ISX and Bypass Oil Filter Systems

[Mrkentee]

(07-22-2025 )45RVLSX Wrote:  Rawze, quick question-my diesel tech was concerned about adding gear oil due to the sulfur in gear oil causing a corrosion issue. What are your thoughts about the sulfur being an issue. Full disclosure this is an ISX in a Motorhome, not an over the road truck, so maybe that makes a difference-less miles, longer time duration between changes-generally 1 per year based on typical 12-15,000 miles( I get about 7 mpg-maybe a tune would help both issues, but not sure there's a payback at my miles/yr). I'd like to do the best thing for the engine as I don't plan on replacing this motorhome in my lifetime-I'm 70 so this is my last one. My LSX typically runs around 207 degrees going down the road, does this seem ok? My LSX is a pre def unit with EGR, does a bypass make sense for this engine? Thanks for this forum, who said you can't teach an old dog new tricks!!

I’ve heard it said that every diesel engine should have a bypass filter, and I agree. But I will say the Fleetguard LF14000 NN oil filter (not sure if that works on your engine) has a built in bypass system they claim. I use both on my ISX, and my oil stays clean.

[ne14jpn]

Tech question - Can I use "Port Location #1" for bypass filter supply pressure feed line referenced from the Engine Oil Cooler picture in Post #9 of this thread?

In Post #15, Rawze mention the ability to use Port #3 or 5 for oil supply line. He had heat issues from the turbo with #3 and ended up using #5 which seems to be the most common port for supply. My issue is clearance to #5 from the turbo outlet charge air tube in my application. The chassis is a 2005 Volvo VNL 780 with the CM870 ISX and Eaton 13 speed. There is not enough room to install a -8 fitting of any sort on my truck in that location.

Port 1 is wide open so please let me know if that will provide a supply feed to the bypass filter? Thanks!

[hhow55]

. Locate a pressurized port such as a galley port, pressure sender
port, etc. AMSOIL recommends adapting off the pressurized oil
port using a fitting(s) to accept the 1/2” JIC female hose end
provided in this system. Purchase of adapters for your specific
application is required.Maybe this helps?

[ne14jpn]

(02-25-2026 )ne14jpn Wrote:  Tech question - Can I use "Port Location #1" for bypass filter supply pressure feed line referenced from the Engine Oil Cooler picture in Post #9 of this thread?

In Post #15, Rawze mention the ability to use Port #3 or 5 for oil supply line. He had heat issues from the turbo with #3 and ended up using #5 which seems to be the most common port for supply. My issue is clearance to #5 from the turbo outlet charge air tube in my application. The chassis is a 2005 Volvo VNL 780 with the CM870 ISX and Eaton 13 speed. There is not enough room to install a -8 fitting of any sort on my truck in that location.

Port 1 is wide open so please let me know if that will provide a supply feed to the bypass filter? Thanks!

Following up with an update - Port 1 is NOT oil! Found this out the hard way when coolant came rushing out. Hope this saves someone the trouble of learning the hard way too. Those plugs can be extremely difficult to get out. I ended up using an air hammer to break them loose after liberal amounts of heat and penetrating oil. They're 6mm hexes and very easy to strip out if you aren't careful.

I was able to get both metric o-ring to -8 AN adapters installed and will hopefully be able to finish up mounting the filter housing and plumbing this weekend. Note on the larger metric fitting that is return and installs in the block above the oil pan: be mindful of the hex on the fitting hitting the block as you tighten it up. I felt it touching as it was getting tight. I removed, took it to the lathe to chamfer the edge and reinstalled with no issue. Doesn't take much to make it happy.

I ended up using Port #3 with a straight fitting and planning to use a 90* end on the hose to get it away from the turbo heat. @Rawze - when you had issues with heat was the fitting a straight? I could see how that would be very close to the housing.

[Rawze]

(03-05-2026 )ne14jpn Wrote:  ...
I ended up using Port #3 with a straight fitting and planning to use a 90* end on the hose to get it away from the turbo heat. @Rawze - when you had issues with heat was the fitting a straight? I could see how that would be very close to the housing.

It was a straight fitting. I did solve some of the heat issue by putting on a double layer of exhaust heat protection wrap around the hoses where it ran nearest to the turbo.