Overfilling fluids is a common cause of leakage and often errors in the venting system create the trouble. Fluid management and proper venting practices are simple. With a few tips your team can avoid being the practice killing culprit. How many times have you seen team oil down the track at the first race or practice of the year? Unfortunately, major track oil downs seems to happen every year - at every track and at every division. Luckily, a British Petroleum Gulf Coast top kill operation isn’t needed. Simple construction tips and standard care get the job done. If nothing else maybe some conversation on the topic will save a few tracks from the dreaded oil downs.
Since most late models run quick change rear ends it is easy to find the proper fill level as site plugs guide the way. Rear end pumps and auxiliary coolers can complicate fill levels so it pays to fill the system with a predetermined amount of fluid. Knowing the exact amount to fill your rear end speeds gear changes at the track and eliminates the chance of over filling. The next time you drain your rear end simply measure the amount of fluid. With the results you can then pre-package the correct amount for a quick refill.
Your rear end breather system, while simple, needs a few tricks to keep your rear end fluid in the car. A baffled vent tank provides added insurance. A roll bar mounted or sheet metal mounted tank version will work on any late model. Mounting your rear end vent tank as high as possible is a good move. Gravity helps any fluid that runs up the line to drain back into the rear end.
Simple things like using a 3/8” minimum rear end vent line help as well – smaller vent lines are prone to clogging. Be sure that the vent hose runs in an S shape but avoids droops in the line where oil can collect thus blocking the air from traveling to the vent. Your vent hose must run continuously uphill from the rear end to the vent. Any hose sag could clog the vent system and you will end up with rear end pressure build up and leaks at every gasket.
You can use a standard vent on the rear end without the baffled reserve tank. Going this route saves a few ounces of weight and if everything in your rear end and in your filling process is done correctly a vent without a reserve tank will work fine. For me – the insurance of a baffled reserve tank on the rear end is a wise choice. The small cost and weight difference give you added insurance.
Rear end heat can be very intense as noted by the fine stench in your garage after a 100 lapper. The overall oil volume in your rear end is small and it does not take much overfilling to create leakage. The heat experienced in a rear end leads to high expansion rates so a baffled tank wins out compared to saving a few ounces with a vent that does not include a reservoir. Vents without reserve tanks work great for venting axle tubes and transmissions.
Engine venting is another easy to design system yet again we see cars oil down the track every year due to overfilling the dry sump tank or improper venting. With a dry sump system a sealed system at the engine seems best. Valve covers are unvented and the typical vents are replaced with a number 16AN line connecting the valve cover with a return back to the vented dry sump tank.
A dry sump breather tank should include internal baffles and plenty of vent area. Running your vent line with out sags wil prevent oil from collecting in the low spots in the line ensuring a free flow of air for proper venting. The sump tank shown includes a drain valve for easy maintenance.
Measuring your dry sump tank to the correct level is simple. A dip stick works fine but you do need to guard against any oil that is in the pan. With a dry sump the pan should have minimal oil but it is good practice to verify the pan is dry and verify that your sump tank level is in the safe zone..
A number 16 AN line from a valve cover back to the sump tank is a proven venting method. The venting is done at the dry sump tank and the engine is “sealed”. Your #16 return line needs to run downhill from the valve cover to the sump tank. At the sump tank, a line is run to your dry sump breather tank and again gravity needs to be considered. The line from the sump tank to the breather needs to run uphill in a sag free fashion.
Since transmissions generate little heat, in comparison to engines and rear ends, a simple vent can be used without a reservoir. The idea is to simply vent transmission pressure due to heat expansion. If you mount your vent as high as reasonable a simple tank less vent will do a great job of keeping fluid in your transmission. That said - taking the simple step of running your vent line without line sag is a great idea. A baffled tank is always a good idea but at the transmission the added insurance is not a requirement as compared to the engine and/or rear end.
A vent without a reservoir works fine on transmissions and axle tubes. Lower pressures and less heat generated in these areas allow the lightweight and inexpensive simple vents to function properly. As with all vents be sure the vent hose is free of line sags so that oil doesn't pool up and impede the venting process.
While you radiator cooling system is completely sealed, an expansion tank will help your car run cooler and ensure you are getting the most from your cooling system. Installation is simple. A ¼” NPT is recommended for an air line bleed. A ½” line is connects to your water pump. The 1/8” fitting allows for venting when your cap pressure is overcome and can be routed to a visible place such as the windshield to alert your driver to a heating problem. The reserve tank gives you the extra capacity as the car reaches the maximum safe water temperature. Routing the vent hose to the windshield gives the driver early warning allowing you the opportunity to identify and repair cooling system issues before they take you out of the race.
Roll bar or panel mounting of reserve tanks works on nearly any car cooling system. Remote vent tanks often include a billet cap filler neck for added security and durability.
Venting your fluid systems properly will add to the longevity of your drive train and help you to avoid embarrassing oil downs.. The tale tell strip of leaking fluid follows you to your pit area for all to see and with simple common sense vent installation you can keep your fluids where they belong.
Go Forward – Move Ahead
Jeff Butcher
8/01/10
