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I definitely will not be running the Racor drain back into sump.
If I were you, i wouldn't either... I'm not done yet with the brainstorm on this for my truck... I like the idea of a flow through catch can to collect it and get rid of it the best...
was going to do a hose to dc vacuum motor ...but it looks like the smog motor does not operate in pass thru...so basically the exit is closed if the motor is off....exploring other options and revisiting some
heres a write up from another forum for a CCV filter I bought but never installed....I was concerned that I would be introducing pressure ...but according to the below...the filter introduces vacuum over most of the 6.7's rpm range. there are 3 different filter densities and I dont know which filter density was used for the test. the filter I have includes a by-pass . It would be good I think if I can convert this to steel media like a catch can.
A very good write up testing a Racor Unit by ElkChaser from a while back.
CCV Mods/RacorCCV4500/Crankcase Pressures/Test Results
#1705314 - 03/16/04 09:30 AM
Most of us know why the CCV crank case vent needs to be modified, for those that don’t know it is in an effort to reduce the oil vapor from getting into the turbo and intercooler where it condenses and is usually only visible at the intercooler tube boots.
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RACOR CCV4500 TESTING
Many thanks go to “dmftoy1” for graciously taking the time and money to remove the Racor CCV4500 off his truck and send it to me for the tests on the Racor. Thanks again Dave!
RACOR CCV4500 CONSTRUCTION
First I will attempt to describe how the Racor 4500 is built. The unit consists of a canister style filter container with an inlet and outlet manifold or head. There is a rubber diaphragm inside of the head with springs both, in between it and the top of the head and between it and the filter socket (top and bottom of the diaphragm). This diaphragm also seals off, from the dirty side (high pressure side), several openings or slots located around the edges of the diaphragm inside the head with a rubber fold that is an integral part of the diaphragm.
The slots appear to be designed to allow airflow to bypass the filter as the folds of the diaphragm are lifted or pushed out of the way. Air can flow from the dirty side (high pressure side) to the clean side (low pressure side). High pressure from the crankcase would cause the diaphragm to move upward against the spring causing the filter minder to push upwards as well as raising the rubber fold of the diaphragm opening the bypass openings or slots. The diaphragm can also move downward against the bottom spring, it appears that it will move down under excessive vacuum (suction) from the turbo inlet. The action of the diaphragm lowering effectively lowers the airflow through the filter or can completely seal off the filter if it was to move down far enough, it also seals the slots in the head even more effectively by pulling the rubber fold down well past the bypass slots.
TESTING THE RACOR CCV4500
All of the following tests were performed with the stock air box, Napa gold air filter, stock inlet tubes on the turbo, programmed with the Superchips 1705 to the Tow Safe mode (60HP) and straight piped with stock exhaust pipes (No Muffler).
I installed the Racor 4500 using a total of 6 foot 4 inches of ¾ inch ID hose. A new Racor filter part number CCV55248-08 was utilized for all of these tests. A 4 inch hose with a 90 degree radius was fitted directly to the crankcase vent connection on the valve cover. On this was inserted a ¾ inch barbed nylon T fitting where I reduced the T fitting size on the bottom by gluing in an barbed nylon reducing adapter. I then connected about 4 feet of ¼ inch pneumatic tubing through the firewall and into the cab and connected it to a Magnehelic Gauge that reads 0 to 1 inch of water column. I then ran from the T fitting to the Racor 4500 inlet with about a 1 foot of the ¾ hose and then ran the remainder of the ¾ inch hose from the outlet of the Racor 4500 to the turbo inlet as would be expected under any normal installation.
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Racor CCV4500 - Static Test (parked and not in gear) with new filter
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The following are the readings taken from that first test.
Interesting thing to note here was that I removed the filter minder cap and plug (indicator) and placed a simple ball point pen in it’s place. The pen never moved up or down throughout all the simulations even under high RPM spikes. If it did move it was only very slight and hardly noticeable.
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Racor 4500 CCV – Simulated Used Filter – Static Tests
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The same installation as above, to simulate a clogged filter I taped paper to the outside of the entire filter. The idea was that the pressure from the crankcase coming from the inside of the filter would push the paper off the filter allowing only a minimal airflow through the filter.
Interesting thing to note here was that the filter minder never moved even under a high RPM spikes.
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Racor 4500 CCV – Normal Operating Conditions (Driving)
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Driving the truck as I normally would and with a new Racor filter installed. The idea here was both to see how unit performed overall as well as how the unit’s performance changed as the filter saturated with oil. Because the diesel engine’s output horse power is not at all relative to the actual engine RPM’s the measurements taken while driving are not a good bench standard so I planned on performing the static tests (parked and not in gear) several times to get an idea of what was going on.
First I will attempt to describe the performance of the Racor CCV4500 while driving.
For the most part unless you are getting into the gas, generally below 70 MPH the crankcase was running at a positive pressure (+0.2 to +0.8). It is interesting to note that for the first 200 miles when accelerating up a hill the unit pulled a negative (-0.1 to -0.3) and it also pulled a negative coasting down the hill. After about 200 miles it never really went into a negative again unless getting into the gas.
While driving up a moderate hill at 60 MPH and not really having to accelerate hard to make the hill the pressure was at a positive as high as +0.8”WC and fluctuated constantly but never went below +0.2”WC. This was true right from the start and performed the same way on flat land as well.
At about 300 miles into the tests, while passing on a grade and spooling the turbo. It definitely brought the crankcase into a negative (-0.1 to -0.2), but as soon as the transmission shifted back into the higher gear it shot right back up into the positive (+0.2 to +0.6).
