I think white smoke was oil shooting out my dipstick holder (with video)

[dreamweaver13]

Here's the short version:
white smoke during idle
turbo was all oily inside - no oil in manifold runners
sent turbo away to PT to be rebuilt
put everything together again and have white smoke on acceleration (above 3-4k rpm)
Did lots of tests. pretty sure it's not a BHG and nothing's wrong with the engine.
Notice that there's a significant oil leak on the exhaust side of the engine. Maybe a drop of oil every 10 seconds dripping off the lower front edge of the tranny.
take off turbo - everything's dry and clean inside

So that brings me to the test I did today.
I plugged up the oil supply with an old knock sensor and made a plate to put over the oil return so I could run the car without the turbo. I wanted to be able to see where the oil was leaking from - since I didn't think my white smoke was coming out the exhaust. I suspected it was being sprayed onto a hot turbo/downpipe and causing the white smoke under acceleration.
I was surprised to see how much oil came out of the dipstick holder. I forgot to put the dipstick all the way in, but I'm pretty sure it would have shot out between the dipstick holder and the red dipstick guide that sits in the block. There was a bunch of oil pooled there. Then I remembered the o-ring at the bottom of the dipstick holder had become brittle/hard and I had thrown it out and tried to put make-a-gasket around it. Guess that didn't work.

and the hose I showed in the video was a PCV hose that usually connects to the intake.

http://www.wam.umd.edu/~weaverjd/supra.test.no.turbo.web.wmv
video is 3.6MB and just over a minute long

 

[bigaaron]

That is some serious blow by! Rings are probably shot or not sealing for some reason. That is why it is burning oil on acceleration also. If compression is getting in the crankcase, then oil can get into the cylinders.
Did you do a compression test on all cylinders?

 

[hottscennessey]

Same problem I have.. presumably, in my case, worn or shot piston rings.

 

[dreamweaver13]

I did a compression test about 2 weeks ago
1- 150
2- 165
3- 150
4- 155
5- 160
6- 145

I didn't really know what to make of the numbers - since they were so different. My compression gauge is pretty crappy, but it could also be a lot of blowby.
Also, when I rebuilt the engine, I was surprised with the large ring gaps I had. I got new Hastings piston rings and ended up not doing any ring filing. My ring gaps were all about .025" out of the box which I considered quite high. I think this might be the source of my unusual blowby.

I just want to make it clear though - I don't think I'm burning much oil. I think it was spraying out of the dipstick assembly somewhere and landing on the manifold, downpipe, or turbo and instantly combusting - causing white/grey smoke.
I also noticed that the red dipstick holder wasn't pressed into the block like it's supposed to. It was kind of just sitting there wiggling around. That was allowing a lot of oil to come out.

 

[bigaaron]

I did a compression test about 2 weeks ago
1- 150
2- 165
3- 150
4- 155
5- 160
6- 145

I didn't really know what to make of the numbers - since they were so different. My compression gauge is pretty crappy, but it could also be a lot of blowby.
Also, when I rebuilt the engine, I was surprised with the large ring gaps I had. I got new Hastings piston rings and ended up not doing any ring filing. My ring gaps were all about .025" out of the box which I considered quite high. I think this might be the source of my unusual blowby.
Plus a difference of 20 psi between cylinders is not good at all. Looks like that thing is going to need to come apart again unfortunately.

I just want to make it clear though - I don't think I'm burning much oil. I think it was spraying out of the dipstick assembly somewhere and landing on the manifold, downpipe, or turbo and instantly combusting - causing white/grey smoke.
I also noticed that the red dipstick holder wasn't pressed into the block like it's supposed to. It was kind of just sitting there wiggling around. That was allowing a lot of oil to come out.

.025? That is too much, even for forged pistons. I think you got the wrong size rings :cry: You are not burning a lot of oil because the compression in the crank case is blowing it right out of the motor! And you were just at idle, imagine how much pressure there is at 12psi!!!

 

[IJ.]

Any PCV system mods done?

DAMN .025"??

 

[dreamweaver13]

I just went for a drive and there was no smoke out the back. Had my dad follow me just in case. I hammered the tube into the block and got a new o-ring for the dipstick holder. That seemed to solve the problem. I'm still getting some drips near the rear of the engine. I'll check those out tomorrow.

