Overheating problem.

[Phillip T Lago]

My 2001 Marquis is fantastic, but I have a persistent problem with the engine overheating on long inclines. Only does in on grades over 7 %. Never on flats in the middle of hot weather, but after a long climb you can see the temp start to climb. Gets to the point that the engine light starts flashing. Always stop and idle back down to normal operating temp. Then continue on my way. Once started up the incline temp starts to climb again. I travel a lot in the winter thru the TN. mountains and the overheating starts but does not reach critical temps like it does in the summer. Does lugging the engine cause this or is there a mechanical malfunction occurring.

[Steve Huber Co-Admin]

Phillip,
Lugging the engine will cause overheating, especially when pulling a hill as the slower engine RPM decreases both the fan and water pump speeds so you get reduced circulation and reduced cooling air through the radiator. When driving in hills, recommend taking it out of cruise control and economy mode, down shifting as needed to keep the RPM at 1600-1800. Don't worry about your speed, your concern should be engine temp. The check engine light will come on around 217 so you want to keep temps below that if at all possible. If your normal temp is around 185 to 190, engine temps on steep hills can reach 200 to 205. Also, be watchful for long slow inclines as they can also cause high engine temps, especially in economy mode and cruise control.
There area a number of threads on this,, for more info.
Steve

[Gerald Farris]

Phillip,
Lugging the engine will contribute to the condition, but from your description, it sounds like there may be a mechanical factor also. My 2000 Marquis (same engine and cooling system) will not heat up above 205 degrees on any incline regardless of how much I lug the engine.

Gerald

[Joel Ashley]

I would first have the hydraulic fan checked for proper operation, as my initial thoughts upon reading your post agreed with Gerald's.

Joel

[Steve Huber Co-Admin]

I'll have to check my fan speed as mine will heat up well above 205 when climbing, especially if I lug it at all.
Steve

[Joel Weiss]

We climbed Cabbage Hill two days ago with the same engine in a somewhat lighter MH.  I've made other posts about the changes I found after replacing the thermostat last spring, this post further adds to those findings.  I assume most of you know that hill and its reputation.  I took it in 4th and never went below ~50 mph going up.  The thermostat continued to cycle all the way up.  In other words I could observe the engine heating up and then see its temperature fall as the thermostat repeatedly opened and closed.  

The Silverleaf never indicated a temp above 199 and that was reached only momentarily before the thermostat began to open.  I actually saw temps as low as 185 during the climb at which point the thermostat started to close to raise it back up.

IMHO there has to be something wrong with the OP's cooling system for him to observe the performance he has reported.

[Bill Sprague]

We climbed Cabbage Hill two days ago ....

I love driving that.  That's an amazing stretch of road!

[Larry Fritz]

Joel, I had nearly the identical experience of the thermostat/s  cycling from about 188 to 196 every minute or so when traveling in the flat Nebraska a couple of years ago. The cycle was very repeatable. When I got home, I replaced both thermostats and have not seen that condition again.

Larry

[Joel Weiss]

Larry:

The thermostat was replaced in the spring and has acted this way since it was installed.  My assumption is that it is trying to keep the engine at 190-195 degrees which is ~5 degrees hotter than the previous thermostat's setting.  I've experienced no issues as a result of its behavior so I've considered it to be "normal."  When I get the MH serviced by my CAT dealer in the spring I'll ask if this is truly is normal.

Joel

[Robert Fish]

