Cat 3126 overheating

[Don Colapietro]

 :-/  Hi,we have a 3126 Cat in a '97 Patriot.  It runs great at lower altitudes, (188 ) but at 3500ft or over the temp really starts to climb.  Yesterday, at 94 outside temp I saw 224!!!  Radiator is clean and t'stat is new.  Any info on the hydraulic fan?  Thermostatic valve, RPM's??  Also have a very annoying knock in the floor behind the driver seat.  It comes and goes for no apparent reason.  I have a lift at home, so I think I've looked at everything.  Just replaced all of the torque rods which made a huge difference in noise and handling but the knock still comes and goes.  Its not metal to metal, more of a hollow knock you can feel in the floor. Hope someone has some clues.  Thanks, Don Colapietro

[Larry Fisk]

We noticed a little knock on the floor in ours and it was something in the storage compartment bumping the floor. I don't have a clue why it's over heating though.

[Richard And Babs Ames]

We have a 1997 Patriot. Run at 1950 to 2200 RPM for best cooling. Our knock was the bushing in the suspension arms. We replaced all as the bushings were shot.

[Don Colapietro]

Thanks for the tip on RPM's.  By the time I got to read it, we had made another day's run and did run at that higher RPM.  Big help!  Temp held at 204 or less at peak.  Have another question regarding the power steering.  Just had the steering gear box replaced due to a major fluid leak.  (stuck in Gillette Wy. for 10 days!!!)  I checked the level in the split tank at the right rear comp.  Is this correct?  Does the main  hydraluic pump also feed the power steering?  Nothing in the manual on this.  Thanks,  Don Colapietro

[Edward Buker]

Don,

That is the way it is on my coach, the main hydraulic pump supports the power steering and main cooling fan. Not sure where your main hydraulic resevoir is on your coach but it should share the same resevoir that powers the fan motor. I had an 89 Beaver that was set up that way and also our 2002. There could be something different about your chassis set up but most likely it is as described above.

Later Ed

[Keith Moffett]

Good question Don

We have the 3126 in our '98 Pat.  The power steering tank you refer to seems to feed only the power steering.   The radiator fan is pump mounted not hydraulic.  I wonder if this is a difference between the Patriot and Marquis or just engines?  
We just upgraded to the Silverleaf and that tells me that we are running closer to 200deg.  than we did last year.  We are due for new extended life coolant so I will get the radiator flushed and a new thermostat.  
Perhaps this might help you as well?
I hold a strong light up to the radiator and check for light passing through both radiators for air flow check.  I wash them gently from outside and in but havent pulled then to clean in between the radiators.
Hope some of this helps you
Keith

[Richard And Babs Ames]

We actually have three hydraulic systems and tanks. The rear plastic, the side steel one by the filters, and the jack and slide (if equipped) you get to from underneath the motorhome behind the side mounted one. We do not have a split tank at the rear.

[Gerald Farris]

All Beaver diesel coaches use the engine driven (main system) hydraulic system to power the power steering system. It also powers the radiator cooling fan if you have a side radiator. If you have a rear radiator, the radiator cooling fan is belt driven by the engine, and the engine driven pump only runs the power steering.

Gerald

[Keith Moffett]

As a side bar to this thread, let me ask this;

Since my extended life coolant is over six years old I am considering having the system flushed and new coolant added.  CAT here cant do it so I would go to a radiator shop that also takes bigger trucks.
1) should the radiator come out so the space between radiators can be cleaned?
2) Replace thermostat?
3) Have I overlooked anything that could be pointed out to the shop?

Thanks
Keith

[Edward Buker]

Keith,

If you have ELC in your radiator from what I saw of the CAT literature and photographs, you basically do not build deposits like you did with the ethelene glycol and conditioner additive system. It has me questioning the need for flushing and sometimes putting cleaners in that are hard to flush out. When you go the cleaner route you end up with a lot of water in the system, residual diluted cleaners, and then you are trying to get the concentration right afterwards.

The ELC has an extender replenishment system also. You could talk to CAT about sampling your current ELC condition and see what they say about the condition and need for replacement.

Personally, I would consider doing just a simple drain out of the radiator base and then replace with fresh ELC. I like to stick with whatever brand is inthe RV if possible. Regarding thermostats, I have never replaced one nor had one replaced on a CAT motor. My last RV had about a 20 year old thermostat in it with about 100k miles and it never failed. That is the real question with low mile RV use of a CAT motor made to go a million mile plus under more extreme conditions, what needs changing by time interval alone? Certainly have them check clamp condition and tightness, check the cooling hose condition for cracking, bulging, and flexibility before draining.  If a hose needs changing they should have that in stock before draining.

