Overheating ISL400

[dean0283]

Ok, here's what I've had done:

New hydraulic pump (made my fan ran per specs), new steel radiator, new radiator hoses, new thermostat. Water pump fine. Ditto fanbelts. Weight is 36, 000 for coach and 6000 lbs for toad for about 42, 000 total (per CAT scale) Coach is 2006 County Coach, tag and rated to 52, 000 lbs, side radiator. The engine was new about 12, 000 miles ago and had the same problem with old engine.

I have driven at 1800 rpms, 1400 rpms with and without cruise control, downshifted to 4th etc.

Engine overheat per Slverleaf to 226 and then derates and if I continue to drive, will shutdown. Does this on grades. Does find on flats. So any ideas, etc

[dickandlois]

What are your Intake manifold temperatures running relevant to the coolant temperature.

What is the range of your Turbo charger pressures?

When did you change the air filter last?

What is your fan belt tension reading?

What is your fuel lift pump pressure?

Have there been any changes in the Silverleaf Trip logs that stand out. Other then the Coolant temperature?

Rich

[tbutler]

We have a 400 ISL. Our coach GVWR is 37,600 and the GCWR is 47,600. Our last weighing we came in with a GCW of 37,925. We have never had any problem with overheating. You are about 4000 pounds heavier or about 10% over our weight. I wouldn't think that little difference would make the engine overheat. We top out in the low to mid 190's on a long grade on a 90+ degree day. Since you had the same problem with the previous engine, has this been a problem since the coach was new? Perhaps the problem lies outside the engine.

[wolfe10]

Have you verified that the fans ARE going to high-speed. Check, but on many, disconnecting the hydraulic fan controller wire defaults the fan speed to high. If it doesn't overheat with wire disconnected (again verify this is how yours is set up) suspect controller issue OR improper input to controller from engine computer.

[john_harris]

My 400 ISL did the same thing. Turns out problem was clogged radiator (road debris) on engine side of rear mounted radiator. Cleaned it and now pulls grades without going over 195 or so. If your rad has been replaced, obviously not your problem, but might help someone else with similar issue.

[dickandlois]

Dean, Fan belts will always be fan belts to me. Regarding your set up it still drives the water pump and if the tensioner spring has become weak you can loose cooling flow.

Brett, mentioned the speed of the fan related to the temperature sensors. Have you changed the filters and hydraulic fluid in the system?

Rich

[desertdeals69]

Make sure the fan in installed the correct direction.

[dean0283]

Sorry for the delay in answering, Rich.

New air filter, turbo pressure to high 30's, all else checked and ok. Nothing extraordinary shows on the Silverleaf.

Hydraulic fluid and filter are brand new. Fan on high sounds like a small turbo prop, blew my hat off when I opened the engine hatch.

Climbing the same grade, when ambient temp is 95 and above engine temp climbs to 226 and above. Same grade, ambient temp about 86, engine temps run about 220 and below.

Driving on flats, I see 199 to 201 consistently. Still baffled. I think, maybe having the sensors checked again may be one more thing to do.

[dickandlois]

Dean,

Just wondering what you intake manifold temps run when you water temps hit 226 deg.

The only time we had major cooling issues was when the thermostat failed, driving at any altitude or temperatures was impossible with the slightest grade.

When its hot (90+) and running at over 5000 ft. I'm right at the point where my temps. start to go above the comfort zone.

The rest of the time everything runs within or near nominal.

Same elevation, same road: early AM or evening when its just a little cooler, back around 80 deg. the engine coolant runs right at 190/195 and the intake temp only runs around 170 / 180 when running up hill.

I do pressure wash after returning from a trip of over 3K when we return home and more often should we travel in dusty areas when a truck stops shows. up.

I'm thinking that the CAC and radiator cooling capacity is maxed out around 90deg. and over 5000ft. pulling a grade for an extended period.

Should one of them fail, I well be looking at resizing both.

Rich.

[five]

My ISL runs right around 200 all the time. Crossing the Rockies it went to 207.

