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Topic: diesel pusher overheating

Posted By: thegriffins on 02/13/10 04:38pm

We have a 350 Cat diesel pusher that overheats with any head wind or incline. We pull a car trailer. The engine heats up quickly at 60 mph and engine coolant will overflow. Is this normal?


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Posted By: overlanders on 02/13/10 04:52pm

Griffins,
This sounds like a typical partially clogged radiator fin situation. Engine oil from the breather or slobber tube collects on the engine side of the radiator, collects dust and dirt and then blocks good cooling airflow. Do a search on the board for radiator cleaning, the subject has been covered a lot on this site. Good luck.,


Posted By: stripit on 02/13/10 05:01pm

Our friends were experiencing a similar condition and went to a radiator shop and had them look. They steam cleaned the radiator and cooler, they spent well over 2 hours cleaning. Cost him just under $300 but the coach runs cool and seems to actual have more power now. He was happy to see some change after spending the money.


Stacey Frank
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Posted By: Ivylog on 02/13/10 05:02pm

No it is not normal I'll bet you have a rear radiator. Sounds like you need to add a slobber tube (a rubber hose added to the engine breather) and clean the radiator. The engine breather is not long enough (most engines are behind the radiator except in MHs) to stop oil particles from the engine getting on the radiator making it easier for it to hold any dirt/dust which reduces air flow. Steam cleaning is better than pressure washing as it's easy to damage the radiator fins with a pressure washer. This cleaning is something you can do yourself, especially if lifting the beds gets you to the engine. Otherwise you have to do it from underneath the MH as it needs to be done from the front of the radiator and will require several times using a good degreaser and lots of water.


This post is my opinion (free advice). It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.

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Posted By: wolfe10 on 02/13/10 06:20pm

Quite a lot of ALMOST correct information.

The air flows from front to back, with the fan pushing the air through the CAC (Charge Air Cooler-- also called after-cooler and inter-cooler) and then through the RADIATOR.

So the dirt is deposited mainly on the FRONT of the CAC, NOT on the radiator.

It has to be cleaned from the FRONT. Access through the bedroom. Take a strong flashlight and look inside the fan shroud/between fan blades. The center will be clean, since the fan blades sling the dirt to the perimeter. VERIFY THAT THE PERIMETER OF THE CAC IS AS CLEAN AS THE CENTER.

This needs to be done at least once a year on any rear radiator coach.


Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240


FMCA Forum: www.community.fmca.com/index

Diesel RV Club:http://www.dieselrvclub.org/


Posted By: pusherpilot on 02/13/10 06:49pm

The clogged radiator is the most common reason for the kid of overheating you describe. Our 2000 Safari had a 300 Cat 3126B, rear radiator, and cronically heated up. Safari installed, under warranty, a "heat kit" that consisted of new rear doors with bigger air slots, an additional grill in the rear cap below the doors, a 9 blade fan, a reduced pully size to increase fan rotation speed, an extended slobber tube and in some cases a new shroud around the radiator.
The mechanic who did the work also warned me that the thermostats, plural, there are two, fail eventually and cause overheating as well. Cat recommended that they be changed on maintenance intervals but I forget what the interval is.
Ron


Posted By: Burro on 02/13/10 07:06pm

Our DSDP was doing that off and on. After many visits to shops across the country, turned out to be a $21.00 sensor that made the fan run. Sometimes it would make the fan run all the time and all seemed well; then again it would make the fan not come on at all and it would overheat...badly enough the engine would stop.

Freightliner, Caterpillar and Newmar threw hundreds of dollars in parts at it (Under warranty) and no help at all. Finally, an old guy in West Virginia figured it out using logic instead of replacing parts willy-nilly.

Just our experience.

* This post was edited 02/14/10 08:58pm by Burro *


Posted By: wolfe10 on 02/13/10 07:14pm

Burro wrote:

Our DSDP was doing that off and on. After many visits to shops across the country, turned out to be a $21.00 sensor that made the fan run. Sometimes it would make the fan run all the time and all seemed well; then again it would make the fan not come on at all and it would overheat...badly enough the engine would stop.

