Engine gauge showing high temps on grade

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Engine gauge showing high temps on grade

October 13, 2016, 10:07:41 am

Another post about the first real trip with the coach. On the Bishop grade towing the '01 Grand Cherokee the temp gauge went to 230 deg. backed off cruise down shifted and temp came down to 210 deg. When at the campground hooked up the VMSpc as I didn't have time at home trying to make the campground by dark. On the way home deliberately caused the temp gauge to get to 230 deg. and the VMSpc showed 192 deg. It was not overheating in the first place just incorrect gauge reading. With the VMSpc I could see the oil pressure and temp gauges were not accurate on this coach at this time. Speedometer good, tach good and volt meter good. I will research on the reasons for the bad readings.

Re: Engine gauge showing high temps on grade

Reply #1 – October 13, 2016, 10:16:08 am

I have noticed on my 95 U-240 that the engine temp gauge will rise by 5+ degrees when the dash heater/ac fan is turned on. Higher the fan speed the higher the engine temp will be. I don't have any electronics to compare to, 3116 cat is mechanical engine(no electronics to check). I have wanted a second temp gauge to compare against.

Pat,

Re: Engine gauge showing high temps on grade

Reply #2 – October 13, 2016, 10:23:33 am

Had similar experience when we crossed Monarch. Went to 215-220 at summit but on descent it would quickly move back and forth from 190 or so to 215. Makes those ascents uncomfortable when you can't drive the gauges. In the end, I followed Brett's and others advice on ascending notwithstanding the reading. Looking forward to what you find.

Re: Engine gauge showing high temps on grade

Reply #3 – October 13, 2016, 10:24:14 am

Pat,

That is a voltage/ground issue with the gauges. Headlights usually do the same thing. As long as the readings are steady, no real reason to be concerned.

Said a different way, if temperature gauge is within a few degrees of that steady reading= thermostatic control, no worries.

Yes, you could add grounds (left side of dash) and/or add a fixed voltage supply to the gauges if it really bothers you.

Re: Engine gauge showing high temps on grade

Reply #4 – October 13, 2016, 12:33:10 pm

My guru buddy tightened the wire ends on the gauges.

Two different temp gauge senders. The VPMS as far as I know is the engines ECU.

Mounted on the block is the temp gauge sender for the dash gauge.

Sounds like the OEM sender is bad or needs reseating?

Mines off ten degrees or so

Factory grounds in dash are extensive. Look at the green wires to a mesh blanket. Unless the other end of whatever ground wire is used is corroded or loose?

Re: Engine gauge showing high temps on grade

Reply #5 – October 14, 2016, 08:33:51 am

Where does the ECU get it's temperature signal?
Must be another temperature sensor on the engine?

Re: Engine gauge showing high temps on grade

Reply #6 – October 14, 2016, 12:32:52 pm

John here is a screen shot of the sides and locations on a m11 celect and celect plus.

The dash gauge runs off the one on the right hand end I think.

Notice the ether start availability

My limited knowledge found that the cam sensor has been upgraded as the original ones got oil soaked internally as the potted sensor leaked and needs to be replaced with a one piece unit.

Symptom was an erratic idle. You could hear the misfires.

Second was the ambient air pressure. Mounts next to the motor now.

I assume it solves some issue.

If anyone finds other updated sensors please post or pm me.

Scribed has a free 932 page m11 shop manual you can read if you want to

Re: Engine gauge showing high temps on grade

Reply #7 – October 14, 2016, 12:45:00 pm

One more

Re: Engine gauge showing high temps on grade

Reply #8 – October 14, 2016, 12:52:45 pm

Another screen shot

Notice the bottom two lines

Foretravels hydraulic fan control was at idle temp of 165 consuming 15hp roughly and full on at 180 degrees consuming up to 50hp.

