Dry sump Sec. Tank breather

Dry sump Sec. Tank breather

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Discussion

V8Dom

Original Poster:

3,546 posts

201 months

Wednesday 24th August 2016
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I've changed my engine breather and fitted a tank on bulkhead from rocker covers. My dry sump tank near the rear I've vented just with a pipe but it's pushing out a lot of oil on a run.. Tank was 2/3 full. Now half.. Anyone know why so much pressure on breather. I thought it would be negative pressure

ROWDYRENAULT

1,270 posts

213 months

Wednesday 24th August 2016
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This maybe it bit basic but I guess if there,s no incorrect question even a simple answer might be of value. Airflow on a dry sump goes into not out of the engine via the valve covers. then out of the engine to the drysump tank and then vented to a catch can with a breather. I have a catch can about 2 inches in Dia and 6 inches tall I drain about a cup of oil water crap about every 3000 miles when I do the oil change. Typically you want the tank to be over 50% and less than 2/3 full when the engine is running. Hope that helps. lee

Storer

5,024 posts

214 months

Wednesday 24th August 2016
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Never had to empty my DS catch tank.

The mist of oil from the cap vent attracts a bit of dust which I wipe off occasionally but that's it.

It is an LS though.


Paul

V8Dom

Original Poster:

3,546 posts

201 months

Wednesday 24th August 2016
quotequote all
I'm wondering because breather pipe at top of dry sump tank is rearward of tank.. When I accurate hard. The oil just with inertia goes up the pipe.. I'm going to try tomorrow with breather pipe in front of the tank

ROWDYRENAULT

1,270 posts

213 months

Wednesday 24th August 2016
quotequote all
my catch tank is behind the dry sump tank in fact it should be mounted so that if for some unknown reason it over flows it does so behind the rear tire. It is an LS motor but I don't think thats got anything to do with the problem he's seeing. Lee

Storer

5,024 posts

214 months

Wednesday 24th August 2016
quotequote all
I should mention that my DS tank is larger than standard/recommended. My catch tank is high up on the firewall too.



Paul

V8Dom

Original Poster:

3,546 posts

201 months

Wednesday 24th August 2016
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My dry sump

V8Dom

Original Poster:

3,546 posts

201 months

Wednesday 24th August 2016
quotequote all



My new breather for rockers

Storer

5,024 posts

214 months

Wednesday 24th August 2016
quotequote all
Not sure where the breather pipe for your DS goes but it needs to be as high as possible, into a catch tank, so most of the temporarily expelled oil drains back into the DS tank.



Paul


k wright

1,039 posts

258 months

Saturday 27th August 2016
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If you have a large enough dry sump pump the only vent that you will need will be the dry sump tank vent. If you have only a 3 stage pump with 2 scavenge stages then the crankcase blow by will exceed the volume of the scavenge sections of the pump and excess air/oil mixture will look for anyway possible to escape the crankcase. If you have vents on the valve covers that will serve as a blow off.

This being said, I'm not sure I understand where you are loosing oil. If it is ending up in the vent tank on your bulkhead then adding a 3rd scavenge stage to your pump will cure it. After you get a large enough pump you can ditch the vent tank and use a vacuum limiting valve on one of your valve covers to prevent high vacuum (unlikely). Peterson sells a nice one.

V8Dom

Original Poster:

3,546 posts

201 months

Saturday 27th August 2016
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Im running 3 stage pump one blanked off. Both rocker covers vent via tank above as in photo. The oil is coming from tank breather on dry sump tank. First off i just had a tube 12 inch long vertical and that pushed oil. Then i ran pipe from tank up roll cage to near top of clam. Still got oil but not as much..

k wright

1,039 posts

258 months

Saturday 27th August 2016
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Dom, If you have the standard 1 inch wide sections on your pump you need another stage. This is an easy addition when you return your pump back to the vendor. When the correct amount of scavenge is available the only vent on your system will be from the top of the dry sump tank. There should be a one way valve that looks like a valve cover breather that prevents pressure in the crankcase.

This is a good link on this subject:

http://nutterracingengines.com/racing_oil_pumps/cr...


V8Dom

Original Poster:

3,546 posts

201 months

Tuesday 30th August 2016
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thanks ken
ill have a look.

, sorry off subject have you sorted your exhaust yet?


Edited by V8Dom on Tuesday 30th August 18:01

k wright

1,039 posts

258 months

Wednesday 31st August 2016
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I' planning on using a couple of flow master round mufflers with internal baffling for street use and keep the current muffler for track days. Just need time.

Cheers

V8Dom

Original Poster:

3,546 posts

201 months

Monday 5th September 2016
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ok im all sorted
oil filler cap that screws onto tank was loose

this somehow cause vacuum in tank and push out of breather. not sure why but sealing that has caused engine not to breathe now.

thanks for help guys