Question about 1991 Subaru Loyale

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1991 Subaru Loyale- oil in air intake

What would cause oil to be sucked or injected into the air intake. We thought the catalytic converter had failed and replaced it. The engine ran fine for a while. We had only driven a short distance when it began to run rough, got some pinging and a large amount of oil smoke ane the engine quit. It will just barely start but not run. Should we remove the PCV system and clean it out and replace the PCV valve? Would that much oil burning cause the Catalytic converter to fail again the quickly?

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  • rlappala Nov 14, 2008

    146K miles. We checked compression: 150, 150,150,120. so I wouldn't think it is blowby. How would we know? My son bought this car (his first) and this same thing happened on the way home. :-(
    I had my mechanic check it out and he said the cat was plugged. He had disconnected it and it ran fine. When we put a new (used) one on, it ran fine in the garage but did the above when driven on the road. I am thinking that we should remove the PCV system and clean it out and replace the PCV valve before replacing the cat again. There is quite a bit of oil in the intake. Thanks for your help.

  • rlappala Nov 20, 2008

    We have had a recurring problem of the excessive oil in the air intake. We checked the compression again. Left side is 140-140; right side is 80-80. The right side increased to 160-100 when we squirted 30wt oil into the spark plug hole and tested again. Does this clearly indicate totally failed rings? It seems odd that both cylinders on the same side are low but only one came up significantly when tested 'wet'.
    We really would like not to have to sell this car for junk. It is in good shape cosmetically and everything else checks out. Does anyone know where we might find a 'good' used engine' It makes sense if we can find one for $500-$600 but not if it will be $1100 or more which is what a guaranteed longblock crate engine would be.
    Any advice?


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There are only a few things that cause oil in the intake, most common is a plugged PCV (Positive Crankcase ventilation Valve), this causes pressure to build from the combustion process and forces oil into the air cleaner/air intake system, and in some cases out the oil seals, another issue is excessive engine blow-by, this is when the piston rings don't seal anymore and the pressure once again builds and forces oil into the air intake, the last and easiest to fix is an overfilled crankcase. Excessive oil burning of any kind will destroy the catalytic converter in a short period of time. How many many miles on the car, does it have excessive blow-by?

Posted on Nov 14, 2008

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  • yadayada
    yadayada Nov 14, 2008

    One other issue is a hole burned in the piston from severe detonation, this kind of sounds like it might fit, do a compression test to find out for sure.

  • yadayada
    yadayada Nov 14, 2008

    120 PSI is low, that is most likely a factor. To check for blow-by take the oil fill cap off with the engine running, there should not be any significant smoke or pressure present, do this with the engine hot.

  • yadayada
    yadayada Nov 20, 2008

    Sounds like you have a scored cylinder(s) or broken or collasphed oil control ring, but it makes no difference, because you will need to rebuild/replace the engine in any case. They make exchange engine long blocks, a long block comes with rebuilt cylinder heads and is by far your best choice.


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My Pontiac grand prix se has no power

Where to start,
- Check exhaust
-- Blueish smoke, Could be Fried Cylendar Rings, Verify With Compression test - Also check if the oil level is going down
-- White Smoke, Could be spark plugs, wires, or coil pack
--- Check oil for a white or brownish foam, if so head or intake gasket.

- if 3.4L, intake gaskets are a common issue, sometimes you can hear it sucking if you accelerate from the throttle body. (Be carefull, moving parts!)

- See if vehicle is having a problem with climbing over a certain RPM, If so
-- Plugged Fuel Filter
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- If automatic
-- See if transmission is kicking down a gear during harder acceleration.

Also note that a bad TPS (Throttle Position Censor) located on the throttle body can cause this as well. Often felt as very poor acceleration or studdering during acceleration.

Failing O2 censor can cause an issue like this as well, unhooking the censor completely will put the car in a failure default setting that will allow it to operate close to normal, but make sure you replace it if it has failed to avoid replacing Catalytic Converter as well.

Start there, but it could be many other things as well. If check engine light is on, get it read. or pick up a code reader and read it yourself.

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My aurora did the same thing, and I did replace the secondary air injection unit, mine has the 4.0 v-8 and the location of the one I changed is near firewall in the middle above the valve cover/coil over unit. see if the vacuum line popped off or melted that's what mine did, and exhaust was escaping did cause veh to perform poorly, and couldn't get but about 65 mph tops on the interstate. changed the rear one and problem solved. however it could be caused by a plugged catalytic converter which could cause the air injection to go bad. I took my catalytic converter off and cleaned/knocked it out. but depending on your local codes if your county requires the emission testing you would need to replace the catalytic converter. Luckily my county does not.

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What is wrong with the car it shows me p0432 code main catalyst efface below threshold (bank2), how do I fix it cause the engine light goes on and stays on?


The code means what it say. The car computer compared the data on amount of air/fuel injected in cylinders with the emission O2 reading from the Oxygen sensor in the air intake (the one after cat converter), and decided that the catalytic converter is not doing its job because emission is too high.

In some case the problem is occasional. Try resetting codes by disconnecting battery terminals (make sure you have stereo code if needed).

If the code comes back, then there are several parts to be tested before replacing cat converter.

Many times the problem is the converter itself. before replacing the converter the mechanic must check for problems resulting in wrong air/fuel mixture, as these may trigger p043.

