hey guys. as in the title, i have an oil problem up in the heads. i drive the car alot at HPDE events so there is alot of cornering involved. i've noticed that after a couple hot laps i'm getting engine oil leaking out of my air cleaner.
currently the car is a warmed over L-81 with 305HO heads. prior to putting the HO heads on, i tried to smooth the casting at the bottom and leading to the drain back holes as much as i could to facilitate drainage. still, i don't believe this was sufficient. the car is still configured similar to stock with the breather tube leading from the passenger side valve cover up to the stock cleaner. the bottom of which gets soaked to the point i have oil dripping out of the snorkel portion onto the engine. the PCV is still on the left side cover to the carb.
1) is there something i can do to keep more oil in the block without starving the valvetrain? i do plan on running a roller tip rocker on this engine soon but any thing i can do in the meantime?
2) should i remove that breather tube for track events and run a simple catch can instead?
3) i have to assume the same condition is in the PCV side, should i do anything with that?
i am planning on building a track specific engine as funds allow. i already purchased a road race pan with trap door baffles, etc. from a forum member last week. unfortunately, that pan won't fit the L-81 because of the dipstick location. i have an early 350 high nickel block i'll be using for that engine. in the meantime, i still want to be able to attend a few events a year without blowing a quart of oil into my air cleaner. suggestions?

 

My wheezer of an L83 (Crossfire) with 150,000 miles was sucking oil, similar to yours. I installed an el cheapo generic fuel filter in the PCV line to trap some of the surplus oil. The line from my PVC connects directly to the manifold (stock). WAIT! I just reread your post. Your oil is being forced back out the intake hose. That sounds to me like the pressure in your crankcase is exceeding the vacuum in your manifold. If the line from the left vc, including the PCV valve itself to the carb, TB, manifold, or whatever, isn't plugged, I think you may have more serious problems. Good luck, and...

RACE ON!!!

 

the roller tips won't do anything, it's not the tip but the pivot ball that needs gobs of oil to keep it from galling. Get some needle bearing fulcrum rockers, they can be had in steel from http://www.enginekits.com for about 200$, I think that's a VERY good price. They look like crowers. With those rockers you can restrict the amount of oil that goes up to the rockers.

 

As CFI-EFI alluded to, not convinced top end oiling is your true problem. Also mentioned. I'd verify a lack of excessive combustion pressure blowby. Make sure the vent and pcv line baffling is adequate as well.


[Modified by arnold, 7:58 AM 3/19/2003]

 

Try finding oil restrictor push rods. I think I used Comp Cams years ago when I used H-Flat cams. It cheap and easy. The holes in each end are just smaller and limit top end flow.

 

I'd bet your problem has to do with the long WOT (ie. no intake vacuum) runs and crankcase pressure from blow-by. I'm not trying to imply that your rings are shot, but that the stock PCV system doesn't do anything at WOT.

I'd investigate into one of those crankcase evacuation systems like Moroso (PN MOR-25900) or Mr Gasket (PN MRG-6002). These use the exhaust to create the vacuum.

There are also some belt driven pump type, but I couldn't find any in my quick Summit search.

 

Clutchdust - BeaterSkark has some good points about WOT.

My last motor had PVC and K&N filter breathers on the opposit side side valve cover.

This new motor has PVC and instead of breathers I use a 3/4 inch hose from the valve cover to the air filter base plate. So at WOT inside the filter you might be creating a very minor vacuum that takes the oil mist and crank case pressure.

Even at wide open throttle some vacuum is created in the plenum unless you have massive CFM throttle blades.

 

barnes has the pumps and if you look at the price tag you will probably faint.

I've had a 45deg pipe w/ check vavle on my exhaust and it works very good (they won't complain about something like that w/ emissions testing here)

 

Clutch dust,
Check out the oil restrictors that go in next the rear cam bearing plug. LOTS of work for you to install but it might be worth it in the end.
...redvetracr

 

I disagree with restricting the oil supply. I feel that a generous supply of oil cools the already overstressed valve springs, and helps them live. In my opinion, you have one of two problems. Either the vent system is clogged or otherwise restricted, or the engine condition is overloading that system. Of course, it could be a combination of both. Good luck, and...

RACE ON!!!

 

I think a road race pan is the answer

I talked to some people who used to race L98's on road courses. They used to get the same problem you were getting. The engine was burning oil. Turned out is was coming up the PVC system and down the intake. The oil system had nothing to do with it. The oil was being thrown from pan up into the heads! :crazy: Lots of G-force, lots of elevation changes! :eek:

I wouldn't restrict it till you find out what's going on.