Hello ladies and gentlemen,  
  I hereby submit my first post on what appears a very informative and entertaining forum.  I'm a new Beaver Marquis owner, and with that in mind, one of the main reasons for obtaining this fine rig, aside from the attributes we are able to enjoy, is the fact that it seems to have a better power to weight ratio, which we were hoping would better enable us to utilize our Tahoe as the towed vehicle.  That has not come to fruition, due to exactly the above described condition.  The fact that we tow (four down) a relatively light Ranger pickup now has not belayed the condition at all.  
  After reading the posts above, it's difficult to determine an exact method of attack, not knowing if all the contributors actually have C12 Cat motors, especially considering that one individual referenced TWO THERMOSTATS.  I wasn't aware that Caterpillar motors had more than one.  Could someone please enumerate?
  With all the above stated, I truly appreciate your input.  It certainly gives a solid trail to follow.
  More facts, I have only just purchased my Beaver and on its maiden-voyage (for us) it immediately began over-heating upon entering inclines.  I stopped in Redding, CA and was told by a Cat. mech. that the radiator was shot, therefore in need of R&R.  That he did for us, along with a complete exhaust system (aftermarket…..the original was shown to be ready to fall off the motor and frame ), to the astronomical tune of sixty-seven hundred.  We subsequently took off for Laughlin and didn't get far before the nightmare returned, with very little improvement.  HELP!
Sincere thanks again, Bob

[Joel Ashley]

Welcome, Robert!

There are others more experienced here than I with overheating, but they'll appreciate knowing the year of your Marquis, any other services done beyond replacing the radiator, and the temperatures you are experiencing.  Did the mechanic determine that the hydraulic fan was operating properly?

Joel

[Edward Buker]

Robert,

I will assume that the radiator is good now but you should check with the repair shop and make sure that the new radiator had the same core design and cooling capability as the last one to make sure that if the radiator was the problem that the new one did not invoke the same problem in another way. Other possibilities are the engine thermostats, the water pump, the hydraulic switch and control circuit, the hydraulic fan motor, or a collapsed hose. There may be other more obscure possibilities but these are the likely suspects.

As Joel mentioned post more info on your problem and the year of the coach. You may want to have a Cat dealer pull the information on your motor by serial number. If Caterpillar has worked on this issue in the past, they can tell you what they did and when, so as to not retrace their steps. If you are climbing and the engine is lugging down some drop a gear using the touch pad and keep the rpms up in the 1800 to 2000 range and see if that helps. That increases the air flow and fluid flow if the cooling fan system is working properly and should help your overheating under normal circumstances.

This problem source can be difficult to diagnose. I would search this forum for a shop that has been successful at sourcing and fixing this kind of issue and go there if at all possible.

Later Ed

[Gerald Farris]

Bob,
Like the two responses above mentioned, the year and model of your coach is important in answering any question about your coach. Beaver has had four different manufactures over the forty plus years of the brand, and hopefully we will see the fifth manufacturer next year when the 2015 Beaver is introduced by ASV. All of these manufactures have changed the product lines over the years, so something that was a problematic item on one coach was not a common problem on another year.

You mentioned the C-12 engine, and if that is the engine in your coach, that means that your coach is from a 1997 to a 2004 that was made by either SMC or Monaco Coach corporation. The SMC era C-12s (1997 to 2002) had brass radiators with virtually no problems, but the Monaco units used a very problematic aluminum radiator in most coaches. If your cooling system is operating properly, a C-12 equipped Marquis can pull more weight than your hitch is rated for without any overheating concerns.

Gerald  

  

[JimCasazze]

I just noticed this post, but I too have started to develop a overheating concern with my '99 Patriot Thunder.  Drove 20,000 miles last year with the temp staying between 185 (normal) and 190 max.   We drove to Alaska from SW Florida and many long climbs, where no overheat problems ever existed.  Then on our return trip I saw our warning system come on during a climb up a Colorado incline.  I geared down to keep RPMs up and the engine did cool off.  However, the engine now routinely reaches 199 degrees even on flat Florida roads.  It seems like something has happened which is causing the engine to run hotter than previously.

The radiator was flushed several times before we left last year and re-filled with synthetic? coolant (no additives needed).   Coolant and hydraulic fluid tanks are full.  I guess I should check the side mounted hydraulic fans and the radiator itself for clogging.  Could that "powdery dust" of Alaska, etc. have clogged the cooling fins?

Any suggestions will be checked out, so thanks in advance.

Jim

[George H. Wall]

Jim, You bet it can!! I've made that same trip to AK from NC on 4 occasions and that volcanic dust is the finnest stuff in the world. It can cross any barrier and clog anything. Clean your radiator WELL and see if that's not your problem. Henry