[dean0283]

I am at sea level to about 1000 feet when I am testing. The road is the Alamont grade, I580 eastbound toward Livermore, ca. I have ran with trans doing the work and with me controlling the RPM and mph.

The sensors check OK, next step is fan controller and fan motor. The radiator is brand new, steel and copper, ditto the thermostat.

Will report when I have new news.

Dean

[squeakkos]

Do you downshift or leave it? How many RPM do you run when going up hill?

[tbutler]

No one has mentioned this yet but the engine is supplied to the manufacturer and then the manufacturer decides what radiator to put with the engine. The size of the radiator and the kind of fan, the fan shrouding, radiator grille opening size, etc. are all determined by the manufacturer. I have heard of cases where radiator size varies for the same engine, some manufacturers going for a larger radiator than others. I don't know what the size of our radiator is, don't know how to measure except for square inches of open space on the radiator. I measure ours at about 24 x 48 inches, about 1152 square inches. I wonder if we are all talking about the same size radiator (measure the finned area only).

[dean0283]

Still working on the problem. With the cooler weather everything is working OK. Still seeing temps in the 216 range on steep hills. I am letting the Allison do the shifting and thinking for me. Seems to be keeping the engine between 1200 and 1600 rpms.

Dean

[casuall454]

Cummins 400 ISL isn't a motor that I have worked on much, however here is a couple of thoughts. This unit is 100% electronic as such the computer will hold fault codes. If you have a mechanic that you use regularly they should be willing to flash your computer and pull any fault codes as a courtesy. The usual fee is $90 to $150 elsewhere.

I saw several others posting suggestions, I would like to offer the following;

1. Flash computer to pull fault codes. ( If no fault codes ) check the following.
2. Serpentine belt for slippage. ( Although a slipping belt is noisy and your charging system would show voltage drop ) While checking for slippage pay attention to the tensioner (yes that spring can be checked using a torque wrench )
3. Coolant system; double check proper level of coolant as well your radiator cap. If the seal on your cap won’t hold pressure that will increase temperature, while cooler weather allows for proper operation. Lastly you can pull the radiator and have a flow test preformed to check for decreased flow, there by decreasing the cooling properties, due to numerous reasons.
4. Proper Install as motor coaches are built on chassis provided by suppliers and then retro fitted by manufacture. They may have changed ( under sized hose or hoses or installed on tight binds resulting in decreased flow ) Under sized Radiator. If you had a larger alternator installed ( Neihoff or Leece Neville ) it’s possible that pulleys could have been changed this would effect the RPM of the water pump, resulting in decreased GPM flow.
5. It is possible that the transmission cooler could also be air flow restricting your radiator, have your mechanic check that as well.

Hope this assists you in cooling your unit.

[dean0283]

I haven't reported back as the weather has been cold. Drove to Abq in Nov (some pretty steep grades on Hwy 58 east bound and I40 though Az andCa. No problems.

But I know with hot weather coming the problem will return. Having the mech do the checks that many of you suggested (thanks). Installing a new regulator and as a back up installing a manual switch so I can default the fan to high, if necessary.

I had the opportunity to compare my fan speed to another 2006 Allego that had the same engine, etc and his fan on high made mine sound like a baby fan, even I reported earlier, my fan speed has increased a lot and is pulling a lot of air. I would appreciate it, if the economy increases, that you think of me as I've tried to do my share. (Insert smiley face & empty wallet here)

Thanks again forthe suggestions and ideas,

Dean

[N8VTXN]

Here's something to check if everything else has failed. If your rig has an exhaust retarder brake, and most diesel pushers do, make sure it's working correctly. If it does not *release* completely when the brake is off, you will have an exhaust restriction. This is bad when your engine needs to produce a lot of power, such as on a hill. Overheating is a sure bet, along with possible turbo damage.

[wolfe10]

And, the ISL is the only engine that could be ordered with either an exhaust brake (less expensive) or an engine compression brake. Don't know which the OP has.

[Lenpa]

Dean,

I have an ISL set at 370hp. The thermostat is a 170 degree one - I thought it should be higher but my mechanic tells me this is correct for this engine.

