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CNG too hot for Nevada? Please help

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  • CNG too hot for Nevada? Please help

    Is it too hot in Nevada to run CNG cars in Nevada or am I just unlucky? I live in Logandale Nevada to enable me to live near and enjoy shared custody of my children and I commute to Vegas every day where I work. I still have to pay child support and the fuel costs are killing me. I'm also a member of the Utah Army National Guard and commute to SLC Utah once a month for drill. As such, I have purchased two CNG vehicles both of which are now inoperable and sitting at two different dealerships. My CNG bi-fuel Chevrolet Cavalier is sitting at a chevrolet dealership in Vegas right now waiting for me to decide if I want them to replace a warped head which they will guarantee for 12 mos or 36,000 miles at the tune of $3,200. If I have them do so it will be the third time I've paid for the same work on the same car. The local and only garage where I live who twice did the same work tell me it is an underlying problem causing the overheating and it will void whatever warranty the dealership gives with their work. I don't know if they are coveing up for the shoddy work they twice did before, or telling truth. I first paid them $1,300.00 to replace the head gaskets about 5,000 miles ago. Then within a few hundred miles I paid them to replace a water pump when it was discovered it was still overheating. When that didn't fix tje overheating they took the thermostat out as a "band aid" to fix a problem they apparently did not know how to fix. As a result, it overheated anyway and instead of replacing the head gaskets this time they decided to put in a new head. Within a few thousand miles it overheated again and warped the new head. Before I had it towed to a Chevrolet dealership I first called the local garage that had done the work and they said they were done with the vehicle and won't even try to fix it despite having paid them over $2,500. Another garage told me I need to take them to small claims court. Any suggestions and has anyone else had the same problems with their CNG Cavalier? I need to figure out if the CNG cars in Nevada just run too hot or what because I have a CNG Ford Contour that I've also replaced head gaskets on only to find the compuvalve went out shortly after and is at a Ford dealership waiting for a compuvalve that been on back order and will be for who knows how long. I learned about the compuvalve problems with the Contours after the fact and that's why I chose to purchase a Cavalier instead. Any suggestions or help would be GREATLY, GREATLY, GREATLY, appreciated!

  • #2
    Re: CNG too hot for Nevada? Please help

    Let me put my amatuer mechanics hat on... If a real mechanic speaks-up I will derfer to them.

    I don't know anything specifically about the Cavalier. I am not sure which you are claiming to cause the other. It sounded like you are blaming the head problems for the overheating.

    Normally it is the other way around. And this is not specific to CNG. Severe overheating will cause your heads to warp. Just replacing the gasket at that point is not enough. You would need to at least have the head surfaced to make sure it is flat, and possibly the block as well.

    If you have warped heads or block, it could allow a gasket failure that could cause overheating due to compression gasses and blow-by into the cooling system. But, it is much more likely overheating caused the initial failure and probably subsequent failures as well.

    In my opinion, your primary focus should be resloving the overheating problem.

    Nevada summers can be a good test of the cooling system for sure. Good luck.

    Comment


    • #3
      Re: CNG too hot for Nevada? Please help

      I would agree with the prior poster about the cooling system problem. The problem is with the engine design--both gasoline and CNG Cavalier's have a head gasket issue (if it overheats). Proper installation of the replacement gasket including a check of the block and head surface is critical to gasket life. Running a flat file over the head and block deck surface will let you know where the problem is. There are better head gaskets and head bolts available in the aftermarket then the original GM parts. Also (I know this will start another issue ) get rid of the Dex-Cool antifreeze and flush the system completely. Check that the radiator isn't clogged from the Dex-Cool--replace it if there is any question. Use the regular old "green" antifreeze at a 50/50 mixture and change it every two years. Check the fan temperature switch to be sure it is coming on at the right time. You should have no further problems. If you ever notice the temperture gauge climbing up towards the red, stop the car, let it cool down and then find what is causing the problem--that will prevent future issues. Remember, there are thousands of these cars running around with no head gasket problems and even though Nevada is hot, the car will work in that enviornment. BTW--anybody who removes a thermostat to fix a overheating problem has no clue about how a cooling system works--if it was a dealer, his action should be reported to the manufacturer--they are just guessing. Head gasket? water pump? thermostat? If the fan is running--bet its a plugged radiator--Thanks Dex-Cool .

