This thing smokes under full boost only

M

Matt McClung

Hotair guy who owns a I/C
Joined
Sep 18, 2001
i did not know I had a problem until I decided to go to the track for fun. Well, my gn smokes, but only on full throttle and held for three to four seconds, then it just smokes until I let off. Does not smoke at idle, or driving, it does not smoke under full boost if done for less than four seconds or so (this is why I didn't know I had a problem, not too many places on the road where you want to lay it down for prolonged periods). Runs good, is strong. Power logger shows no knock, etc. I have two breathers one in each valve cover, pcv valve is the RJC piece and checked that it's good. Cross over pipe is dry. Turbo is a few years old, precision 6266. Need to check the down pipe internally I guess. Any ideas?

Thanks
Matt
 
Just my guess, but I would think the oil pressure and RPM at WOT for over 4 seconds would be pushing oil through the turbo seals?
 
Nick Micale said:
Just my guess, but I would think the oil pressure and RPM at WOT for over 4 seconds would be pushing oil through the turbo seals?
Click to expand...

That's what I'm thinking as well. When I built the bottom end last year with a stroker crank, I wanted to make sure it had good oil pressure. Well it's been really good. Even after fully warm and 10w 30 oil, the pressure is aroun 25 psi at idle and at WOT, the relief spring is getting a workout as the gauge is aroun 75 psi.
 
Matt McClung said:
i did not know I had a problem until I decided to go to the track for fun. Well, my gn smokes, but only on full throttle and held for three to four seconds, then it just smokes until I let off. Does not smoke at idle, or driving, it does not smoke under full boost if done for less than four seconds or so (this is why I didn't know I had a problem, not too many places on the road where you want to lay it down for prolonged periods). Runs good, is strong. Power logger shows no knock, etc. I have two breathers one in each valve cover, pcv valve is the RJC piece and checked that it's good. Cross over pipe is dry. Turbo is a few years old, precision 6266. Need to check the down pipe internally I guess. Any ideas?

Thanks
Matt
Click to expand...
Pull the turbo off and drive it.
 
Rafs-T-Type said:
I just had the same issue and it was a blown HG.
Click to expand...

This crossed my mind, but I've had blown head gaskets before and it always caused a misfire and when pressuring the crankcase, it would smoke a lot more, to the point of smoke coming in the cabin. I know it's possible to have a very small head gasket leak, but you would think the BLM's would be off and not run this good.
 
Matt McClung said:
This crossed my mind, but I've had blown head gaskets before and it always caused a misfire and when pressuring the crankcase, it would smoke a lot more, to the point of smoke coming in the cabin. I know it's possible to have a very small head gasket leak, but you would think the BLM's would be off and not run this good.
Click to expand...


I will perform compression tests and leakdown tests as well to see if any variation exists between cylinders.
 
Matt McClung said:
This crossed my mind, but I've had blown head gaskets before and it always caused a misfire and when pressuring the crankcase, it would smoke a lot more, to the point of smoke coming in the cabin. I know it's possible to have a very small head gasket leak, but you would think the BLM's would be off and not run this good.
Click to expand...

My car ran perfect even with it blown. I did get some smoke in the cabin under boost though. Cylinder even had decent compression, Just a little lower than the others.
 
I am having the exact same issue...only under high boostst do I get smoke... my oil pan gasket is trashed and it has leaked since the day I got the car. I am pretty sure under full boost it is spraying the exhaust and causing smoke. I am installing a new oil pan gasket over the 4th. I know it is not my turbo as all my pipes are clean (no oil). Plugs look great as well.

On your breather grommets are they the open type or are the one to prevent oil getting past? I have read that the oil preventing type are too restrictive, I cut mine so they are open. I also installed a true check valve on the pcv.

I know I have an excess blow by issue but I going to nurse it along this summer and "try' to keep my foot out of it. I just got the car so I want to do some stuff before doing a rebuild this winter. The car runs great which is the deceiving/tempting part.

My car also has high oil pressure... 60 at WOT... 20 at idle... I wonder if this common issue has something to do with it??

Good luck.
 
