An exhaust leak through the downpipe wouldn't cause a drop in performance, it would just be louder. I would still get the downpipe repaired however. Blue/gray smoke does mean oil burning. Did you check the turbo for shaftplay? If the turbo is whining while driving under boost, then it's shot....

I'm definitely going to get a new DP, i'm gonna go with the Megan 3" DP for now and I'll add the rest of the exhaust kit later on.

As far as shaftplay goes, i'll have to do a search to see exactly how to check that. Other then that, the turbo sounds normal to me. I'll post back in a bit, once I check the shaft play.

Think about what size downpipe u want. I have a 3" from the turbo back and a ported evo manifold. Before I got my evo turbo I would hit full boost of 14psi at just a lil over 2k rpms and full boost on my evo turbo was about 2700 rpms. Great for short runs but kinda hurt my top end. You also have to think of boost creep with a 3". Also another point (and I didn't look at you're profile to see what you are running) don't run a 3" down and a go any smaller on the cat or the rest of the exhause or you will creat turbulance and actually hurt hp. Lol.....One more thing and I'll shut up. I personaly like RNRracing downpipes. Just my 2 cents.

Good thinking... I actually hadn't thought about the effects of just running w/ the 3" DP and then back to 2.5" cat and cat back. I think i'll pony up and get the whole killer kit right from the get.

UPDATE: I'm actually running out of daylight, so i'll have to check the shaftplay tomorrow, i just finished SeaFoaming the engine due to the rave reviews on the forum about doing so. BTW, performance seems to have dropped a bit more after the SeaFoam. I'm going to get the whole turbo system fogged sometime this week.

check your old DP for oil...If you have oil in the DP the turbo is shot

May I suggest getting a 2.5" downpipe, or at least until the flex section and then 3" after........

Its way easier as far as fitment, and 2.5" easily supports over 400hp

Checking for shaftplay is easy man....

Take the intake tube off the turbo and stick your fingers in the turbo, grab the turbo shaft(if you will) and try to wiggle it up/down/in/out. If its real wiggly, its bad....

A little bit of play is normal, but you want little to no play in the turbo shaft

I'd figure out where that burning oil is coming from before you go spending money on a DP. You might want to spend that cash on fixing that problem. Compression test would be good, and if compression is low, leakdown test.

Only check shaft play on a cool motor!! Side/side shaft play is normal as long as the compressor wheel doesn't rub the housing. Also check that the shaft spins freely. In/out shaft play is bad. You won't have oil in your intake or exhaust necessarily from a turbo with in/out shaft play, but in/out shaft play (any amount) is a sign that your turbo is not going to last much longer. Other than that, the procedure described by Eastwood95 is correct.

And I don't think you're going to creep with a 3" exhaust on a T25. Maybe if you had an evo3b16g.

Go read the stage 0 mods, as they are a prerequisite for any stage 1 mods. This includes getting your car in proper running condition (i.e. not burning a lot of oil).

I don't see a boost gauge in your profile. Does your tester have a pressure gauge on it? How much do you pressurize, and how quickly does it leak down? That's not going to help with burning oil...just another suggestion related to your boost leaks.

I'd definitely spend some time finding out what all is wrong with your car before spending on upgrades.

I agree with that. Maintanence may even net you more horsepower than modifications if you need it bad enough, I.E: leaks, cracked manifold, turbo wearing out.

AWDfrank said:

I agree with that. Maintanence may even net you more horsepower than modifications if you need it bad enough, I.E: leaks, cracked manifold, turbo wearing out.

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I agree as well, don't get me wrong... fixing this problem is #1 on my list of things to do. And as far as I'm concerned, fixing my leaky DP would be considered maintenance. If i'm gonna invest any money into a part, it's not going to be just to fix it, but upgrade it as well. (Unless your talking about my leaky intercooler piping as buying the intercooler kit that i want isn't cost effective right now)

You're right kenamond, as of right now I don't have a boost gauge installed (it's actually sitting in the garage, i'm waiting on the pillar pod, it should be here any day). When I did my boost leak test i set the output pressure to 20 psi and was carefull, as well, to not pressurize for too long a period of time. As far as how long it took to depressurize, i couldn't tell you, only because I didn't have a gauge installed to see when there was no pressure at all anymore, but i didn't hear any other leaks. That's why i want to get the intake piping fogged so that i can visually see where the leaks are.

