MarinerCoachman

Overheating Cat 330-Discovery

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My mechanic and I need help solving my overheating probliem with the Cat 330 hp in my 2004 Fleetwood Discovery. I have owned it since July 2010. It over heated on a trip from TX to MT right after I bought it. The shop found a bad fan/water pump belt and tensioner needed adjusting. Also several bad hoses and clamps.Fulshed cooling system and repaired and came back to TX without issue. Next trip about two months later interrupted by elevated temp. Back to the shop. Removed radiator with great difficulty because of rusted bolts and nuts. Found lower 1/3 to 1/2 of radiator externally plugged with what looked like dried mud. Cleaned reinstalled and was sure that was the problem. Trip to OU last fall without issues. This weekend trip to beach interruped by serious overheating and a tow tow to the shop for more diagnostics.

Anyone have solution or similar story with tips on correcting?

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wolfe10   

Welcome to the FMCA Forum.

As you already posted, the first "suspect" with a rear radiator diesel is a plugged CAC/radiator. Note: CAC= Charge Air Cooler= After-cooler= Inter-cooler-- all names for the same piece of equipment that takes hot intake air from the turbo and cools it down on its way to the engine. Since it is FRONT of the radiator, that is where the vast majority of the dirt will accumulate.

Access the top of the engine/fan shroud area from the bedroom or closet. With a strong flashlight, look inside the fan shroud/between fan blades. It WILL be clean-- the fan blades sling the dirt to the perimeter. Verify that the perimeter is as clean as the center. Pay particular attention to the lower quadrant where dirt and debris first accumulate. Insufficent air flow through the CAC and radiator WILL cause overheating.

Also, with your 3126, it wouldn't hurt to reach under and check water belt tension-- it is NOT tensioned by an automatic belt tensioner.

Let us know what you find.

Brett

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The thermostat failed on my coach and we went through the same items before it was replaced.

The saddle portion that holds the spring an valve assembly in place, split at the top and the thermostat could not open and close properly. It might be a good item to check.

Rich.

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I did the all routine stuff, then noticed that the fan blades felt gummy... Sure enough, my regular pressure washing (using Delicate tip for radiator halves, of course) after applying copious degreaser wasn't doing the trick.

It took an hour of scrubbing with degreaser and a stiff-bristled brush, reaching down through the bedroom closet floor, to get those blades looking pretty...

One thing I'll do more of this season: pull my speed back and downshift to increase my rpm, when the temp creeps over 200F.

"Understanding Coach/RV Performance" is a publication distributed by Caterpillar, they briefly address cooling in the C7 engine.

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wolfe10   

Andy,

While raising engine RPM when under load WILL lower engine operating temperature, I hate to see you burn extra diesel (which this WILL DO) to baby the cooling system. Yes, if very high ambient temperatures and long grades, this may be needed, but I would suggest that it is a "report card" that tells you to "tune up" your cooling system. One of the criteria for determining if a tune up is needed is: "Did the coach run at cooler temperatures under the same conditions earlier in its life?"

As discussed, the "tune up" includes:

Cleaning front of CAC and also the radiator.

Insuring that coolant is at proper level, still in good shape (use three way test strips that test for SCA, freeze point and pH).

Insure that the water pump belt is in good condition and properly tensioned (it is NOT on an automatic tensioner).

Verify that thermostat(s) are not over 3 years (per Caterpillar recommendation). BTW, Caterpillar calls thermostats "regulators".

Brett

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I have done all of this to my motorhome: clean radiator, new regulators, new ELC, new coolant hoses and I always maintain RPMs around 2000-2200. However, when climbing long steep grades on warm days my engine will overheat. I have a Cat 3126B-330HP with side radiator. I have been considering the use of somekind of water mist system to help cool the radiator. Has anyone had any experience or thoughts on such a system?

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wolfe10   

With a side radiator, first question is how is the fan speed controlled. Most have a low/high fan speed controller. If it is stuck on low, engine temperature WILL continue to rise.

With a side radiator or a rear radiator with fan clutch, there should be a range of temperature that you see:

Lower one is that dictated by the thermostat. From thermostat setting (say, 195 degrees F) to where the fan cuts to high SHOULD be 4-5 degrees. If the fan cuts on too soon you just pay HP and MPG to run it.

