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38403Re: [classicrv] Lets talk about overheating problems

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  • Bill Miller
    Feb 13, 2013
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      I had a similar situation on a Cat 3208 Diesel. It would overheat like crazy on any steep hill. I did all the normal stuff, as you have, and then I had an electric fan installed in place of the regular factory fan. I had it wired so I could turn it on manually from the cab. Problem solved.

      I found out after I got rid of the truck, that the factory fan and radiator were to small for the application. That truck was meant to be a local delivery van or garbage truck; I had it hauling a 48'   flat bed trailer.

      You may need to look at a bigger radiator, bigger fan, or full time fan as opposed to clutch operated.

      mainiac bill

      From: Sirrobyn0 <sirrobyn0@...>
      To: classicrv@yahoogroups.com
      Sent: Wednesday, February 13, 2013 2:27 AM
      Subject: [classicrv] Lets talk about overheating problems

      Ok, let me preface this by reminding the group that I have been a automobile technician for the last 20 plus years, so I know how engines are supposed to work, but this one on my old RV has me stumped.

      So the RV is a 1977 Dodge Flair Class C 22 foot with the Dodge 360 engine. It has had some moderate engine overheating problems, usually most noticeable in 80+ weather, more prone to happen on hills, but I have always been able to control the engine temperature by turning on the cab heat. Not much fun in hot weather but better than the side of the road.

      Next heat related issue. When we first got the motorhome 12 years ago it would vapor lock in 70+ degree weather. 70 degree is not all that hot, I added a pusher pump back at the fuel tank, and insulated the lines in the engine compartment which has helped some, now it only vapor locks when the weather is 85 or hotter.

      Second to last heat related issue, percolation. Anytime it is over about 70 degrees outside, stop for fuel or a rest stop, after a few minites of the engine being turned off you'll smell fuel and have to floor it to get it to restart. What is really funny is sometimes it will percolate, then a few moments after starting, it will vapor lock... Actually it's not a bit funny. I open the hood first thing every time we stop the motorhome to help counter act the heat, which again helps.

      Final issue I suspect is heat related, and this can happen in almost any weather. Going up a long steep hill, that requires a lot of throttle this smell will come up. It reminds me of hot metal, this is more likely to occur in cooler weather, because in hotter weather I have to drive slower on the hills to keep the engine temps down. I suspect that under the load of a long hill the exhaust manifolds are getting very hot, possibly glowing hot. I just had to replace both of the exhaust manifolds because they had cracked, also the gaskets were burned to a crisp.

      I have done all the usual stuff to fix overheating.
      Radiator rodded out.
      Thermostat replaced.
      Fan clutch replaced.
      Hoses and belts replaced.
      I'm sure I have tried more that I can't remember at the moment.

      And yes the original OE. fan shroud is in place and in good shape.
      The heat riser was removed from the exhaust manifold sometime back, and there exhaust is free from restriction.

      Though the motorhome runs great otherwise, I suspect this is being caused by retarded ignition timing or to lean of a carburetor. I cannot see the timing marks on the harmonic balancer, with a light due to the location of the power steering pump and air pump on the block. There isn't a mark on the flywheel, although there is a hole present in the bell housing, for that setup, but the transmission was replaced just before we bought it, and the torque converter was replaced at that time.

      I have access to a 4 gas analyzer at work, and was thinking of hooking it up to see how rich or lean the carburetor actually is.

      So you guys out there that know these Dodge 360 better that I do, what do you think is causing all these heat issues?
      Any good ideas on how to set the timing other than doing it by ear?

      Thanks for the advice,

      [Non-text portions of this message have been removed]
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