Freightliner, Caterpillar and Newmar threw hundreds of dollars in parts at it (Under warranty) and no help at all. Finally, an old guy in West Virginia figured it out using logic instead of replacing parts willy-nilly.

Just our experience.


Yes, sensors, switches and hydraulic systems come into play with SIDE radiators. Most rear radiator coaches have direct drive fans, so none of that would apply.


Posted By: thegriffins on 02/13/10 07:31pm

Thank you so much for all of the information and guidance. This is our first diesel pusher and we have a lot to learn! We appreciate all of your shared experience!


Posted By: Executive on 02/13/10 08:33pm

thegriffins wrote:

Thank you so much for all of the information and guidance. This is our first diesel pusher and we have a lot to learn! We appreciate all of your shared experience!


A lot to learn, yes, but aren't they sueweeeeeeet.....[emoticon]...Dennis


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Posted By: tcr1016 on 02/13/10 08:56pm

Try changing the thermostat. Also pressure wash the outside of the radiator. At Cummins they told me, many calls of overheating are due to radiator fins being clogged with dirt on Diesel Pushers.


97 GMC Savana Van 5.7L (132,000 miles).


Posted By: wolfe10 on 02/13/10 09:00pm

thegriffins wrote:

Thank you so much for all of the information and guidance. This is our first diesel pusher and we have a lot to learn! We appreciate all of your shared experience!


I tried to send you a PM (Private Message), but you have that feature turned off. PM me if you like.


Posted By: iasm on 02/13/10 10:43pm

our last trip we were having heat as you describe and stopped at a repair facility and they found one of the thermostats broke.the engine with one stst open would flow enough water for mild driving but if it was enough for the hills.


Posted By: wolfe10 on 02/14/10 09:29am

iasm wrote:

our last trip we were having heat as you describe and stopped at a repair facility and they found one of the thermostats broke.the engine with one stst open would flow enough water for mild driving but if it was enough for the hills.


This is one of the reasons that Caterpillar calls for replacing thermostats (called regulators) every three years as preventive maintenance. So, yes, a failed thermostat can cause overheating in any engine.

But, a clogged CAC/inter-cooler/after-cooler is by far the most common cause of overheating in rear radiator DP's. Therefore it needs to be cleaned at least once a year-- more often in dusty areas.


Posted By: Horsedoc on 02/14/10 09:47am

We had a 300 Cat with the same problem. The crankcase breather was dumping oily smoke right into the fins on the cooler and into the radiator core. The people in Gaffney at the Freightliner factory shop already had a piece for the fix and installed it to dump the smoke below radiator bottom. Steam cleaned the whole area and that was then end of the overheating problem. Seems the oil was attracking all the dust and debris that was sucked up from the coach passing over dusty roads or dirty road splash.
I cleaned it at a quarter car wash by soaking it with degreaser and then washing with hot water. Did this twice. Amazing the amount of oily gunk and trash that got washed out.


Posted By: fatboylust on 02/14/10 03:19pm

Been there too with the dirty radiator, cleaned it myself with two cans of engine cleaner/degrease. Use a liquid engine cleaner rather than a foaming type as the liquid penetrates the fins better. Follow the product directions. Apply from both sides of the radiator/turbo inter-cooler and yes it can get messy. As noted above do not pressure wash. I added an extension to my crankcase vent to reduce the chance of clogging the radiator again. Good Luck, FBL


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Posted By: lanerd on 02/14/10 04:00pm

fatboylust wrote:

Been there too with the dirty radiator, cleaned it myself with two cans of engine cleaner/degrease. Use a liquid engine cleaner rather than a foaming type as the liquid penetrates the fins better. Follow the product directions. Apply from both sides of the radiator/turbo inter-cooler and yes it can get messy. As noted above do not pressure wash. I added an extension to my crankcase vent to reduce the chance of clogging the radiator again. Good Luck, FBL



Good info fatboy. A couple of questions, when you entended your slobber tube, what did you use and where did you relocate the end of it?

Most people recommend something like "Simple Green", but I've often wondered about brake cleaner or engine degreaser.

Ron


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Posted By: wolfe10 on 02/14/10 04:08pm

I am not a proponent of using harsh engine-clean chemicals, particularly with aluminum inter-coolers. Simple Green or even Dawn dish washing detergent work fine.