Normal temps on flat ground runs very close to the 170 point. When I hit the hills (Bighorn Mountains) last August and let the Allison do it's thing the temps start to climb fast. Going up (eastbound US 14) is about 15 miles of 6-8% grade. Letting the Allison do it's thing let the RPM stay around 1500 (4th gear) resulting in the rapid rise in temp. By manually downshifting (3rd) to keep the RPM between 1800-2000 the engine stayed below 190. You have to keep air moving through the engine. Third gear provided more than enough speed due to very twisty roads with some 25-35 mph turns. Wouldn't want to go up much faster anyway.

Do you have an exhaust temperature (Pyrometer) on yours? By keeping the RPM up you will keep the exhaust temps down resulting in lower engine temperature.

Lenp

[MadHungarian]

Dean, not to butt in, but let me ask you this - you say your fan is blowing and it blows off your hat, but, just for grins, can you tell us if heat is actually exiting the engine compartment? Like most vehicles, and especially modern cars, trucks and industrial equipment, everything that's packed and crammed into the engine compartment is dependent upon cooling air entering and exiting. Is there an inlet/outlet that may be clogged? Does your diesel have a cold shroud in front of the radiator that isn't opened all the way? Just asking....

[dickandlois]

Dean, The items that come to mind one should check.

1- Water pump drive belt and the spring load on the belt tension roller.

2- Possible defective thermostat, the portion that holds spring in place can fail. This can cause the temperature issue you are describing by restricting the flow coolant.

When was the last time the system was flushed and the thermostat replaced ?

Rich.

[Cruzer]

We had an ISL400 on our 2004 Bus and now the same engine in our 2007 Bus. The difference was the chassis. Maybe something similar would apply to your situation. After all, it sounds like you have all of your components in good shape. The radiator was replaced, the fan blows your hat off, and the engine (therefore the water pump) is quite new. Plus, your last engine ran hot too.

Our '04 Bus was on a Freightliner chassis. Tiffin, as well as others, had issues during that era once the hotter burning EPA-2004 spec engines came out. Freightliner used a 1,050 sq in radiator. Then they stacked the charge air cooler right behind it as well as the hydraulic oil cooler. This meant that the radiator never got cool air, only preheated air. When climbing mountain grades out west the engine would overheat regularly. The 400ISL had plenty of torque but I was relegated to manually downshifting prior to starting those grades so that the engine's water pump would spin faster and the intake airflow was also increased. This helped prevent the temperature from climbing too far. Freightliner had a series of recalls that I went through but they were all shots in the dark that didn't correct the root of the problem, which was the too-small cooling system. The system wasn't redesigned until the new EPA-2007 emissions came out with the diesel Particulate Filters.

Their recalls revolved around wrapping reflective tape around the air intake hose, adding a bunch of dampers to redirect the radiator airflow, replacing the Dexron hydraulic oil with 15W-40 engine oil to keep the hydraulic fan speed higher, and eventually a new oil cooler because the heavier 15W-40 oil ruptured the existing coolers, which were never designed for the thicker oil. All I could do was anticipate and downshift.

Our '07 Bus is the same engine but on a Spartan chassis and a heavier tag axle coach. Spartan's cooling system uses a 1,326 sq in radiator, a charge air cooler that is stacked vertically above the radiator and an oil cooler also stacked so that everything gets a shot of clean air. This coach never breaks a sweat in any circumstance and I've climbed some steep stuff at high altitudes, drive in 106 degree heat, etc.

My point is that your cooling system may not be large enough. I don't know how your system is designed (size of radiator, stacked versus inline, etc) but it's possible you may have some design issues that can't be easily corrected. If not, I would look at airflow because you seem to have everything else taken care of. Not having radiator shroud that is effectively matched to the fan makes a huge difference on being able to get the air flow through the radiator. Also, making a way for the hot air to exit the engine compartment is also critical. You may need to add some vents or screens. If you think that may be the case, remove one or both of your engine bay doors and go for a test drive. If it no longer gets hot, your air outflow might be the problem.

