I'm running a 396 sb stroker with a vortechsupercharger and the thing won't stop finding places to leak oil. I know it is because I am creating too much crankcase pressue. I do not have a PCV valve, I know that would help, but would it help enough? I have also heard that PCV valves dont handle boost well. Any input or ideas are appriciated.

 

Do you have vents in both valve covers?

 

I have a stock bottom end L98 engine running a 175 shot of nitrous and have had the same problem. It would blow oil up out the dipstick tube. I vented both valve covers with open breathers and that took care of most of the problem. I drive my car alot though and hated the stink. I then installed a smog pump from an LT-1 car up by the drivers side headlight, connected a hose from it's inlet to the driver's side valve cover, and a hose from it's outlet to the exhaust. Still has an open breather on the passenger side. Works like a charm, no oil spit at all anywhere now. Has about 3,000 miles on it with this setup and working great.

 

Now that's a brilliant idea!

 

I have vents in both valve covers. I like the LT1 smog pump idea, how did you route it into the exhaust?

 

It's an LT1's version of the AIR system.

There's an opening in the exhaust manifold, a central one, so it's not pointed at the exhaust valve.

Here's my EM headers that maintain the fitting.



Another alternative would be to run a catch can, put a check valve when the stock lines run, and perhaps run a line to the inlet side of the blower.

 

While a good idea in context, it just doesn't work. The blower will suck from the path of least resistance, which unfortunately is not a maze of tubing, catch-can, into the valve covers.

You need a dedicated vacuum pump that will suck the excess psi from the crankcase. The solution is not cheap in the form of mechanical (belt driven) vacuum pump or electric pump. I choose the electric route, as you have enough stuff running off the belt of a blower car.

There are several routes on the electric side (i.e. '80s series Caddy vacuum pump, Lightning / Cobra pump, or European 3 series Bimmer). I find that the BMW pump works well with integrated catch can, that has to be emptied rarely (if you have minimal blowby), but keeps the underhood areas clean. You still must have a vent in one of the valve covers, but it certainly reduces the potential for a mess.
Aaron

 

Sounds like you need to perform a leakdown test... If it's got that much blowby there is something amiss.

 

Do you run the pump all the time? I wonder if it will hold up to constant running? Also, does it cause any problems with the o2 sensors? ie. adding extra air causing the sensors to think it is running lean and therefore adding fuel?

I really like the idea and im considering doing it to my na car to keep it on the road a little longer before having to re-ring it.

 

yes.. the air injection reaction system does not work full time.. it is summoned to perform at certain areas of operation such as on decel, it pumps air to keep the "pop pop pop pop" sound from happening and lowering emissions by completing combustion of unburned fuel going out the exhaust.

some have used it with success but it would need to be routed past the O2 sensors.. I would maybe try using it in conjunction with a swept crank case evac system that welds into the exhaust.

Aaron is correct that it would be marginal at best and that stronger pumps which can withstand oil contamination and continue to work on a continuous duty cycle would be better suited.

and if you are blowing the dipstick tube out at operating temperature then your rings are gone and your seal is poor. in most cases the crank case evac system would be nothing more then a bandaid. you will realize more power with a engine refresh or a rebuild.

Chris

 

I have the LT1 electric pump direct wired to a wire that is on all the time when the key is on, so yes, it runs all the time. I had an 02 bung welded in (downstream of the 02 sensor) then screwed a stub of pipe into it, and clamped high-temp heater hose to it. All is working great. Don't know how long it will last but I can buy about 20 used LT1 smog pumps for the price of a true vacuum pump. Doubt I'm getting much vacuum out of this pump but I'm not really trying, I just let it pull through the crankcase to vent the blowby.

lcvette, I might be losing some power to blowby but you might be surprised. My engine runs perfect, when I pull the evac line out of the valve cover and watch I get the slightest little bit of almost invisible smoke just barely drifting out. Even when revved up that's all I get. I've seen the same thing on fairly new engines. If I had a bad ring seal problem it would look like a smokestack, or at least I'd be able to feel the air blowing out with my hand. I have no blowby issues whatsoever using the stock pcv system without nitrous and have no problems revving to over 6000 rpms, but when spraying nitrous the cylinder pressures are so high that I get extra blowby. On a 150 shot with HSR intake and CC503 cam and reworked 113 heads I made 417 hp and 419 tq at the wheels on a Land and Sea dyno, with a subpar tune (too rich), false knock, and stock catback. At the high end of the rpms on the dyno while spraying it did smoke a little out the breather that is on the passenger side. The dyno operator said he has seen many that soak the breather with oil and are strong runners for many years. I now run an LT1 catback and a 175 shot and a better tune, all else the same. I still have no oil coming out anywhere. Not bad, IMO, for a high mileage stock bottom end. I might be leaving some power on the table due to blowby but not enough for me to pay for a bottom end rebuild right now.

 

Aaron has stated the proper way of venting. I have stated the poor white trash way of venting. Follow his advice if you can afford it. If I could afford the proper way I would. I would also have a blower and a forged 383 and hopefully someday I will. I have no idea how long the LT1 electric pump will last being used as a crankcase evac. I tried the stock belt driven L98 pump for this, it died in about 1000 miles. This LT1 pump is 3,000 miles in and going strong. I was hoping to get about 2,500 to 3,500 miles out of it since that's what I drive in a year. At $20 to $30 for a used pump I'll replace it every year if I need to. Point here is, to the OP, even with a brand new motor, you likely will need to run some sort of pump if you don't want oil spitting out and the stink of open breathers. There is likely nothing wrong with your engine.