308 heater pipes ... which is return ? | FerrariChat
Buy

308 heater pipes ... which is return ?

Discussion in 'Technical Q&A' started by nevpugh308, Jul 8, 2004.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. nevpugh308

    nevpugh308 Rookie

    Apr 13, 2004
    32
    Midlands, UK
    Full Name:
    Neville Pugh
    #1 nevpugh308, Jul 8, 2004
    On my 308GTS euro carb, the two pipes which go to the heater matrix at the front of the car (cabin heater, not radiator) ... how do I tell which is the feed and which is the return ? (one pipe connects to the rear bank cylinder head, and the other pipe connects to one of the carb bases)

    Thanks !
    Nev
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,506
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, Jul 8, 2004
    Nev -- The line connected to the carb base is the vacuum source for the brake booster.

    For the heater lines -- (On the US version 308GTS) the hot water leaves the fitting on the 1-4 cylinder head, goes to the cable-controlled valve under the front bonnent, leaves the valve, and is "T"eed to feed the two heater cores. The return lines from the heater cores are "T"eed back together and the single return line feeds into the main coolant return line under the front of the car.

    So to answer you question more directly:

    1. the water line from the 1-4 cylinder head goes to the cable-controlled valve under the front bonnet.

    2. the vacuum line from the #4 carb base goes to the brake booster on the master cylinder.
     
  3. nevpugh308

    nevpugh308 Rookie

    Apr 13, 2004
    32
    Midlands, UK
    Full Name:
    Neville Pugh
    #3 nevpugh308, Jul 8, 2004
    Steve, many thanks for the reply. Ah, well whaddya know, I've just learnt something, you're right it's just an air pipe (I've just popped it off). I always assumed that because (on my car) the two pipes are the same diameter and are cable tied together, they were the feed and the return !

    Right, time to go searching "up front". :)

    I'm trying to figure out, by the way, where to fit a Kenlowe Engine Preheater which needs to go on the return from the heater matrix back to the engine .... another question then, if the heater matrix return goes into main radiator return back to the engine, where is the engine thermostat in this equation .... on the radiator feed or return pipe ? (I'd assume the feed ?)

    Thanks
     
  4. Spasso

    Spasso F1 World Champ

    Feb 16, 2003
    14,652
    The fabulous PNW
    Full Name:
    Han Solo
    #4 Spasso, Jul 8, 2004
    On most cars the thermostat is put between the engine and the radiator feed.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,506
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #5 Steve Magnusson, Jul 8, 2004
    You're right. The 308 thermostat is located where the hot coolant exits the cylinder heads -- it then either directs the flow back into the engine or into the main coolant pipe that feeds the radiator. See page C10 in the 308GT4 WSM (if you don't have a copy of the 308GT4 WSM you can download it from Steve Jenkin's Ferrari website). You might also check the cooling flow diagram on ~page 61 in the OM and ~TAV 20 in the SPC -- if you put those three figures together you can draw a complete coolant flow map. (You can get the OM from the Owners Site and the SPC illustration from the FerrariUK spare parts site).

    I think you do need to be careful here and really understand the 308 system because some systems always have coolant flow in the heater core, whereas 308 do not -- so this might affect how you need to do the plumbing and/or operate the preheat system (e.g., you might have to manually open your heater valve when using the preheater).

    Is the "preheater" an electric heating element that is just wrapped on the outside of a coolant line?
     
  6. nevpugh308

    nevpugh308 Rookie

    Apr 13, 2004
    32
    Midlands, UK
    Full Name:
    Neville Pugh
    #6 nevpugh308, Jul 8, 2004
    I'd already thought about the "having to have the heater on" bit. Not too much of a pain, I'd just have to have a big sign in the garage to remind myself :)

    You can see the item here (though it's slightly changed as the new unit is a cylindrical unit 3" dia 6" long) http://www.kenlowe.com/pre-heaters/cars/index.html

    It's a fully contained unit, including heater, pump, thermostat (takes the engine coolant temperature to 85 degrees in about 20 minutes) and so on. You just have an out of the way socket somewhere (under front or rear deck, say) where you plug it in to the mains.

    Nev
     
  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,506
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #7 Steve Magnusson, Jul 8, 2004
    Interesting gizmo -- I think it could go in the front bonnent hose (item 48 in the 161/78 SPC) that runs from the heater cores back to main coolant return line OK.
     
  8. nevpugh308

    nevpugh308 Rookie

    Apr 13, 2004
    32
    Midlands, UK
    Full Name:
    Neville Pugh
    #8 nevpugh308, Jul 8, 2004
    Oh yes, I see the one ... page 52, kinda hidden behind the image of the radiator.

    Thanks for your help :)
     

Share This Page