outside temps were 80s and 90s. The engine would heat to maybe 205 or so when pulling long hills and the trans heat would be close to that. Back on the level and the engine would drop down to 190 and the tranny would follow suit. When we first got this 225 the CAC was seriously plugged and engine temps on the way home were real high, 220 or so. Trans temp stayed in the normal range.

Also, I posted awhile back when I encountered some real high tranny temps. We traveled a steep long winding road (not recommended for trucks) with lots of 15mph hairpin turns. The engine (CAC all nice and clean) didn't heat over 210 or so but the tranny climbed near 300 (just below that number on the gauge). I pulled over when I could, idled high for a couple of minutes and it dropped right down. The Allison manual says you shouldn't exceed 300 and to do just what I did (high idle until it cools).

After the high temp incident I posted here and over on rv.net. The rv.net gang responded with hysteria and calumny. The foreforums group, with calm and aplomb. No sweat.
jor

Re: trans and engine temp - scare me or reassure me

Reply #2 – June 09, 2011, 09:49:45 pm

220 is hot, but will do no permanent damage to the engine.

I would start by changing the thermostat (Caterpillar calls them Regulators). If it will not open fully, it could cause this.

Also, depending on hydraulic fan system (most replacements were different than the OE, so there are different systems out there), you may need to turn up the pressure to the fans. Determine what pump and fans you have and ask James Triana about proper PSI. Verify that the pump bracket is not broken allowing the belt to slip-- pull hard on the hydraulic pump belt and make sure that the bracket and pump do NOT move.

Your 240 should not run over 200 degrees engine temperature unless pulling long grades in 100+ degree temperatures.

Brett

Re: trans and engine temp - scare me or reassure me

Reply #3 – June 09, 2011, 09:56:52 pm

So nice to read, calm, responds to important questions. What a great group of members. Those with great questions, and then those with great answers.

Will be watching the temp gauges, as the TX summer gets going. Notice the gauges climb on hills and then fall on the down slopes.

Thanks to everyone for answers to questions I don't even have thought of yet.

Re: trans and engine temp - scare me or reassure me

Reply #4 – June 09, 2011, 10:08:26 pm

Our old coach, with a 3.9 Isuzu diesel, would never go above 180, no matter what we did to it. The trans would climb from a little hill, and we would pull over a 240, knowing it would keep going up if we continued.

I checked and we climbed about 2000 feet today, and had some good wind. I will hose out the CAC, just for good measure, watch the gauges until we get home and address the regulator and fans.

oldMattB

Re: trans and engine temp - scare me or reassure me

Reply #5 – June 09, 2011, 10:38:45 pm

I drove the same route today that I drove a couple years ago. Today the temps never got above 190 on the Silverleaf but the outside temp was 45. Last time the temp at Rapid City was 110 and I was pushing 220 on the engine. Heat and altitude hurt the ability of the fans to pull air and cool the radiator. You did not hurt the engine but next time if heats up like that take your foot out of it and slow down a bit and you will be fine. I just took it from 100% load to 75 and it stopped climbing last time.

Re: trans and engine temp - scare me or reassure me

Reply #6 – June 09, 2011, 11:34:08 pm

When your coach engine temp hits 220 as several of you have mentioned, what about your temperature alarm ? Isn't it going bonkers? When my engine temp hits just over 205, it starts "chirping", and by 210 it's a full-blown alarm. It's hard to ignore that alarm, so I slow down or pull over. Does the kind of engine make a difference? Mine is the mechanical 8.3 Cummins. Is it possible to change the threshold on the alarm, or should I just leave it at 205-210?

Re: trans and engine temp - scare me or reassure me

Reply #7 – June 09, 2011, 11:56:42 pm

Quote

what about your temperature alarm ?

