WAWalker

Not necessarly. The Y-pipe is mounted solid to the engine, the rear cat is mounted with fairly stiff rubber bushing mount to the trans................after the donut connection the rest of the exhaust is hanging from "rubber bands". So the rear part of the exhasut can move more than the Y-pipe and cats. The donut connection with spring bolts is were the "give" is.

Thats the one.

German specs. Gutantight:) I don't know, I never torque them, just snug them up. Kind of like a spark plug, the O2 sensor has a crush washer, tighten tight enough to crush it.

5/97-5/99 2500cc Outback & SUS, PN 44200AC161. Refured to as Exhaust Pipe, Rear. $155.48 + 14.95 min. S & H.

Useing a "code checker" at a local auto parts store, you probably only have access to the ECU codes, not the TCU codes. Far as I know the only scan tool that will comunicate with the TCU through the DTC, is the Select Monitor. Other wise you have to jump through some hoops to manualy pull the codes. Don't have that procedure handy at the moment, but I'm sure someone will chim in, and point you in the right direction.

I'm with you Skip. I think at some point in that cars life, someone took the center pipe from a 90-94 Legacy, gutted the cat (which did not get a rear O2 sensor) and stuck it in there. At least thats what the pictures in my Subaru parts quick reference guide, and memory tells me. What he got was right, what he took out was wrong, but worked.

Mtnrider9800, You have the '99 OBW 120 some thousand miles correct? You don't have a misfire or hesitation accelerating from a stop. On Subarus, secondary brake down in the ignition is most noticable under highest engine load (accelerating form a stop usually). Still, if plugs are not NGK, and wires are not Genuine Subaru, if it were my car I woud change them. CEL illuminates at ~70mph, misfire #4 code stored. But engine seems to run fine. I my experiance this is a mechanical problem in the valve train. Not engough valve lash clearance. Exhaust valves hanging up in the guides. If the exhasut valves are hanging in the guides, the problem would come and go, and not nessasarly cause a rough idle. At idle engine runs rough. Can be many things, but in context with the misfire @ 70mph....................... Tight valves If the valves are tight, an ajustment might take car of the problem, depending on how much the car has been driven with the vlaves not properly sealing.

Don't know. As I have been specializing in Subarus for the past 6 years. I have done a few Toyota and Honda's in that time, most when ARI was still the main supplier, and before the parts houses were selling new axles.

There is deffiently a learning curve when it comes to which parts to buy from who. I stock as may Genuine Subaru parts as I can. I am a huge fan of OEM parts. As far as axles go.................... When I first opened my doors for business, I only stocked OEM Subaru axles. (remaned by ARI) Very good quality, at a very high price, 1 year 12k mile warranty. Had an outter CV joint ball cage failure on one 13 months after installation. Napa axles at the time were ARI remans. at a considerably lower price, with a liftime warranty. I started stocking Napa ARI remans. Buying 10-15 at a time I got a bigger price brake. Replaced more of those due to torn boots than failure of the joints. Life was good. ARI went out of business..................Everyone including the dealership was scrambling to find a new axle supplier. Napa already had their line of "New Max" axles. Negotiated a deal with local supplier, and the new axles were only costing $5 more each and I didn't have to mess with returning cores. Axles were working great, wasn't having warranty issues, life was good. Then one day............I have ~10 axles on the shelf, I install 4 on one car, swap axles side to side, still have a clicking joint. Install two used axles, noise is gone. Start pulling the other new axles out of the boxes, noticable slop in the DOJ's. Send them all back, get a new batch. Pull axles out of the boxes, noticable slop in the DOJ's. Send them back, get some remans. (Supplied by Cardone who Subaru is now getting their axles from) Same "New Max" axles in reman boxes. Same slop in DOJ's. Tried one anyway, same noise. I can't take it anymore. On to new supplier. I am now stocking "remaned" Car Quest axles. Price is a little higher, but core charge is only $7.14, so I don't have to shell out twice the cost of the axle to stock them. I would say at least 98% of the time, the boxes contain new axles (but different than the Napa ones). Very seldome do I get an actual remanufactured axle. So far so good, haven't had warranty issues. I think there is a supply and demaned problem in the remaned axle industry. The supply of rebuildable cores is diminishing. Any axle I have ever purcased for the dealer ship is in fact a remand OE axle. (no new made in China joints or shaft) So aparently the "quality" remaned axles go to supply the OEM dealers first. The after market gets what is left of the remans, and the balance of the demaned is filled by new made in China axles. JMHO. It is a balancing act for sure. Sorry for the long winded post. But that's my story.