I have nothing against a water mist system IF you use distilled water so you don't get mineral deposits built up on the cooling system which would further reduce air flow through the cooling package.

And, when you say you cleaned the radiator, be sure you clean BOTH the CAC and the radiator. The CAC is the first thing in the air flow and therefore collects most of the debris in a sandwiched cooling system.

Brett

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Brett, Thanks for the reply! I always do the sandwich from both sides and between layers using Dawn and lots of water but never have opened the sandwich. You mention the fan hydraulic controller could be a problem. I guess the only way to tell if the fan controller is working properly without test equipment is by sound of the fan when engine is hot or cold. I notice that my fan is very loud and feels like its moving lots of air when engine first starts and is cold. After it warms up the sound seems to be a lot less as well as air flow. This has always happened. I never have listened to the fan when the engine is overheating, maybe I should or maybe I should take it to a repair facility and have it checked. Thanks again for your thoughts and advice. Don M

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v35pilot   

I own a 2004 Itasca Meridan 39W with the 330 Cat engine. I had a bad overheating problem coming from New Mexico back to Oklahoma City.

After getting back I called the Freightliner shop to get it in to be checked. Service Writer asked me if I had extended the "Slober Tube". He said before 2007

all engines had a crankcase breather tube coming out bottom of engine.

I was told the the tube comes down from the crankcase and was letting oil fumes go back and mix with dirt to gum up the

radiator. I got a hose and clamped it to tube and ran it back so the oil fumes would exit behind radiator.

I then spent three hours with garden sprayer and Simple Green. I would spray into radiator from front and back. Then I went thru floor in closet spraying into the back side.

After letting Simple Green set for 30 mins. I flushed radiator with water. I was told DO NOT use power washer as it will bend fins of radiator. I repeated

this twice till the water was coming out clean. I could not believe the crud that came out.

The ground was black with dirt and caked up oil. I have taken several trips and not had anymore overheating.

Hope this helps

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I was told DO NOT use power washer as it will bend fins of radiator.

Good point.

If you're lucky enough to have a power washer with a "Delicate" tip, it might be okay: vigilance and a little common sense is the key.

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Hi Brett,and all others! I use Simple Green and apply it with a nice little engine degrees-er I found that attaches to my air supply,it puts out a nice fine mist of siphoned degrease-er.

I release the belt tension-er and that lets me turn the fan with ease. I can then get into the corners with this nicely angled sprayer.

I then use an electric powered pressure washer that supplies about 1700 psi and water from my hot water tank that I set at around 190+ degrees. The hot water and Simple Green work well and to date no damage to the CAC or Radiator.

Now ! Having said that, a great deal depends on how close you have the nozzle and if there is any substantial degradation regarding the items being cleaned. Always figured that if they are bending and little pieces are coming off they are not going to last much longer anyway.

After cleaning, I try to spray some nice new black paint on things. Now this can upset the DW, but the smell dissipates after closing the doghouse and I keep the windows open for a few days. Timing is everything.

Because if she is around when the paint is first applied , I'm most likely going to windup under the doghouse cover. LOL.

Rich.

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hi rvndonbon,

I had the same problem with our coach , we have a Cummins with a side radiator. Always was going to overheating on

long hill climbing. We solved our problem. We removed the big mudflap on the back of the coach.

Here is my reason:

I taped a 6 inch long pieces of rope with a small washer on the bottom of the coach behind the rear wheels and had a friend

of mine drive next to the coach going up a steep grade ,and it pulled the ropes & washers upwards into the engine compartment

then we removed the mudflap and did the same run again. This time the ropes & washers were at a angle downwards & to

the back. The difference was that the temperature never went past the 1/3 mark as before I had to stop because of

overheating. I don't know if this is your problem, but surely a cheap way to if this fixes your Issue. I feel that with a side

radiator the engine sobber issues that the Cat engines have does not pertain to your situation.

I hope this helps.

Sincerely,

the old marine

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wolfe10   

FYI. ALL diesel engines prior to 1/1/07 had "slobber tubes"/crankcase breather tubes. So all brands need their breather tubes extended to behind the fan shroud (intake) for the cooling package.