I suppose I could actually install the gauge without mounting it. It wouldn't be hard to disconnect the gauge when the pillar comes in and then mount it.

I'm going to go check the shaft play and then afterwards do another boost leak test. If I still can't come up with any results, then i'll be looking for a shop to do a leakdown test.

OK... so, there does seem to be some shaftplay. I'm estimating like 1/8 up and down (at the tip of the shaft, not the fins) and maybe 1/16 in and out. Also, it seems to spin freely, but only clockwise (i think, maybe the other way around. Either way, it only spins in one direction). Is this normal? The fins look to be in good condition too as far as I can tell.

Boost leak test will happen later this afternoon.

95CarbonEclipse said:

I agree as well, don't get me wrong... fixing this problem is #1 on my list of things to do. And as far as I'm concerned, fixing my leaky DP would be considered maintenance. If i'm gonna invest any money into a part, it's not going to be just to fix it, but upgrade it as well. (Unless your talking about my leaky intercooler piping as buying the intercooler kit that i want isn't cost effective right now)

You're right kenamond, as of right now I don't have a boost gauge installed (it's actually sitting in the garage, i'm waiting on the pillar pod, it should be here any day). When I did my boost leak test i set the output pressure to 20 psi and was carefull, as well, to not pressurize for too long a period of time. As far as how long it took to depressurize, i couldn't tell you, only because I didn't have a gauge installed to see when there was no pressure at all anymore, but i didn't hear any other leaks. That's why i want to get the intake piping fogged so that i can visually see where the leaks are.

I suppose I could actually install the gauge without mounting it. It wouldn't be hard to disconnect the gauge when the pillar comes in and then mount it.

I'm going to go check the shaft play and then afterwards do another boost leak test. If I still can't come up with any results, then i'll be looking for a shop to do a leakdown test.

Click to expand...

A leaking DP isn't a big problem, performance-wise, but if you're getting exhaust in the cabin at stop lights, that's not good. If not, spend money on the important stuff like that burning oil.

I'd do a compression test before the leakdown. If you think you'd use it often enough or have some cash for it, a compression tester is cheap ($60). You can do the test yourself to see if it's even a compression issue. If so, the leakdown test tells you a lot more. Below are some links for both tests:

Compression: http://www.geocities.com/dsmgrrrl/FAQs/compression.htm
Leakdown: http://www.geocities.com/dsmgrrrl/FAQs/leakdown.htm

Also, for boost leak tests, a spray bottle with super-soapy water will show you the smaller leaks that you can't hear. Yes, small leaks make a difference. Look for where it's making bubbles. I'd describe boost leak testing again, but there are plenty descriptions on the forum. Just check the following: vaccuum lines, IC pipes (holes), IC (holes), couplers, BOV flange, BOV, TB gaskets, BISS, TB shaft seals, IM/head gasket, injector insulators, PCV. Harder boost leak to find is intake valve seals.

Yes, you could pull the boost gauge out of the box and plug it into your BOV vaccuum line (on the BOV end), but you might only be supplied with a "T" fitting, and you'll need a straight fitting (few cents at a hardware store). Or you could cap the extra barb on the "T".

Also, check out the following tech article for wiring your gauge backlight to the dimmer switch. Worked for me a few weeks ago:

http://www.dsmtuners.com/forums/showthread.php?t=241353

Of course, i forgot that i should do a compression test first. Although compression seems to be fine, i'm going over to a buddies house tonight to do the boost leak test and he's got a compression tester. (I borrowed it before when i first got the car last fall). So, tonight it'll be boost leak tested and compression tested.

On the boost leak test, i've heard people say to use soap and water before, but exactly how do you use it? Just spray the entire IC piping starting below the turbo and then working your way to the intake manifold?