Sensors in the air intake and air intake itself must be tested, check MAP sensor and intake structure for leaks. Replace air filter. Check the vacuum for leaks. Check IAC. Check O2 sensors.

If there is no problem under the hood, check the state of other parts comprised in the exhaust system and eventually replace the cat converter.



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1991 Subaru Loyale Wagon. Fuel injected. Whern car gets warm from running, or sitting in sun and cabin temps get above 70F or more, car cranks but won't start. Been 3 years or more of this. Replaced...

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Hi my subi surges if i gas it fast but if i ease the gas on it picks up sweet as

Fuel filter may be cause but more likely your catalytic converters are clogging up on you! Just had them done on my moms 96 Legacy and it takes off like new. I would take it to someone you trust for the testing to be sure before you replace for they are not so cheep but they do go bad and thats how hers started. Here is a some info to get checking if this is it.

The catalytic converter is our main line of defense against air
pollution, so it's important to make sure it is functioning efficiently and passing exhaust without creating undue restrictions that might reduce performance, fuel economy or emissions. That's one of the reasons for periodic vehicle emissions testing. If the converter isn't working, you won't pass the test.
If the your converter is plugged, it will create a restriction in your exhaust system. The buildup of backpressure will cause a drastic drop in engine performance and fuel economy, and may even cause the engine to stall after it starts if the blockage is severe.
The easiest test for converter plugging is done with a vacuum gauge. Connect the gauge to a source of intake vacuum on the intake manifold, carburetor or throttle body. Note the reading at idle, then raise and hold engine speed at 2,500. The needle will drop when you first open the throttle, but should then rise and stabilize. If the vacuum reading starts to drop, pressure may be backing up in the exhaust system.
You can also try to measure backpressure directly. If your engine has air injection, disconnect the check valve from the distribution manifold, and connect a low pressure gauge. Or, remove the oxygen sensor and take your reading at its hole in the manifold or headpipe. Refer to the backpressure specs for the application. Generally speaking, more than 1.25 psi of backpressure at idle, or more than 3 psi at 2,000 rpm tells you there's an exhaust restriction.
If there appears to be an exhaust restriction, disconnect the exhaust pipe just aft of the converter to relieve pressure and recheck the readings. CAUTION: The pipes will be hot so wait awhile for things to cool down. If vacuum goes up and/or backpressure drops, the problem isn't not a plugged converter but a plugged muffler or collapsed pipe. If there's little or no change in readings, the converter is plugged.
Just because a converter is passing gas doesn't mean it is okay. If the catalyst inside is contaminated or worn out, high carbon monoxide (CO) and/or hydrocarbon (HC) readings will be present in the exhaust. If you have access to a high temperature digital pyrometer (or an oven thermometer will do), check the converter's temperature fore and aft. A good converter will usually run 100 degrees F hotter at its outlet than its inlet. Little or no temperature change would indicate low efficiency, or a problem with the converter's air supply. Converters need supplemental oxygen in the exhaust to reburn pollutants, so if the air injection system or aspirator valve isn't doing its job the converter can't do its job either.
Check the air injection pump, belt and check valve. If you suspect that the check valve is allowing exhaust to flow backwards, remove it and blow through both ends. It should let air pass in one direction, but not in the other. Examine the air injection manifold, too, because it tends to rust out and leak air. Check the diverter valve to make sure it is working correctly, too. It should be routing air to the converter when the engine is at normal temperature.
On engines with aspirator valves instead of air pumps, you should hear and/or feel the fluttering of the internal flapper as the engine is idling.
Causes Of Converter Failures Fouling, clogging, melt-down and breakage of the ceramic substrate inside a converter are common conditions that can cause problems. Plugging is usually the end result of a melt-down, which occurs because the converter gets too hot. This happens because the engine is dumping unburned fuel into the exhaust. The excess fuel lights off inside the converter and sends temperatures soaring. If it gets hot enough, the ceramic substrate that carries the catalyst melts.
The unburned fuel may be getting into the exhaust because of a bad spark plug or valve, but an overly rich air/fuel mixture is another possibility. In older carbureted engines, a heavy or misadjusted carburetor float may be the underlying cause. But on newer engines with "feedback" carburetion or electronic fuel injection, the engine may not be going into "closed loop" (the normal mode where the computer regulates the air/fuel mixture to minimize emissions).
A bad oxygen sensor or coolant sensor may be giving the computer bogus information. A sluggish or dead O2 sensor will make the computer think the exhaust is running lean, so the computer will try to compensate by making the fuel mixture rich. A coolant sensor that always indicates a cold engine will also keep the system in open loop, which means a steady diet of excess fuel. But it might not be the sensor's fault. A thermostat that's stuck open or is too cold for the application can prevent the engine from reaching its normal operating temperature. So if your converter has failed and needs to be replaced, the engine should be diagnosed for any underlying problems before the new converter is installed.
Another cause of converter clogging and contamination is excessive oil consumption. Worn valve guides or seals can allow oil to be sucked into the engine's combustion chambers. The same goes for worn or damaged rings or cylinders. Oil can form a great deal of carbon, and metals present in the oil can contaminate the catalyst. A compression check or leak-down test will tell you if the rings are leaking, while a fluttering vacuum gauge needle will help you identify worn valve guides.

Nov 03, 2010 | 1990 Subaru Legacy

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