Hi, I need help to narrow down the exact cause of converter freezing problem on my EL 1997.
My observations and the car history are listed here.
1) Got LPG Fitted in 2010 at 120000 km, now it is around 188000km.
2) Looks like the previous owner modified the thermostat (drilled a hole etc) as the engine temperature indicator always stays close to “C” and also;
** The radiator top hose warms up within a minute or so after engine is started.
** The small coolant hose from the top of thermostat housing is always running coolant back to coolant reservoir.
3) I always keep coolant reservoir level close to the maximum.
4) For 2 years no LPG problem.
5) I always start on petrol to warm up for 3-4 minutes.
6) While Engine running on petrol the LPG converter heats up quite quick 3-4 minutes
7) The converter starts cooling down when engine is converted to run on LPG.
8) In 20-25 minutes of suburban driving I can see frost building up on converter.
9) On highway driving the converter thickly ice up in 30 minutes.
10) Converting engine back to petrol starts melting the ice in a few minutes.
11) Engine Head Gasket, water pump, radiator checked and are OK.
12) Can’t be an air lock in the converter or coolant lines as these run very hot on petrol.
13) I checked the converter in/out coolant lines and they are clear.
14) I also checked water flow through converter, it’s ok.
15) Can’t blame the thermostat as for 2 years no LPG converter freezing problem.
16) Converter is installed parallel with heater, Teed in before the heater Tap so the condition of heater core should not be an issue.
PLEASE HELP, Thanks Rick

Try item 15, change your thermostat for a new one.

I'm with SWC and make sure you get an LPG one... There is two types for the these cars...

ford-4l-and-6-cylinder-f1/ef-temp-ranges-t124775-15.html

Cheers,
Tim

ford-lpg-hydrogen-hho-cng-conversions-f44/freezing-converter-t125734.html