I had a real similar problem. I also have high oil pressure, but found out it was the turbo. Swapped another turbo on it and the smoke issues totally went away. I need to send the old unit off to have it repaired to see what the issue was, but never got around to it


Sent from my iPhone using Tapatalk
 
Matt McClung said:
I will perform compression tests and leakdown tests as well to see if any variation exists between cylinders.
Click to expand...

Well, I have compression results.
Cylinder 1 160psi
Cylinder 2 165psi
Cylinder 3 163psi
Cylinder 4 160psi
Cylinder 5 165psi
Cylinder 6 160psi

This appears to be good.
One thing I have not seen is two of the plugs (cylinders 5 and 1) have the porcelain and steel thread separated, not coming apart but I could spin the porcelain inside the steel threads, so even though these cylinders were firing, they were leaking compression through the plugs. The plugs are AC RT42s.

I'm really starting to lean towards the turbo. Maybe I should try a restrictor for the oil?
 
Matt McClung said:
Well, I have compression results.
Cylinder 1 160psi
Cylinder 2 165psi
Cylinder 3 163psi
Cylinder 4 160psi
Cylinder 5 165psi
Cylinder 6 160psi

This appears to be good.
One thing I have not seen is two of the plugs (cylinders 5 and 1) have the porcelain and steel thread separated, not coming apart but I could spin the porcelain inside the steel threads, so even though these cylinders were firing, they were leaking compression through the plugs. The plugs are AC RT42s.

I'm really starting to lean towards the turbo. Maybe I should try a restrictor for the oil?
Click to expand...
Just pull the turbo run it without or try another turbo
 
Well, I have the GN1 black valve covers and it has the push in style breathers. One of the breathers has been breathing better than the other as when I took out the elements, one is white and the other is the color of oil. The one not breathing as well still has the rubber "door" in the bushing that installs in the valve cover and the other side was cut out. I just cut out the flap or door in the rubber bushing so any pressure can escape the block more easily. I have to try and test drive it somewhere where I can open it up without risc to myself or someone else.
 
Well, after opening the other breather bushing. And replacing the plugs with fresh R42TS gapped at .025. I took it for a ride tonight and went down one of those two lane roads in the middle of fields and no houses. Gave it WOT for as long as I felt comfortable, actually I went further than my comfort level and saw no smoke. Ran really strong and was able to put pretty much all the power to the ground (still had the DOT slicks on it), and WOW is all I can say. I'm going to test and tune on Wednesday night to really see if I have this problem licked.
I'll report back then. Thanks to all who have replied.
 
Sorry to revive an old thread but I figured it was better than starting a new one:

Similar issues with the same valve covers and grommets. Last night after doing some driving and spirited pulls with the same smoke I noticed that the lower edges of those grommets had oil seeping around them but the white foam inserts were clean. If those breathers aren’t working well is that a likely candidate for all the smoke after WOT pulls?

Going to pull the intercooler and downpipe today and look for oil to double check and be sure.


Sent from my iPhone using Tapatalk
 
precizion818 said:
I had a real similar problem. I also have high oil pressure, but found out it was the turbo. Swapped another turbo on it and the smoke issues totally went away. I need to send the old unit off to have it repaired to see what the issue was, but never got around to it


Sent from my iPhone using Tapatalk
Click to expand...

Had the same issue myself with a fresh rebuild. I thought it was something wrong internally to the engine and it turned out to the a turbo issue. The turn had no obvious signs of being the culprit until swapped out. My old unit is just sitting around till I feel like dealing with it


Sent from my iPhone using Tapatalk
 
You must log in or register to reply here.

Similar threads

Paulmac201
Summit Racing Breather Tank
2
Replies
39
Views
2K
T- Type Tim
T- Type Tim
G
Strange sound under boost
Replies
3
Views
472
Grassguy
G
M
Skipping/sputtering under boost.
2
Replies
25
Views
2K
mommasGN
M
D
PCV Help?
2
Replies
33
Views
2K
Clark6
C
N2BUICK
Name that TV cable
Replies
7
Views
856
N2BUICK
N2BUICK
Top