MonkeyPop Posted January 27, 2006 Share Posted January 27, 2006 Hi all, new to your very nice forum. Wife and I bought our 2000 OBW new. Pretty sure it's the SOHC. From the getgo, I noticed that coolant level would go down between oil changes. Dealer said (and I'll paraphrase), "well, it's not normal, but it's not unusual". Car has never had overheating issues, green puddles, gunk in the oil or coolant, loss of power, loss of fuel economy, rough running, or fuel mixture probs. A few green drips now and then is about it. Scheduled maint. performed pretty regularly, and "magic coolant conditioner" added within week of receipt of letter. Fast forward to 162,000 miles. "Check Engine" light came on, took it to local dealer. He says it needs a new catalytic converter, and the head gasket is leaking: estimates about $2,700 to repair. Yikes! Questions I haven't been able to find answers to: Does the external leak with the SOHC get progressively worse and/or is it indicitave of imminent failure (i.e. leaking into cyls or dumping coolant entirely or cracking block)? Or is it more of an enviromental concern, enticing curious kittens to lick up the occasional drops and having to add 8 ozs of coolant every 5,000 mi? Does the on board computer thingy actually monitor the catalyzing performance of the converter, or does it measure exhaust temperature at different points in the exhaust path? Or has my Cat (Cats?) just reached the end of its expected life, and the service guy is making an educated guess as to why the check Engine Light is on? Also, do the heads need to be removed to "Inspect" the valve clearance? Any advice or thoughts would be most appreciated. Thanks! Quote Link to comment Share on other sites More sharing options...
2X2KOB Posted January 27, 2006 Share Posted January 27, 2006 The engine computer monitors the voltage output of a second oxygen sensor that is installed behind the catalytic convertor, which measures the oxygen content of the exhaust gas stream and therefore the efficiency of the catalytic convertor. That's the plan, anyway. There's some belief that, on this specific car, the computer's parameters are set to be too sensitive which results in frequent setting of the check engine light with the P0420 code. When I had the same problem (at 150k) a new oxgen sensor fixed it. You might have a bad cat, but a new sensor is a lot cheaper. If you can turn a wrench and splice wires, you can try a $70 generic replacement first. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 27, 2006 Share Posted January 27, 2006 i agree with replacing the O2 sensor first. i wouldn't replace the cat converter just yet. had they replaced the cat it probably would have fixed the problem because they would have installed a new O2 sensor with it. i'd probably go to a different mechanic too. head gaskets can last a long time while leaking. they can also fail. i've seen dodge neon's (the older ones go through headgaskets on a regular basis) and older subaru's go many 10's of thousands of miles on slowly dripping head gaskets. in two different cases i put 30,000 or more miles on a leaking headgasket before i finally replaced it and they never failed completely. one was leaking internally and the other was external. the internal leak, i still have the head and would post a picture if i could, but there was significant wear of the head for a very small area where the leak was occurring. it is repairable but i just replaced with a new head since i have extra motors. this is not recommendable but i would choose this option before getting a new car payment (not that i'd ever buy a new car, but if i had too do that.) surely each case is different, but my external leak never got worse, just a few spots of green on the cross member (under the motor) every now and again. neither cases had oil/coolant mixing. the internal leak did eventually get worse very quickly, the external leak never got any worse before i repaired it after a long time of waiting. best bet is to replace the gasket of course. if it starts to get hot though you better quit driving or it will blow in short order. my coolant system is typically in excellent shape so i keep my cars running cool. the heads do not need to be removed to inspect the valve clearance. i believe the dealer charges quite a bit for this.....$300 or something. Quote Link to comment Share on other sites More sharing options...
friendly_jacek Posted January 27, 2006 Share Posted January 27, 2006 The engine computer monitors the voltage output of a second oxygen sensor that is installed behind the catalytic convertor, which measures the oxygen content of the exhaust gas stream and therefore the efficiency of the catalytic convertor. That's the plan, anyway. There's some belief that, on this specific car, the computer's parameters are set to be too sensitive which results in frequent setting of the check engine light with the P0420 code. When I had the same problem (at 150k) a new oxgen sensor fixed it. You might have a bad cat, but a new sensor is a lot cheaper. If you can turn a wrench and splice wires, you can try a $70 generic replacement first. You are all correct except that 2000+ uses A/F ratio sensor and not an everage, cheap O2 sensor. The good news is that front OEM is like $60 and rear OEM is more like $160 though. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 28, 2006 Share Posted January 28, 2006 Have you added the Subaru coolant conditioner stop leak? It could help your engine. The heads don't have to come off for a valve adjustment on your car. I have a 99 Forester with 123,000 and I just changed the front oxegen sensor on a code PO420. It has kept the check engine light off for a month so far. I don't know if this will cure the po420 permanently as I suspect the cats are tired, but what the heck it was cheap and easy and the light is off. Oxegen sensors are tired after 100,000 miles anyway so this is just maintence at the worst. If your car does not lose too much coolant you may be ok keeping it full. Some folks seem to run these for years with a small leak as you seem to have. The woman I bought my car from said she always had to add a bit of coolant. Quote Link to comment Share on other sites More sharing options...
MonkeyPop Posted January 28, 2006 Author Share Posted January 28, 2006 Thanks for informative responses. Had a long discussion with the service manager, who said that at 160,000 miles, it was "wise" to replace the head gaskets, and that the Cat surely needed replacing as it is nearly impossible to replace the O2 sensors as they just break off in the Cat and ruin it. I asked him if they would replace the gaskets with the "new, leak-proof" gaskets, and he gave me a rather condescending reply that gaskets are never leak-proof. So I asked him if they would replace the faulty factory installed gaskets that prompted the "coolant conditioner" campaign with the newer, improved version. He admitted that yes, there was a newer gasket that the factory now specs. Anyway, told him I'd think about it, and took the car to a friend who runs an independant German car shop. We put the OB on his smog machine, and the Cat is working fine. Put the car on the rack, looked at the O2 sensors, said he could replace them in 5 minutes. He thinks one of them might be "lazy", but as car is still running fine, just leave it as is for now. Looked at the driver's side head, shows evidence of a tiny ongoing leak, which sometimes collects in the trough formed by the cross member, and dribbles onto the exhaust occasionally. He recomended I just add some more sealant/conditioner to the cooling system, and keep an eye on the temp gauge (as both my wife and I were trained to do by our fathers as part of standard driving procedure). Thanks again for the input! Quote Link to comment Share on other sites More sharing options...
cookie Posted January 30, 2006 Share Posted January 30, 2006 On a 160,000 mile engine I think I agree with your buddy. I live in San Mateo and of course we don't have salt, but it took me very close to the five minutes your friend estimated to replace the front ox sensor.Let us know how adding more conditioner works out becuse a lot of folks may have to go this route in the next few years. Being a cranky ex-mechanic I had the latest gaskets fitted and run the conditioner too. Quote Link to comment Share on other sites More sharing options...
nipper Posted January 31, 2006 Share Posted January 31, 2006 i think your buddy is dead on and the dealer is yanking you. O2 sensors are replaced all the time, the trick is to have the exhaust warm and be careful you dont burn yourself. External leaks if its not pouring out dont sweat it. You know you have it and understand how to deal with it. Just add premix AF and youll be golden. nipper Quote Link to comment Share on other sites More sharing options...
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