Said another way, this affected Cats, Cummins, MB, DD, etc.

And overfilling any of their crankcases resulted in the access being "puked" out the breather!

So, if you have oil coming out (any engine) first "suspect" is that someone overfilled the crankcase.

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rvarner   

hi rvndonbon,

I had the same problem with our coach , we have a Cummins with a side radiator. Always was going to overheating on

long hill climbing. We solved our problem. We removed the big mudflap on the back of the coach.

Here is my reason:

I taped a 6 inch long pieces of rope with a small washer on the bottom of the coach behind the rear wheels and had a friend

of mine drive next to the coach going up a steep grade ,and it pulled the ropes & washers upwards into the engine compartment

then we removed the mudflap and did the same run again. This time the ropes & washers were at a angle downwards & to

the back. The difference was that the temperature never went past the 1/3 mark as before I had to stop because of

overheating. I don't know if this is your problem, but surely a cheap way to if this fixes your Issue. I feel that with a side

radiator the engine sobber issues that the Cat engines have does not pertain to your situation.

I hope this helps.

Sincerely,

the old marine

Bingo, I posted this info a long time ago when I lost my long flap to a road "alligator" but I didn't think anybody listened to me. I ordered and installed the rubber flaps behind the rear wheels and, I swear, the MH ran cooler. I have a rear radiator tho and didn't think it would apply to a side mounted unit but apparently, it does. I did not do scientific research like you did. It just happened.

Richard

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tajfish   

Since I have the floor up in the Discovery to change out a actuation pressure sensor, I think I will inspect and clean the CAC and radiator and check on the slobber tube. These forums have a way of keeping me busy with projects. Sounds like I may be over time on my "regulator" also. Does anyone have a drawing showing the location of the regulator ? Experience with changing it out ?

Thanks,

Tom

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wolfe10   

The effect of removing the rear mud flap is very highly dependent on the sq ft of rear grill area. Some coach makers left very little grill area in the back of the coach to "improve looks".

So this is not a universal solution. Example: our coach has a side radiator and the rear grill is 5' by 3'. PLENTY of area for the hot air to escape.

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This sounds like something to consider on my motorhome since I have one grill low on the back that is only 9"X48" and one on the acess door half way up that is 8"X48" and that means I only have about 6 sq.ft. of grill area. I might try first to leave the 2'X4' acess door open and see if there is a change in the overheating problem. Before I remove the flap I might try to bend it up to see if that helps. Thanks for the ideas! Don

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I have no suggested solutions to the originator for his problem. I do have a similar problem that is not being solved by the various garages that have serviced our 2007 Newmar Ventana for overheating/shut down engine warning light and buzzer. Thus far our coach has had 5 clutch fans replaced, 1 thermostat, engine belts, fan control solenoid, shroud at rear of radiator stack to prevent hot air from being pulled back into the engine compartment, and the coolant drained and replaced. Our coach has a rear radiator. Our most recent failure occurred on 6/29/12. At the present time we are in Fort St. John, BC, Canada at a Rotary RV Park waiting for Cummins dealers to open, it's Canada here and many are closed for the holiday.

Clearly repairs that have been made in the past have not gotten to the root cause of the problem. When the clutch fan goes it has to be replaced, the friction disk is worn to the point it can no longer engage the fan and the engine overheats. Thus far none of the shops have mentioned having cleaning the Charge Air Cooler (CAC), or any other part of the radiator. Could this be the problem?

When the system is operating properly, the engine temperature cycles between 200° and 212° and I can hear the fan cycle on and off. When the engine overheats, the temperature continues to rise and I can no longer hear the fan cycle on.

We're spending $$$$$ to have each of these clutch fan assemblies replaced. If anyone has insight as to the root cause of the problem, it would be greatly appreciated.

John Smith

2007 Newmar Ventana Diesel pusher

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John, always a good idea to have the radiator and CAC cleaned. I do mine every other year, and if I have traveled through some longer construction sites or dirt roads it gets a bath at a car or better yet truck wash while on the road.

