Thread: Crankcase ventilation

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Hi All,

I have read just about every post on this subject and I am 84.3% sure that my problem is due to a lack of a PCV Valve.

My 400 Chev with all the goodies has now been in and out of my Torana 4 times to replace my oil pan gaskets due to leaks at the front and rear. If it has not been the front it has been the back or both??!!! I have tried several techniques and gasket brands. This has been a very frustrating problem as I have only been able to do about 5 miles each time before it starts to leak again.

I am using 1 breather on each valve cover instead of 1 breather and 1 PCV. Is it possible that my crancase pressure is causing the problem and would a PCV work better to reduce pressure than 2 breathers? Alternatavely, could my oil pan be warped or something?

Any suggestions or past experiences would be appreciated. I have spent 2 years building this car from the ground up and am still unable to drive it because of a stupid oil leak!!

Thanks heaps

Originally posted by thebigsy
Hi All,

I have read just about every post on this subject and I am 84.3% sure that my problem is due to a lack of a PCV Valve.

My 400 Chev with all the goodies has now been in and out of my Torana 4 times to replace my oil pan gaskets due to leaks at the front and rear. If it has not been the front it has been the back or both??!!! I have tried several techniques and gasket brands. This has been a very frustrating problem as I have only been able to do about 5 miles each time before it starts to leak again.

I am using 1 breather on each valve cover instead of 1 breather and 1 PCV. Is it possible that my crancase pressure is causing the problem and would a PCV work better to reduce pressure than 2 breathers? Alternatavely, could my oil pan be warped or something?

Any suggestions or past experiences would be appreciated. I have spent 2 years building this car from the ground up and am still unable to drive it because of a stupid oil leak!!

Thanks heaps

If your engine has (all the goodies) I would try two free flowing breathers per each valve cover.If this does not work you have some other type of issues.

Thankyou Mr. Erikson...

So, swapping one of the breathers for a proper PCV system (whether it is a closed or open system) will make no difference to the crankcase pressure, but putting 2 breathers on each valve cover may give my engine the breathing capacity it needs and therefore lower the pressure?

Is it a common problem for 2 breathers not to be enough (keep in mind that I am not sure if crankcase pressure is the problem and adding 2 more breathers is not something that I am going to do unless I am sure)?

My engine is built from all quality parts and makes 500hp and 500ft/lbs. I do not rev it past 6000rpm. All components are brand new and were assembled with attention to detail. This motor has only done dyno time and about 20 miles.

Thanks again

If you're making 500 lbs/ft or torque and 500 hp with a 400 small block Chevy, then I would say it is not leaking enough compression past the rings to be blowing the pan gasket out of the motor, especially with two breathers on the valve covers. The pan is likely junk.

Originally posted by thebigsy
Thankyou Mr. Erikson...

So, swapping one of the breathers for a proper PCV system (whether it is a closed or open system) will make no difference to the crankcase pressure, but putting 2 breathers on each valve cover may give my engine the breathing capacity it needs and therefore lower the pressure?

Is it a common problem for 2 breathers not to be enough (keep in mind that I am not sure if crankcase pressure is the problem and adding 2 more breathers is not something that I am going to do unless I am sure)?

My engine is built from all quality parts and makes 500hp and 500ft/lbs. I do not rev it past 6000rpm. All components are brand new and were assembled with attention to detail. This motor has only done dyno time and about 20 miles.

Thanks again

Yes,it is common.On all the circle track engines I have built over the years I install two breathers per side.Even in street driven engines at this horsepower level it becomes important.

thebigsy, if you have 2 open breathers, driving around town and below 6,000 rpm's, thats all the breather you need. sounds like you need to find out where the leak is.

I suppose it won't hurt to try a PCV or twin breathers on each valve cover before I remove the engine again .

Thanks Richard, I will inspect the brand new oil pan once I pull out the engine (hopefully I wont have to!!)