Don,
I never had an alarm sound on the 5.9. the book doesn't mention an alarm, however, it does note a red water temp light but I haven't seen it go on despite high temps. Now that you mention it, I'd better check and make sure it is operational! Thanks.
jor

Re: trans and engine temp - scare me or reassure me

Reply #8 – June 10, 2011, 08:48:20 am

No one mentioned changing their driving approach under extreme heat conditions. Manually take the tranny out of overdrive and make sure to keep the engine rpm's above 1500, shifting down further as necessary.

Re: trans and engine temp - scare me or reassure me

Reply #9 – June 10, 2011, 09:23:36 am

I consider myself an expert on engine temperature of the 5.9 Cummins. I spent three years and wasted several thousand dollars learning about their acceptable operating temps. I finally found a publication from Cummins that said 240 degrees is the max temp a 5.9 should run. It is not unusual for the 5.9 to hit 225 or 230 on 100 + days on up hill grades. It does not take much of a hill to shoot temps up to 220 but it should go back down as soon as you go down hill or pull off of the road. It may run at 205 or 210 on a flat. I never had and alarm go off on my U225 and it hit 220 a number of times.

Dave, don't forget you have that Super Dooper, NASCAR auxiliary radiator to help you Keep Cool. Make sure you have it turned on in this weather.

Re: trans and engine temp - scare me or reassure me

Reply #10 – June 10, 2011, 11:02:46 am

No alarm on mine till 225 I think. I down shifted into third gear and kept the RPMs about 1850 or so and it kept the temps in the 186 degree area. Though I did the same thing when it was 110 out and I was up at the 215 to 220 range so outside ambient temps make a huge difference as does the altitude.... I was at 5700 feet and it is just harder to cool up there if it is hot out.

Oh and I had a new thing happen on the downside. Well new to me to see it as I have silverleaf and it worked this time. I was in 3 gear going down the other side and the retarder was on and i was coasting along just fine and it creeped up to 45 and the tranny upshifted to 4th while showing the gear selected was still 3rd. So I upshifted and kept it at 45 and it finished off just fine.

Re: trans and engine temp - scare me or reassure me

Reply #11 – June 10, 2011, 11:17:13 am

For those with a transmission retarder, remember the retarder produces a LOT of heat.

To dissipate that heat on long downgrades, it is better to use higher engine RPM/lower retarder setting to achieve that same braking HP than to run in a higher gear with higher retarder setting. The faster speed of the water pump will keep the engine and more importantly the transmission temperature down.

Brett

Re: trans and engine temp - scare me or reassure me

Reply #12 – June 10, 2011, 11:30:27 am

Quote

I finally found a publication from Cummins that said 240 degrees is the max temp a 5.9 should run.

Hey, Kent. Post a link to that reference, please. The only info I've found is in the Cummins Factory Service Manual which doesn't directly address the issue. It just says that the thermostat is fully open at 203 degrees. It sounds like the Cummins has acceptable operating temps much higher than the Cat. I wonder if that is the case.
jor

Re: trans and engine temp - scare me or reassure me

Reply #13 – June 10, 2011, 12:46:50 pm

Quote from: jor – June 10, 2011, 11:30:27 am

Quote
I finally found a publication from Cummins that said 240 degrees is the max temp a 5.9 should run.
Hey, Kent. Post a link to that reference, please. The only info I've found is in the Cummins Factory Service Manual which doesn't directly address the issue. It just says that the thermostat is fully open at 203 degrees. It sounds like the Cummins has acceptable operating temps much higher than the Cat. I wonder if that is the case.
jor

As it turns out, the Cummins mechanical BT5.9 has a higher normal operating temperature than any other Cummins that I have found. I would send you the link but I can no longer find it. It may have been saved on my old lap top. If so, its long gone.

During my 2 1/2 year quandary regarding hot weather operating temps, I started by asking three different guys at the local Cummins dealer and got three different answers, all lower than the actual standard operating temps. Naturally I wasn't comfortable with their answers so I got a phone number from them and called Cummins Inc. technical. They were the first and only verbal reference that said 240 was the upper limit but I was talking to a young guy that was just reading off of a computer and did not instill confidence. When I asked him to send something in writing he said he couldn't do it so then I didn't really trust what he said. I later spoke to the Cummins regional field service rep and he didn't know for sure but thought 225 was the upper limit. I never received a written confirmation from him either.