The DOHC and SOHC head gaskets are different. The DOHC head gasket revisions were obvious. The SOHC (in 2000 and newer outbacks) head gasket part number has changed, but there has been no obvious revision to the gasket itself. Personaly I wouldn't have a problem going with the Cometic head gaskets on this engine. JMO.

True. But when you run a repair shop by yourself and buy any were from $3k-$6k worth of parts each month, it is enough just to keep up with the ordering (by part number), unpacking, checking to see that all parts on the invoices were received, and put them on the shelf. At some point you have to rely on your supplier to supply the parts that match the part number that was ordered. I do check the axles now before signing the invoice though.

I was useing the NAPA "NEW MAX" axles, started getting a bunch of them with sloppy DOJ's that would make noise. Now I am using axles supplied by Car Quest. These are also completly new axles. They are deffinetly different than the NAPA axles. So far so good on these. Other than getting a bunch of mis boxed axles.

Yes the tach marks are 500 and 750. No need to have the tach read below 500. I used NAPA remaned axles for a long time. ARI went out of business, so I started buying the NAPA NEW MAX axles. Got a batch of bad ones, tried the remaned axles, different box same new axles same problem. Haven't used them since. If the engine idle was lower after the timing belt replacement, I would look there first. No the throttle stop should NOT have been messed with. There is no adjustment that can be done to the IAC on an '03 so that shouldn't be an issue. So far they have a fairly low failure rate as far as I know, so I wouldn't be in a hurry to replace that. If the shudder is worse since the time belt replacement/idle drop. First thing first. Check cam timing.

You say the rear u-joint was tight? How tight? Could you move it in it's full range of motion? If you feel a side to side shudder, and noise from the rear of the car, under acceleration it could be that rear u-joint. If the noise is comeing more from the front of the car it could very well be and DOJ.

Oh, and just to clear the air, so we can all still be friendly. None of this is personal. What pushed my button and got me into this discussion was a referance (actually two) from Wikipedia. Both defining "engine braking" but one said one thing the other said something else. Basicly the way I read it was........... They were saying that "compression braking/engine braking" in desiel trucks was grossly inefficient, and that gasoline engines had an advantage due to the throttle plate restriction (increased vaccuum). I still don't know what is really happening inside of the cylinder when "engine braking". But, I do know that when towing my camp trailer behind my (throttled) gasoline powered pickup, "engine braking" what ever it may be, is grossly inefficient when decending a long step hill. Untill you get into a very low gear at a very low speed. It is no different in a loaded 18 wheeler, when not using the "jake brake". This is why you pass so many semi's comeing down mountain passes just creaping along with the hazard lights flashing. So I thought that to totally dismiss the idea of "compression braking" as it is so inefficient, and say that "vaccuum braking" was better was streching it. I still feel that way to a point. But will always be curious as to what is really going on inside the cylinders. "Engine braking" either way is grossly inefficient in slowing the weight of a vehicle going down a long step hill. Untill you reach a very low speed in a very low gear. Even in a car.

Exactly Yes. All the afeormentioned items that cause friction (energy loss due to heat). Power loss due to lack of cumbustion. And yes, throttle plate restriction. It all resaults in normal engine deceleration. No one factor necessarily being significantly greater than the other to be able to define what is happening as compression or vaccuum braking. IMO. As there are rotating parts in the entire drive train, from the tires all the way through the transmission. There is rotational inertia in the drivetrain also created in the drivtrain also. There will be some energy loss in the drive train (heat loss). Especially in the clutch on a MT, and in the clutches and torque converter in a AT. So the higher the RPM the more energy lost in the drive train. Ok, you got me again. If it wasn't for the engine is would take for ever to slow a car from 60 to X mph. It is the last link in the chain. So as far as defining the process goes............."Engine braking" works.