While driving at below 55 or in city driving the crankcase was at a positive pressure (+0.2 to +0.8) unless I asked for some horses like when leaving a stop light, as soon as I let off, or as soon as the transmission shifted or I went into normal acceleration to maintain a speed the pressure went back to positive.
Progressively over time as the filter saturated with oil and debris the pressures crept higher and higher, I have to admit it was performing pretty well in the beginning but as time wore on the pressures kept rising. Near the end of my tests at speeds of 70 MPH and accelerating only to maintain that speed the crankcase pressure was showing slightly positive (0 to +0.2). While at the very beginning and continuing through the first 200 miles it was showing a slight vacuum (0 to -0.2) and this was the only time I saw a maintained vacuum under normal driving conditions.
The following are static test pressure readings after driving with filter installed.
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Racor CCV4500 – Static Tests After Driving
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Miles / RPM / Reading
0 / 700 / +0.3 to +0.4 Positive Pressure
0 / 1100 / 0.0 Neutral
0 / 1500 / -0.32 Negative Vacuum
0 / 1750 / -0.60 Negative Vacuum
First Leg
(Tested upon arrival)
Miles / RPM / Reading
20 / 700 / +0.3 to +0.4 Positive Pressure
20 / 1100 / 0.08 Positive Pressure
20 / 1500 / -0.2 Negative Vacuum
Second Leg
(Allowing the truck to sit for 4 hours and then performing this test)
Miles / RPM / Reading
164 / 700 / +0.4 to +0.5 Positive Pressure
164 / 1100 / +0.24 Positive Pressure
164 / 1500 / -0.1 Negative Vacuum
Third Leg
(Allowing the truck to sit overnight about 12 hours and then performing this test)
Miles / RPM / Reading
314 / 700 / +0.5 Positive Pressure
314 / 1100 / +0.26 Positive Pressure
314 / 1500 / -0.1 Negative Vacuum
Fourth Leg
(Tested upon arrival)
360 / 700 / +0.5 to +0.6 Positive Pressure
360 / 1100 / +0.28 Positive Pressure
360 / 1500 / -0.02 Negative Vacuum
Upon completion of these tests the filter still appeared to be clean and new, the canister had just a trace of oil and the outlet or suction hose had no oil visible and was dry to the touch.
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Racor 4500 CCV – Filter Minder / Bypass Test
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Removing the Racor CCV4500 from the truck, I capped off the suction side of the unit. I then installed the reduced T fitting from the above installation and utilizing a different Magnehelic gauge that measures a range of 0 to 3 inches water column I pressurized the unit to determine when the filter minder would raise up (consequently the diaphragm as well).
The filter minder fully extends at about 0.5 Inches of water column, again this is with the suction side capped off, while in operation I had seen positive pressures in excess of +0.8 inches of water column and the filter minder never moved. If it had the indicator plug would have stayed in that position as that is how it is designed. I can only assume that the pressures inside the head of the unit is much lower (due to the vacuum created by the turbo) than those measured just after the crankcase vent connection.
In an effort to show the relationship between the Racor CCV4500 and both the stock crankcase vent and the open crank case vent I went ahead and performed tests on these as well utilizing the same 6 feet of ¾ inch hose.
The stock vent occasional will go into a light positive pressure, at idle and sometimes while coasting as well as during lower power (almost lugging) conditions. Really getting into it cause a vacuum well in excess of the gauges capabilities to read beyond the -1.0
Open Crankcase Vent
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Open CCV – Static Test (with 5’ 4” of ¾ hose)
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RPM / Reading
700 / / +0.04 to +0.1 Positive Pressure
1000 / +0.1 Positive Pressure
1500 / +0.12 Positive Pressure
For the most part the crankcase runs at +0.2 pressure while in gear and driving at all speeds, spikes as high as +0.4 with hard acceleration were noted as well as some instances of the pressure actually going into a negative. I suspect that the air flow across the end of the hose was creating some pressure fluctuations such as the negative readings.
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CCV Filters - Home Made Variations
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I built and installed several variations of custom filter setups using PVC pipe, steel wool, scotchbrite pads and even copper pot scrubbers in an effort to come up with a coalescing filter. I even tried an empty PVC pipe arraignment. With any of these filters installed or just the PVC pipe empty I found that the crankcase pressure actually increases in proportion to the range of the RPMs. At idle the pressure range had increased up to +0.05 to +0.15 and while under acceleration the pressure increased up to +0.8 in wc and above.
Again I am not an expert, just thought I’d share what I have found while testing all of these set ups out. After doing these tests I am still convinced that an open vent is the only way to go. However in the near future I plan on testing the exhaust bung mod and see what happens with that. (Come to your own conclusions)
From what I understand (From an international mechanic with 16 years under his belt) International/Navistar was using the same set up as the Ford PSD on their commercial engines up until 1996 when they changed their design and went back to an open vent with a draft tube. I do not know if they have tested any filters or exhaust bungs but I do find it interesting that they are still building them with an open vent to this day.
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I had taken several pictures of the dash cluster with the Magnehelic held up reading positive pressures while driving down the road with the Racor CCV4500 installed. I also took some of the Racor installation. In the next few days if anyone wants to see them I can get them posted up.
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**Again many thanks to “dmftoy1” for loaning me his Racor for these tests.
John
I think Stealth might sell the one that NCHornet made popular Sam.
Last edited by speakerfritz; Jan 20, 2026 at 05:09 PM.
Fritz, I skimmed the text wall but didn't read it, that said what loads and boost levels were the engine under during the tests ?
I ask because keeping a vacuum on the crank case (cc) with little to no boost is an easy ask but during extended hi load/hi boost situations is where the task gets logarithmically more difficult to achieve.
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