Thermostat is not fully open until 195

Waste of hp and mpg IMO and testing

Re: Engine gauge showing high temps on grade

Reply #9 – October 14, 2016, 01:10:06 pm

Restriction chart

Re: Engine gauge showing high temps on grade

Reply #10 – October 14, 2016, 05:50:38 pm

Thanks Bob,
I see the two sending units!

Re: Engine gauge showing high temps on grade

Reply #11 – October 14, 2016, 08:37:26 pm

Where does the 15-50 HP statement come from? Simple solution Bob, Disable the hydraulic fans. You will have all that extra HP.

Re: Engine gauge showing high temps on grade

Reply #12 – October 14, 2016, 09:47:25 pm

Not to be rude but the research is available if you have the nerd time to look around.

The guys that replace the factory rear radiator fans web page shows more power loss reductions than the 50 on certain models.

If my personal suggestions do not agree with what you think is correct then I would suggest you ignore them and continue using the coach as .Foretravel made it.

JOR here designed electrical cooling fan systems for locomotives and was nice enough to contact me when I posted about the un expected occasional large increase in RMPG on our coach on flat level ground and no change in altitude I verified using a iPhone GPS program just to make sure that an altitude change was not influencing my data.

That got me going through ever system to see what could consume so much power.

Enough to go from 8.3 to over 10. Then go back down after 10-15 miles.

Only large power consuming device on the engine was the fan control. Shop foreman at rincon truck center the Cummins dealer in San Clemente, ca mentioned that the fan on high could easily consume 40hp. Plus heat the engine oil up excessively causing fan motor failures at lower than expected hours.

Which seems to match the reports here.

Went through the brakes three times. Rebuilt the alternator. Changed the air cleaner to a Donaldson Blue foam element on advise from Pittsburgh power who race Diesel engines.

Had the cummins shop weld a beautiful 5" low restriction exhaust system and install a 5050xl resonator.

Replaced the cam position and ambient air pressure sensors.

Adjusted the valves and injectors.

Replaced the leaking Winn system with a new Parker system.

Replaced the pilot Xza-1's with new ultra fuel efficient Xza-3+ "h" rated tires for less power consumption. 90/100 psi

Had the cummins shop check on the actual engine specs in the coach.

Talked to the cummins salesman at southern power in Atlanta to verify what was sold to Foretravel

Talked to my old buddy James T. To see if he had any specific knowledge about thermostat selection and such.

You could hear the crickets over the phone. No info. Did not want to get it on them I think.

Bought a higher temp fan controller and had it installed and ran it but it turns out the dynamatic model numbers are not the temp they are designed for.

Then I ran across a beaver owner selling a 199 degree spare controller unit from his coach for a fraction of a new price.

Turns out all the coaches have 199 max fan speed controllers

Had it installed and went on two separate drives. One 800 miles and the other this month of 3800 miles.

Total mpg is 8.3 towing 3,600 at 70 mph and downshifting and revving hard where needed and disregarding heavy winds as far as mpg.

What I want is more power. IMO these are slightly gutless.

The industry around this time was found out to have faked their emission results. Big stink 20 years ago.

My opinion is that my old coaches had their motors turned up by the distributors for the OEM Rv manufacturers use.

Now by 97 the motors had to be correctly emission built.

By 2000 or so cummins changed the engine family top end parts to a multi shot high pressure fuel rail system and a variable turbo which greatly increased the power and passed emissions.

As no one officially can boost the engines power past the 450/1450 build stock I had no other choice but to fine tune what I was given.

Everything works as a package.

I got more torque and hp which resulted in more mpg but that was not the original idea.

Drove many coaches at similar weights long ago who would run away from this coach still.

Different emission standards. Different days.

Re: Engine gauge showing high temps on grade

Reply #13 – October 14, 2016, 10:05:58 pm

Bob is right about fan hp requirements. Brett Wolfe posted this link a while ago.
.http://www.rvtechlibrary.com/engine/Cat_RV_Performance.pdf
I have tried installing ram air type scoops on my present coach to try and provide
enough air thru radiator without needing hyd fan cooling, dosn't help much.
Jim

Re: Engine gauge showing high temps on grade

Reply #14 – October 14, 2016, 10:48:44 pm

Before I replaced my ignition solenoid under the dash my gauges would go up and down due to the voltage fluctuation as I turned lights, wipers, and defroster fan on and off, so I'd check the solenoid.