As far as my comment about the WRX valves bending the shaft.......................I did leave out the fact that the valve steam is longer, or at least there is more steam exposed between the head of the valve and the end of the valve guide. That is why they will bend the steams. Not the case with the 2.5L DOHC engine. I was just trying to make the point that a cylinder leak down test is better than just a compression test. But in the case of the 2.5's a compression test will probably always show low compression if a valve is bent. Sorry to mislead you.

I agree. It takes engergy to create vaccuum. Aparrently just not a lot of energy. And in the contexts of the disscusion, and when compaired to all the other loads you mentioned, it becomes a smaller part of the equation that one might think. I did find some equations to determine energy used to compress air but haven't run across any for vaccuum yet. I guess there are worse things we could be thinking about. It's been fun. Watch the EGR thread for more on the energy used to produce vaccuum, and it's effect on fuel milage. Might be a while, I will need time to do some more home work.

True. Many. PCV valve is a one-way valve, and will allow air to flow one way but not the other. Properly working they should always flow air from the crank case to the intake as long as the intake pressure is lower than the crank case pressure. In the case of a back fire on a NA engine (Intake pressure becomes higher than crank case pressure) the valve will close to act a a "flame arrestor" to prevent ignition of the HC's inside the crank case. Or on a forced induction engine, the PCV will close under boost to prevent pressureizeing of the crank case. Back to the oil burning. Oil burning on prolonged decel or imediatly after. Is mostly leaking valve guide seals. The increase in vacuum that we all agree is present, is acting more on the intake value guides as they are directly in the area of lowest pressure (Intake system). They are exposed to the increased vacuum weather the valves are closed or open. Were as the pistion rings are only exposed to this vacuum increase when the intake valves are open. The pressure on the low side (crank case side) is the same for the valve guide seals as for the pistion rings. Because the intake valves are exposed to the highest amount of vacuum when closed (under decel) this is when worn valve guides are going to leak the most oil. The oil is collecting behind a closed valve. When the valve opens only a small amount of this oil will make it into the cylinder due to the low volume and speed of the air/fuel entering the cylinder. When acceleration is resumed, air/fuel volume and volocity increases, fuel injectors are spraying more fuel at the back of the valve washing the oil into the cylinder to the point that the oil burning becomes obvious from the smoke out the tail pipe. Yes, some oil can be drawn past the rings under these conditions. So because the rings are only exposed to the increased vacuum ~1/4 the length of time as the valve guides...................and once oil is sucked past the rings it will actually creat a better seal ( think wet compression test). Worn valve guides and seals are the most likly cause of excess oil buring on or right after prolonged decel, on an engine that has compression readings that are in spec. Excessive oil burning all the time, or only under acceleration will point to poor oil control due to worn rings (rings not "scraping" oil from the cylinder walls. Or blow by (compression is probably not going to be good).

Hm, funny how that car is 20 some years old. Fuel and emissions controls have come a long way in 20 years. I didn't say fuel milage.................I said control. The quest for more power and less emissions has hindered improvements in fuel milage. But it has been possible to make more power with less emissions through the use of better control. If your RX made the same power and could pass the same emission standard as a modern car then we could start makeing compairisons to see were the manufacturer is going wrong. The feds just pass a new CAFE standard law. 35mpg for passanger cars, I believe is what I heard on the news. Will be interesting to see what car builders are going to do about that. I'm sure to start out they will find ways to exempt themselves. Like Subaru's increase of ground clearance so they would only have to meet the light truck standard rather than the passanger car standards.

Gary, Thats cool that you take the time to help locate parts for other people.

With all that said. I totally agree that there is energy lost due to the restriction of a closed throttle plate, but the energy losted due to the increased vacuum will be mostly regained somewere eles. Just as compression if any would be negated buy combustion. If in fact. Due to the increase in vacuum and reduced air volume in the intake. The cylinder is not filling with enough air to produce compression. And say that there is still a low pressure if not equal to the intake vacuum, once the valves are closed after the intake stroke. And this low pressure/vacuum is actually "pulling" the piston up on the compression stroke. That means that the increase of vacuum due to the throttle plate restriction, is in turn producing power on the compression stroke. So is it a wash? Or am I still missing something.

