Noob questions

[Dalee1104]

Whats the best fluid you guys use for your differentials? I recently did it but found while replacing the hear oil it really wasnt too bad and after replacing the oil it seems my car doesn't shift as smoothly especially in cold weather. Any fluids out there that might help that out?

[Brighton96]

I used Pennzoil marine GL5 80w-90, I forget the exact weight, I just used whatever spec and weight the dealer said to. But I used marine oil because it can hold more moisture, in the off chance water got in there and also cause it was on clearance. Ive been running it for about 30k and will be draining it soon and replacing it with mobil or equivalent higher end fluid.

[TickerPyro]

I run Mobil 1 Gear Lube 75w-90.

[Dalee1104]

So here's a pretty dumb one relating snow driving. So I have a pretty good set of winter tires on my car and i also got new r1 concept brakes, yet to put them on. Just really out of curiosity when your breaking in the snow there's a threshold of where your wheels lock up and abs kicks in. Beyond that threshold means the brakes are grabbing beyond the amount of traction in the tires. My tires are great but breaks not so much at the time. Technically speaking wouldn't putting newer more aggressive brakes on make it easier for my car to lock it's wheels based on my braking input or would the threshold probably stay about the same?

[TickerPyro]

The more pad/friction you have the faster you are going to hit the ABS threshold. But the whole idea behind ABS is to assist in stopping so having good brakes on the car is a good thing. If you are hitting the ABS limit, you either need to learn how to downshift instead of breaking or some better snow tires, or both.

This is just info... Not saying you don't know how to drive Heheheh.

[Dalee1104]

Oh yeah I heavily rely on rev matching and engine braking to smoothly slow the car down which is probably why my breaks have lasted as long as they have lol

 

I was just thinking about the science behind that question and i was assuming that it mostly will come down to the amount of traction within the tires

[Dalee1104]

Fixed the clockspring issue I was having with my wrx wheel today and also finally was able to find an exhuast leak right before the cat. It's super small so if it weren't cold enough for me to see the hot air I wouldn't have found it. It seems as though it's been getting bigger with time but its right at the flange so i assume that's the p0420 culprit.

 

I also reset the ecu to try and reset the airbag light I had and clean the terminals. I pulled the battery, held the brake for 30 seconds or so, then left it off for about 30 mins. Putting it back on everything was reset and good to go. This includes all the learned settings about my car, and I gotta say when my ecu doesn't learn my settings the car runs so so much better. I'm gonna fix the exhuast leak but if that doesn't fix the cars feeling, is there a way to trick the ecu into not learning it's settings?

[Dalee1104]

Upon further inspection turns out I have more then just a leak. Got the car on a lift and was able to see that every exhuast gasket is leaking all the way around. I'm assuming this is from shops using cheap gaskets. Is there a recommended gasket that holds up better then the others?

[RustyRuu]

As far as the brakes go I just replaced pads all around with EBC brakes and I was just getting use to them before it snowed but was definitely kicking abs off more in the snow just because I was not use to the feeling of them yet. I don't have to mash my brakes to make them work its more of just a touch now.

[Dalee1104]

So it's been a bit since I've updated but i was able to get the msd coil pack in, got all my exhaust leaks fixed, experimented with different MAF sensor leaving the most reliable one on and even got the intake tube out of a 95 taking out the harsh bends. I would say the overall smoothness of the car was a lot better and it just feels a little healthier. After installing the intake tube I noticed low rpms the car stumbles with light throttle. It stumbles and i got a pending fault on the ecu for a cylinder 4 misfire. Can't remember the number I think it was like p0304 or something. I've read causes for this being bad wires, intake leaks, bad sensors, and some not great condition valves.

 

I've been worried it's a valve because I remember doing the compression test and 1 cylinder was lower then the rest but still within range. I'm wondering if that 1 has gotten damaged to start causing a misfire due to not closing all the way? At least that's what I read.

 

I installed a different MAF, reset the ecu, and took the car for a spin. Normally under light throttle the car would increase in rpms, stumble and hold still for a second, then continue to increase. I was able to under light throttle and load to get the car to stumble consistently but received no cel from it misfiring or anything. I'm hoping it's not a valve, but then as I was listening in the engine bay I had the throttle trying to replicate that stumble and the fans kicked on which made it consistently stumble in a much wider range of the lower rpms. This makes me wonder if its something electrical? The issue has always been there but it was small so i never noticed it but installed the coil pack, and intake tube has made it more prominent. What's your guys opinions

[doublechaz]

Some sensors ground to the intake and some to the block. There should be a ground from both of these to chasis. Could you have disturbed the one from the intake while doing all those intake related things?

