crankcase pressure problems!!! help please!

blackstallion12 · Feb 28, 2010

68 mustang 289 bored .030 over comp cams 294s cam, lifters, springs, 10.5:1 compression, flowtech headers, 2 1/4 dual turbo mufflers.

now that you know the settup here is the issue.. i rev no higher that 6500 i drive somewhat aggressive but know how to take care of my car and dont abuse it. last night i got home and my dipstick was popped up about 3-4 inches and oil was on the bottom side of the hood. also i have 2 breather caps.... NO PCV HOOKED UP. i dont want to run a pcv if i dont have to. i understand that my crankcase pressure is way too much and this scares me. oil leaks from the breathers as well.

i just put a new breather on driverside valve cover because it was saturated with oil and wasnt useful.

now i need suggestions on what kind of evacuation system to use? they offer systems that weld to the exaust pipe BUT those are stricktly race only.

i could run a pcv but i dont like the idea of pumping smoke into my engine also the lose of carb suction.

i was also thinking just big breather tubes into a catch can but i dont know if that would work or be sufficient..

Please guys if you have had similar problems or know what to do i am open to all suggestions. thank you so much.

Rusty67 · Mar 1, 2010

Are you sure the problem is crank case pressure ? What kind of oil and oil pump are you using ? Do you have a good/accurate oil pressure gauge ? Maybe your oil pressure is just WAY to high ?

JR4 Motorsports · Mar 1, 2010

Rusty67 said:
Are you sure the problem is crank case pressure ? What kind of oil and oil pump are you using ? Do you have a good/accurate oil pressure gauge ? Maybe your oil pressure is just WAY to high ?

How is high oil pressure causing the dipstick to pop out? I would put a real oil pressure gauge on it, but I don't think the crank case pressure is due to that. I think it is more of a blow by issue, but lets have a little more info on the engine, please.....

Heads, pistons, how long since rebuild, etc...
Thanks

blackstallion12 · Mar 1, 2010

i have 65 289 heads that i did a fresh rebuild and port job. screw in studs, new guides. 194int 150exh new seals. pistons are cast flattops with moly rings. about 15000 miles on rebuild and i thought it could be rings but it doesnt smoke while driving or full throttle.

rbohm · Mar 1, 2010

stop wimping out and run the pcv valve. that is what is was designed for, providing positive crankcase venting.

blackstallion12 · Mar 1, 2010

JR4 Motorsports · Mar 1, 2010

The stock PCV valve is ok for regular driving, but if "Spirited" driving means foot to the floor for a little while, the PCV is not going to keep up as there will be more blow by and less manifold vacuum to vent the crankcase.

Can you do a compression test, or a leak down test?

blackstallion12 · Mar 1, 2010

yes i can do a compression test quite easily. thats also what i read is that pcv s sometimes dont keep up with high rpm thats why i dont run one. im sure it would help a lil bit but not solve the problem. i used to run a pcv but it never seemed to work very well. im not sure if i need a large diameter hose or what but i will do a compression test and post asap.

but also if i do have excessive blowby (besides replacing rings and a new hone) i would still need some sort of crankcase evac system right?

Tanus · Mar 1, 2010

I have mine to exhaust, daily driver, causes it to smoke a little but no big deal

rbohm · Mar 1, 2010

if you really dont want to use a pcv valve, you can do what the racers do, use a closed system cap, these have a hose nipple on them and you need two of them, and use a small tank to run the hoses to to vent the crankcase, while not allowing oil to leave the engine. you can also use a vacuum pump from a diesel engine to evacuate the crankcase, they are designed to run the power brakes and other vacuum operated accessories. the vacuum pump system has been shown to add about 10hp on a 500hp big block because of the negative crankcase pressure.

coolblue65 · Mar 1, 2010

honestly I think you are way overcomplicating this, it will cost you about $10 to put the PCV in and be done with it. The PCV will keep up with your spirited driving just fine. Unless you are planning on running on road course for 20min full out sessions or have a serious race engine anything but a PCV isn't really necessary.

Tanus · Mar 1, 2010

rbohm said:
if you really dont want to use a pcv valve, you can do what the racers do, use a closed system cap, these have a hose nipple on them and you need two of them, and use a small tank to run the hoses to to vent the crankcase, while not allowing oil to leave the engine. you can also use a vacuum pump from a diesel engine to evacuate the crankcase, they are designed to run the power brakes and other vacuum operated accessories. the vacuum pump system has been shown to add about 10hp on a 500hp big block because of the negative crankcase pressure.

