R&R Front O2 Sensor on 97OBW 5SPD

[SuperSubaru]

So I finally put the OB on the ramps this last weekend to find out where the massive oil leak is coming from - looks like the timing cover gasket (guessing) was over torqued and pushed out. I am due for new belts anyway, so I will keep adding oil and dealing with smoking exhaust manifolds until I can save the coin to have the belts - and whatever is leaking underneath the cover replaced.

 

I need a new front O2 sensor, so I figured I could do that in a snap as well. But alas, it is placed neatly at a point where nobody could change it out easily. But I noticed something else...

 

It looks as though I could unbolt the exhaust manifold from the block (3 nuts, each side) and let gravity pull it down to allow easy access to the front O2 sensor.... Is this true? Do you have any other tricks I should know about before tackling this one?

 

I will be using a universal, since the business ends are identical - I need room to do some splicing and soldering of the wires as well.

[cookie]

I've not done one on your car, but on my Forester I just opened the hood and reached down. The ox sensor is fairly hidden but you can follow the wire. It also takes a good big wrench and a fair bit of ooomph to get out.

[outback_97]

So I finally put the OB on the ramps this last weekend to find out where the massive oil leak is coming from - looks like the timing cover gasket (guessing) was over torqued and pushed out. I am due for new belts anyway, so I will keep adding oil and dealing with smoking exhaust manifolds until I can save the coin to have the belts - and whatever is leaking underneath the cover replaced.

 

SuperSubaru:

 

Is yours leaking oil from the timing cover gasket? If so, it's probably the oil pump o-ring... here's what mine was doing, there weren't puddles on the ground but as I drove the car around it would leak and the oil would blow backwards:

 

 

Sorry I don't have any insight on the O2 sensor but your comment about oil leak + distended timing cover gasket caught my eye.

 

Steve

[porcupine73]

I've done front O2 sensor on '96 Legacy (not Outback); not sure how similar it is to your '97OBW, but I just used unhooked the connector and put a 6pt wrench on it (I think it was like 22mm) and squeezed the wrench up in there (didn't disconnect any exhaust). It was a little bit of a snug fit reaching up in there but was doable. Maybe some of those special O2 sensor sockets would help?.

 

The trick (for me anyway) was to run the engine for maybe a minute (to warm up the exhaust) and then press on the wrench pretty hard. The manual says not to use too much force or it could damage the bung.

 

I bought the Bosch universal O2 sensor and had to cut the connector off the old sensor and splice it up to the new one. I wish I'd just have ordered OEM instead of being in such a hurry.

 

Not a bad idea might be to soak on some good penetrating oil like Kroil a couple days before trying to remove it. And use a little antisieze on the new O2 sensor when putting it in of course.

 

Oil leak could be o-ring as already mentioned and/or screws on the back cover of the oil pump backing out and pushing oil out the front crank seal. Anyway, I'd plan on replacing the timing belt too if it's old or is oil soaked as you'll have to remove the oil pump to replace the o-ring and/or check the back case screws anyway. And since changing the timing belt, checking all idlers for freeplay/grease leakage, checking out the water pump as a candidate for changeout, and replacing the cam seals maybe, and if the timing cover gasket(s) are damaged, replacing those too.

[Gnuman]

So I finally put the OB on the ramps this last weekend to find out where the massive oil leak is coming from - looks like the timing cover gasket (guessing) was over torqued and pushed out. I am due for new belts anyway, so I will keep adding oil and dealing with smoking exhaust manifolds until I can save the coin to have the belts - and whatever is leaking underneath the cover replaced.

 

I need a new front O2 sensor, so I figured I could do that in a snap as well. But alas, it is placed neatly at a point where nobody could change it out easily. But I noticed something else...

 

It looks as though I could unbolt the exhaust manifold from the block (3 nuts, each side) and let gravity pull it down to allow easy access to the front O2 sensor.... Is this true? Do you have any other tricks I should know about before tackling this one?

 

I will be using a universal, since the business ends are identical - I need room to do some splicing and soldering of the wires as well.

 

the O2 sensor takes a 7/8" flare wrench or offset wrench. This is a universal size for O2 sensors. As for the leak up front (notice how we all jumped on that bit?) That is the more important problem. The gasket cannot be "pushed out" by overtorquing the cover bolts. They have a stop, or shoulder, on them to prevent this. Your timing belt cover gaskets are damaged. You spoke of a "massive oil leak". That means that at least one, if not all, of your seals are leaking on the front of your engine. It is also very likely that your timing belt has become oil soaked, and needs to be replaced. I recomend replacing all the seals (4 cam seals, front crank seal, oil pump O-ring, valve cover gaskets, spark plug gaskets, the grommets that seal the bolts that hold the valve covers on) as well as the timing belt cover gaskets (one on top, and one on the bottom) and the timing belt. While you have the oil pump off, tighten the screws that hold the backing plate to the impeller, to prevent future problems. To do all of this, I would remove the engine from the car. In that case, I would also replace the oil seperator at the rear of the engine with a metal one (your engine came with a plastic one, that is prone to failure, from the factory), and I would even consider replacing the headgaskets, if that has not already been done.

If you are replacing the headgaskets, you will also need intake manifold gaskets, and exaust manifold gaskets. Total parts for all of this is under $300 at 1stsubaruparts.com. The rest is your labor, or that of a mechanic.

 

If you do decide to pull the engine, the O2 sensor will be just hanging there in the breeze, and can be changed in a matter of seconds. the more serious work of resealing your engine will make it more reliable and trouble-free for annother 100K miles. . .