And extending the crankcase breather tube is easy. Determine the ID of the crankcase breather hose-- Caterpillar's are 1" ID. Buy a barb to barb fitting and 4' of oil resistant hose the same ID. Two hose clamps and a few nylon zip ties completes the package.

The only have toos are to extend the breather to behind the intake for the fan shroud and IMPORTANT, do not form a drip loop-- the hose must continue to lead downward.


Posted By: Burro on 02/14/10 09:03pm

wolfe10 wrote:

Burro wrote:

Our DSDP was doing that off and on. After many visits to shops across the country, turned out to be a $21.00 sensor that made the fan run. Sometimes it would make the fan run all the time and all seemed well; then again it would make the fan not come on at all and it would overheat...badly enough the engine would stop.

Freightliner, Caterpillar and Newmar threw hundreds of dollars in parts at it (Under warranty) and no help at all. Finally, an old guy in West Virginia figured it out using logic instead of replacing parts willy-nilly.

Just our experience.


Yes, sensors, switches and hydraulic systems come into play with SIDE radiators. Most rear radiator coaches have direct drive fans, so none of that would apply.


Well, there ya go! I am not an engineer and I don't even play one on TV. [emoticon] I learned something new. Thanks!


Posted By: lanerd on 02/21/10 11:10am

Thanks Brett... another question. If I extend my tube rearward, pass the radiator.... won't the front of the toad then be covered with the oily residue? I do have a Roadmaster Guardian across the front of my toad, but still.....

thanks

Ron


Posted By: Jim@HiTek on 02/21/10 11:52am

I just zip tied a plastic jug with wide mouth to the end of my slobber tube under the engine. After 4 years it has around a quart of oil in it. Time to empty. Keeps oil from being blown back to the toad area and off the rad of course.

I like Wolfe10's extension, I'll try that with a jug on the end if I can place it in a convenient place while keeping the tube running downhill. Right now I have to crawl under the RV to empty or remove the jug.


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Posted By: keith and sharon on 02/21/10 12:03pm

wolfe10 wrote:

I am not a proponent of using harsh engine-clean chemicals, particularly with aluminum inter-coolers. Simple Green or even Dawn dish washing detergent work fine.

And extending the crankcase breather tube is easy. Determine the ID of the crankcase breather hose-- Caterpillar's are 1" ID. Buy a barb to barb fitting and 4' of oil resistant hose the same ID. Two hose clamps and a few nylon zip ties completes the package.

The only have toos are to extend the breather to behind the intake for the fan shroud and IMPORTANT, do not form a drip loop-- the hose must continue to lead downward.
Be careful with simple green, make sure it is rinsed off thoroughly, it will corrode aluminum we used to use it to clean aircraft but our company banned it due to possible corrosion in areas it may not get of. Or we had to super dilute it and then it wouldn't work as well.


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Posted By: Snomas on 02/21/10 12:34pm

My radiator had rusted out fins and I had to replace the radiator to correct an overheating problem that occured on long grades in the Rocky's. No problems since and in fact my engine temp ga hardly ever reaches 200 degrees ( mostly runs at 180) where before I had some trips that it reached 225 to 230 and the dash alarm just screamed at me. Also the trans runs much cooler.


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Posted By: Archie Kravitz on 02/21/10 03:32pm

Quote:

Thanks Brett... another question. If I extend my tube rearward, pass the radiator.... won't the front of the toad then be covered with the oily residue? I do have a Roadmaster Guardian across the front of my toad, but still.....


Yea, but it won't rust


Posted By: wolfe10 on 02/21/10 03:52pm

lanerd wrote:

Thanks Brett... another question. If I extend my tube rearward, pass the radiator.... won't the front of the toad then be covered with the oily residue? I do have a Roadmaster Guardian across the front of my toad, but still.....

thanks

Ron


Ron,

If you are using the correct oil capacity for your engine and the engine is OK, you really should not get enough oil to foul the toad.

But even a tiny amount of oil vapor into the front side of the CAC (Charge Air Cooler, aka inter-cooler, aka after-cooler) will let the dirt deposit on the front of the CAC and will quickly clog the air flow.