95CarbonEclipse said:

Of course, i forgot that i should do a compression test first. Although compression seems to be fine, i'm going over to a buddies house tonight to do the boost leak test and he's got a compression tester. (I borrowed it before when i first got the car last fall). So, tonight it'll be boost leak tested and compression tested.

Click to expand...

Let us know!

95CarbonEclipse said:

On the boost leak test, i've heard people say to use soap and water before, but exactly how do you use it? Just spray the entire IC piping starting below the turbo and then working your way to the intake manifold?

Click to expand...

Yep. If it leaks down quickly, you'll probably want to work in secitons. First, just do a leak test, pressurize to 20psi (NEED A PRESSURE GAUGE OR YOU COULD BLOW SEALS!). See how quickly it leaks down.

If it leaks very quickly, try listening for hisses while someone else is pressurizing. Big leaks may not make bubbles.

Once you get the major leaks identified, work your way back in sections from coupler to LICP, to coupler inspecting a few places at a time. It may drop quickly, so you may have to do several tests before you get all the way to the head. Just spray the crap out of things to get the leak-prone places wet.

If you have the BISS cap still, pop it off and spritz the head of the BISS in the little well. Spray both TB gaskets so that the top, sides, and bottom are wet.

You'll probably fix things in stages. If you have to pull something apart to fix it (TB gaskets) make sure you do that last so you dont re-tear it apart later for another leak and re-introduce a leak you'd already fixed in the process.

Don't be suprised if you have to order new parts as a result (PCV, injector insulators, TB gaskets, couplers, etc.).

Good luck.

Yup work in stages. you'll be able to find all the leaks just a real pain in the ass. good luck

Okay, so i just got back from doing a compression test and a boost leak test. First off, the compression test read: 167 170 167 165. This sounds pretty low to me, but there all within 5 points so it should be good. While I was at it, i got new wires and new NGK Iridium spark plugs and replaced those as it was long overdue.

Then, after my buddy finished cutting the cat and putting on a resonater that I was sitting on since I got the car, I did the boost leak test.

I found a small leak between my checkvalve and inline fuel filter (PCV valve > Fuel Filter > Check Valve > Intake Manifold) where the hose wasn't completely locked into the checkvalve properly. Fixed that, retested and couldn't find anything. In fact, it seemed to be holding pressure pretty well seeing that when i pushed on the valve stem a few seconds later I could hear the air being released.

But, the test drive was inconclusive, didn't really feel any better really, although i did notice that if i was to gradually accelerate it felt decently strong as compared to when i would just romp on the gas it felt sluggish.

Looks like i'll have to find a shop that knows how to do a leakdown test. Any other suggestions??

UPDATE: Okay, so i just picked my car up from the shop after having a leakdown test performed and they told me that i've got a "10% leak coming from my valve stem seals" and that they recommend having those replaced. They also compression tested it and said that all cylinders were between 150 - 160, which they said was normal (in fact, the owner of the shop said that it's on the high side actually). I also had a boost leak test done by them smoking the piping and found no leaks.

So, this would explain as to why I'm burning oil, but would this have an effect on my performance?

Also, how difficult would it be to replace the valve stem seals myself and save me the $400+ that they estimated it would cost me to have them do the job?

95CarbonEclipse said:

UPDATE: Okay, so i just picked my car up from the shop after having a leakdown test performed and they told me that i've got a "10% leak coming from my valve stem seals" and that they recommend having those replaced. They also compression tested it and said that all cylinders were between 150 - 160, which they said was normal (in fact, the owner of the shop said that it's on the high side actually). I also had a boost leak test done by them smoking the piping and found no leaks.

So, this would explain as to why I'm burning oil, but would this have an effect on my performance?

Also, how difficult would it be to replace the valve stem seals myself and save me the $400+ that they estimated it would cost me to have them do the job?

Click to expand...

150-160 is still within service limits, and 178 is "perfect", so I'm not sure why they thought it was high (look at that compression test page I included in a previous post - it lists all of the specs).

As for the boost leak test, you need to pressurize to like 20psi, stop applying pressure, and watch the gauge to see how slowly it leaks down. It will hold pressure just fine for a long time, but it won't hold at a constant of 20psi if you still have leaks. So hearing a hiss when you pulled the tester off doesn't mean you don't still have leaks. If you did this, post how many seconds it took to drop from 20psi to 19psi. If it takes more than a second, you're fine. Some claim they can hold steady for a while.