I use simple green in the spray bottle and apply it on both the inside and outside exposed areas. When at home I have access to my large air compressor to spray the engine with an old engine cleaning wand and low pressure,pressure washer. It gets a good cleaning.

The Engine temperature runs at 183 to 185 on average when things are clean. Your thermostat my run hotter on the newer unit.

I do know when the radiator needs some TLC, because the temp starts to run over 190 on average.

With all the fan issues. Personally, I would be looking for a fan system that runs continually. Setting the speed at a point that keeps the temp at a point the engine runs well on 90 % of the grades you encounter.

Rich.

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wolfe10   

John,

Absolutely the #1 cause of overheating on a rear radiator configuration is blockage of the fins (outside) of the CAC (Charge Air Cooler).

You can verify this yourself. Access the top of the engine through the bedroom or closet. Shine a strong flashlight (at night makes it easier to see) inside the fan shroud/between fan blades. The fan blades sling the dirt that it sucks up to the perimeter. Verify that the perimeter, particularly the lower perimeter is as clean as the center. If not, clean it!

Brett

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grandyp   

Freightliner came out with a modification extension to the slobber tubes 3-4 years ago for the 330 Cat., however after ordering the modification tube for $220. I decided that a trip to the hardware store for 1 inch cooper pipe and some elbows accomplished the same if not better results. Refer to Freightliner web page for the modification.

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wolfe10   

grandyp,

Yes, the crankcase breather on ALL diesels (Caterpillar, Cummins, etc) need to be extended to behind the fan shroud so the oil mist and moisture they are supposed to emit are not sucked up by the fan and deposited on the front of the CAC (Charge Air Cooler) where they attract dirt and block air flow. All diesel engines built before 1/1/2007 need this modification.

It is important that the extension ONLY RUN DOWNHILL from the engine with no drip loop.

Brett

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lloyd21   

I HAVE A 2007 FLEETWOOD DISCOVERY 39V 330 CAT.

WE OVERHEATED COMING FROM THE GULF COAST BACK HERE TO CHAPIN, S.C. ENGINE WENT INTO THE LIMP MODE AND I KNEW WE HAD REAL TROUBLE. FOUND A PLACE TO CAMP FOR THE NIGHT. GOT ON THIS SITE AND READ EVERYONE'S POST ESPECIALLY BRETT'S ABOUT THE FLASHLIGHT AND MY RAD AND CAC WE COMPLETELY CLOGGED-UP.

SPRAYED WITH SIMPLE GREEN AND PURPLE POWER, THE TARP WE PLACE ON THE GROUND WAS COMPLETELY COVERED WITH DIRT AND GREASE, WORKED ALL DAY GOT ABOUT HALF OF THE AREA CLEANED. BACK ON THE ROAD THE NEXT DAY OUR DISCOVERY RAN COOL AS COULD BE.----

THANKS EVERYBODY YOU REALLY SAVED US.

HARV AND NANCY

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In most cases you are correct radiator blockage is the cause however on my 2007 Freightliner chassis, rear radiator I have had the electric portion of the viscus/electric fan clutch fail twice. The engine will run at normal temps until you pull a load on a hill then the electric portion of the clutch activates and kicks the fan into high speed. I don't know how long the clutch was bad as we don't have any mountains in Florida, but the Rockys did me in. Freightliner help line told me to stop for about 15-20 min which would allow the viscous portion of the clutch to basically thicken so that the viscous clutch would then work again.

We limped lots of miles until we made it to a dealer to replace the clutch. However the first time it failed the dealer blamed the radiator as being blocked. I insisted that he do diagnostic on the fan clutch as It had had an electrical issue when the coach was new and I did not want to pay 8hrs labor for an unneeded maintenance item (clean the cooler) that the Warranty company would not cover. Guess what the electric clutch had failed and was covered under my extended warranty plan.

I questioned Freightliner and they have a new and improved clutch however the second time I had a failure it was the new and improved one that was installed. I don't know when they started using this type of clutch sometime prior to 2007 and to the best of my knowledge they still use it. It does not matter what engine you have as it is a Freightliner supplied part.

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wolfe10   

Viscous hub fans on Freightliner chassis were rare.

Check with Freightliner with your chassis VIN to confirm the type of fan control your chassis has.

Brett

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