I tried to do that by modding the stock smog pump to suck, instead of blow. It didnt work and unfortunatly it ruined the pump, but it was a good idea.... in theory, haha

tx65coupe · Mar 1, 2010

It also sounds to me like your over reving the engine a bit. I don't think it needs to really rev past 6k. I think 6500 is beyond peak hp/tq. I would also suggest putting the PCV back on.

blackstallion12 · Mar 1, 2010

coolblue65 said:
honestly I think you are way overcomplicating this, it will cost you about $10 to put the PCV in and be done with it. The PCV will keep up with your spirited driving just fine. Unless you are planning on running on road course for 20min full out sessions or have a serious race engine anything but a PCV isn't really necessary.

price has nothing to do with it... i used to run a pcv but it didnt work it still spued oil and it didnt allow the engine to run to its potential. i think most pcv caps are too small of diameter.

blackstallion12 · Mar 1, 2010

tx65coupe said:
It also sounds to me like your over reving the engine a bit. I don't think it needs to really rev past 6k. I think 6500 is beyond peak hp/tq. I would also suggest putting the PCV back on.

i dont think you took the time to read my original post but the solid lift cam i am running makes power from 2500 to 6500 so i dont think 6 is murder for my lil engine but thanks

blackstallion12 · Mar 1, 2010

rbohm and tanus thank you so much!! but i have a question. what did the boss mustangs use for breather setups? also i looked into the exhaust idea but im afraid i might burn the car down if the oil catches on fire but if you say you use that on your daily driver i like that idea.

j69302 · Mar 1, 2010

blackstallion12 said:
price has nothing to do with it... i used to run a pcv but it didnt work it still spued oil and it didnt allow the engine to run to its potential. i think most pcv caps are too small of diameter.

thats not the pcv valves fault. sounds like something else is wrong. PCV valves are good for the engine they help keep it clean. I used to run without one and the oil vapors that came out of the breathers(even with a filtered one) just got all over the hood and made a oily dirty film all over. Put the pcv system back in.

The PCV is actually good for the engine though. It allows blow by vapors to get removed by getting sucked back into the intake system. while these get removed fresh air enters your engine through the breather. this keeps the highly acidic and corrosive blow by gases to not eat up your oil and metals inside the engine.

If you are getting anything but gases/vapors high enough up to go through your PCV/Breather valve you got other problems. do your valve covers have baffels in them? excessive blow by? could possibly even have a oil return problem, maybe oil is not draining out of the heads as fast as your pump is pumping it. If your heads are filling up with oil, this closes off the path to the breathers/pcv effectively making it a closed system, which ended up turning your dipstick into a pressure relief valve.

Im just throwing some other stuff to look at.

Also a vacuum pump is no different than a PCV valve with the exception of being engine driven instead of vacuum from the intake. You're still going to be sucking oil.

blackstallion12 · Mar 2, 2010

j69302 said:
thats not the pcv valves fault. sounds like something else is wrong. PCV valves are good for the engine they help keep it clean. I used to run without one and the oil vapors that came out of the breathers(even with a filtered one) just got all over the hood and made a oily dirty film all over. Put the pcv system back in.

The PCV is actually good for the engine though. It allows blow by vapors to get removed by getting sucked back into the intake system. while these get removed fresh air enters your engine through the breather. this keeps the highly acidic and corrosive blow by gases to not eat up your oil and metals inside the engine.

If you are getting anything but gases/vapors high enough up to go through your PCV/Breather valve you got other problems. do your valve covers have baffels in them? excessive blow by? could possibly even have a oil return problem, maybe oil is not draining out of the heads as fast as your pump is pumping it. If your heads are filling up with oil, this closes off the path to the breathers/pcv effectively making it a closed system, which ended up turning your dipstick into a pressure relief valve.

Im just throwing some other stuff to look at.

Also a vacuum pump is no different than a PCV valve with the exception of being engine driven instead of vacuum from the intake. You're still going to be sucking oil.

i am deffinately not discrediting you. you have excellent ideas! my father thought the same thing you just said about the oil basically filling the valve cover up and that seems like a reasonable possability but i have a stock replacement pump which doesnt mean it cant flow a high amount of oil but id like to think thats not the problem. and yes you are right my engine shouldnt be spitting oil out of everywhere it makes me sad. i have not done a leakdown test and probably should. i will hook up some sort of evac system whether that be a pcv or other type of evac.

also would just large diameter tubes coming out of the valve covers plummed to a catch tank work? or do you actually need vacuum to pull the gasses out?

i dont mean to be disrespectful to anyone im just annoyed with myself and im getting discouraged also i cant spell very good so i hope i dont scare away any help i have insane respect for you guys and im just a kid new to this obsession so please dont think of my stubborness as disrespect or offensive

tx65coupe · Mar 2, 2010

blackstallion12 said:
i dont think you took the time to read my original post but the solid lift cam i am running makes power from 2500 to 6500 so i dont think 6 is murder for my lil engine but thanks

Sorry, most setups I have seen don't make power after about 6k.

blackstallion12 said:
i dont mean to be disrespectful to anyone im just annoyed with myself and im getting discouraged also i cant spell very good so i hope i dont scare away any help i have insane respect for you guys and im just a kid new to this obsession so please dont think of my stubborness as disrespect or offensive

Don't feel bad, we all have issues that take us a while to figure out. Don't let it discourage you from your project.

blackstallion12 said:
price has nothing to do with it... i used to run a pcv but it didnt work it still spued oil and it didnt allow the engine to run to its potential. i think most pcv caps are too small of diameter.

When you say PCV caps, what exactly are you referring to, the oil breather cap or the rubber grommet that the PCV sits in?

tx65coupe · Mar 2, 2010

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