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      • #4
        Re: CNG too hot for Nevada? Please help

        Thank You both!!! I agree the primary focus should be fixing the overheating problem. Am I wrong in expecting the garage to find that out for me? After all, overheating is what I brought it to them for in the first place. FYI the most recent overheating that warped the new head happened only one time since the new head was replaced. And, it was sudden. The needle began approaching the red and was in the red before I could even get off to the side of the road. The local garage is saying that's why they think it's CNG related and I should have taken it to someone who works on CNG cars yet they didn't tell me that before they took my money and then told me my car was fixed. I know it's a judgment call that I'm going to have to make on my own, but what are your opinions, please. Should I replace the motor altogether or trust the Chevrolet dealership will honor the warranty they are willing to give on their work? Your reply's have made me realize the dealership is charging me almost $700.00 for having to tear down and diagnosis of a warped head but they have not given me a diagnosis for what is causing the overheating. Just a quote for what they will charge for another new head.

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        • #5
          Re: CNG too hot for Nevada? Please help

          P.S. before the local garage replaced the new head I sat in the garage for four hours watching them test the fan, the direction of the flow in the radiator, etc. and they said they were sure the radiator was not plugged. That's when they removed the thermostat as a "band aid" and told me I wouldn't need it because the thermostats only function was to allow the heater warm up sooner and it's warm enough in Nevada.

          Comment


          • #6
            Re: CNG too hot for Nevada? Please help

            OK--lets talk about the thermostat a little. It's there to get the engine to operating temperature (not just the heater) quickly and to then regulate the temperature. Because the engine is computer contolled, fuel mixture (i.e. the "choke" in old cars) is based on engine temperature. Removing the thermostat will run the engine in a rich condition longer then needed, possibly delaying convertor light off, fouling plugs etc. What most people don't realize is that the thermostat is also a flow regulator for the cooling system. Look at one, the opening the water passes through is smaller then the hole it goes into. This slows down the rate at which water passes through the radiator. There is a speed at which the water must flow through the radiator to be able to transfer the most heat to the air---believe it or not, if the water passes too fast, it is not in the radiator long enough to allow the heat transfer to take place and therefore will not cool as well. In addition, many vehicles can get into cavitation problems with the water pump at high flow rates. If you really feel you need to run without a thermostat, take the guts out of it and replace body of it back in the hole. It is not possible to completely remove the Cavalier thermostat anyway as it supports the rubber ring that seals the water outlet to the engine . Back to your problem. What does the temperature guage say? It should climb quickly to around 195 degrees at which point the thermostat regulates. If the car is parked, it should level off at that point and then climb again (A/C off) to a slightly higher point at which time the cooling fan should start. The fan should be on when the A/C is running. If the guage reading climbs again, when does it start? Driving or stopped? You say the radiator isn't plugged but how did they determine that it is not? Has anyone looked between the radiator and the A/C condensor to make sure there isn't anything blocking the airflow? Is the little rubber spoiler in place under the radiator? Are you running a 50/50 mix of antifreeze? What does the inside of the plastic tank that holds the antifreeze look like? Is it clean or is there some brown looking stuff on the sides of it? Finally, does this only happen on CNG and not on gasoline?

            Comment


            • #7
              Re: CNG too hot for Nevada? Please help

              If the car is otherwise in good shape, if it were me , I would fing a good guaranteed used engine . I 'm not a mechanic but I have seen a lot of folks spend a lot of money on head gasket repairs , and never got a lasting fix.

              Just my $ .02 worth.

              Comment


              • #8
                Re: CNG too hot for Nevada? Please help

                An engine replacement would not necessarily corrrect a cooling problem.

                The Dex Cool is a major consideration. My father-in-law had an issue with it in his mini-van. He noticed coolant levels going down with no apparent leaks. He found out the Dex Cool had eaten through the intake manifold gasket and was allowing coolant to get into the engine. Luckily he caught it and had it repaired before serious engine damage was done. He did a bit of looking around on the internet and found a lot of discussion about Dex Cool. Get rid of the Dex Cool.

                I really wonder about the competance of your shop. My small independant mechanic used an infrared scanner on my radiator to be able to see the radiator was blocked.

                Comment


                • #9
                  Re: CNG too hot for Nevada? Please help

                  Phoenix and St. George have ngv's with no problems and are equally as hot as logandale. The dexcool also makes sense because the newer chevy malibu's are notorious for intake gasket failure. Don't know if you have one but make sure you don't have a bra on the front of the car in 100+ temperatures they don't allow enough air on small cars.