I talked to at least a dozen "Diesel Pros" and got varying answers from them as well. In 2010 I spoke with the field service rep for Spartan Chassis at the FMCA convention in Albuquerque. He had been with Cummins for 28 years and was considered their best guy on mechanical engines. He didn't know the answer for sure but thought 225 to 230 was the right answer. He promised to research it a send an email to me. I received nothing further and he did not return my calls.

During this 2 1/2 year period, I spent well over $2000 with Cummins having everything checked and another $1000 on pulling, disassembling and rodding the radiator. I installed three thermostats and a water pump. No change. Cummins just kept saying my gauge was running 10 degrees too hot. I also changed out the gauge and sending unit. Still no change.

All of this frustration and expense was caused by your coach. When Jeff and I were traveling together, he was running at 185 to 195 while I was running 195 to 210 in summer months. As far as I know, his/your coach never got over 205. I have a very strong dislike for your coach for fooling me.

My final and successful attempt to keep my/Dave's coach cooler was adding an aluminum NASCAR radiator behind the evaporator behind the front grill. I tapped into the 3/4" radiator hose with a couple of T's and an on/off valve. That extra cooling dropped my top operating temperature about 12 degrees on a 100+ day. Then one night I found a technical document published by Cummins that said the standard operating temps for a mechanical BT5.9 in a motor home was 185 to 240. I printed several copies and saved the link. However we have moved since then and I have a new laptop. I truly regret that I can't find those references now but trust me it was there, it was obscure and it was from Cummins. Its possible that it I found the link in a post on IRV2 or one of the other RV forums. It was not on Foretravel Yahoo or Foreforums.

The only reason for the long, long story is to help keep others from suffering as I did. I could have put a Banks system on the coach for less cost and Dave would be even more thrilled with his new coach. If you are at high altitudes on hot days, I wouldn't be too concerned until I got over 230. But if you are like me and a little conservative, you could install a Desert SuperCooler (Desert Supercooler information) like I have on my U300. I have not had occasion to use it but the PO put it on because he lived in Colorado and ran in the mountains frequently. I wish I had known about it back when I was going crazy over my U225.

Again, sorry for the verbosity. This is just a subject on which I have become overly zealous.

Re: trans and engine temp - scare me or reassure me

Reply #14 – June 10, 2011, 12:58:10 pm

I would check on the super cooler. As I recall Jon Harris had this system in his 95 U300 SE (Cat 3176). He needed some new nozzles for it. When we tracked down the family the husband who marketed it had passed away. The wife still had a few parts and sent them to Jon.

Re: trans and engine temp - scare me or reassure me

Reply #15 – June 10, 2011, 03:23:52 pm

Yes by all means buy the desert cooler if you love spending big money.
For me, I used a 5 gal gas can (PVC), windshield washer pump, tubing, hose, and made the nozzels from very small copper tubing, the tubing size was what the hose fit proper from the washer system, very small, cut the tubing with side cutters, made for a perfect spray pattern, then ty-raped the nozzel tubes (2) to engine where they would spray on the radiator, works great. And when you get clogged nozzels you can switch to windshield washer fluid, it will not clog your nozzels.
I had it hooked up with a SPST bat handle switch, pushed it on when needed, did not take a lot of fluid, maybe a quart on most mountains.
Worked great for me on my many engines in the MCI bus
FWIW

Re: trans and engine temp - scare me or reassure me

Reply #16 – June 10, 2011, 04:24:08 pm

Quote from: Dave M – June 10, 2011, 03:23:52 pm

Yes by all means buy the desert cooler if you love spending big money.
For me, I used a 5 gal gas can (PVC), windshield washer pump, tubing, hose, and made the nozzels from very small copper tubing, the tubing size was what the hose fit proper from the washer system, very small, cut the tubing with side cutters, made for a perfect spray pattern, then ty-raped the nozzel tubes (2) to engine where they would spray on the radiator, works great. And when you get clogged nozzels you can switch to windshield washer fluid, it will not clog your nozzels.
I had it hooked up with a SPST bat handle switch, pushed it on when needed, did not take a lot of fluid, maybe a quart on most mountains.
Worked great for me on my many engines in the MCI bus
FWIW

