Coolant hose blew, big mess followed | FerrariChat
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Coolant hose blew, big mess followed

Discussion in '365 GT4 2+2/400/412' started by 180 Out, Mar 2, 2013.

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  1. 180 Out

    180 Out Formula 3

    Jan 4, 2012
    1,286
    San Leandro, CA
    Full Name:
    Bill Henley
    #1 180 Out, Mar 2, 2013
    I had an interesting old car adventure today. I was getting a Smog Check II sniffer test. I know from previous sniffer experiences that my car tests dramatically lower as the cat heats up. So before I got to the testing station I had my oil temp up to 100 degrees. Then I left the motor running while the tech and I talked and rolled the car onto the rollers and all. We ran the test, which requires 60 seconds at 15 mph and 60 seconds at 25. The hood is up, to allow the inductive rpm sensor to clamp around a plug wire. At the conclusion of these runs the tech switched off the engine and got out. We were standing with our backs to the car, looking at the print out. Next thing I knew there's a POP from the engine compartment and we are being showered with coolant. It was shooting from the area of the thermostat, six or seven feet into the air and the plume spread out like a patio umbrella. The testing cart, the guy's phonebook sized manuals, and my poor car got soaked. Me too, a bit.

    The source of all this fun was the bypass hose at the bottom of the water pump. It had a split a couple inches long. I guess I was fortunate to have this hose let go while I was already in a repair shop, rather than on some back road 100 miles from home. The shop owner, a Laotian named Kho, leaped to the rescue. He got two hoses of the proper diameters to match the radiator hose and the bypass hose, and cut sections out of them to replace both of the upper radiator hoses and the bypass hose.

    Here's another bit of fun: we discovered that the thermostat was installed backwards! What this means is that my car's bypass circuit was never functional. The correct function, during warmup, is for the coolant to exit the top of the engine block and enter the thermostat housing and, with the thermostat closed, follow the bypass hose to a T-junction with the lower radiator hose. When the themostat opens the path to the top of the radiator, via the upper radiator hose, the thermostat also has a seal which closes the hole leading to the bypass hose. With my thermostat facing the wrong way, during warmup the coolant merely hit the close passage to the radiator. The hole leading to the bypass hose was on the other side, on the radiator side of the assembly, not on the engine side. I guess I don't like to think about how this affected the warming up of the engine block and heads. I hope they weren't injured. I always keep the revs low until the oil temp gauge starts to move, by which time the coolant is nearly 90 degrees and the coolant's path to the radiator is open. I'm glad I got this corrected. If anyone is curious to check his own thermostat, the correct configuration is for the housing to be angled toward the front. There's also an arrow stamped into the housing, which should be pointing to the front.
     
  2. rustytractor

    rustytractor Formula 3

    Mar 25, 2012
    1,078
    London
    Full Name:
    Russell Schacter
    #2 rustytractor, Mar 3, 2013
    That's a real PITA, any permanent damage to you or stains to the car?

    As you say, bit of a mixed blessing really that at least you weren't stranded in the middle of nowhere when the hose let go.

    Good to know what to check to make sure we don't have a similar problem though so thanks for posting this.
     
  3. theobordeaux

    theobordeaux Formula Junior

    Jan 13, 2011
    482
    Bordeaux (France)
    Full Name:
    Theodore
    #3 theobordeaux, Mar 3, 2013
    Last edited by a moderator: Sep 7, 2017
    Hi,

    I had a similar problem and it has been some time I solved it by simply removing the thermostat bypass, the engine takes a little longer to heat but I would not have the same failure.
    I opened a topic on this problem:

    http://www.ferrarichat.com/forum/technical-q/326049-explosion-coolant-running-highway.html

    We must follow the methodology of troubleshooting to determine the problem :

    1 - Check the operation of Thermostar bypass (1). For this purpose it is to extract the three hoses which it is coupled to soak in water at 212° F to see if the valves open and close in accordance with its function.
    If this first test is successful, we move to Phase 2.
    2 - Verification of the fans. This requires the disconnect switch (2) which switch and bring together two son (ignition on to the key of course) to determine if the fans are working or not. If the fans do not always turn, it is necessary to check the relay number 22 (right) (7) and over No. 25 (left) (8) that bring them into action. These relays are located behind a flap under the front passenger carpet. If the fans do not turn must then either fix them or change them! Also remember to check the fuses (9) that even if they look like one in the photo below may not work.
    Sometimes, a seemingly good fuse is evil in the fuse holder, resulting in overheating causing corrosion of the contacts.
    3 - The level of coolant (5) must be about 3 or 4 cm below the maximum level of the radiator, to avoid unnecessary spillage in the expansion tank during expansion of the liquid. The radiator cap (3) must be a flat plug.
    4 - The expansion tank (6) must be empty of coolant and cap (4) shall be set in accordance with the original one is 0.9 bar (or 0.7).

