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Kevin C.
Kevin C., Subaru Master Tech.
Category: Subaru
Satisfied Customers: 1727
Experience:  34 years of Subaru service experience, ASE Master Technician.
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I have a 1998 Subaru Outback Limited that has been a

Customer Question

I have a 1998 Subaru Outback Limited that has been a mystery.It has had the water pump and timing belt replaced.It has a new radiator cap and coil.It will run till it gets to a certain temperature and then the idle drops to 3-400 for about 5 seconds and then it dies.It will restart when it cools,and then runs fine for another 10-20 minutes.I just did the liquid block test and it passed(not head gasket).No white smoke,no oil in antifreeze.I have had 5 different shops tell me everything from catalytic converter ,coil,O2 sensor,head gasket,and nothing!I bought the car in Feb. for $2600 and can't give it away now.I am ready to start random,y replacing sensors in hope of fixing it.The car runs great when it does,but it can;t be depended on.Can you help me?
Submitted: 1 month ago.
Category: Subaru
Expert:  david craig replied 1 month ago.

Hi Im David and thanks for visiting the site. Has any shop scanned the vehicle for fault codes? if so what are the codes and what did they do to attempt to fix them? Usually when a vehicle is acting this way it is due to an ignition component thermal breakdown failure. runs great, reaches a certain temp, shuts down, cools off starts back up.... rinse and repeat... without knowing any possible codes the most likely suspects are the crankshaft position sensor, the ignition control module and the ignition coil.

Customer: replied 1 month ago.
Autozone scanned and reported PO420:Catalyst efficiency below threshold-bank 1
Probable cause 1) Rich A/F Ratio
2) Ignition system malfunction
3) Faulty catalytic converter
I replaced the coil and it still malfunctioned.Should I replace the Crankshaft position sensor or the ignition module next. None of the shops here want to do either:one told me to see a muffler shop and to check the catalytic converter.I don't see how that would cause this problem.They charged me $40 to tell me this when I went in to get the O2 sensor replaced.
Expert:  david craig replied 1 month ago.

the P0420 code is being generated by the rear oxygen sensor. that would not cause the condition you are reporting. to get rid of that code 50% of the time would be to replace that sensor. but before doing so, i would do a back pressure test of the exhaust system to see if the cat is clogged. if so then replacement of the cat is mandatory.

Expert:  david craig replied 1 month ago.

to see if the crankshaft position sensor is at fault, this is an unusual but effective way of finding out. put some ice in a sandwich baggie and take it with you while driving the car. when the stall condition occurs take the bag of ice and hold it to the sensor for 30 seconds. then start your car. if it starts right away, replace the sensor. unless you just want to replace the sensor which i wouldnt do unless i knew it was the cause.

Expert:  david craig replied 1 month ago.

checking in to see how its going

Customer: replied 1 month ago.
Hi David. While using your tips,the car quit starting at all.Spark was good,fuel pump bad.Replaced the pumped now it starts again.Could the stopping when warm have been the fuel pump going out?It has not stopped after heating up since I changed the fuel pump! I still have to resolve the PO420 code. I will price for a back pressure check .What is a good price range to pay for that test? Thanks again.
Expert:  david craig replied 1 month ago.

absolutely. if the fuel pump has some years on it, it could overheat and start to malfunction until cooled back down. its one of many possibilities that would be hard to diagnose being that its inside the tank. i am gald you have it figured it. now for the 0420, like i said its probably the rear 02 sensor, back a back pressure test is needed to confirm. all i can say is that at my shop i charge 60.00 for one. but prices vary a lot from shop to shop.

Expert:  david craig replied 1 month ago.

checking in to see how its going

Customer: replied 1 month ago.
Hello.Thanks for checking back.I have put about 150 miles on the car and it has not quit once.It seems as though it may have been the fuel pump.Now, when I let it get real warm,there is a spewing of vapor/steam/oil? near the firewall on the driver's side.It even manages to fog the windshield up somewhat.The spewing comes in short bursts about once every 10-15 seconds.I have not been able to pinpoint it yet.I sure hope it's not the head gasket!It seems this model is notorious for blowing head gaskets.What do you think?
Expert:  david craig replied 1 month ago.

are you overheating at any times?

Expert:  david craig replied 1 month ago.

are you smelling coolant?

Customer: replied 1 month ago.
Not over heating now.I think it could be the smell of coolant.Motor would sometimes run hot until a mechanic friend tried a trick we learned on youtube.He drilled some holes in the thermostat.Something about preventing airlock due to a poor design? I am fearing head gasket!
Expert:  david craig replied 1 month ago.

have a block test do to the radiator to see if any hydrocarbons(engine gases) are making its way into the coolant.