While the site was down I had some time to do a little home work and a lot of thinking. I was wrong. But I have a better understanding of the internal cumbustion engine! Newton's Third Law of Motion For every action there is an equal and opposite reaction. So................................The engine can not slow the car down from any given speed any more efficently than it can accelerate the car to that same given speed. So engine braking does not happen without the addition of another system to make it happen. Enter the "jake brake" on vehicles that have a real need for engine braking. Have I lost my mind? I'm thinking we could spend the next month performing running engine compression tests, crank case vacuum tests, try to find someone to do dyno tests...............................And we will never be sure what all is taking place inside these engines on decel. But if we did I think we would find that it all comes back to.................... The one thing that the engine has to over come to get the car up to speed. Friction.

I may be wrong about this, on the more modern cars. I read something today, that claimed that today's cats will effectively remove NOX from the exhaust. Apparently to the point that EGR is no longer used to reduce NOX production during combustion. It claimed that well controled use of EGR actually will increase fuel economy. I will have to look into this a little more.

Ok, I just did another experiment with the Select Monitor on my car. I'm for sure learning some things I didn't know. To me that is part of the beauty of this board. It keeps my mind working, and helps me to learn new things. I work on these cars day in and day out, but will never know all there is to know. So, I took the car out on the freeway with the Monitor hooked up and selected some data peramaters to record. Vehichel speed RPM MAF O2 Sensor Fuel injection Manifold relative pressure (vacuum) (Atmospheric pressure here is 25.5) (Vacuum is -17.3 inHg on fully warmed up engine) As soon as I go closed throttle on decel. This is from crusing speed of 80 mph, 3200 rpm. Fuel injection = .26 ms MAF = 3.91 g/s 02 Senosr = 0.00 volts (These reading stay fixed no change so I won't list them again) So what little fuel is being injected is buring (or not detectable) according to the O2 sensor. Vacuum = -20.5 inHg Down shift from D to 3 @ MPH = 68 RPM = 2725 Vacuum = -20.5 inHg Rpm comes up to 3050, speed drops to 66 mph, vaccum come up to -20.8 inHg. At 63 mph, rpm's start to rise, vacuum constant @ -20.8 inHg. As rpm's rise to a peak of 3575, speed stays constent @ 63 mph. Next drop in speed and rpm's is @ 61 mph / 3375 rpm, vacuum -20.8. Down shift from 3 to 2 @ MPH = 58 RPM = 3200 Vacuum = -20.8 inHg Rpm comes up to 4400, speed drops to 56 mph, vaccum fixed @ -20.8 inHg. At 52 mph, rpm's start to rise, vacuum still constant @ -20.8 inHg. As rpm's rise to a peak of 4525, speed again stays constent @ 52 mph. Next drop in speed and rpm's is @ 48 mph / 4075 rpm, vacuum -20.8. So........................... At idle with throttle plate closed = -17.3 inHg At 4400 RPM with throttle closed = -20.8 inHg (And this is the max vacuum that can be achieved without the car ever moving) From 700 RPM to 4400 RPM it is only drawing another 3.5 inHg. And from the start of inital decel to the start of "engine braking" (shifting down), the differance is .2 inHg. Initally, when a lower gear is selected, there is a reduction in speed. As rpm's rise there is no loss of speed. So is there any engine braking taking place at all? I'm thinking more and more it is all gear reduction and normal friction of the rotating components that is providing the "braking". There is combustion taking place and no more resistance due to higher vacuum then when you rev an engine up and let off the gas quickly. Also taking into account that when decending a long step hill in a lower gear, the car will initally slow down, then start to build speed and rmp's again. I read somewere that in this case the engine will be "driven" at the same speed and rpm's as it will "run" under acceleration in any given gear. Is "Engine Braking" just and old wifes tail?