Catalytic Converter

Neighbor has a beautiful 2003 4.2L. Always garaged. It overheated, and he made the mistake of letting a friend mess with it. They removed the thermostat among other things. Net result is that they blew the head gasket. Coolant did not enter the oil passages but did get into the combustion chamber, which explained all the white exhaust. The consensus is that not only is the engine ruined, but so are the catalytic converters. He is getting ready to scrap the car which tears my heart out. Putting in a used engine might pencil out if I could get away with using EPA cats instead of CA approved units [CARB certified].
This being an OBDII vehicle, as I understand it the car is just plugged into the smog machine. If it does not set a code, it passes. Visual check of the engine for mods.
I support the war on emissions. I’ve seen the results of several tests that show that while CARB cats may produce slightly lower exhaust emissions, EPA cats produce comfortably passing numbers. I hate to see such a beautiful car wind up in the wrecking yard because it’s 2 cats cost almost $3k.

I am not sure that this is as dire as you suggest. This car may be saved with new head gaskets and replacement of the removed parts. Get it running properly with the existing cats they may not be damaged by the vaporized coolant they injested. I have heard that CA approved cats are very expensive, a friend had his stolen from his Toyota pickup AND Prius and was told they had to be replaced with CA approved ones to pass the visual inspection. Not sure if every smog station goes to that length however. CARB rules can be a real PITA, I moved out of state.

I spoke to a former colleague of mine who worked for Jaguar Land Rover for many decades in the Southern California district and he does not believe the cats would be damaged by coolant. He further indicates that with his two private cars he has never had one put on a lift during a smog check to inspect the type of converter fitted. With OBD2 cars they are simply plugged into the machine that determines if they pass. Earlier cars got a sniffer test in the tail pipe.

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Thanks for that information, John. It is extremely helpful. All my cars except my daughter’s 09 Hyundai Accent are OBD1 and got the full treatment. One guy went so far as to look underneath my 90 Buick Reatta. I did smog her Hyundai and was surprised at how quickly it went. Warmed it up, plugged it in, visual of the engine compartment, done.
I took the Jag to 2 mechanics. Both ran compression tests. Both said 2 adjacent cylinders had none [both tried putting some oil in the cylinders to see if was rings; no change]. One confidently said it needed an engine. The other said he would have to remove the heads and see what damage there might be, a process that would add additional cost if an engine was required.
I’m not sure if a blown head gasket, even if it resulted in some burned valves, would result in complete loss of compression.
Now working with a 3rd mechanic to discuss the value of taking off the heads of my 135k motor to see if valve job is preferable to a $1700 used engine [supposedly with 91k on it].
As you suggest I will worry about cats after I get the car running.

Thanks Richard, keep us posted, I’ll be following this case for my education. Good luck.
P.S. I have a friend here in Eugene with a 2008 XJ, 240,000 miles and still going strong!