Posted By: lanerd on 02/23/10 03:36pm

ok, thanks for the info. My C7 is only two years old and I keep the oil level right on the mark all the time. I have not seen any evidence of oil on the slab under the MH, nor any on the fins of the intercooler....at least none that I can see from laying underneath changing the oil.

I do like the reservoir idea that Jim mentioned. Is there any "pressure" coming out of the tube or does the oil just "drain" (drip)?

Ron


Posted By: wolfe10 on 02/23/10 03:52pm

lanerd wrote:

ok, thanks for the info. My C7 is only two years old and I keep the oil level right on the mark all the time. I have not seen any evidence of oil on the slab under the MH, nor any on the fins of the intercooler....at least none that I can see from laying underneath changing the oil.

I do like the reservoir idea that Jim mentioned. Is there any "pressure" coming out of the tube or does the oil just "drain" (drip)?

Ron


Though the crankcase breather has virtually no pressure, there IS volume. So, don't restrict air flow. Said another way, make sure if you use a container, that the size of the openings exceed the ID of the hose.

And when you say you "keep the oil level right on the mark all the time", have you calibrated the dip stick to verify that the dipstick is accurate? All diesel engines are installed over enough different angles that ASSUMING the dipstick is accurate may not be true.


Posted By: TEO on 02/23/10 05:41pm

The lack of a slobber tube is not the only potential problem. I had a worse situation after I installed the slobber tube and cleaned the radiator. A short time later it started to overheat again. I had a leak in one of the pressure senders that was spraying a heavy mist of oil on the inter cooler/radiator.

The problem of overheating is still the same, oily dirt that stops proper air flow.

Paul


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Posted By: Jim@HiTek on 02/23/10 06:12pm

wolfe10 wrote:

lanerd wrote:

ok, thanks for the info. My C7 is only two years old and I keep the oil level right on the mark all the time. I have not seen any evidence of oil on the slab under the MH, nor any on the fins of the intercooler....at least none that I can see from laying underneath changing the oil.

I do like the reservoir idea that Jim mentioned. Is there any "pressure" coming out of the tube or does the oil just "drain" (drip)?

Ron


Though the crankcase breather has virtually no pressure, there IS volume. So, don't restrict air flow. Said another way, make sure if you use a container, that the size of the openings exceed the ID of the hose.

And when you say you "keep the oil level right on the mark all the time", have you calibrated the dip stick to verify that the dipstick is accurate? All diesel engines are installed over enough different angles that ASSUMING the dipstick is accurate may not be true.


I haven't calibrated my dip stick but I did find if I fill to the mark that it just blows out 1 quart in short order. So now I underfill by one quart. Even then, the slobber jug holds some blow by. I would say, experiment! Fun! Just like school.

Oh, and as always, listen to Wolfe10.


Posted By: wolfe10 on 02/23/10 08:05pm

Jim@HiTek wrote:

I haven't calibrated my dip stick but I did find if I fill to the mark that it just blows out 1 quart in short order.


Step #1 is to VERIFY the correct oil capacity. If a Caterpillar 3126/C7, use this document which lists oil capacity which includes oil filter. This document supersedes your owners manual or other older information: http://ohe.cat.com/cda/files/517742/7/LEHT9288.pdf?mode

Next, calibrate the dipstick at your next oil change-- it cost $0.

From an article for the Caterpillar RV Engine Owners Club:

CALIBRATING THE ENGINE OIL DIP STICK

We continue to see questions about oil "consumption" and oil on radiators and toads on RV.net and other RV sites. It seems to be universal across all brands of diesel engines.

THE NUMBER ONE CAUSE IS AN OVERFILLED CRANKCASE. CALIBRATING THE ENGINE OIL DIP STICK TO ENSURE THE CORRECT OIL LEVEL IN THE PAN "FIXES" OVER 90% OF THESE PROBLEMS.

If you "think" your engine has an oil consumption problem, you are seeing oil mist on your toad or you just want to verify that yours is correct; you need to verify that you are using the correct amount of oil. To determine the correct oil capacity for your engine, go to: http://ohe.cat.com/cda/layout?m=72021&x=7 . Click on your engine family. This Caterpillar Corporation source supersedes your owner’s manual. Note: the quantities listed INCLUDE the oil filter and is the total amount of oil you put in when changing oil and filter.