[SuperSubaru]

SuperSubaru:

 

Is yours leaking oil from the timing cover gasket? If so, it's probably the oil pump o-ring... here's what mine was doing, there weren't puddles on the ground but as I drove the car around it would leak and the oil would blow backwards:

 

Steve

 

 

That is exactly where mine is leaking from, but the gasket looks old and over-torqued and is being pushed out. There are drops everywhere I stop (not puddles), but the most annoying thing is the smoking from oil cooking on the exhaust manifolds as it blows back.... if I am moving I don't notice it at all... but at stop lights or heavy traffic, it is visible that my car is smoking

[SuperSubaru]

the O2 sensor takes a 7/8" flare wrench or offset wrench. This is a universal size for O2 sensors. As for the leak up front (notice how we all jumped on that bit?) That is the more important problem. The gasket cannot be "pushed out" by overtorquing the cover bolts. They have a stop, or shoulder, on them to prevent this. Your timing belt cover gaskets are damaged. You spoke of a "massive oil leak". That means that at least one, if not all, of your seals are leaking on the front of your engine. It is also very likely that your timing belt has become oil soaked, and needs to be replaced. I recomend replacing all the seals (4 cam seals, front crank seal, oil pump O-ring, valve cover gaskets, spark plug gaskets, the grommets that seal the bolts that hold the valve covers on) as well as the timing belt cover gaskets (one on top, and one on the bottom) and the timing belt. While you have the oil pump off, tighten the screws that hold the backing plate to the impeller, to prevent future problems. To do all of this, I would remove the engine from the car. In that case, I would also replace the oil seperator at the rear of the engine with a metal one (your engine came with a plastic one, that is prone to failure, from the factory), and I would even consider replacing the headgaskets, if that has not already been done.

If you are replacing the headgaskets, you will also need intake manifold gaskets, and exaust manifold gaskets. Total parts for all of this is under $300 at 1stsubaruparts.com. The rest is your labor, or that of a mechanic.

 

If you do decide to pull the engine, the O2 sensor will be just hanging there in the breeze, and can be changed in a matter of seconds. the more serious work of resealing your engine will make it more reliable and trouble-free for annother 100K miles. . .

 

Well I guess the timing belt gasket is damaged. I wish I could do it myself, but as this is a daily driver, I will need it back on the road as soon as possible. I don't have the tools in my garage to pull the engine. And while a mechanic takes it out, he might as well R&R the 130,000 mile OEM clutch (along with all the seals and belts and so forth). So I am guessing, average mechanic rates for the midwest (Rockford, IL) for the tally to be around $2000?

[SaltCar]

The timing belt cover gasket is a dust and weather seal it does not hold oil.

 

Read about timing belt changes and head gasket changes and all of the related work. You are on the right track thinking about the clutch. I would have to at least consider getting another car at this point. If you want to drive this one another 100K, fix it, if not, maybe sell.

[SuperSubaru]

I don't know if it would be to my benefit to sell. After investing $2000 into it, I know it would be good for another 100K. The starter and alternator have already been replaced, if I am light on the pedal, I can still pull over 28 mpg on the highway (religiously get 26-27 - checked nearly every tank). Plus, it's paid for.

 

I don't think I could get anything as reliable for the $2000-2500 in repairs that the Sube needs. I don't know if the timing belts have ever been done, and couple that with a new clutch... this might act like a whole new car to me (and up the MPG ever so slightly more).

[outback_97]

The timing belt cover gasket is a dust and weather seal it does not hold oil.

 

Correct, if it sounded like I implied that, I didn't mean to. When I asked if the timing cover gasket was leaking oil, I meant is that where the oil leak visibly manifests, with the appearance that it is distended out, and oil blowing on the area behind that when the car is in motion. Sounds like that is indeed the case.

 

Well I guess the timing belt gasket is damaged...

 

SuperSubaru, in case you missed what Gnuman said, the timing belt itself potentially being damaged by the oil is the bigger concern... the timing cover gasket being damaged is much less of a problem, more a symptom or side effect of a potentially much larger problem. Not trying to be redundant here but striving for clarity.

 

Steve

[SuperSubaru]

SuperSubaru, in case you missed what Gnuman said, the timing belt itself potentially being damaged by the oil is the bigger concern... the timing cover gasket being damaged is much less of a problem, more a symptom or side effect of a potentially much larger problem. Not trying to be redundant here but striving for clarity.

 

Steve

 

Understood - there is no oil that should leak out of there... so the oil leak is deeper, and simply is showing itself because on top of the oil leak the gasket is also damaged... had that not been a bad gasket, it may not have showed there is other things wrong.

 

Either way, timing belt replacement - and whatever else under there causing this - is the next on the list.

[FSRBIKER]

If you haven't done the head gaskets do it all like others said. It's simply not worth tempting fate as it's only a matter of time before they go. Reseal the whole motor, new head gaskets and a new clutch and run it for another 100K+.

 

You can probably find a Subaru tech in your area that will do the work for you so you can save some cash.

[SuperSubaru]

If you haven't done the head gaskets do it all like others said. It's simply not worth tempting fate as it's only a matter of time before they go. Reseal the whole motor, new head gaskets and a new clutch and run it for another 100K+.

 

You can probably find a Subaru tech in your area that will do the work for you so you can save some cash.

 

Any Subaru Techs with the abilities/experience/tools at home to pull this engine, feel free to contact me - if you are looking for a little side work. I will gather what I can in parts, and leave the rest to you. I live outside Rockford, IL - but would drive about an hour in any direction for the right price.

 

email me at kevin.koss@us.army.mil... and we can iron out the details offline.