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Caution Crown vic and Ford owners, avoiding coolant volcano

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  • Caution Crown vic and Ford owners, avoiding coolant volcano

    Hello all ford owners, my issue was with 1999 ford factory dedicated CNG. I was pulling off of the freeway and I pushed the throttle up to %75 once off the freeway dropped back to idle at the first light. Noticed at the light that there was coolant spitting out from under the drivers side front corner of the hood (coolant tank is on the passenger side) and when I started off from the light a bit of coolant fog on the inside of the window. Temp was in the middle as normal but stopped at a gas station a block up to check it. Under the hood everything is soaked with coolant, (and I mean everything) added a bunch of water to the tank but no obvious leaks. Started again and kept adding water, finally the gush stated from the coolant tee between the back of the intake and the heater core where the branch is for the coolant loop that goes to the rear for the CNG.

    The problem: instead of crimping in a $.50 steel tee into the hose assembly they opted for the $.05 crappy plastic one. After years of heat and coolant the tee material was so deteriorated that it crumbled in my hand. After I had a few tools delivered to me (lucky was only a few blocks from home) I was able to cut the aluminum crimp off I was able to get it back on enough and get a hose clamp on it to limp it home to with only a minor coolant leakage. you will need to remove the alu crimp carefully, I used some side cuttrers and opened it up like a can openner.

    The tee was the consistency of a fortune cookie.
    The upper one was the one the failed, the upper and lower hoses are different sizes on the heater side 3/4 and 5/8, 3/8 on the CNG side.

    instead of buying an over priced assemble form ford that would be back ordered for weeks if even available and have the same plastic tee's, I opted for new metal tee's

    I could have put something together with 5 or 6 fittings but it would have been ugly so here’s what went in.

    1- 5/8 pre soldered tee (3/4 OD), the pre soldered ones have the ridge that holds the hose and clamp on
    1- 3/8 hose x 3/8 male NPT

    Shortened the threaded end by about 1/8" and turned a little off of the diameter so it would clear the inside of the 5/8 tee, and bottomed out on the hex. Did this on the lathe so if you don’t have one, or a friend with one, you could do it with a grinder. Also shortened the tee back to the ridge. soldered together and a little paint, good for the life of the car.

    I will be replacing the lower one too but the fittings are a little differn't I will post the the info for it also.

    I suspect that all the factory CNG fords may have a similar set up so carefully check them, and if they look like plastic go buy some fittings and be ready to do some soldering before you poke around too much.

    Attached Files
    Last edited by turnintires; 05-24-2010, 08:37 PM.

  • #2
    Re: Caution Crown vic and Ford owners, avoiding coolant volcano

    here are the rest of the pics
    Attached Files
    Last edited by turnintires; 05-24-2010, 08:43 PM.


    • #3
      Re: Caution Crown vic and Ford owners, avoiding coolant volcano

      One thing we all might consider, when the coolant level drops below the temperature sensor, the temperature sensor is no longer accurate so it will not accurately reflect engine temperature. The only way the temperature gauge will change its reading until the temperature engine block goes up -- and that is too late. The bottom line is that when you see a big coolant leak shut down the engine. Hope yours not damaged.


      • #4
        Re: Caution Crown vic and Ford owners, avoiding coolant volcano

        That is exactly what I was thinking, the temp sensor is on the intake, and fortunatly the hose that I lost was on the down stream side of it. so it appears that because it was only about a minute or so from when it blew to when I stopped I think i just emptied out the tank heater core and part of the rad. I am glad the wife wasn't driving it, she may not have noticed the gush of coolant.
        Last edited by turnintires; 05-30-2010, 12:57 AM.


        • #5
          Re: Caution Crown vic and Ford owners, avoiding coolant volcano

          Thanks for this thread, it helped me isolate the problem on my 2001 CV. In the morning I would drive for about 8 miles, the temp gauge would stay on dead cold. Somewhere between 8 and 10 miles it would ramp up to pegged and the red temp over heat light would come on. Coolant would be blowing out of the radiator cap, then like magic the temp would go down to the normal range and life would be good until the car was cold again, then it would do it again. My first thought was the thermostat, replaced it and still had the problem. Yesterday, after filling it with coolant I drove one block and it was gushing again. I could also hear what I thought was air in the cooling system (inside the heater core), like the radiator wasn't full. I tried purging the air, no luck. Meanwhile every morning the fuel gauge would read empty and as I drove it would slowly climb to full. Then the dreaded thing that no CNG owner want to hear, my wife came out and said "I smell gas". So I know gas is leaking and my cooling system is jacked. Those two don't come together except in the cylinder, maybe a blown head gasket and a leaking injector? So I'm going after the thermostat (again) in case I got a bad one and to my surprise I have bubbles of CNG coming out of the cooling system.

          It turns out the bad boy is the CNG heating system down under the car by the fuel shutoff. Seems the gas will freeze the valves and pipes if it doesn't get heated. No bug deal, I'll just pull it out and replace it. Ha ha... A quick trip the Ford dealer and the parts guy starts laughing, there are no replacement parts for it and it only comes as an assembly. The price was $3000! Yikes, so I pull it out and the problem is a small rubber o-ring that cracked and let CNG into the cooling system. I'm going to try generic O-rings to seal it up and if that doesn't work I'm going to epoxy the nut into the housing (since there are no serviceable parts inside anyway).

          Does anyone know where I can get CNG rated O-rings? Thanks for listening...


          • #6
            Re: Caution Crown vic and Ford owners, avoiding coolant volcano

            Use 90 durometer Buna-N o-rings for CNG. If you do not specify 90 durometer, they will give you the softer 70 durometer.