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71bmr02

oil recovery tanks,they do work

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while working on installing a different intake manifold (carb equipped),i discovered a lot of oil staining in the runners of the mainfold being replaced and in the intake chambers of the head. some research led me to oil recovery tanks which appeared to be a logical end for the problem where no egr system is in place. My car is a 71 and the egr system was removed by a PO.

this morning i mocked up a tank using a castrol oil plastic bottle and it works. i drove a 40 mile round trip and measured the oil accumulated in the bottle at .5 ounce or approx 15 ml. I was surprised at the amount which seems like a lot to me for distance traveled. it seems like that much could seriously dilute the gas stream lowereing the octane and create carbon buildup problems.

looks like i'll purchase a real recovery tank

hope this is helpful

G

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If you make or install a catch bottle for crankcase / oil vapor, keep in mind the following important thoughts:

Make sure the canister is well vented. If not, it will pressurize (or worse yet, allow the crankcase to over-pressurize and the engine will ooze oil from every blown seal!)

The last one I made took some trial and error engineering:

I found the feed from the valve cover had to be pointed DOWN inside/into the bottle, or else it would just blow out the inlet hole. Mine entered horizontally, so I fabricated an internal baffle to keep the vapor aimed downward into the bottle.

That vapor from the engine contains a good amount of water from condensation. You may not want that re-entering your oiling system.

Check and empty the bottle frequently!

Flaws with "modern" crankcase ventilation valves include possible failures in which ice crystals jam the internal check valve and engines begin CONSUMING their own oil....quart after quart...until they seize. I used to replace crankcase vent valves about 4 times a week when I worked for an indie BMW shop in Baltimore, as they would cause erratic running issues and countless fault codes on our customer's cars.

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Thanks, the bottle is just a mock up but it proves to me they do work. i did carry the crankcase oil/vapors all the way to the bottom of the bottle via a tube same dia as the tube from the rocker cover. the vent tube from the bottle to the carb filter housing is taken from near the top of the bottle and oriented in a horizontal position. i did note the oil accumulated in the bottle was milky colored indicating a lot of water vapor is being discharged out the rocker cover, but i expected that.

The points about pressure build up and water vapor are well taken. The finished bottle should have adequate ventilation to prevent pressure problems and water vapor may stay locked up in the accumulated oil so it won't be that much of a problem.

G

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Amusingly, a 3' length of 5/8" oil- resistant hose that vents upwards

works just fine, too-

the trick is to keep the end free from restrictions like a filter.

What I learnt.

t

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Yep, that's how it was done on the old American V8s, etc. until people started caring about not venting that to the atmosphere. Now the goal is to still not vent it to the atmosphere but vent less (if anything) into the intake by trapping the oil in a bottle. Not a big deal and not a bad idea.

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