ThePhotographersGarage
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Hello gang! It's need an extremely long time since I've been here, like 15 years ago long, back when I owned #426/2000 when I was in college.
Anyways, I've gotten back in the GVR4 game and I'm working through an excellent example of a bone stock '91 that has started to blow an enormous amount of smoke. A quick breakdown of the car: Car was a one owner car for a long long time where it was her daily driver. As it turned out she was driving it around for a long time with a cracked hot side on the turbo and cracked manifold, and while the car drove for her just fine, the car was pretty much making no boost. Car was acquired by a friend who is a pretty good wrench and is familiar with these cars. He was able to take care of the timing belt/water pump, fix issue with the BIS, thermostat, all fluids (some clown in the past ran MTF in the transfer case!), get the ECU recapped, replaced the exhaust mani w/ a later style unit, and he was able to find a good rebuilt stock 14b from a turbo rebuild shop that had it sitting on a shelf in a box the back for like for like 20 years.
He then ran it a bit and noticed that there was a big leak from a hairline crack in the valve cover. Likely somebody in the past gorilla torqued the VC down and cracked it. He also noticed that the PCV valve was not only bad, but the incorrect unit and it was one for an NA car. That's why the leak just now showed itself. The car was now actually making boost and it blew pressure past the wrong PCV valve and pushed oil past the cracks in the VC. RR'd all of that, new OEM and correct PCV valve and off to the races.
Car then ran flawlessly for about 150 miles including some hard pulls, freeway time, idle time, etc. I bought it from him and about 20 miles into my drive how after a 5th gear pull from like 55mph-75mph I noticed a cloud of smoke when I let off throttle. Tried a few other times and same deal, heavy smoke after a short pull. I limped it home (all temps, etc where great) and I'm now looking to trouble shoot everything. Even a quick start up and just idle around to move the car and it smokes enough to make the neighbors close their windows and give me the stink eye. We've got a few theories, but before I yank the turbo out of the car I figure I would float some ideas out there and see if maybe we are overlooking some things here.
I've pulled the PCV valve and did a simple suck/blow test (tasty) and it seems to be working correctly. It's a new OEM part, so that's to be expected. Pulled the boot from the air box to the turbo. There's a coating of oil over the entire inside of the boot. I'm not sure if this is new and fresh from the current issue or left over from the prior PCV valve issue, but it was not smoking prior to the new issue. The turbo spins freely and has a small (seemingly normal) amount of side to side play and I can't feel any real in/out play so the turbo FEELS ok. Looking from the underside of the car there's drop or two of oil on the outside of the body of the turbo on the cold side. I pulled the turbo oil return line from the oil pan and about a pint of oil ran out (likely mostly from the pan, certainly not all out of the turbo/line. The gasket on the pan was correct and nothing to show that it was blocked up or physically restricted to prevent the oil from returning properly.
So here are the working theories:
1. The bad PCV system before pressurized the crankcase enough to stress the rebuilt turbo's oil seal and after a higher speed top gear pull it was enough of a stress that it ended up being the straw that broke the camel's back and "blew the seal out" on the turbo. After all that turbo sat on a bench in a box for 2 decades. The fix is to fish out the turbo and send it out to be rebuilt again, clean all the piping, intercooler, etc of oil.
2. Even though the PCV valve seems to be working correctly, there's still an issue with the PCV system which is pushing oil into the intake tract and causing the smoking issue. The turbo itself is OK, however the crankcase is still pressurized and we've got a combo of the pressure pushing oil into the intake and also keeping oil from properly draining into the pan due to that positive crank case pressure (hence the oil seen on the outside of the turbo, she's full of oil). Fix is to correct what ever is wrong in this PCV system, clean the intake out as best I can, then run it clean and hope I don't poison the Cat in the process (CA Smog is a thing). Any ideas on what to look for? Seems like too significant of an issue on a bone stock car for a simple "Add a catch can bro" solution.
3. Something else entirely.
The car is otherwise brilliant and completely sorted out. Cold AC and everything. Let me know any thoughts or ideas and I'll start throwing some time and labor into diagnosis at the car.
