OIL Breather's
 

Fella I work with asked for your advice and Idea's.

He had a 540 freshend with a B&M 250 blower.
I think it's a 565 now could be wrong though.
29' PowerQuest.

Anyway's finally has 20 hour's on it and this
past saturday he opened it up good for awhile.

When he came off plane he noticed all sorts
of smoke coming from the engine bay.

Opened the hatch and noticed quite a mess
all coming out his single oil breather. It all
settled down in a few minutes, but he has
never had this problem in the past and is wondering
the cause of it.

Should he have two breather's?

Should he run the other style with returns to the
carb?

He is going to switch to mobil synthetic and wondered
if that mattered returning it to the carb?

That day: water temp was 150 degree's
Oil temp was 180 degree's.
Lake water was 60 degree's.

Thanks for any idea's

Cougarman

Re: OIL Breather's
 

What do you mean by "mess":confused:
Smoke ? oil? or both?
You really shouldn't have anything at all. Could be the rings aren't seated yet and he's getting blowby pressurizing the crankcase and blowing oil and stuff out. But at 20 hours the rings should be ok..unless there is a problem:(

Unrelated to the problem, but 180* oil seems too cold. Shouldn't it be 215* to 240*? I guess it depends where it was measured.

One mans finding......
 

I had the same problem intermittently on our blown 540 all year. On occasion during a hard run I would blow out a good amount of oil out the breathers as well as the dipstick. Sometimes at least a quart. This only happened when under heavy boost (7-9 lbs) and I would also feel a slight hesitation in the motor on these occasions.
I had run compression checks and leak downs with perfect results which pretty much eliminated my thoughts of ring blow by.
I’m sure there are less drastic reasons but this what I have just found.
I tore the motor down just recently and found something very interesting! The FelPro head gaskets, although not blown thru the compressed fire ring, had the composite material on cylinders 2,6,7 and 3 pushed right into the lifter valley. These are the weak spots on GM blocks and others that don’t have the extra head bolt holes. It without a doubt looks as though the heads were lifting under heavy boost and blowing right past the head gasket fire ring. There are witness areas of carbon running directly to the valley. From what I can tell this is a direct cause of my pressurized crankcase when running hard. Also a compression test nor a leak down would reveal this problem.

I run (ran) Edelbrock heads that came with very small chambers. These chambers were achieved by angle cutting at the factory and then some more milling by me to up the compression on a then 454. These heads as well as the GM aluminum only have 9/16 decks to begin with and probably less than ½” after all was said and done.

I’m going to go with new 3/4" thick deck heads (Canfields), either FelPro Wirelock gaskets with an o-ring groove or the new Cometic gaskets and good ARP studs in place of bolts.
The new heads will lower my CR from 9.3 to 8.3 as well. 7-9 lbs with 9.3:1 could have also contributed to the problem ;o)

Of course his may just need two breathers or something simple :(

Sorry to ramble; it’s just fresh on my mind :crazy:

Dave

We had an event here called the river shiver and the same thing happened to a friend. My boat has a Whipple and I noticed the dipstick pushed out a few inches from it's seated position as well. The problem is blowby or windage related. Running in cold water the engine nevers gets up to a decent operating temp. A hard run at these temps can cause the oil to whip up as the crank spins. Once the breather gets saturated with oil, it doesn't breathe very good. I'm thinking about installing a thermostatically controlled oil cooler to keep the oil up to temp. The Whipple uses no engine thermostat so it never sees over 100 F with cool water.

I had a similar prob on a 468 1171 blower motor. O ringed the block and used copper head gaskets, 4 tall breathers on the valve covers (2 ea) and the problem went away.

Dan

Not much Boost
 

I know he's not running much boost maybe 3 to 4
pounds of boost. Really conservative, however
it is the first time he has run a blower.

Seems like it dynoed around 610 hp.

So maybe that is the difference and why he never
had the problem when it was carbureted.

And I believe most of his boating is NOT in the
boost. So maybe now that he finally got into
it for awhile it started to wake things up.

So do you feel if he went to four breather's
2 per valve cover, that this would go away?

He said the whole engine bay now has a oil
film on it.

He is also running an oil Thermastate.


Cougarman