    In fact, it was the thermostat bypass that did not work. The valve was blocked and turned the coolant closed loop engine / motor bypassing the radiator. For this reason, the engine warmed much and the coolant was flowing well and the expansion tank.

    In any case, thank you heard me helped to solve this problem, I also thank Pierre C. one of our forum members of the European Ferrari 400 Club which allowed me to formalize the methodology of diagnosis.

    Theodore
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  4. jacques

    jacques Formula Junior

    May 23, 2006
    877
    Los Angeles/Florida
    #4 jacques, Mar 3, 2013
    About ten or twelve years ago, a faulty thermostat almost cost me my engine in the swealtering Florida heat. I removed the thermostat from the system, and never looked back. As the previous poster Theo in France stated, it takes a little longer for the fliuds and oil to heat up, but the car (1980 400i) functions beautifully. BTW, I inserted an oriface into the main hose, exactly like a race-gate to modifiy the flow , and the water temp. guage seldom passes 90c, or straight up. Thank you for the validation, Theo. Jq.
     
  5. Ashman

    Ashman Three Time F1 World Champ
    Owner Silver Subscribed

    Sep 5, 2002
    33,242
    MA
    Full Name:
    John
    #5 Ashman, Mar 3, 2013
    Theodore, that is a very helpful diagram and description but I would be cautious about bypassing the thermostat/bypass hose permanently.

    In my experience the cooling system on the 400i is very effective and has plenty of capacity to keep the engine temperatures properly controlled even on very hot days and in slow moving traffic. What this means to me is that I would expect that the thermostat does occasionally open and close in normal traffic or on cool or cold days in order to keep the engine temperatures at optimal working temperatures.

    For example, here in Connecticut I often will drive my 400i throughout the winter as long as there is no snow or salt on the roads and I can tell that the engine temperatures sometimes are at the lower end of the range that I would consider optimal (i.e. water at 90 C and oil at 100 C) when ambient temperatures are below freezing. I think, but am not certain, that in these conditions the thermostat is opening and closing to make sure that the engine temperatures stay warm enough.

    The other drawback, as you point out, is a longer warmup period. With an 18 quart oil sump and a good cooling system, it takes a good 5-7 miles of driving before the temperatures are up to normal and this would extend the warmup period which, for someone impatient like me, would be difficult to accept! :)

    Do any of the more technically expert Ferrari 400i owners have an opinion on whether the thermostat continues to function after full warmup?
     
  6. theobordeaux

    theobordeaux Formula Junior

    Jan 13, 2011
    482
    Bordeaux (France)
    Full Name:
    Theodore
    #6 theobordeaux, Mar 3, 2013
    Yes you are right Ashman is good logic especially when you are in an area where the temperature differences are important. But if we consider that removing the thermostat keeps the temperature lower its suppression has allowed me to have no doubt about his blocking. I am in an area where the temperature differences are small.
    Good advice, in fact, is to let him do his job.
     
  7. 180 Out

    180 Out Formula 3

    Jan 4, 2012
    1,286
    San Leandro, CA
    Full Name:
    Bill Henley
    #7 180 Out, Mar 3, 2013
    Kho poured water over the hood, roof and trunk. The roof and trunk seemed clear of stains, but the trunk had some ugly stains. When I got home I gave the car a double wash, using Turtle Wax "Ice" soap and another Ice product called "Liquid Clay." This is a soapy liquid with visible white polish solids in it. I like this product a lot. It strips off old wax and leaves a literally squeaky clean surface. Unfortunately the trunk stains survived this treatment. My next step was Meguair Ultimate Polish, by hand. (I have also used this with a random orbital polisher.) The polish took out the stains. Whew!
     
  8. rustytractor

    rustytractor Formula 3

    Mar 25, 2012
    1,078
    London
    Full Name:
    Russell Schacter
    #8 rustytractor, Mar 3, 2013
    Bill, glad to hear it all came good with a bit of hard work.

    All's well that ends well, eh ?
     

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