@GCecchetto
Can you link/comment more about this?
Thanks.
I'm planning to do a detailed write on this, but I'll give you the abbreviated version here. One of the main causes of HEUI pump failures in 3126 and C7 engines is the oil cooler/oil filter housing. The main issue is that the oil cooler gasket surface that the oil filter housing seals against isn't flat. In the case of my oil cooler, vertically across the gasket mating surface, it was out by over 30 thousandths in about 4.5 inches. In my case, being a 2008 C7, the new style metal gaskets were installed, but there is no way they can correctly seal when the surface they are sealing against is that far out. Older engines had fiber gaskets that would literally blow out. The result of being dirty oil bypassing to the clean oil side, and that oil goes straight to the HEUI pump. This is a significant cause of low mileage HEUI pump failures.
Speaking with Josh, who does the Adept Ape youtube channel, this is a chronic problem. He told me has had to order 3 new oil coolers to get one that was acceptable to install. CAT is aware of this problem and have updated the oil filter housing, the gaskets, and developed a HEUI pump prefilter to filter and unfiltered oil bypassing the oil filter before it enters the HEUI pump.
In installed the latest design oil filter housing, with the new updated gaskets, and I also replaced the two check valves and associated springs, O-rings, and plugs in the oil filter housing. Rather spending $1000 on a new oil cooler that wasn't likely to be flat either, I took my oil cooler to a lapper and had it lapped to an extremely precise lever of flatness for $200. My HEUI, at 9500 miles, was already spitting out metal, so I replaced the HEUI pump. I also installed the new style injectors that have screen on them. Next was CAT's HEUI prefilter to catch anything damaging before it makes it into the HEUI pump, and then the IFS filter kit that filters the oil coming out of the HEUI pump before it goes into the head. That way if the HEUI pump fails, it can't destroy the injectors.
A point of note, the compressor that CAT specs on a C7 are smaller that the compressors on our trucks. Because of the size of the compressors on our trucks, you can't install/replace the filter in CAT's prefilter kit without removing the compressor. You need to remove the compressor anyway, for the first install due to where the HEUI pump oil supply line bolts to the block, so you can install the filter at that time before installing the compressor, but once the compressor is in place, you cannot service that filter without removing the compressor. That didn't work for me, so I relocated that filter as you see below.
I also included a photos showing how I mounted the IFS filter. The max pressure in the line coming out of the HEUI pump is around 4800 psi, so I wanted those line as short as possible and I didn't want them bridging the gap from engine to frame where there is the most differential movement.
I would urge anyone with a 3126 or C7 to be proactive and pull you injection actuation pressure sensor and stick a flexy pick up magnet into the HEUI oil galley and see if there is metal on it. if there is, you're driving a ticking timebomb.
The CAT documents are attached below.
This is how I reconfigured the CAT HEUI prefilter.
These two images show the IFS HEUI post filter mounting.
And the whole thing buttoned back up.
