Ventana Cooling Plenum

[teamwally]

We lost a day in Redding, Ca when the fan clutch failed and the overheat alarms came on. Apparently the 2nd time on our new to us 07 Ventana 330 ISC/ Spartan has had a new clutch, previous owner did not have the software updated for multi speed fan. OOPS. Thank you Star Warranty and Redding Frieghtliner. A couple of days later Newmar called at the behest of Spartan who offered to have a restrictor placed on the driver side cool air intake. Newmar rep said they wold cover up all but 9" of the duct opening. Being the resourceful guy I am I used black duck tape. With the new clutch and restricted duct instant readout mileage has gone WAY up, usually in the 9-10 range at 60mph. Coach average with 9000 miles was 6.1 Has anyone else gotten this advise ? My guess is the restriction increases the veloicty of air thru the radiator thus requiring less fan engagement, hence better mileage.

[Fred Longhi]

I have a Ventana also. '07 with ISC 330 and Spartan chassis. I believe my fan runs all the time -- no clutch. I get about 8 MPG at 60 MPH, but it is getting a bit better as I put more mileage on the coach.. It is up to 15,000 miles now. Is the air intake you are talking about the visible one from the outside of the coach on the drivers' side?? If so, what does it feed... in other words where does that air go.

Thanks,

Fred

[teamwally]

Fred, the air from the intake at the top rear corner on the drivers side feeds the air intake and passes thru the radiator. Based on what I learned from the dealer you may want to check for the software update at a Cummings or Frieghtliner or Spartan facility. This update enables variable speed mode on the fan. Only takes a couple of minutes and may improve mileage as well.

[teamwally]

And now the update, the replacement fan clutch lasted less than 300 miles, failed after Redding,Ca to Ashland,Or over the siskiyous. Rolled into Medford with the temp at 240 and alarms going off. Good news was I had Frieghtliner do the work in Redding so Frieghtliner service in Medford did the replacement for free. I did spend $200.00 to have the coolant drained and refilled. Tech said it was at 29%, whatever that means and did not affect the failure.

[spike45]

Quote:

Originally Posted by teamwally And now the update, the replacement fan clutch lasted less than 300 miles, failed after Redding,Ca to Ashland,Or over the siskiyous. Rolled into Medford with the temp at 240 and alarms going off. Good news was I had Frieghtliner do the work in Redding so Frieghtliner service in Medford did the replacement for free. I did spend $200.00 to have the coolant drained and refilled. Tech said it was at 29%, whatever that means and did not affect the failure.

Most likely 29% glycol content based on freeze point reading. That is too low on the antifreeze content for good cooling efficiency on an ISC, ISL which operate normally in the 210F range under full load. Lower glycol content equates to lower coolant boiling point. Lower boiling temperatures are usually the result of film boiling which creates a lot of steam in the coolant flow. Steam bubbles are as bad as air bubbles in that the coolant is less liquid thus a poorer heat transfer fluid. Engines are designed and tested with 50/50 coolant solutions. All heat load calculations and performance are based on 50% antifreeze content.

[teamwally]

Thanks for the info, I knew the 50/50 cooled better, I didn't know the why.