Visible smoke from exhaust between shifts

[bsbllfit7]

Hello everyone just trying to find out whats wrong with the car. Its a 1995 Talon Tsi AWD with 109XXX miles. It had a head rebuild within the last 25K miles and is running on the stock T25 Turbo. Now just recently i have noticed that when i boost fairly hard and shift gears when i start to accelerate in the new gear i can see a puff of blue smoke behind my car and can smell the smell of burning oil. I have just installed a catch can between the valve cover and the intake tract. Just trying to figure out what this problem is.

Also i checked the turbo for shaft play and it was very very minimal if any play at all.

 

[TrevorS]

If it were your turbo, I'd expect the blue smoke to continue during your boost, but apparently that's not happening. I'd say it's just ring blow-by. How are your compression numbers? Have you cleaned your PVC valve?

 

[bsbllfit7]

havent done a compression test yet on this car. and no i havent cleaned my pcv. how do i go about doing that?

 

[DGajre777]

havent done a compression test yet on this car. and no i havent cleaned my pcv. how do i go about doing that?

How to do a Compression Test

Just buy a new PCV and replace the one on your valve cover. I always get OEM PCVs.

 

[AndrewD5418]

You replace the PCV valve, you don't clean it.

 

[bsbllfit7]

mmkay sounds like a plan ill try and get an oem pcv here in the next few days and let you guys no how it went. Ive been reading up on it and this sounds like the culprit here in this case.

 

[DSM1G90]

Tonnage of vacuum is created when the motor is at high revs when the throttle plate gets immediately closed. Thus, the vacuum is pulling up oil past the oil rings and gets burned off-ususally a sign of a good tight top end, but the bottom end is weak, as in your condition of the recent head job on a high mileage block.

It's always best to do both ends-if you're going to do a head, do the rings and bearings as well with a motor with that many miles on it.

If you drive normally, you won't have this vacuum issue since you're not winding up the motor real tight between shifts.

Good luck-DSM

 

[DzNutz]

Be sure to get OEM!!! The aftermarket cheapies dont hold up on the turboed motors. ALWAYS go OE MITSU for this part.

For what it is worth...

Daryl

 

[bsbllfit7]

bearings and pistons were checked when the head was removed and compression was good at the time of the head rebuild. I will do compression again but i dont think that that is the problem

 

[No_Skillz]

Is your BOV recirculated?

 

[TrevorS]

You replace the PCV valve, you don't clean it.

I've been cleaning PCV valves for many years in many cars. Why does it need to be replaced?

PS. Just looked it up in my 1990 Eclipse Service Manual and it clearly states to either clean or replace!

 

[DSM1G90]

compression was good at the time of the head rebuild

Compression can be good, yes, but how are the oil rings...a little bit of a different story here....I'm pointing this to tired oil rings - why of the recommended bottom end rebuild on a top end rebuild. I've seen 160psi compression on all fours with oil burning motors before.

Why does it need to be replaced?

It's always best to replace since the valve cone inside of the unit can get flat spots on its sides causing improper air metering when in use along with the spring losing tension after a few years in service.

Yes, you can clean them to keep them rattlin', but are they still doing what they're designed to do after all of that cleaning ....?

What's $ 5 bucks for a new PCV valve?

-DSM

 

[TrevorS]

It's always best to replace since the valve cone inside of the unit can get flat spots on its sides causing improper air metering when in use along with the spring losing tension after a few years in service.

Yes, you can clean them to keep them rattlin', but are they still doing what they're designed to do after all of that cleaning ....?

What's $ 5 bucks for a new PCV valve?

-DSM

Well, I'm at least satisfied that after 125K, it probably makes sense to replace mine -- cost me $6 though !

 

[bsbllfit7]

ya im just really pointing towards the pcv as the problem here. I heard that its a check valve and you shouldnt be able to blow through it, well the other day i took mine off and blew into it and it went clean through to the other side. Sound like a bad pcv to anyone else?