If it turned out to be an intake valve seal that's leaking, this is also a boost leak, but it wouldn't explain smoke coming from the oil cap; the intake seal is in the intake port which shouldn't have any exhaust in it. Maybe both seals are leaking. Below shows the seal replacement procedure. Not the same as a boost leak test .

http://www.vfaq.com/mods/Valvestem-seals.html

kenamond said:

If it turned out to be an intake valve seal that's leaking, this is also a boost leak, but it wouldn't explain smoke coming from the oil cap; the intake seal is in the intake port which shouldn't have any exhaust in it.

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I think you may have misunderstood what I said. What i ment was, while I had the car in the shop for the leakdown test, I also had them do a boostleak test. I still haven't got my boost gauge installed yet so checking the PSI and how long it holds isn't possible. This is the case for MOST cars out there (only us gearheads have boost gauges), so in order for a shop to do a boost leak test, they fill the turbo plumbing with some kind of white smoke and then lightly pressurize to see where the smoke escapes from.

They did this and didn't find any boost leaks, so I'm good in that department (with the exception of valve stem seals, if that can leak boost too).

Does that make more sense, or did I misunderstand what you were saying??

Holy crap... Changing those seals sounds WAY too complicated to me. Maybe I'll try to get a hold of TurboWop to see if he's done this before.

95CarbonEclipse said:

I think you may have misunderstood what I said. What i ment was, while I had the car in the shop for the leakdown test, I also had them do a boostleak test. I still haven't got my boost gauge installed yet so checking the PSI and how long it holds isn't possible. This is the case for MOST cars out there (only us gearheads have boost gauges), so in order for a shop to do a boost leak test, they fill the turbo plumbing with some kind of white smoke and then lightly pressurize to see where the smoke escapes from.

They did this and didn't find any boost leaks, so I'm good in that department (with the exception of valve stem seals, if that can leak boost too).

Does that make more sense, or did I misunderstand what you were saying??

Click to expand...

Heh...we both did a bit of misunderstanding each other. If they pressurized to 15-20psi for the test, and they could see even small leaks, then you're probably good. It would've been nice if they pulled the oil cap and looked for the smoke stuff they injected. The intake valve stem seals would leak up under the valve cover and out the hole.

If they only put 5psi into it, that won't tell you if you have no boost leaks. You have to go as high or a bit higher than the boost the intake is seeing which could be as high as 15psi with boost spikes even on a stock car.

Maybe you can call them and ask if they know what pressure they used.

If you haven't made a boost leak tester yet I'd recommend the one below; I made one without the gauge, and it's a pain because you don't know the pressure (how much you're adding or how quickly it leaks down) from in front of the car.

http://www.dsmtuners.com/forums/showthread.php?t=201554

And you don't need a boost gauge.

Yea, that boost leak tester is WAY nicer then the one I made. I'll have to visit Home Depot and pick those parts up. Thx for showing me that thread.

UPDATE!! I know it's been a while since I started this thread, but I think I finally found out what my problem was all along. It turns out (in my opinion) that the shop I took it to, doesn't know shit! After a lot of thought about how a leakdown test works, I was wondering how they could tell what percent it was leaking at the valve seals. I mean, even it being in perfect shape would net SOME loss in pressure when performing the leakdown. Not only that, but I don't think that "10% leak" from my valve seals would result in smoke "pluming" out the tailpipe during moderate to low boosting and ONLY during shifting.

Then it FINALLY hit me last Friday... like a bong hit, ...a big, smoke filled bong hit that makes you cough your kidneys up... or, like the smoke coming out of my tailpipe when stopped at a red light. Yes my friend... my T25 has expelled it's last breath of forced air.

I'm actually happy this happened, because now I know that once I replace my T25 (most likely with another T25), I can FINALLY start adding upgrades to my car! FINALLY!!! Anyway... i hate when people don't report back on their threads, so here is my update!

Thanks Everyone!!