I tell you what, I would pay anyone $1000 to gaurantee that I will have no leaks next time I put this engine in!!

No other suggestions?? Like I said, it has been the front and rear oil pan rubber seals which are causing me grief. Sometimes front, sometimes rear, sometimes both.

Thanks guys

be sure you are useing the right gaskets, some of the pans used a dif, rubber seals. did the gasket set have more than one rubber seals? seem like i ran into that a long time ago.

you said it was leeking oil now right?
since the pan will need to come back off get a strait edge ruler and check the pan mounting rails and looc close to the rear and front pan lips to see if it looks warped or out of shape.

it could be that when you last installed the oil pan gasket the gasket had moved on you. and caused it to leek again.

are you overfilling it with oil?

are you alternating between tightening the pan bolts in a crisscross pattern?

if you feel that you should try a PCV valve on the engine , remember that it will only do its job of pulling air through the crankcass if you putt the PCV valve in one valve cover with out any other filters or vents for air. the pcv valve must pull air through the engine coming "in" from the other valvecover.

or you can get a crankcase evacuation pump, that is belt drivin and pulls larger amounts of air through the crankcase, to releave exsessive pressure in the bottom of the engine.
if you decide to go this route you can either buy a performance pump, or you can build one if you can make your own brackets, and use a smog pump off of a bone yard car, to serve as a pump on your car.

hope i was helpfull.

be sure you are useing the right gaskets, some of the pans used a dif, rubber seals. did the gasket set have more than one rubber seals? seem like i ran into that a long time ago.

I used the thick front seal from the gasket sets. After dummying up the thin seal there was a large gap and it would have never sealed. To be honest, the thick front seal seemed a little too thick and became quite squashed after installation

At the moment, my rear seal is leaking. The past times it has leaked, all has seemed fine for a while and then a small leak would start at the front usually and then followed by one at the rear and they just seem to get worse the longer I leave it.

I think your problem is in the pan, and or gaskets. you have enough breather, if you dont then you need a another motor.

Originally posted by lt1s10
I think your problem is in the pan, and or gaskets. you have enough breather, if you dont then you need a another motor.

Ohhh! Don't say that!! Another motor?

I will be welding the sump on before I get another motor

Originally posted by thebigsy
Ohhh! Don't say that!! Another motor?

I will be welding the sump on before I get another motor

if you got enough blow by that two breathers want take care of it, then welding the pan up want help it. it'll just blow the valve cover gaskets out then. fix the pan gaskets and i think you'll be ok.

Thanks everyone,

I hope this is the last time... All advice was appreciated and I will keep you all posted on how it goes... Imagine getting a taste of all this power and not even being able to go to the strip for some racing!

It's extremely frustrating but there is no use crying over spilt oil!!

Thanks again
Adam

if your in a pinch, and cant afford to keep on redoing the gasket, try 3M Weatherstrip Adhesive: Yellow on the block mounting serface, the timing cover and rear of block. use your finger to apply it evenly but not to thick, " its messy but works very well", "and make sure when you install the ruber endseals first make sure they are lined up and seated right , then before you istall the side gaskets dab a little glue on where the side gaskets meat into the ends of the seal , install the side rail gaskets, and dab a little RTV on the ends of the endseals , make sure they are all lined up with bolt holes let it sit for 2 or 3 min, and carefully place oilpan up to the block and start a few bolts, as you install more bolts finger tight, make sure the gasket didnt slide inwards , tighten all bolts by hand at first, to make sure the pan has seated to the block square . torque all bolts down in an alternating pattern, starting from the senter and working out going from side to side and front to back. torque the bolts a little at a time not all at once. but be carefull not to overtighten the bolts as this can sause the gasket material to split and you will have a leak again.

this is what I do when I run into one of those type of problems, it is the only thing that seems to always work. good luck, and make sertan the you hit every bolt and dont skip one when torquing.

here is a picture of the glue, it will bond metal to ruber or cork with great strength.