 

[bsbllfit7]

and yes bov is recirculated its a ngr performance type s and im boosting right under 1 BAR on a stock t25

 

[chico904]

ya im just really pointing towards the pcv as the problem here. I heard that its a check valve and you shouldnt be able to blow through it, well the other day i took mine off and blew into it and it went clean through to the other side. Sound like a bad pcv to anyone else?

Well, it's supposed to be able to blow through one way, towards the IM, just not both ways. Dont bother buying a new PCV valve, just clean it. What you want to do is install the USplastics check valve directly after the PCV valve and before the IM. Here is the link for the valve you want to buy. Check Valves - US Plastic Corporation
So just to be clear, take your PCV valve out, clean it, reinstall. Buy, and place the USplastics check valve I linked after the PCV valve and before the IM. Make sure you have the arrow on the check valve pointing towards the IM so that air can leave the valve cover and go into the IM, but not the other way around.

 

[bsbllfit7]

and this check valve will eliminate the problem of the smoke coming on at full boost between shifts?

 

[chico904]

and this check valve will eliminate the problem of the smoke coming on at full boost between shifts?

That, i don't know. I know that this will rule out the PCV system. One other thing to do to that will help all-around is to install a catch can between the valve cover and the intake.

 

[bsbllfit7]

i installed a catch can a week or so back between the intake and valve cover. This is actually when i started to notice the problem haha

 

[TrevorS]

Well, it's supposed to be able to blow through one way, towards the IM, just not both ways. Dont bother buying a new PCV valve, just clean it. What you want to do is install the USplastics check valve directly after the PCV valve and before the IM. Here is the link for the valve you want to buy. Check Valves - US Plastic Corporation
So just to be clear, take your PCV valve out, clean it, reinstall. Buy, and place the USplastics check valve I linked after the PCV valve and before the IM. Make sure you have the arrow on the check valve pointing towards the IM so that air can leave the valve cover and go into the IM, but not the other way around.

I just got one of those based on your earlier recommendation, and it's cheaper than a new PCV valve, until you add shipping that is (but still pretty cheap !

 

[bsbllfit7]

TrevorS was it effective for what you needed it for, and what were the problems you were having that made you get one of the check valves

 

[TrevorS]

TrevorS was it effective for what you needed it for, and what were the problems you were having that made you get one of the check valves

I got it on the suggestion of another member since my exhaust was very gray under strong boost and I thought it was due to oil blow-by. However, I've since concluded it's more an AFR issue (swings a little rich under strong boost). So, I've not yet installed it -- I'm just going to keep an eye on my exhaust and oil level and see how it goes. In the meantime, my PCV valve is original (125K miles ago , and as I was picking up a turbo gasket set anyway, I decided, what the hey ! So, for now, I'm going to install the new PCV valve and leave the U.S. Plastics on the shelf.

 

[bsbllfit7]

mmkay good to know. Ill probably end up going with both the pcv valve and the check valve just to make sure that isnt the problem. If its the rings then ill just have to tough it out for now and keep an eye on the oil level. Will adding more boost change the amount of oil that is burning off under boost? I ask this because i plan on upgrading the turbocharger from the stock t25 to an evo 3 16g.

 

[TrevorS]

mmkay good to know. Ill probably end up going with both the pcv valve and the check valve just to make sure that isnt the problem. If its the rings then ill just have to tough it out for now and keep an eye on the oil level. Will adding more boost change the amount of oil that is burning off under boost? I ask this because i plan on upgrading the turbocharger from the stock t25 to an evo 3 16g.

The more boost pressure, the more blow-by, and so yes, it probably will! I've read the extra check valve can really help control blow-by oil loss. I did a leak down test and my pressure loss was mostly rings, so I'll probably end up installing the US Plastics valve.

 

[bsbllfit7]

so the check valve actually helps with the blow by with higher boost? Sorry if these are dumb questions just trying to figure out if ill run into too much trouble by throwing that evo 3 in there