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                  • #10
                    Re: CNG too hot for Nevada? Please help

                    There has been some great information given here. The only thing I have not seen is to pressure test the cooling system - especially after it had been supposedly been fixed. I should hold pressure. Anybody check the radiator cap?

                    With aluminum head, if the engine blew a head gasket the head should be surfaced -- no question. I believe in the file too. The head may need to be hydrostatically tested for cracks. Also have a machinest, that knows, check the deck thickness of the head and make sure it not too thin from machining.

                    I agree with Larry, 50/50 mix of glyocol and distilled water. Make sure the lower radiator hose is not clasping at higher RPM (no stiffener inside the hose). Make sure engine grounds are good to reduce electrolysis. If you don't change the coolant, it will become an electrolyte.

                    Whoever said it was right CNG will not cause an engine with a good cooling system to overheat. All you're losing with CNG is cylinder cooling from the vaporizing of the fuel -- going from a liquid state to a gaseous state. If that causes a problem, then you have a marginal cooling system.

                    You may want to consider a good used engine. If an engine is overheated too badly the rings can loos the elasticity (ability to hold against the cylinder wall), and you may end up with an oil burner -- CNG a hard carbon in the cylinder don't mix.

                    Hope this gives you more to condisder

                    Larrycng

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                    • #11
                      Re: CNG too hot for Nevada? Please help

                      Yes Larry, there has been some good information here. I'm going to give it to whomever I decide to finish the work, and I hope others here can benefit from it as well i.e., Dex-Cool. I still don't know what I should do but the information I've gotten here has enabled me to approach the garages as an educated consumer. For example, the postings here have prompted me to ask the service manager why the $700 they want to charge me for merely diagnosing that the head is warped doesn't tell me if there's an underlying problem causing the engine to overheat. He told me they were unable to make that determination because the car had no fluid in it when the tow company delivered it to them. When I told him I'm concerned about laying out money to have another new head only to find an underlying problem would void the warranty on their work he said he would talk to his mechanic and get back to me. He was supposed to get back to me yesterday and he hasn't. I've also talked to the owner of the local garage who is also going to talk to his mechanic and get back to me by tomorrow. I'll let you all know the results.

                      Comment


                      • #12
                        Re: CNG too hot for Nevada? Please help

                        Best of luck to you.

                        At this poiint it would be difficult to diagnose a cooling problem without a running engine. Unless you had them go ahead and pull the the radiator and had it rodded along with checking/replacing the coolant pump. Of course they would be shots in the dark and could possibly be an extra expense.

                        LarryCNG is correct in pointing out you could have other engine damage as well depending on the severity of the overheating. It is possible for valves to warp (should be inculded in changing the head) or bearings in the lower end to sieze and/or spin (not good).

                        Generally two things cause overheating

                        1.) Creating too much heat for the cooling system to handle - bad timing, engine overload (even an alternator siezing up), trasmission slipping etc.

                        2.) A cooling system that is not properly getting rid of the heat - blockage (radiator, thermostat not opening, as Larry suggested, it is even possible a lower hose can collapse due to suction), water flow (pump impeller corroded etc.), slipping belt (this is a very simple fix which is sometimes overlooked), air flow (on older cars the fan clutch, on newer the elctric fans - or other blockage or poor routing of the air flow).

                        Hope this gives you some other ideas. There may be a few I left out.

                        ..

                        Comment


                        • #13
                          Re: CNG too hot for Nevada? Please help

                          1 more small idiotic item the radiator cap must vent properly for system to work..........could gum up after a head gasket issue
                          Last edited by happily; 04-04-2009, 10:09 PM.

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                          • #14
                            Re: CNG too hot for Nevada? Please help

                            As an update, the Chevrolet Dealership discovered the hose to the bottom of the radiator was missing and allege the local garage that fixed it must have either not put the clamp on or didn't put it on tight enough. I'm guessing because they were only charging me for the parts for the second head/head gasket repair, and no labor they were in a hurry and got sloppy. Only time will tell I guess. In the meantime, I'm out close to 5k :-(

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                            • #15
                              Re: CNG too hot for Nevada? Please help

                              opps with no coolant the rings got very hot if the head is still on the motor I would run a comp check dry than wet if low readings with dry and they come up alot wet the rings are done just my 2 cents worth good luck and I would have a talk with the first shop and if they dont want to make good take them to small claims court if they left the hose clamp it is there fault

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