Thanks gang!
-Frank
Anyways, I've gotten back in the GVR4 game and I'm working through an excellent example of a bone stock '91 that has started to blow an enormous amount of smoke. A quick breakdown of the car: Car was a one owner car for a long long time where it was her daily driver. As it turned out she was driving it around for a long time with a cracked hot side on the turbo and cracked manifold, and while the car drove for her just fine, the car was pretty much making no boost. Car was acquired by a friend who is a pretty good wrench and is familiar with these cars. He was able to take care of the timing belt/water pump, fix issue with the BIS, thermostat, all fluids (some clown in the past ran MTF in the transfer case!), get the ECU recapped, replaced the exhaust mani w/ a later style unit, and he was able to find a good rebuilt stock 14b from a turbo rebuild shop that had it sitting on a shelf in a box the back for like for like 20 years.
He then ran it a bit and noticed that there was a big leak from a hairline crack in the valve cover. Likely somebody in the past gorilla torqued the VC down and cracked it. He also noticed that the PCV valve was not only bad, but the incorrect unit and it was one for an NA car. That's why the leak just now showed itself. The car was now actually making boost and it blew pressure past the wrong PCV valve and pushed oil past the cracks in the VC. RR'd all of that, new OEM and correct PCV valve and off to the races.
Car then ran flawlessly for about 150 miles including some hard pulls, freeway time, idle time, etc. I bought it from him and about 20 miles into my drive how after a 5th gear pull from like 55mph-75mph I noticed a cloud of smoke when I let off throttle. Tried a few other times and same deal, heavy smoke after a short pull. I limped it home (all temps, etc where great) and I'm now looking to trouble shoot everything. Even a quick start up and just idle around to move the car and it smokes enough to make the neighbors close their windows and give me the stink eye. We've got a few theories, but before I yank the turbo out of the car I figure I would float some ideas out there and see if maybe we are overlooking some things here.
I've pulled the PCV valve and did a simple suck/blow test (tasty) and it seems to be working correctly. It's a new OEM part, so that's to be expected. Pulled the boot from the air box to the turbo. There's a coating of oil over the entire inside of the boot. I'm not sure if this is new and fresh from the current issue or left over from the prior PCV valve issue, but it was not smoking prior to the new issue. The turbo spins freely and has a small (seemingly normal) amount of side to side play and I can't feel any real in/out play so the turbo FEELS ok. Looking from the underside of the car there's drop or two of oil on the outside of the body of the turbo on the cold side. I pulled the turbo oil return line from the oil pan and about a pint of oil ran out (likely mostly from the pan, certainly not all out of the turbo/line. The gasket on the pan was correct and nothing to show that it was blocked up or physically restricted to prevent the oil from returning properly.
So here are the working theories:
1. The bad PCV system before pressurized the crankcase enough to stress the rebuilt turbo's oil seal and after a higher speed top gear pull it was enough of a stress that it ended up being the straw that broke the camel's back and "blew the seal out" on the turbo. After all that turbo sat on a bench in a box for 2 decades. The fix is to fish out the turbo and send it out to be rebuilt again, clean all the piping, intercooler, etc of oil.
2. Even though the PCV valve seems to be working correctly, there's still an issue with the PCV system which is pushing oil into the intake tract and causing the smoking issue. The turbo itself is OK, however the crankcase is still pressurized and we've got a combo of the pressure pushing oil into the intake and also keeping oil from properly draining into the pan due to that positive crank case pressure (hence the oil seen on the outside of the turbo, she's full of oil). Fix is to correct what ever is wrong in this PCV system, clean the intake out as best I can, then run it clean and hope I don't poison the Cat in the process (CA Smog is a thing). Any ideas on what to look for? Seems like too significant of an issue on a bone stock car for a simple "Add a catch can bro" solution.
3. Something else entirely.
The car is otherwise brilliant and completely sorted out. Cold AC and everything. Let me know any thoughts or ideas and I'll start throwing some time and labor into diagnosis at the car.
Thanks gang!
-Frank
