Automobile Question (autogas/LPG related)

W2

This is gonna be long, by the way, I'll provide a TL;DR at the bottom.

I am hoping someone here with a little more mechanical knowledge than myself could support a theory that I've had re: my car. Also, you know, feel free to point out any little holes in my knowledge.

I drive a 1990 Ford Falcon EA, it's dual fuel petrol and LPG (autogas I believe is the American term for it.)

I think I may have a problem with my head gasket (and I am going to get this checked out/fixed regardless), I think it might be leaking, as the car is losing water and there is no visible leak underneath the car or in the motor that I can see.

My problem, though, is that the car is losing a fuckload of water, and I imagine that a leak in the headgasket would not cause the car to lose so much under normal operation.


Now, as I understand it, the way a car is cooled (at its most basic level) is that water flows through the motor. Heat transfers from the motor to the water, which then flows into the radiator which cools the water with the aid of air travelling over the radiatior from the front of the car. The cooled water then flows back into the engine, the cycle repeats. Am I correct so far?

With an LPG fuel system with a converter, however, the heated water from the engine is required to flow through the converter to prevent the very cold liquid gas from freezing all the moisture in the air around it before it can vaporise and travel into the carburetor. The heated water from the converter I assume just flows back through the radiator and into the engine.

On startup, running on LPG, I have only been able to travel a very short distance before the converter freezes solid.

I have been running the car on LPG only for months now, for the last couple of months the car has not started or run on petrol at all, a problem I only just rectified today by replacing the carburetor and the related wiring. Runs okay on petrol now, and after running on petrol for a few minutes to allow the water in the cooling system to heat up properly I can switch over to LPG and run without any freezing.

My theory, then: the converter freezes solid and all the water in the system before the converter has nowhere to go except to leak out at whatever point I'm actually losing water. Under normal operation, some water will leak, but since the converter essentially dams the flow, it all just leaks.

Does that sound solid?






TL;DR - could a freezing LPG converter exacerbate water loss caused by a leaking head gasket.



Thanks very much.

Zeon

Ok, i had to look up what LPG was because ive never heard it refered to as that before, or autogas either. Here we just use the term propane, although its not entirely propane.

Anyway, about your problem, i dont think thats the case. If what you are describing was happening, youd be overheating that engine fairly quickly since the coolant wouldnt be circulating at all.

Best way to tell if you have a leak or youre burning the coolant is to start the car, let it idle up to temperature, then sit there and rev the engine. If you see water pouring out from somewhere under the car, there's youre leak. If you see clouds of white smoke behind you, youre burning coolant. To find the source of a leak, you can buy dye from an autoparts store and add it in with the coolant. It will leave a bright streak wherever youre losing water.

On the other hand, theres only 2 real reasons why you would be burning coolant. Blown headgasket, or cracked block. Both have the possibility to cause massive coolant loss, depending on the severity. However, both are fairly noticable in terms of power loss and throttle response.

Unfortunately i dont have any experience at all in dealing with propane/petrol hybrid cars, so im not sure if maybe theres something i dont know about how the LPG system runs that could be causing a massive coolant leak. The only thing to remember though is that the coolant needs to be going somewhere, so its either going through the engine and coming out in your exhaust, or its draining out from the bottom of your car.