Re: Engine gauge showing high temps on grade

Reply #15 – October 14, 2016, 10:56:53 pm

Thanks for the link.

On the Caterpillar engine the article says that 50 hp for the fan at 1800 rpm. 12 hp at 1400 rpm. At 65 mph my coach runs about 1400 rpm. 102 hp for aerodynamics, 80 hp for rolling resistance, 12 hp for the fan. At 5 mph headwind adds 25 hp demand. If you are trying to go 55 mph up a 6% grade in 4th at 100% load on your M11 at 1800 rpm then maybe the fan will use 50 hp. Hard to say, this document is for a Cat engine with perhaps an engine driven fan. I guess you could estimate the hydraulic fan on the FT uses about the same. Under most driving conditions the hp demand for the fan is small compared to all other hp demands.

Lots of energy being spent trying to gain a couple extra hp that are much easier to gain with some driving behavior modification. There for the taking if you want it. We all do what we want to do.

Just saying...

Re: Engine gauge showing high temps on grade

Reply #16 – October 14, 2016, 11:03:43 pm

Jim change the controller. Zero difference in the temp gauge,

To be able to drive the coach hard and still get good mpg is the iceing on the cake,

Too impatient to do a long level drive at 60 to get 10 plus mpg. Trust me it's there

Re: Engine gauge showing high temps on grade

Reply #17 – October 14, 2016, 11:12:00 pm

I am a little confused about the different fan controller temperatures. Can these coaches stay under 199 deg. without the fan working? If not the only difference I see is 50 HP loss at 180 deg. or 50 HP loss at 199 deg. The fans will have to come on either way.

Re: Engine gauge showing high temps on grade

Reply #18 – October 14, 2016, 11:30:39 pm

Quote from: craneman – October 14, 2016, 11:12:00 pm

I am a little confused about the different fan controller temperatures. Can these coaches stay under 199 deg. without the fan working? If not the only difference I see is 50 HP loss at 180 deg. or 50 HP loss at 199 deg. The fans will have to come on either way.

Good point, think you will need the hyd fan regardless. Tried scoops over intake for radiator thinking ram air effect would negate need for fan, wrong there. Probably if ambient temps low enough, and low load on engine, might be able to keep engine water temps cool enough to just cycle on engine thermostat and not need fan. Need to go to Alaska next winter to test this theory. My fan now comes on at 200 degrees and shuts off at 190.

Re: Engine gauge showing high temps on grade

Reply #19 – October 15, 2016, 02:22:03 am

Seems the controllers have a ramp up in speed. Not on or off.

By selecting the 165 degree idle temp and the 180 full speed the foretravel selection locked the fans on high if warmed up.

My long drive at a steady speed and having the rmpg jump up at times in mild conditions seems to show that the controller finally saw 165-170 temps at its location in the cooling pipe.

By changing the controller to a 185 Idle to 199 full on has the fan on idle speed not off at the nominal 177 degrees that the engine runs at under a mild loading.

The cat chart shows the power draw curve.

The idle not off position is because of the charge air cooler. It requires some fan all the time
And my rmpg jumped up quite a bit.

Slight downhill from Pueblo towards Omaha at 65 towing I hit 11.5 rmpg for 100 miles or so. Picture posted here

The caveat is all the parts may be necessary to see the max benefits.

But I cannot imagine no one not seeing a noticeable improvement in both torque and rmpg by not overdriving the fan system.

Someone posted a kit here to replace the danfoss fan electric controller system on another brand with the same dynamatic 199 degree controller and the necessary hydraulic hoses to replace the troublesome electric system with the dynamatic piloted wax capsule proven reliable system.

