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"Nasa Ames asked RVS to assist with a engine temp study by installing 9 heat sensor in the engine area connected to a graph recorder. At 65 MPH on hi 5 w/l00 ambient temp the engine compartment exceeded 350, above the carborator." - Jim Black, FMC Yahoo Website Msg #6181 Feb 28, 2008.

"I came across an old article from the FMCA magazine yesterday. August, 1983 pg 51. cont. on page 160. FMC Overheating. Very interesting. Nasa ran some engine bay temp tests using 9 sensors mounted around the engine bay. they ran a 400 mile trip and recorded 300 degrees above and forward of the carb. They recommended a dual exhaust system which after installed brought the temp in that spot down to 160 degrees. This was done with 90 degree ambient temp. ..." - Correspondence with Bill Sitton (President FMC Owners Club), Aug 8, 2012.

...end quote.

There are two temperature related items: one is the temperature of the air in the engine compartment at various locations, and, secondly, the temperature of the air passing through the radiator which is what is germaine to the cooling of the ENGINE coolant.

There are reasons to look at the temperature at various locations in the engine compartment. At the top of the engine in front of the carburator is one of them as that will possibly affect carburator performance and will also affect the life of the wiring and connectors that run across the top of the fire wall in that location.

However, the temperature at that location is NOT engine compartment temperature. It is the temperature of ONE POINT in the engine compartment. Based on your information, it was one of NINE locations where the temperature was measured. What was the data for the OTHER EIGHT locations amd what were those locations? The location that you have referenced most likely has very poor air flow as there is solid metal on the top, front, and bottom of that location. Air to the rear is also blocked by the carburator. I would expect that location to have a high air temperature.

You have also noted that by changing from the original large muffler to a dual exhaust system the temperature in the quoted location dropped from 300 plus degrees to approximately 160 degrees. You did not qualify your statement as to the applicability of the data only pertaining to those coaches that still run the original muffler and do not have a dual exhaust system.

This is what you have asked of me: "FMC Owner Test of air temp in Engine Bay ? Who ? What was FMC Serial # ? When ? Test results are available where ? Just where was the thermocouple(s) ? Pictures ?"

I hereby ask the same questions of you as where are the tests etc. that support your position that drawing air from the rear COOLS THE ENGINE better than the original configuration. You have set up your coach with the arrangement that you propose ("I have a 20" alum blade steel hub stock Chrysler SUCK fan on my #120 ... " ); however, you have NOT provided any actual data as to actual performance. Do you have any documented performance data with YOUR coach? At what speed? How many miles? Ambient temperature? Engine compartment temperatures? Engine coolant temperature?

Getting back to my original statement that I disagree with your statement that "... (tries to cool 230 deg radiator water with 300 deg + air heated by the exhaust manifolds) ... I have not changed my mind and still disagree with the implications of that statment as I feel that the quoted support material does NOT apply to the air flow that cools the engine. That air flow temperature data probably was part of the eight data points NOT discussed in either the article nor by Jim Black. It is those data points that are meaningful when it comes to COOLING THE ENGINE. Jim Black was a good salesman. One of the things that he sold was dual exhaust systems!

I have operated three FMC coaches: 1046, 386 and 87. All three were properly cooled and operated at 180 degrees engine coolant temperature with the original pusher fan which pulled air out of the engine compartment, passed it through the radiator and then out the rear. That could only happen if the the air passing into the radiator was much cooler than the engine coolant and much cooler than what you have alluded by your single data point.

I also find it interesting that new coaches today, that have rear engines, use either a side mounted puller fan or a rear mounted PUSHER fan. To my knowledge, NONE use a sucker/puller fan that draws air from the rear and pushes it into the engine compartment. It appears that the engineers at Fleetwood (and other manufatures) still conclude that with a rear facing radiator, the best configuration is to use a fan drawing air from inside the engine compartment and sending it through the radiator and out the rear of the coach.

I await your road test data and recommend that others do the same before changing the fan setup in their coaches.

A cool pusher,

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