This is funny! I was thinking about this last night. I have heard it is quite effective, when the "problems" have been addressed but the heat problem remains. I know JC Whitney sold kits for cars and trucks. The only downside I see is a dirty mess around the intake, and a little more attention needed to keep the radiator (and CAC) clear from build-up.

I checked my pump bracket and it is fine, and I flushed out the CAC with a hose.

Are the hydraulic fans on any sort of thermostat? They hardly move when the engine is started and idles, but seem to move lots of air when the engine is hot and idling. The pump pressure might be an issue...

Also, we have used the dash air for the first time on this trip. Would that make a difference? I am guessing the evap is in the front, and the additional heat from driving the AC compressor would be to negligible to measure. Am I right?

Have any of you been to the Military Glider museum in Lubbock? Pretty cool!

oldMattB

Re: trans and engine temp - scare me or reassure me

Reply #17 – June 10, 2011, 05:11:42 pm

Matt,

You started typing your reply inside the quote, which makes the whole thing look like a quote. If you or anyone else makes a mistake in a reply or error in a post, you and you alone can change it after it has been posted. In the upper right hand corner of your post is the word "modify". Click on that word, you get your message in a reply like window, make corrections, and click "save".

Just trying to help, not be critical, others including myself have made this mistake.

Yes, the fans are on something similar to a thermostat. They get more pressure and run faster with hot coolant. Running the dash air on my coach would make almost no difference since it has it's own condenser location and electric fan. The evaporator is the part that does the cooling and it's in the dash. My condenser is on the left rear side and the radiator is on the right rear. I do not know where it is located on your coach but I'm guessing in the front, and if so would make almost no difference in engine temp.

Re: trans and engine temp - scare me or reassure me

Reply #18 – June 10, 2011, 05:19:13 pm

Hi Matt,
Our 1997 U 320 has fans that kick into high speed at 180/185 degrees coolant temp. My friends 2000 U 320 does the same. He had both hydraulic fan motors replaced, new lines etc, that was over $8,000.00. That stuff gets expensive quick.
Raymond

Re: trans and engine temp - scare me or reassure me

Reply #19 – June 10, 2011, 05:23:38 pm

Matt B,
You do not need a lot of windshield washer fluid being pumped all over everywhere making a mess. I just used the same window washer setup as used on a car, they do not spray a lot . Setup the nozzels to spray into each side of radiator, near the center, as the fan will pull it in and between the fan and the temp of radiator, the water seems to vaporize, as there is never a mess, or if there was one, it dries up before I stop. It does not take much water to make a mist, a mist is all you need, noneed to hose it down like a fireman would.
Ever notice on a rainy day, how cool it runs, just from the mist in the air. Seems most folks like to spary a lot of water on the fan, radiator, no need for that.
Been there, done that

Re: trans and engine temp - scare me or reassure me

Reply #20 – June 10, 2011, 05:59:47 pm

If you use either distilled or R.O. water, there will be no deposits. If there are, a gallon of cheap vinegar applied to the deposits will take care of the nasty white stuff. A pint of vinegar in the dishwasher works wonders also. Same with "hard water" spots on paint jobs.

Hardware stores sell the little brass nozzles and special pvc fittings used in DIY pvc cooling systems along with the little filter that keeps particles from clogging the nozzles. Cheap for the whole thing. Don't forget the little filter!

Good input and research on the above topic from members.

