Check Engine Light Intermittent

[Carl Boger]

Steve when it really started heating up I was down in 3rd then 2nd, and 1st a few times.  This was about a 4 mile narrow road with maybe a 8% grade.  Steep but not impossible.  On the interstate initially I had been in 6th when it flashed the first time, I simply slowed down to 55 on that lesser grade and it cooled right down.  I will have to check on the economy mode, really I am not sure.

I do have a rear radiator, but my CAC is mounted on the side. 

I have noticed that when it goes from normal to hot it goes up in a hurry. 

This overheating has only shown up since I started pulling the CRV.  Really when I finally found a pullout I was creeping, but near the top.  After I let it cool down waiting it pulled its way to the top under some power.  Not fast, but not creeping either.

I had the engine serial number run by Dave Atherton and it came back either rebuilt or re-manufactured.
I am not totally sure what that means!  I am supposed to have the 330 hp version of the 3126, but I am really not sure that is what I have.

At least going home should be mostly downhill or level, and I will be using the heck out of the exhaust brake in a lower gear on that 8% grade.

After I get it home it I plan to drain the antifreeze, flush it, and clean the fins yet again.  Honestly looking through what you can see it does not look that bad.  If I didn't think the campground would go crazy I would hit the radiator with coil cleaner and wash it off before the trip home.

Thanks everyone!

[Eric Maclean]

Carl
Cooling systems are all about flow wheather is coolant or air any one of the following could cause your problem
The cooling demands on any vehicle increase with speed the magic number being 50 MPH at which the wind resistants drives the engine torque requirements much higher and hence require higher cooling capacity.
My point is on a vehicle with a marginal radiator heat exchange capabilities the problem will likely only show up under high way conditions or climbing where the cooling demand is at its highest .

A couple of things to check
1) is the fan shroud all there and fit with equal gap all around.
2) is the fan complete ( no missing blades or peices)
3) is the fan installed correctly remember this is a pusher fan and if installed backwards the geometry won't be right and efficiency suffers.
4) are the rad fins clear at the outter circle of the fan sweep ( this is where they plug up first) as this is the highest air flow through the fan
5)check the sepentine belt tensioner they tend to seize and not maintain spring tension allowing belt slip and under drive fan at high RPM as the fans  horse power demand increases exponentially
6) are all the block off panels in place around the radiator to keep the air from repassing through the rad

7)are both thermostats( regulators) installed and working correctly ( check in a pot of hot water on a stove to see opening temperature using a candy thermometer
8)is the water pump moving enough water( possible impeller deterioration)or loose belt ( remove pump and visibly check impellers blades
9) are the radiator fins in good shape not bent ,loose ,rotten or missing.
10) it's possible the radiator tubes are partially plugged internally blocking flow and there fore cooling ability

I know this is a long laundry list of possible but you may find your problem amount them
And as Steve mentioned you have to keep the RPM up to promote proper cooling as lugging on long hills will generate more heat requiring higher cooling capacities than the system can produce at the lower ( lugging ) RPM.

Hope some of this helps
Eric

[Carl Boger]

Eric,

To relay to your suggestions:
1  The fan shroud is original and complete.  I had actually thought about cutting and attaching mending plates to give me better access, but have not done it.

2  The fan is complete and not missing any blades.

3  I am pretty sure it is installed correctly, but will verify once I get ready to leave tomorrow

4  The Fins appear to be clear

5  The belt tensioner appears to be ok and both belts are brand new

6  The black plastic is still in place around the outside of the radiator if that is what you mean by block off panels

7  I will have to check or just replace the regulators.

8  I am hoping that the water pump is still good since I just replaced both belts, but that may be an issue

9  The Fins look decent, not new but decent

10  As far as a internal blockage I am leaning in this direction, I at least plan to flush and refill the system.

RPM's may have also been part of this issue,  When I started up the grade I had no idea it would be that long or 8% ( the sign is on the uphill side).  I was dropping gears, but sooner would have been better, and at some point I only had about 30% of the power since it was derated. and there was no where to pull over.

Since I am still at the campground, with ify wifi and no cell signal, can someone tell he what Antifreeze I will need to get, and how much the system holds.  If wifi holds out  I could at least get that on the way.

Thanks for the help everyone, I as still waiting for that perfect trip where absolutely nothing goes wrong!

[Eric Maclean]

Carl
Providing someone hasn't changed out the antifreeze your coach would most likely have come with regular GREEN non long life antifreeze if you have an older Aquahot with external domestic hot water loop it would use the same type of antifreeze.
Some people have changed out the original antifreeze for long life antifreeze ( usually orange) to gain a longer service life
Personally I'd stay with what was factory installed .

I can't remember the exact amount but 7.5 gallons sounds familiar
The antifreeze needs to be a diesel engine antifreeze and should be mixed 50/50 concentrate and distilled water and a SCA additive which you sh be able to get at any good truck parts store.

The SCA  level should been tested annually and fortified if needed the SCA is the additive which controls corrosion of internal parts liked the water pump impeller.
SCA test strips can be bought at your parts store as well.

https://parts.mhc.com/products/cat-sca-1

https://www.cumminsfiltration.com/eme/analysis

PS
If the antifreeze is not cut to 50/50 and left as full strength concentrate the ability to transfer heat is deminished as the coolant is too thick. This becomes a problem when straight concentrate is used often to top up the system .

Hope this helps
Eric

[Richard Davis]

Carl (and Eric)
The Cat 3126 is a bored block engine and not a sleeved cylinder engine.  Therefor it does not require SCA's to minimize cavitation corrosion around the replaceable sleeves.  It certainly does not hurt anything if used, but testing and replenishing is not necessary.  Since it is a bored block engine, any quality automotive antifreeze is adequate.  I also prefer the concentrated varieties mixed with distilled water to achieve a 50/50 mix.  The premixed stuff costs about the same as the concentrated, so it is certainly a bit cheaper to go that way.  The last 3126 I flushed and filled had about a 10 gallon capacity, so I would start with 5 gallons concentrate and 5 gallons of distilled water on hand.  If you are concerned about flushing out contaminants, you may want to drain it and completely fill it with distilled water, run the engine until warm to circulate the water and then drain a second time.  There will still be some water in the system (you cannot get it all out without some significant disassembly and hose removal).  Then you can put in the 5 gallons of concentrate antifreeze followed by however much distilled water is required to completely fill it.  I do not remember if you have to "burp" the 3126 block when you refill it to get the air out (you might check to see if there is an air bleed plug on the thermostat housing), perhaps someone who's memory is better than mine can chime in. 
Richard   

[Carl Boger]

Thanks Richard and Eric,

I just got back home without any issues.  I did top off the antifreeze before leaving, and I left it in 5th gear on the interstate, and drove 55 to 60 the whole way home. The highest coolant temp I saw was 212 degrees, but it mostly ran between 185 and 200 on the Magnum display, slightly less on the dash gauges.

I also paid more attention to the route on the way down.  It was mostly a 8% grade and 35 mph for about 15 miles up the mountain.  I should probably have started out slow and stayed slow going up, but I still think my cooling system can use a tuneup.

I was using the exhaust brake coming down and had to be in 3rd gear or lower to keep it under 35.  Not terrible, but not my idea of a good time either. 

In the next few days I will probably buy out the grocery store of distilled water, thanks for everyone's help.

I will try to take this one logical step as a time until it is running correctly, and if I never get out of 5th gear in hill country well that is ok too.