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General Boards => Technical Support => Topic started by: Don Colapietro on July 11, 2012, 05:47:01 PM

Title: Cat 3126 overheating
Post by: Don Colapietro on July 11, 2012, 05:47:01 PM
 :-/  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
Title: Re: Cat 3126 overheating
Post by: Larry Fisk on July 11, 2012, 06:12:47 PM
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.
Title: Re: Cat 3126 overheating
Post by: Richard And Babs Ames on July 11, 2012, 08:05:56 PM
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.
Title: Re: Cat 3126 overheating
Post by: Don Colapietro on July 14, 2012, 07:24:13 PM
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
Title: Re: Cat 3126 overheating
Post by: Edward Buker on July 14, 2012, 09:08:05 PM
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
Title: Re: Cat 3126 overheating
Post by: Keith Moffett Co-Admin on July 15, 2012, 12:07:27 AM
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
Title: Re: Cat 3126 overheating
Post by: Richard And Babs Ames on July 15, 2012, 12:36:28 AM
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.
Title: Re: Cat 3126 overheating
Post by: Gerald Farris on July 15, 2012, 04:45:33 AM
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
Title: Re: Cat 3126 overheating
Post by: Keith Moffett Co-Admin on July 16, 2012, 10:56:43 AM
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
Title: Re: Cat 3126 overheating
Post by: Edward Buker on July 16, 2012, 02:51:42 PM
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
Title: Re: Cat 3126 overheating
Post by: Gerald Farris on July 16, 2012, 04:05:37 PM
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
Title: Re: Cat 3126 overheating
Post by: Keith Moffett Co-Admin on July 16, 2012, 11:46:55 PM
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
Title: Re: Cat 3126 overheating
Post by: Larry Fritz on July 17, 2012, 04:21:19 AM
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
Title: Re: Cat 3126 overheating
Post by: Robert Fish on December 17, 2013, 03:00:46 AM
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.
Title: Re: Cat 3126 overheating
Post by: Gerald Farris on December 17, 2013, 04:21:43 PM
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      
Title: Re: Cat 3126 overheating
Post by: Robert Fish on December 17, 2013, 08:57:04 PM
Thanks Mr. Farris,
  That's a good recommendation.  I believe I have addressed the problem twice on BAC's Forums, so please accept my apologies.  Of course I have excuses but won't lay them on you.  Thanks very much for your thoroughness.
  As we keep our Marquis in Fort Mohave, we're looking for reputable repair facilities.  I haven't seen any mentioned, at least to this point, in the Laughlin vicinity, but Mesa sounds like a plan, not TOO far to go.  Any knowledge further would be welcomed.  
  Much thanks.  
Title: Re: Cat 3126 overheating
Post by: Doug Allman on December 19, 2013, 01:24:15 AM
We had a 1991 Contessa with a 3116 Cat. I had all the problems Bob was explaining even after I changed the radiator, after cooler and installed a larger oil cooler. Not as bad an overheat and was pretty good IF we were not towing.
As Gerald points out get the hydraulic cooling system checked out by someone who knows what they are doing. There are two parts that are critical to this system working properly, the hydraulic fan motor and a temperature sensing block that directs the fan motor to turn the rpms that are needed to cool the unit.

The 1991 Contessa was on a Gillig chassis and so that is where I speak from regarding the temp block. When the fan motor was not working correct it caused a mid overheat just going over the so called mountains in Tennessee. Climbing up to get out of the Badlands in summer it went over 250. We always had to unhooked anything towed on a real steep or long grade if the system was not working in total.

When the temperature block was not working the fan motor never ran more rpms than when it was on a cold or just warm motor, almost just lazily moving. If the temp block is working it sometimes would sound like you have an airplane in the engine compartment, but the engine never overheated. It did not take fan long for it to run at a high speed to bring coolant back to normal operating temp while you were climbing and towing.

And Bob I wouldn't be too discouraged as although CAT is ALWAYS pricy those items they replaced may now not haunt you as a breakdown some where in time on a Sunday afternoon in no mans land. They were over 12 years old and as much as our coaches set it is most always worse than if they were in use.

We picked up a 2004 Marquis in Costa Mesa in August 2012 with 36,000 miles and in May 2013 we outed $4700.00 to get the Allison from locking up in 5th gear. Seems that there has been a problem with this trans during warranty period and then at 32,000 mile just 10,000 miles prior to us having the same problem at 42,000 miles. I just conversed with a retired Allison fluids engineer and I am going to write Allison - but I expect I will get nothing but the corporate jargon of out of warranty.             After the initial being peeved about the cost I am fully back to being totally happy with the Coach and would not trade it for anything. We were and are extremely happy with our BEAVER coach(s).

One aside we learned when we picked up the 2004 and had a great bearing on us getting it. It is the last year Beaver Coaches were built in Bend. It is also very near the last time when you could get a CAT, built by CAT, in your coach. While we were in Costa Mesa at brokerage there were two New Coach Owners that came in and with less than 8000 miles both had their C-13 CAT's blown. NOT happy Campers to say the least.

CAT no longer makes their motors due to the emissions requirements and whomever does does not do what CAT did, obviously. We listened as numerous others are taking their existing coach's and having them refurbished as they have the running gear that will last most all of us a lifetime of RVing but just want to update. The quality that is coming out of most manufacturers since the early 2000's is non existent today. A Beaver, pre 2004 is a gem to own.

BOb, One thing we did change and this was learned from our Contessa as it had Koni's, get rid of the Bilstien shocks if you have and get a set of KONI's on. You want to experience a super ride this is the way to do it. No more porpoising or side sway roll, tire slap etc.  Best pricing is from website in El Cajon California, SHOX. Make sure what mounts you have and call Koni direct in Tennessee to get correct part number.   We had to drill out, and it is not that difficult if you do it in steps if you have a workshop, to get to the 3/4" hole in the eyes of the shock. They have a seperate part number that El Cajon did not show.