Re: trans and engine temp - scare me or reassure me

Reply #21 – June 10, 2011, 06:00:53 pm

Quote from: Jerry Whiteaker – June 10, 2011, 05:11:42 pm

Matt,

Yes, the fans are on something similar to a thermostat. They get more pressure and run faster with hot coolant. Running the dash air on my coach would make almost no difference since it has it's own condenser location and electric fan. The evaporator is the part that does the cooling and it's in the dash. My condenser is on the left rear side and the radiator is on the right rear. I do not know where it is located on your coach but I'm guessing in the front, and if so would make almost no difference in engine temp.

On the OE hydraulic fan arrangement on the U240 and at least one rendition of the replacement pump/fan motor, they are NOT thermostatically controlled. On the replacement on ours (from Foretravel) the maximum PSI is easily adjustable, but is not temperature related. I put in a "T" fitting and place for pressure gauge. I turn my max pressure down in the winter, up in the summer.

Again, you need to determine what hydraulic system YOUR COACH has and get with James Triana on how it should be set up.

Brett

Re: trans and engine temp - scare me or reassure me

Reply #22 – June 10, 2011, 06:22:37 pm

Always think of something to add after hitting the post button.

This has started off to be an especially early, hot summer. If there is anything to be conservative about, it is engine temps. I can't think of a worse nightmare than to be stuck on the side of the road in roasting temperatures with a giant vehicle spraying antifreeze on the ground. If you have to drop a gear and take a little longer getting up that grade, do it. I like the tortoise and the hare analogy.

Another good reason to have an extra belt and know how to put it on for your hydraulic engine fan system (where applicable) and if you pop one, don't hit the override switch. Stop and fix it!

Every morning walk around should include a check of the plastic coolant tank level.

Re: trans and engine temp - scare me or reassure me

Reply #23 – June 10, 2011, 07:49:47 pm

Happy to report, drove home today, up wind, totally different wind conditions and gauge temps. Showed 10-20 degrees cooler headed into the wind today. Pulled some short steep hills, pulling the Avalanche which I know to be too heavy, but what I have. We plan to tow some, and also un-hitch and double drive as needed if the temps are high, or the terrain suggests the need if we can get out west this summer.

We might look at getting a lighter toad for long trips next winter, this week the Avalanche was needed as a work truck for the jobs we had to do.

Backing off the throttle has always been my solution, on most anything thing with an engine. Has worked since we bought a new VW Campmobile in 1973, to sailboats, to the truck pulling trailers and now our wonderful coach.

Re: trans and engine temp - scare me or reassure me

Reply #24 – June 12, 2011, 08:15:20 am

Quote from: Dave M – June 10, 2011, 03:23:52 pm

Yes by all means buy the desert cooler if you love spending big money.
For me, I used a 5 gal gas can (PVC), windshield washer pump, tubing, hose, and made the nozzels from very small copper tubing, the tubing size was what the hose fit proper from the washer system, very small, cut the tubing with side cutters, made for a perfect spray pattern, then ty-raped the nozzel tubes (2) to engine where they would spray on the radiator, works great. And when you get clogged nozzels you can switch to windshield washer fluid, it will not clog your nozzels.
I had it hooked up with a SPST bat handle switch, pushed it on when needed, did not take a lot of fluid, maybe a quart on most mountains.
Worked great for me on my many engines in the MCI bus
FWIW

Ha! We used to do that with our race cars. Mount a few nozzles ahead of the rad, and after the run, hit the switch. Cooled the rad and engine down real fast. I remember finding some adjustable brass nozzles at a hardware store that worked real well.

I'll be adding a system like this to my coach, although am considering a higher pressure 12v pump with misting nozzles with generate a superfine spray (50 - 80 micron particles). Could even hook the pump to a relay triggered by an auxiliary temp sensor, so it's automatic.

On my initial trip home from Florida, ambient temps were in the 90s with high humidity. The temps on my 91 U225 5.9 Cummins were at about 200, and the MT643 Allison was around 160. By nightfall the outside temps has dropped to around the mid 60s, and coolant temps had dropped to around 160, with the tranny in the 120s.

Do any of these coaches come with an external transmission cooler? Has anyone added one? Just curious.

Steve

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