The electric was low/high. Not progressive

Re: Engine gauge showing high temps on grade

Reply #20 – October 15, 2016, 08:19:29 am

Quote from: Roger & Susan in Home2 – October 14, 2016, 10:56:53 pm

On the Caterpillar engine the article says that 50 hp for the fan at 1800 rpm. 12 hp at 1400 rpm. At 65 mph my coach runs about 1400 rpm. 102 hp for aerodynamics, 80 hp for rolling resistance, 12 hp for the fan. At 5 mph headwind adds 25 hp demand. If you are trying to go 55 mph up a 6% grade in 4th at 100% load on your M11 at 1800 rpm then maybe the fan will use 50 hp. Hard to say, this document is for a Cat engine with perhaps an engine driven fan. I guess you could estimate the hydraulic fan on the FT uses about the same. Under most driving conditions the hp demand for the fan is small compared to all other hp demands.

At what RPM does the fan on a U320 operate? Does that fan RPM vary directly with engine RPM?

Re: Engine gauge showing high temps on grade

Reply #21 – October 15, 2016, 10:25:38 am

Quote from: Caflashbob – October 15, 2016, 02:22:03 am

Someone posted a kit here to replace the danfoss fan electric controller system on another brand with the same dynamatic 199 degree controller and the necessary hydraulic hoses to replace the troublesome electric system with the dynamatic piloted wax capsule proven reliable system.

The electric was low/high. Not progressive

My 98 8.3 has the mechanical fan control system. I presume it's variable. Barry Beam has a valve installed on his and he can test to see if the fan speed is variable. I've never seen the fans running full blast with fast engine rpm...by the time I get to the rear of the RV they slow down!

My temp gauge never goes above 180deg

Re: Engine gauge showing high temps on grade

Reply #22 – October 15, 2016, 10:45:57 am

Thanks Bob for helping us figure out what you trying to do.

David, Bob seems to be saying that it is a variable speed based on the controller. I don't know. He says normal is minimum speed at 165, max at 180°. Looks like he changed his to minimum at 185 and max at 199. Seems to have gotten him a normal coolant temp in the high 170's.

Your '95 and my '01 are probably not the same as his '97 as the M11 was transitioning during this period to Celect, Celect+ and finally the ISM11. My ISM11 runs at (coolant temp) 178° almost all of the time. The highest I have ever seem it is 188°. Bob's seems to be running warmer with the higher fan controller temps, now about where mine does. I talked to an SOB owner this summer with a new Phaeton. His ISM11 was running about 200° and he was thinking 6+ mpg was pretty good. I like the 8ish I get just fine.

We did Denver to HWH in Iowa, 700 miles, 65 mph, one overnight along the way, 11mpg + for that leg. A bit downhill and some tailwind helps. Going the other way would have been ugly. 70 mph would have burned a lot more fuel and would have saved me only 45 minutes over two days.

This thread seems to have wandered away from the OP question about his gauge behaviors.

Re: Engine gauge showing high temps on grade

Reply #23 – October 15, 2016, 12:12:48 pm

My temp gauge before and after the controller change basically looks identical. Maybe up 3-4 degrees on the VPMS on flat ground

A call to make grimes might show which controller is in what years/models.

Stands to reason foretravel figured this out sometime and changed the controller.

There is a part number on the controller.

Running 200 would be ok but I would verify that number on a VPMS if not already done.

Back pressure from a too restrictive of a muffler should make any of our engines run hotter under a higher load.

Krush I assume your radiator is the same as the other models. You have extra capacity compared to a 320

My temps seem to have gone down with my changes. Less increase up long hills

Re: Engine gauge showing high temps on grade

Reply #24 – October 15, 2016, 12:57:20 pm

RRadio had a post a while back about spraying water on the radiator / CAG when temps rise. Sounds like a great idea to me, just haven't implemented it yet ( not a lot of traveling in hot, hot country yet, dang it ☹️ ).

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