I know, that's what I thought as I was measuring them in the cylinders. The box said they were for the 7M L6 3.0. I got them through my machine shop - Hastings rings. It's possible I measured wrong with the feeler gauge or didn't push them far enough into the cylinder, but it was still a huge gap.
And I don't have forged pistons. I don't know where you got that idea - maybe all the clatter coming from my engine. I assure you they are stock pistons. But next time they will be wiseco.

PCV system: There is a catch can mounted in front of the radiator off to the right close to the headlight motor. The vacuum source is the pre-turbo intake pipe.

 

[bigaaron]

I just went for a drive and there was no smoke out the back. Had my dad follow me just in case. I hammered the tube into the block and got a new o-ring for the dipstick holder. That seemed to solve the problem. I'm still getting some drips near the rear of the engine. I'll check those out tomorrow.

I know, that's what I thought as I was measuring them in the cylinders. The box said they were for the 7M L6 3.0. I got them through my machine shop - Hastings rings. It's possible I measured wrong with the feeler gauge or didn't push them far enough into the cylinder, but it was still a huge gap.
And I don't have forged pistons. I don't know where you got that idea - maybe all the clatter coming from my engine. I assure you they are stock pistons. But next time they will be wiseco.

PCV system: There is a catch can mounted in front of the radiator off to the right close to the headlight motor. The vacuum source is the pre-turbo intake pipe.

The problen is not the seal at all, because the oil level is well below that height. The problem is the obvious exhaust pressure in the crank case pushing the oil out. Your machine shop sold you the wrong size rings, but you knew the ring gap was too big before you assembled the engine so you can't really say it was all their fault. I know its a bad situation and a real bummer

 

[dreamweaver13]

If the oil level is too high, would there be a similar effect - even if there is less blowby?

I take responsibility for installing the rings. But there isn't really anything I can do now to fix it. (or is there?) I will have to wait until the next rebuild.

I'm trying to think of any other side effects this will have besides reduced power and it trying to blow oil out the dipstick. I'm guessing there may be a lot more oil circulating through the intake from the PCV system.

thanks for the help

 

[Joel W.]

PCV system: There is a catch can mounted in front of the radiator off to the right close to the headlight motor. The vacuum source is the pre-turbo intake pipe.

It looks to me, like you are running without vacuum to the PVC system in the video? Is that correct?

I would fix that first and try it. :dunno:

 

[bigaaron]

It's not a good idea to drive it like that, and it will probably get worse.
You can see exhaust gas coming out of the pipe in the video, and the compression test shows something is wrong also.

The oil will be filthy within hundreds of miles. The pressure will try to push oil out of the dipstick hole, and if it can't, it will push out your front and rear main seals or anywhere else it can. The intercooler will fill up with oil. If you run it the cylinder walls could get damaged, and the plug/s in the bad cylinders will foul out and then it will missfire. If it runs low on oil the bearings and cams will get trashed.

The best thing you could do is fix it now before the motor is junk.

 

[dreamweaver13]

Joel: yes, I was running without a vacuum source in the video. That's just because I didn't have a pre-turbo intake pipe to connect it to. It usually has a vacuum source. I'm sure it helps suck out some of the pressure - but I'm sure that's not enough.

bigaaron: thanks for the diagnosis help. I'm beginning to suspect something worse than just large ring gaps - maybe a cracked ring or piston or something similar. I wish I had a scope to inspect the pistons through the spark plug hole. I'm off to college soon (without the supra), but I am looking into a rebuild with some wisecos. Just don't have time to work on it in the near future.

 

[supra90turbo]

lol i want to hear that in person.. that's hilarious...

i've got nothing else to add to the conversation though... everything i thought has been said already.

 

[dreamweaver13]

it was loud, but no louder than I expected.
The backfires were really cool though. I had my dad bring it up to 4000 rpm and then let off. Definitely made me jump.

I was just looking through my measurements and the ring information on the box of the Hastings rings. I also looked them up on the Hastings site. They were supposedly for my bore which was the standard 83mm.
How much does honing take off the cylinders? I wouldn't think it would be more than a few thou. Maybe I am over the limit for using the std pistons and rings.
And the max limit for #1 ring gap is .0291". I was below that, but just barely.