Now, CALIBRATE THE DIP STICK. Since the same engines/dip sticks are used in many different applications with different angles of installation, do not ASSUME that the dip stick is correctly marked. Calibration costs $0.

At the next oil change, drain oil, remove old filter (as usual). Then install the drain plug and new oil filter and add the engine's correct oil capacity LESS THE NUMBER OF QUARTS you want between the "ADD" and "FULL" marks (let's say 2 quarts). So for a C7 with 19 quart capacity you would add 17 quarts. Run the engine a few minutes, shut off and wait until oil has descended into the pan (at least 30 minutes and an hour is safer). Pull the dip stick and use a file or dremel tool to mark the oil level "ADD". Add the remaining two quarts, let the oil settle in the pan, pull the dipstick and mark this the "FULL" mark.

In many/most cases, you will find that your engine "throws out" the access oil and then "consumption" settles down to next to nothing. Put in the correct amount and your "consumption" issues may go away.

This applies to all ages (including brand new) of motorhomes and boats with every brand of engine.

Also, when checking the oil level with the dipstick it is safest to do it in the morning after the oil has had all night to flow back to the pan.

Do not add oil until the level reaches the ADD mark.

Finally, make a sticker to affix near oil fill: OIL CAPACITY INCLUDING FILTER: xx QUARTS.


Posted By: ccruchet on 06/17/10 06:19am

Do you just put the Dawn soap on the outside of the radiator and spray it down? I have had this happen before and took it into freightliner and they steamed it out good and that seemed to help. I am asking the dealer to extend the slobber hose also and give it a good clean again. But I have a trip coming up tomorrow and would like to clean it out before heading out.

I have also noticed that when going up hills i need to downshift and that takes care of the overheating as well. Has anyone else seen this to help the situation?

Thank you.


Posted By: wolfe10 on 06/17/10 06:38am

ccruchet wrote:

Do you just put the Dawn soap on the outside of the radiator and spray it down?

Thank you.


In a word, NO, that is not where the vast majority of the dirt will be. Yes, you will do as you suggest, but figure it will only remove about 10% of the dirt.

Air flows from FRONT (front of coach) where it picks up a lot of road dirt (36'+ coach and 6 tires traveling at highway speed). The air then passes over the hot (and sometimes oily) rear axle, transmission and engine. Then the cooling fan sucks it up and pushes it into the CAC and THEN into the radiator before it exits the BACK (back of coach).

So the vast majority of the dirt is "filtered" out by the FRONT OF THE CAC. THAT is where you need to clean. Access it from the bedroom/closet. Look inside the fan shroud/between fan blades. The blades sling dirt toward the perimeter, so make sure the perimeter is as clean as the center.

Best way to clean is to route a garden hose with garden nozzle up from the outside so you can reach it from the bedroom/closet. If just dirt, water works fine. If oily residue, yes, Dawn works fine.


Posted By: lanerd on 02/26/10 03:08pm

wolfe10 wrote:

lanerd wrote:

ok, thanks for the info. My C7 is only two years old and I keep the oil level right on the mark all the time. I have not seen any evidence of oil on the slab under the MH, nor any on the fins of the intercooler....at least none that I can see from laying underneath changing the oil.

I do like the reservoir idea that Jim mentioned. Is there any "pressure" coming out of the tube or does the oil just "drain" (drip)?

Ron


Though the crankcase breather has virtually no pressure, there IS volume. So, don't restrict air flow. Said another way, make sure if you use a container, that the size of the openings exceed the ID of the hose.

And when you say you "keep the oil level right on the mark all the time", have you calibrated the dip stick to verify that the dipstick is accurate? All diesel engines are installed over enough different angles that ASSUMING the dipstick is accurate may not be true.



Yep, that was done on the very first oil change. I don't find any consumption between changes, so I don't think I have much (if any) coming out my slobber tube. During last oil change, I inspected the tube and could not find any evidence of "wet" oil around the outside edge of the tube's outlet. I'm going to crawl back under there and see if there is any space to put some sort of reservoir that will allow plenty of breathing space for the tube.

thanks for the info

Ron


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