If you have a side radiator it usually stays pretty clean with a simple gentle spray rinsing from the outside. If you can get a light in where the fan is at night and look through from the outside you should be able to get a good sense of what is in there. If you have no overheating issues pulling the radiator is beyond what I would do and again has consequences if the work was not done right. Rear radiators have much more of an issue here and cleaning them many times is required. These are my own thoughts....Maybe Gerald can comment on his thoughts on ELC and thermostat replacement, he has far more experience and wisdom on this subject than I have here.

Later Ed

[Gerald Farris]

Keith,
I do not understand why you are considering pulling the radiator if you are not having a problem. Having a shop R&R (remove and  replace) a radiator is very expensive for preventive maintenance.

I would have Cat run a coolant analysis on your ELC (extended life coolant) before changing it. However if you just want to change it, I would just drain and refill or flush with water only and refill. However if you flush with water, use a gallon or two of full strength ELC in the refill, then finish refilling with 50/50 premixed to get your mixture correct.

I am not a big fan of replacing the engine thermostat as preventive maintenance. My coach is 12 years old with 120,000 miles and I am still running the original thermostat that I have no intent of changing. I realize that since I perform my own service work, I am not worried about finding a shop to replace a defective thermostat if one fails, however I have seen new thermostats fail as often as original ones when used in the mileage ranges that Beavers see.

Gerald

[Keith Moffett]

Thanks Ed and Gerald both.  This gives me perspective related to the issues in this thread.  My running temp. Has gone upslightly and that was the motivation for changing ELC.  The book says six years. I believe CAT has a test kit.
Since the radiator is rear mounted and light isnt getting through as much as it used to, is there a better way to clean the gap?
Keith

[Larry Fritz]

Keith: If you have the radiator removed, you are likely in for at least a $1000 bill. Mine was done a few years ago in a 37' Patriot because the radiator exterior was clogged.  It takes the better part of a day and two people most of the time. There are a zillion things to disconnect and remove and pursuade to get the rear radiator out. Once out and on the concrete, it is a piece of cake to clean it with a pressure washer. Unfortunately, nearly impossible to clean well as mounted in the coach.  I bought a pistol grip pressure washer hose end with no extension which lets me get in there to clean a bit better which I do annually now. It helps.  With the CAC in the way, it is hard to get the radiator really cleaned (I am not talking about flushing the inside of the radiator). I use simple green when washing mine annually. If pressure washing be careful not to bend the fins on the radiator.

Larry Fritz
98 Patriot
3126, 37', rear radiator

[Robert Fish]

Hello Gentle Souls,  
  I'm jumping into the conversation long after the  fact but am having much the same overheating issue with my newly-acquired 2002 Marquis.  Mine began immediately upon driving the first hundred miles from the point of acquisition…Albany, Oregon.  One of the reasons for upgrading to this 500+ HP Cat motor was to enable use of a larger towed vehicle, the Chevrolet Tahoe.  We presently tow a Ford Ranger, much lighter than the Tahoe but the overheating issue put the Kibosh on that idea, at least until and IF the issue can be resolved.  From reading the above,  the answer appears not to be so cut and dry.  
  We stopped in Redding, CA after having troubles negotiating the Cascades with the Ranger in tow.  The CAT repair facility I used, which was recommended by a fellow RVer met at the RV Rally in Albany, Oregon, was A&N Diesel.  They seemed very helpful but recommended the replacement of the radiator, after showing me deterioration of parts of both the exhaust system AND radiator components, hoses, etc.
  Yes, it was expensive to say the least, but to say CAT had us over a barrel would be pretty accurate.
  We picked up our Marquis after a week and a half, as A&N explained that there were several jobs ahead of ours.  We paid the price grudgingly but figured our problems were properly addressed.  As you can imagine, it turns out not to be the case.
As soon as an elevation change was attempted, the motor overheated again, not as severely granted, but nonetheless overheated to the point that the motor began shutting itself down, reducing power.  The only thing that worked to any degree was to back way off on the accelerator, traveling less than 25 mph over hills.  You question the rpm's?  I never allowed the motor to go below 1800 r's, usually not below 2000 on grades.
  Consequently I must say that I'm extremely downhearted at this point, having spent all that money with no joy in the result column.  I figured simply replacing the thermostat should be sufficient.  I don't have knowledge as to whether or not the thermostat was replaced in Redding, but reading the above it sounds less likely.
  Any further suggestions would be very much appreciated.  Signed, Bob
  P.S. other than the latter, I love our "new" Marquis.

[Gerald Farris]

Bob,
From your description above, I would suspect a malfunction in the hydraulic cooling fan system for the radiator. There is also a possibility that you could have a defective engine thermostat. Regardless, the only way that the problem can be determined is through a thorough diagnosis of the cooling system that you apparently did not receive the first time. Many technicians do not thoroughly diagnose a complaint. Instead, they just look for the easy and obvious problem regardless of whether or not that is the main or only problem. On the farm, we called this only picking the low hanging fruit.

Gerald