Otherwise - downshift often - LOL.

[wildebill308]

I haven't reported back as the weather has been cold. Drove to Abq in Nov (some pretty steep grades on Hwy 58 east bound and I40 though Az andCa. No problems.

But I know with hot weather coming the problem will return. Having the mech do the checks that many of you suggested (thanks). Installing a new regulator and as a back up installing a manual switch so I can default the fan to high, if necessary.

I had the opportunity to compare my fan speed to another 2006 Allego that had the same engine, etc and his fan on high made mine sound like a baby fan, even I reported earlier, my fan speed has increased a lot and is pulling a lot of air. I would appreciate it, if the economy increases, that you think of me as I've tried to do my share. (Insert smiley face & empty wallet here)

Thanks again forthe suggestions and ideas,

Dean

I think you need to find out why his is moving so much more air.

Bill

[dean0283]

Well, I'm back. It appears the fan motor (part number 551101299200) has failed completely. The engine overheated on flat freeway. So I am now waiting for the new part. Mechanic bypassed everything and the fan runs on high all the time. Temps are between 178 to 185, but the weather is still pretty cool here (bay area in Ca.)

I have removed the big County Coach mudflap, the CAC is front of the radiator. I do run the engine onhills ar 1800 rpms & some the time engine temp was below 225 and other times went above 226 and derated and died. Same hill and roughly same ambient temps (above 100).

Thanks for the suggestions. Dean

[TipSanders]

Dean,

We towed a 2009 Ford Flex from Pensacola Fla out I-10 all the way to Phoenix in June 2013, overheating when we started up the Continental Divide from Las Cruces NM. We have a 2005 Monaco Diplomat 40PRQ with 66k on it (at the time) and the Handbook says the three combined factors of high ambient temperature (pushing above 100 up to 104 degrees on that leg), towing (Flex is about 4600+ lbs) and climbing upgrade, would cause overheating. I literally opened my hatches above the engine, ran my generator and ran both 15k roof air units full speed to force cooler air down through the hatches and that seemed to help get us to a park ( can't remember where) for the night. I bought cleaner and tryed to wash out my radiator core with a water from a hose, (though they all looked clean) and took off the next morning before dawn to catch the cooler temps. I figured the road temp was probably 130 or more and with the rear radiator on my Diplomat I think the air being sucked up came straight from the road but who knows. All I know is that when I got to Phoenix, I called the Rocky Mtn Cummins center and they said to bring it in. We were already on the far side (north) of Phoenix about 40 miles but we re-routed and got there at the dealed by 8:00. After telling them our issue, and what we had done, they took us in around 10:00. I asked them to replace the 195deg thermostat with a 180 and they also replaced the serpentine belt and 'pressure washed' the radiator components (engine radiator, Charge Air Unit, and transmission cooler) and we got out of there at 8:00PM. An all day repair, $900 and 2 free Cummins hats (one for me and one for the better half) and we were back on the road. This was middle of June and before the temps in Phoenix soared into the hundred & teens later. We went on to Williams, toured the Grand Canyon for 2 days then on through Vegas and overnighted in Leeds, Utah before going on through Salt Lake into Idaho where we stayed a couple of days before going on through Montana, Wyoming, and South Dakota visiting more friends and back home to the Chattanooga area (Cleveland, TN). I said all that to say I believe the combination of temps, towing and grade were the main reasons we ran hot, no damage fortunately because I really tried to keep it cool. We did have an air leak in the Turbo unit before we got to St Louis which caused a loss of boost. Again, I contacted the Cummins dealer there and they got me right in and out within about 3 hours (including lunch break) and it was a $158 charge for diagnosis and tightening an air line fitting on the control box (or something) and we were on our way home without incident. I can't say enough about the Cummins dealer in St Louis. If I would have known the advantages of a side radiator model before buying our Diplomat I might have made a different choice but I like my Diplomat and I like the Cummins 400ISL in my coach. Plenty of power for 40' and I think I am now looking for a smaller, lighter dingy!!