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Blowing oil out of Breather


car21milton

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Hi,

I have a 2002 that I am racing. I take it to 8,000 - 8,500 rpm.

At high revs it blows oil out of the breather and fills up the catch tank. In a 45 min race it blew out nearly 2 pints of oil.

I believe this is normal for the M10 engine at high revs. I am thinking of fitting an oil separator.

Does anyone else get these problems?

Is there any thing I can do to stop it?

Any ideas / suggestions would be most helpful.

Thanks in advance.

Bob.

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Here is the fix, check out my website. I have some info on this page about exactly what you are experiencing.

http://bmw1602.lostbrazilian.com/v1/store.php

and read my build blog post about it. I have a few pictures of what other racers have done as well.

this is a well know racing m10 issue.

http://bmw1602.blogspot.com/2006/09/valve-cover-modification.html

68' 1602

98' ///M3 Sedan

88' ///M3 Sold *

06' ///M3 Competition Pkg Sold *

http://www.bmw1602.com/

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Perry and some of the skidmark guys also regularly spin thier m10 past 8k.

If you running 336 cams thats where you making power.....The main issue was always broken rockers not valve springs. Valve springs can handle up to 17k rpm(properly sprung).

Now that they make billet rockers that not a problem anymore.

68' 1602

98' ///M3 Sedan

88' ///M3 Sold *

06' ///M3 Competition Pkg Sold *

http://www.bmw1602.com/

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Hi,

We are using VACmotorsports uprated springs, bigger valves, hardenend collets and titanium retainers. Using Jeff Ireland bilet rockers.

The oil issue is a real problem though.

We have just put another plate over the existing hole. We now have 2 plates that go across the hole rocker cover.

Fingers crossed that this will work.

Bob.

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Aha, see, that's what we were wondering...

yeah, one of the problems I've found with the breather is that it wants to

be able to re- ingest the oily air that comes out of it. Freely.

A 2' piece of 5/8 tube leading to the catch can seems to work-

but the catch can has to have a 1/2" breather hole in it.

And that breather can't be obstructed at all- just putting a filter on it

made mine start to puke oil. Remove filter, life good again.

That's been my experience. Others modify the valve cover- significantly!

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Our catch tank (sorry can) is using a 5/8 pipe to it and has an unrestricted 1/2 inch outlet. (Bit spooky eh)!!!!!!!!!

The last race we did was a 45 min race and it filled the 1.75 litre (possibly a US quart but not sure) catch can. We also had lots of oil under the bonnet / hood.

When we dipped the oil after the race the level was on the min mark. It was on the max mark before the race.

I'm starting to think that the only real solution is an oil separator with a drain back into the sump.

I am still open to suggestions though.

As an aside we had the capillary oil gauge feed from the head and under race conditions were reading very low oil pressure. (We have fitted a bung which restricts the oil flow to the head. This has a 3mm hole). We moved it to the oil cooler sandwich plate and the pressure is now reading a lot higher.

Anyone else reading from the head?

Just wondering what oil pressure people are now running on race engines.

We are seeing 90psi on start up with a good 60psi with hot oil during racing.

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no need to reivent or use a separator.....just do what I did.

I used to push 1 quart or so a session (25mins)

Now I bearly get 1-2 drops. I can probably run all season and maybe empty out 200ml....

Once again we block off the stock breather, extend the oil filler tube, add baffles in that extension and take the oil breather line from the top of that extension (after the baffles).

It really works great. Just ask a few of the people that are running my valve covers....not sure if they see the thread but I have sold a few.

That's great oil pressure...... I usually see 30-40psi hot or lower sometimes. Then again I'm rebuilding my engine now.

Maybe your seeing low oil pressure under braking and during cornering. Thats caused by using an unbaffled oil pan. If you have a fast '02 with sticker rubber....I would highly recommend a race oil pan. unfortunately they are like $800+ . This is why soon (next month or so) I will be making my own. I might make a few extra ones to sell. Should be cheaper than the korman ones.

68' 1602

98' ///M3 Sedan

88' ///M3 Sold *

06' ///M3 Competition Pkg Sold *

http://www.bmw1602.com/

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  • 1 month later...

Hi,

Just an update if you are interested.

We obtained an oil separator from an Alfa Romeo 147 2.5 litre petrol engined car.

We did a 15 minute qualification run and it put about a quarter litre of oil in the catch tank.

We did a temporary fit of the separator by fitting the separator high so that it would drain down the dipstick. We did a 25 minute run in a race (was supposed to be 45 but the gravel at Brands Hatch is deep!!!!!!!). We had no oil in the catch tank.

Over the winter we intend putting a drain into the sump so that the separator will drain straight into the sump.

Hopefully we should have no more problems.

Cheers,

Bob.

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