GERALD
Thank you for the reply to my question.  You alway sare so good about explaining things, especially to me.  
Something that logically seemed so simple to me, certainly has a lot of ramifications.  WOW!
Again thanks for your insight and expertise.
Leah

Bill,
Yes the engine thermostat does open and close to maintain the engine temperature, and yes a thermostat failure on a fairly new Cat engine is rare, but it does happen. However, the reason that I said that there was almost no chance that a defective thermostat was causing the overheat problem in this case, is because of the conditions under which it happened.

The coach overheats only on a grade if the coach is not downshifted to bring up the RPMs, and the condition can be duplicated under the same conditions, but the coach does not overheat at any other times.  If a thermostat was sticking, it would not only stick under a very specific set of conditions, and stick every time that those conditions exist. The thermostat is a heat regulated mechanical valve that has no way of detecting whether you are climbing a hill or not.

Gerald    

While I can't speak to the Cat thermostat specifiacally, I have never seen one "stick" closed.  They are typically designed to fail open which would cause the engine to run cool.

Quoted from Gerald Farris

...... If a thermostat was sticking, it would not only stick under a very specific set of conditions and stick every time that those conditions exist. The thermostat is a heat regulated mechanical valve that has no way of detecting whether you are climbing a hill or not.  

Thank you for taking the time to answer, Gerald.  I learned something that may be useful someday.

Bill

Quoted from Dick Simonis

While I can't speak to the Cat thermostat specifiacally, I have never seen one "stick" closed.  They are typically designed to fail open which would cause the engine to run cool.

Thanks!  I didn't know that either.  It does make sense they should work that way.

I thought all '08 Contessa's were 425HP Cats.  I can think of other reasons to abandoned the Cat engine and have considered all options.  A re-power is simply not cost effective.  I looked at trading the coach but the cost was also too much, especially given I would be move down in quality and size.

My '08 Contessa has been on CAT's chassis dyno and the power was very close to that advertised, but there was some reduction on turbo boost, due to the charge air cooler being at the edge of Cat's acceptable parameters.  My coach routinely runs between 190 degrees and 206 degrees.  A range that's within Cat's specifications.

The marine engines are a whole different animal, so don't think you can get anywhere near their horsepower ratings.  Marine engines run much cooler at a constant 185-190 degrees due to sea water heat exchangers.  Also marine engines don't have the strict EPA requirements, so you won't find exhaust regeneration systems on a boat.

Gil
'08 Contessa Westport 42

Gil

"I thought all '08 Contessa's were 425HP Cats."

Not necessarily.....I ve seen a lot of '08 Contessa's with 400hp.  I wouldn't buy one until they had 425 hp.

Curious, what is the torque of the newer 400 - 425 CATs as oppose to the older C12 425?

Dick,
The 425 HP C-9 can be rated at either 1250 or 1350 lb-ft of torque. I am not sure which version Monaco used, or if they may have used both versions.  The 400HP C-9 is rated at 1250 lb-ft of torque. The 425 HP C-12 can be rated at either 1450 or 1550 lb-ft of torque, and SMC did install both versions in Beaver coaches.

Gerald

Fascinating.  CAT seems to have the HP and torque ratings really dialed in, and I'm sure there is a great reason for having so many variations in the same engine.  I suspect that later model years are affected by emission controls, that were added as time passed.

Reckon I will be content with our C12 at 425/1550.  At first I thought ours might be underpowered, as the chap next door was mentioning that his Prevost was running 500 hp and 1900 torque, so I kind of figured that was normal for a DP.

Back to the thermostat issue,  I've seen lots of thermostats that fail to open "stick closed" but have never seen one that will open properly, then close while the engine is still above opening temperature.  I guess this ages me, but I have often placed a suspect thermostat in a pan of cold water, with a meat or candy thermometer in place, turned on the heat and watched for it to open while watching the  thermometer. That was the way we tested them.  BTW, on my marine diesels, we notice the temperature climb as we approach full throttle. Even with a properly functioning salt water to fresh heat exchanger, the top end of the horsepower range will produce enough heat to almost overcome the system. I have found that even one barnacle in the raw water intake would cause and overheat condition. Much like a dirty radiator.

Thanks ALL,

Hot is 220-225

The Aladin and engine led say the same temp.

Is there anyone that has the C9 400 in a 42 to that can confirm this is happening to them also?

Thanks David