What issues besides the secondary pump going out do people have?
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I am not bashing on the pumps. They work great and do exactly as advertised... I just would not recommend them on a Daily driver that see 15-30k per year.
I also have very little experience with the kits that use a Stock HPOP as the secondary pump. The only guy I knew that was using it said it had issues with starving the pressure from the low pressure oil pump. I would imagine the stock HPOPs would have much better longevity.
Pumps seem to leak/blow out around 15k + or - 5k
I have seen them blow the front seal, leak in between the cases, and totally grenade themselves and send oil through the IPR screen. Most guys I know that run them for extended miles will keep extra IPR screens and change them out every oil change.
It takes a little while to get the tuning dialed in for some guys. All out race tunes with big injectors seem to have less issues because they use up all the oil pretty easily. Some guys have issues with HPO spikes that blow open the IPR valve and surging the HPO system. That can easily be remedied by an experienced tuner.
If you are like me... and always working on the truck, changing turbos, changing injectors, etc... then taking the kit on and off SUCKS, it is not hard at all but adds time to simple tasks. After a while the lines can develop leaks, just like any hydraulic system. But taking them on/off makes that much more likely.
Once again... I am not anti-twin HPOP. I have one sitting right here ready to go on my race truck. I just regret having it on my daily driver. I put about 30k on my truck per year. I went through 3 pumps and then all the lines started leaking (from being taken on/off all the time). It was a nightmare for me.