[Setnev]

So it's been a bit since I've updated but i was able to get the msd coil pack in, got all my exhaust leaks fixed, experimented with different MAF sensor leaving the most reliable one on and even got the intake tube out of a 95 taking out the harsh bends. I would say the overall smoothness of the car was a lot better and it just feels a little healthier. After installing the intake tube I noticed low rpms the car stumbles with light throttle. It stumbles and i got a pending fault on the ecu for a cylinder 4 misfire. Can't remember the number I think it was like p0304 or something. I've read causes for this being bad wires, intake leaks, bad sensors, and some not great condition valves.

 

I've been worried it's a valve because I remember doing the compression test and 1 cylinder was lower then the rest but still within range. I'm wondering if that 1 has gotten damaged to start causing a misfire due to not closing all the way? At least that's what I read.

 

I installed a different MAF, reset the ecu, and took the car for a spin. Normally under light throttle the car would increase in rpms, stumble and hold still for a second, then continue to increase. I was able to under light throttle and load to get the car to stumble consistently but received no cel from it misfiring or anything. I'm hoping it's not a valve, but then as I was listening in the engine bay I had the throttle trying to replicate that stumble and the fans kicked on which made it consistently stumble in a much wider range of the lower rpms. This makes me wonder if its something electrical? The issue has always been there but it was small so i never noticed it but installed the coil pack, and intake tube has made it more prominent. What's your guys opinions

 

Dreaded cylinder 4 misfire...I just rebuilt an STI with zero compression in cylinder 4. Owner thought it was a cross-threaded spark plug, so she bought a new head for it. Turned out to be a burned valve. Only way to find out for sure is with a boroscope down the spark plug hole and inspect the valves.

[Dalee1104]

So with a burned up valve, how long do you think I can make this engine last me?

 

Not saying that's for sure what it is yet but if it were considering that cylinder was the one with the lower compression, how long would it last me?

 

Reason I ask is because I'm just trying to save up to rebuild a 98 ej25 and then sell this beloved legacy I've had for 3 years now and try and find a 96 to 01 impreza 2.5 rs with a blown engine and but the ej25 in there. Still unsure if i should sell the legacy or not though

 

Also what might I be looking for with the horoscope. Like what in the valve will show me it's bad or not

[Setnev]

Theoretically if it is a burn valve, the answer to that question depends on how bad the valve in question is.

 

Here is what the one in the STI looked like when I pulled it out. Mind you, there was a constant misfire in cylinder 4 due to no compression

 

 

When you have no compression and misfire as a result, the car isn't driveable without causing serious issues. The STI barely ran.

 

It didn't take long for her to get from a small random misfire in Cylinder 4 to a full on burned valve. Took about 2 weeks.

 

Now this is all hypothetically the case if it is that diagnosis, of course.

[Dalee1104]

Oh damn, that's decently brutal looking lol I'll use a boroscope tomorrow and take a look at the valves in cylinder 4. Cylinder 4 is the passenger side closest to the firewall correct?

[doublechaz]

I'm pretty sure once a valve starts to burn out the fire shooting through the hole cuts it out until it looks like the pic above. By that point the mixture doesn't really burn anymore so no further erosion. I expect that valve seat was pretty bad as well. Could it be recut?

[Dalee1104]

Was that question for me chaz? I'm not too sure but I don't really plan on doing head work to this engine either way just because I think it's time for me to upgrade to a newer car. Maybe not necessarily newer but I've always wanted a 2.5 rs so i really wanna try getting one of those

[Setnev]

Oh damn, that's decently brutal looking lol I'll use a boroscope tomorrow and take a look at the valves in cylinder 4. Cylinder 4 is the passenger side closest to the firewall correct?

 

Cylinder 4 is the driver side rear.

 

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/20/8f/fc/medium/0996b43f80208ffc.gif

 

I'm pretty sure once a valve starts to burn out the fire shooting through the hole cuts it out until it looks like the pic above. By that point the mixture doesn't really burn anymore so no further erosion. I expect that valve seat was pretty bad as well. Could it be recut?

 

She just bought a bare head and I transferred everything over. The only defect on the head was stripped threads in the spark plug hole. The valve seat was actually in decent shape. I think she ended up selling the head for a couple hundred bucks.

[doublechaz]

That question was to Setnev since he's seen one first hand recently.

 

Sounds like that seat could have been recut if desired. I guess the valve seat is able to dump enough heat into the head that usually only the valve gets burned away? Makes sense. Especially once the valve starts to go it probably doesn't seat as well so can't dump heat into the seat.

[Setnev]

Normally, I've either seen the seat fail and take the valve with it or the valve fails and seat is fine. With the STI valves, they're sodium filled, so it's just adding more acceleration to the burn out.

[TickerPyro]

If the car burns oil you are probably eating a valve.

It is not often that a seat fails on a subaru, it is always the valve itself. The only real way to make a seat fail is to blow oil by that is still on fire and you are melting the valve anyway. This all stems from leaks valve seals or 250k motors that the valve has stretched and gained seal clearence.