Sump breather setup?

[EWPurdy]

Anyone know the proper sump breather setup for a carbed motor. I'm in the process of converting CIS to PMO and want to be sure. I've seen examples of catch cans/breather tanks with filters as well as hoses venting the gases back into the air filter housings. Opinions and pictures welcome!

[john walker's workshop]

hard to say what's proper, but PMO supplies a small K+N filter to slip on the breather tube on the filler neck. stays dry if the oil level is about 1/2 way between the marks.

[911pcars]

There isn't an official breathing setup, but an ideal one would be a system to catch and separate blowby and oil spray, then route the blowby back to the air intake. This system also prevents an overfilled oil tank from puking oil directly into the intake. A drain fitting at the bottom would be convenient.

I've seen race cars with the oil tank breather hose stuck into an empty orange juice container (vent to atmosphere) which, I suppose, follows most track requirements. You can also purchase a fancy spun aluminum overflow tank and mounting bracket. There are also tanks made for coolant overflow, but the fittings would have to match the hose ID's.

I plundered a pik-a-part vehicle for it's thin, rectangular plastic wiper reservoir and adapted some PCV fittings and radiator/heater hose from the local parts store. It sits in the right corner of the engine compartment.

Here's one particularly neat install (vented to atmosphere):


Sherwood Lee
'69 "rs"
http://members.rennlist.org/911pcars

[David McLaughlin]

I ordered a JEGS catalog for just this reason. They offer two sizes of overflows at least one comes with a top mounted filter and a bottom mounted drain. I plan on buying the small one once I figure out which size fitting I should get. Can anyone explain the AN fittings to me?

I can't seem to find the product in their online catalog, but I'm sure it's there somewhere. www.jegs.com

[EWPurdy]

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay prrfnbr=2462&prmenbr=361

If the link doesn't work, go to Jegs.com and do a search on "sump breather."

I'm still trying to figure out how to get the whole system neatly plumbed using AN fittings/Adapters and the original diameter breather hose which looks to be about 1" ID or 25mm.

[T Bird]

This is how I did it on my 72 T:


The black can in between the carbs back by the firewall is part of the PMO vent kit. The hose entering the can on the left comes from the charcoal cannister in the trunk and vents gas fumes. The larger diameter hose entering the can from the right vents fumes from the oil tank. The gas and oil fumes are sucked into the Watershields via the two hoses.

Another vent line plugs into a fitting on the shroud and conducts forced air through the charcoal cannister and back through the hose that enters the can on the left.

Good luck.

[cegerer]

Stoddard did my conversion and simply vented it into the back of the right rear wheel well. Have never noticed a problem with blowby or leakage. However, I REALLY like that Jeg's setup.

Sherwood: Is that your 69's motor? Stunning!! -- Curt

[EWPurdy]

http://www.cantonracingproducts.com/tanks/breather_tanks.html
http://www.petersonfluidsys.com/tankacc.html

[cegerer]

Glad I read this thread. I went out and checked my breather hose from the gas tank/cannister and it is basically just stuck into a hole in the back of the shroud. I think I'll buy a breather tank from Jeg's with 2 fittings and route the oil and gas line hoses to it.



Thanks. -- Curt

[911pcars]

Curt,
Sorry to say that's not my engine. It belongs to a fellow RGrupper from Washington who was at the first RGruppe meet in 2000. His first name is Rob, forget his last name sorry to say. Perhaps Randy W. or Randy J. can assist. BTW, his trunk was just as impressive. http://members.rennlist.org/911pcars/ParkPics.htm

The Canton and Peterson overflow jugs are real nice and priced accordingly. It gets pricier if you use AN fittings and matching hoses (-16/-12?) to connect oil tank and both carbs.

Sherwood

[Raymond]

don't forget guys that you will have carbon monoxide in the cabin of the car if you just simply put a filter on the end of the hose. you may not introduce any particulates into the oil system with the filter and an orange juice can may catch any runoff, but the noxious fumes WILL be present if you don't route the blowby back into the motor. i did a thread sometime back showing my one-off solution.

i tried the filter thing and it just didn't address the fumes. carbon monoxide is a silent but deadly.

[Formerly Steve Wilkinson]

CO from the oil tank????? My setup is PMO's specified one--small filter right on the oil tank--and it works fine.

Stephan

[EWPurdy]

The gases in question here are crankcase gases which, depending on the condition of your rings, may contain some nasty stuff. However, I've seen plenty of cars with the simple can and filter setup and no provision for feeding the gases back into the intake. I believe the reason for venting the crankcase gases into the intake was purely legal in nature.

[Raymond]

i agree that the condition of your rings has a big part in how much blowby you encounter, but all engines will belch certain amounts of carbon monoxide through an open line. the factory's method of addressing this was to route the breather hose through the carbs (or MFI) and back into combustion.

i also note the factory didn't (at least on my particular car) have any kind of catch can or tank. it was simply all routed into the air cleaner.

[J P Stein]

I have a catch can in the trunk of my 914 with one of those breather filters inside it. It's then vented to the atmosphere.
During normal street driving it stays dry.
I have found 6 to 8 oz or oil in it after an AX, however.
An inquiry on the Racing list (rennlist) produced the info that this is due to "slosh" from the oil tank and is not at all uncommon (from both 914 and 911 racers).

The thought of running that oil thru the carbs or blowing it all over the engine room leaves me cold.

[joehahn]

J.P., post a picture of your set up.

I bought a heat resistant tupperware thing that is going to magically transform itself into a catch can tonight. I was simply going to route the thin (not the big hose) tube at the base of the air cleaner housing into the top of the can. I don't need anything else do I? This is simply to catch oil instead of it dripping through the hose's current routing (through engine tin onto right heat exchanger, then case, the driveway)

Joe 68 L

[CamB]

My BMW has a metal Motul oil can with holes drilled for venting (from the PO).

It is getting surface corrosion slightly, so to piss off my more fastidious friends (who want me to spend money on a proper setup), I might remove it and paint it satin black .

[cegerer]

OK, I just went out and checked the CO level at my breather hose end. It is routed through the sidewall and into the right rear wheelwell. My detector only goes 0 to 2000PPM. I placed the test receptor up inside the hose to reduce any ambient CO from the exhaust pipe. It quickly exceeded 2000PPM, then settled back to around 950PPM, than went back to over 2000PPM, etc. Granted, this is not a scientific test as there are many variables. But it does indicate that Carbon Monoxide is an issue that needs to be considered. -- Curt

[EWPurdy]

Science!!!
Gotta love it.

Thanks Curt.

[J P Stein]

Joehahn:
Sorry for the delay. Work and sleep got in the way.
This is some pretty hi-tech stuff, not as hi-tech as Tupperware, but right up there

It's an item that formerly did service as a mixed nuts container.....
seems appropraite