Difficulties Installing the Fleetguard CV51106 Crankcase Ventilation Kit

[spike45]

On several posts I have replied that Fleetguard makes crankcase oil/fumes separator, CV51106. It is a very good product but in the matter of installing it on an ISC or ISL the difficulty is the location on the engine of the existing crankcase fumes disposal / oil separator. Early C8.3 engines had the fumes tube mounted on the valve cover, a good place for it. For whatever reason, Cummins moved it to an area behind the lube oil filter on the right side of the block. This lower location is positioned in an area that has more oil splash inside the block thus making the separation of oil with the Cummins separator much less successful. Our OCV could improve that except for the existing vent tube mount location prevents much success with our kit.

Picture 0090 shows the existing fumes tube from the Cummins ISL separator mounted behind the oil filter head.
Picture 0099 shows the OCV separator oil return hose on the left and the fumes/oil line coming from the existing on-engine separator.
Picture 0108 shows the problem. The 90 degree elbow installed per instructions. That elbow becomes a trap that allows condensed liquid oil to collect at the elbow. Especially in cold weather this could become sufficient to the crankcase blowby fumes from reaching the OCV housing. This could result in increased crankcase pressure which could cause front and rear crankshaft main seals to leak. If they have to be replaced, the rear main is replaced by removing the engine! The front main is easier but still very expensive to fix.

Because of this I DO NOT recommend installation of the Fleetguard OCV or any other that utilizes the existing connection. It is better to replace the existing polyethylene hose with a black rubber hose of some length. At the end of that hose install the catch bottle with the vent holes. Make sure that bottle is large enough. With the high HP ratings of some ISL engines the blowby can become significant but still be acceptable. Using a catch bottle with insufficient vent holes may result in the bottle being blown off.
I apologize for having mentioned this product for this engine. It works very well for ISB, ISM and ISX. Some ISB engines already employ the catch bottle technology in a Cummins design. Stay with that if you have it. Just remember to dump the bottle.