BTW do you have a high pressure or a high volume pump installed?
A high volume pump will suck the pan dry on a road course.

 

i wouldn't have thought the pan would be the solution but i can't wait to get it in the car anyway. too bad it's the wrong dipstick location for this block and it will have to go in with the other engine, whenever that's done. :rolleyes:
i do have a hight volume pump but it was doing the same thing even before that was installed. the main reason i don't think it's a condition of the engine is i see no evidence of this during normal 'spirited' driving, then at HPDE events on street tires i begine to see it. when i run the 'r' compound tires, it gets more severe. with the 'r's i can loose 1/2qt in a day through the air cleaner. the good thing is it's not coming back into the engine but it make a hell of a mess on the outside of the engine. :nonod:
:cheers:

 

:iagree: I would not restrict the oil. You need to relief the pressure. If you have a roller cam you need the oil draining down from above. I had the oil blowing problem and I have a high pressure oil pump but I cured mine with proper venting. :yesnod: :yesnod:

 

I agree with trying oil restricting push rods. If you can't find them easily, you can have them made by Smith Bros 541-388-8188.

This will allow full oiling to your cam/lifters, but will slightly limit the amount of oil squirting into the top of your heads.

 

I would not put oil restrictors in the block because you only put them in when you have a solid lifter cam but you nead it for hydraulic lifters.
You can put a vacuum pump on it but pumps cost a lot I have seen people take a Ford air pump and use them you can get them cheap but you have to be careful not to turn them to much because if you do then the pump will pull all the oil from the pan to heads, a friend of mine did that he swaped the pulls and the pump was spinning faster then the crank and he mest up a 434ci engine.
I would just get me some valve cover and put good breathers on them, I would not put in a check valve on my exhaust because sometimes the valves get stuck and then the exhaust will blow out all your seals in your engine.

Jay

 

Since this problem manifests itself at track speeds and NOT during normal driving, I'd say that you have a bad case of high rpm ring flutter pressurizing the crankcase to the point oil is blown back up the clean air hose to the air cleaner base.

Sorry, but you'll need to re-ring the engine to solve this problem. :eek:

 

re-ringed in october '02.
guys, it's got to be related to drain back. i regularly run this engine to 5500 on the street (i.e. straight line, not cornering) and have no oil control problems from high crankcase pressure, etc. thanks for the advice so far. i will probably go with full roller rockers and reduced meter pushrods and see what happens there.

 

Is the engine still under warranty from the re-ring job? If so take it back. Ring flutter doesn't correct itself and eventually leads to ring failure.

IMHO based upon racing SBC's, it's definitely crankcase pressure that blowing the oil up the clean air hose into the air cleaner, not pumping your valve covers full of oil to the point that oil fill ups the clean air tube and g-forces sling it upstairs to the air cleaner. (This can occur in circle track racing since you're always turning left, but you said you were doing track days.)

Just because you do a high rpm run for less than 60 seconds without experiencing this problem on the street means nada. (I can't think of any track I raced that had hot lap times of under a minute.) Sustained high rpm (above 4500) on a road course with just one cylinder with faulty rings will pressurize the crankcase with blowby to the point that oil will follow the escaping crankcase gases wherever they go.

Restricting the oil supply to the upper clylinder head via the pushrod is a good idea for race cars, not so good on street cars where the oil is partially cooled by spraying against the valve cover before returning to the sump. If you do use the restricted pushrods, think about adding an oil cooler. :thumbs:

Definitely keep a sharp eye on the problem whatever you do. The worst case scenario is blowing oil out of the valve covers onto hot exhaust causing a fire!

Good luck! :seeya


[Modified by mr.beachcomber, 10:07 AM 3/23/2003]

 

clutchdust,
I don't understand how turning can effect drainback to the point where it would force oil up the pcv tube into the intake. If the oil is reaching the drainback holes, it's going to drain the same. The only way oil can get to the top of the head is via the pushrods and it will give the same amount for both straight line as well as turning.

I do understand that the drainback holes are not in the ideal location on the SBC, but arn't all SBC heads drainback in the same place? If so, then this would be a common problem at the track.

Just to add a little to this post, GM Pn 22062562 is electric vac pump that MCA84 used for PCV. See http://forums.corvetteforum.com/zero...409290#2409290 for more discussion on it.


[Modified by BeaterShark, 11:14 AM 3/24/2003]